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THE

CAMBRIDGE NATURAL HISTORY

EDITED BY

S. F. HARMER, M.A., Fellow of King’s College, Cambridge ; Super-
_ intendent of the University Museum of Zoology

AND

A. E. SHIPLEY, M.A., Fellow of Christ’s College, Cambridge ;
University Lecturer on the’ Morphology of Invertebrates

VOLUME V

~PERIPATUS -
: By ADAM SEDGWICK, M.A., F.R.S., Fellow and Lecturer
of Trinity College, Cambridge

MYRIAPODS

By F. G. SINCLAIR, M.A., Trinity College, Cambridge

INSECTS

‘PART I. Introduction, Aptera, Orthoptera, Neuroptera, and a portion of
Hymenoptera (Sessiliventres and Parasitica)

By DAVID SHARP, M.A. (Cantab.), M.B. (Edinb.), F.R.S.

BIOL. DEPT.
UM. TORON 10.

per eta: ar ©

“it GF ZOOLOGY

London
MACMILLAN AND CO., Lim1tTEep

NEW YORK: THE MACMILLAN COMPANY

1901

All rights reserved

* Creavit in ccelo Angelos, in terra vermiculos; non superior in illis,
non inferior in istis. Sicut enim nulla manus Angelum,.ita nulla
posset creare vermiculum.”—SainT AvuGUSTINE, Liber soliloquiorum
animae ad Dewm, Caput IX. .

First Edition 1895. Reprinted with corrections 1901.

CONTENTS

SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BooK

PERIPATUS

CHAPTER I

INTRODUCTION— EXTERNAL FEATURES— HABits —BREEDING— ANATOMY—
_ ALIMENTARY CanAaL—NeErvovus SysteMm—THE Bopy WaLi—TuE Tra-
CHEAL SysTEM—THE MuscuLaR SystEM—THE VASCULAR SYSTEM—THE
Bopy Caviry— NEpuHRIDIA — GENERATIVE ORGANS — DEVELOPMENT—
SYNOPSIS OF THE SPECIES—SUMMARY OF DISTRIBUTION .

MYRIAPODA

CHAPTER II

InrRoDUCTION — HABITs — CLASSIFICATION — STRUCTURE — CHILOGNATHA—
CHILOPODA — SCHIZOTARSIA — SYMPHYLA—PAUROPODA—EMBRYOLOGY—
PALAEONTOLOGY . e.5 83

. . -* . . . . 7

peat ioe INSECTA

CHAPTER Ill

CHARACTERISTIC FraturES oF Insect Lire—SocrAt INsects—DEFINITION
OF THE CLAss INSECTA—COMPOSITION OF INSECT SKELETON—NUMBER OF
SEGMENTS—NATURE OF SCLERITES—HEAD—APPENDAGES OF THE Mout
—_Fyrs—THorax—ENTOTHORAX—LEGS— WINGS — ABDOMEN OR HIND
Bopy—SpirracLEsS—SYSTEMATIC ORIENTATION ; : ,

PAGE

83

if

vl CONTENTS

CHAPTER IV

PAGE
ARRANGEMENT OF INTERNAL ORGANS—MuvuscLES—NERVous SysTEM—GANG-
LIONIC CHAIN—BRAIN—SENSE - ORGANS—ALIMENTARY CANAL —MAL-
PIGHIAN ‘TuBES— RESPIRATION— TRACHEAL SysTEM— FUNCTION OF
RESPIRATION—BLoop oR BLOOD-CHYLE—DORSAL VESSEL OR HEART—
Fat-BODY—OVARIES—TESTES—PARTHENOGENESIS—GLANDS . d a

CHAPTER V

DEVELOPMENT

EMBRYOLOGY — Ecos — MicropyLEs — FoRMATION OF EMBRYO — VENTRAL
PLATE—EcCTODERM AND ENDODERM—SEGMENTATION—LATER STAGES—
DrtrREcT OBSERVATION OF EMBRYO—METAMORPHOSIS—COMPLETE AND
INCOMPLETE — INSTAR — HYPERMETAMORPHOSIS — METAMORPHOSIS OF
INTERNAL ORGANS—INTEGUMENT—METAMORPHOSIS OF BLOWFLY—HIs-
TOLYSIS—IMAGINAL Discs—PHYSIOLOGY OF METAMORPHOSIS—Ecpysis. 148

CHAPTER VI

CLASSIFICATION — THE NINE OrpERS oF INsEcTS— THEIR CHARACTERS—
PACKARD’s ARRANGEMENT—BRAUER’S CLASSIFICATION—CLASSIFICATIONS
BASED ON METAMORPHOSIS — SUPER-ORDERS—THE SUBDIVISIONS OF
ORDERS . tag ; ‘ : : : ; ; : . EDN 5 bs

CHAPTER VII

THE OrDER APTERA—DEFINITION—CHIEF CHARACTERSSTICS—THYSANURA—
CAMPODEA—J APYX — MACHILIS — LEPISMA — DIVERSITY OF INTERNAL e
STRUCTURE IN THYSANURA — EcTOTROPHI AND ENTOTROPHI — COLLEM-
BOLA—LIPURIDAE—PoODURIDAE — SMYNTHURIDAE—THE SprRING — THE
VENTRAL TuBE—ABDOMINAL APPENDAGES—PROSTEMMATIC ORGAN—

TRACHEAL SysTEM— ANURIDA MARITIMA—COLLEMBOLA ON SNOW—
Lire-HisTor1ks OF COLLEMBOLA—FossIL APTERA—APTERYGOGENEA—
ANTIQUITY AND DISTRIBUTION OF CAMPODEA . : ‘ ‘ 4 . 180

CHAPTER VIII

ORTHOPTERA—FORFICULIDAE, EARWIGS—-HEMIMERIDAE r \ ; . 198

CONTENTS Vii
CHAPTER IX
‘ PAGE
ORTHOPTERA CONTINUED—BLATTIDAE, COCKROACHES ‘ 220
CHAPTER X
ORTHOPTERA CONTINUED—-MANTIDAE, SOOTHSAYERS - 242
CHAPTER x4
ORTHOPTERA CONTINUED—PHASMIDAE, WALKING-LEAVEs, SticK-INSECTSs 260
CHAPTER XII
ORTHOPTERA CONTINUED—ACRIDIIDAE, Locusts, GRASSHOPPERS . 279
CHAPTER. XIIt
ORTHOPTERA CONTINUED—LOCUSTIDAE, GREEN GRASSHOPPERS, KATYDIDS 311
CHAPTER XIV
ORTHOPTERA CONTINUED—GRYLLIDAE, CRICKETS . ‘ ‘ - 330
CHAPTER XV
NEUROPTERA—M ALLOPHAGA—EMBIIDAE 341
CHAPTER XVI
NEUROPTERA CONTINUED—TERMITIDAE, TERMITES OR WHITE ANTS E 356

vill ) CONTENTS

CHAPTER XVII

PAGE
NEvROPTERA CconTINUED—PsocIDAE (Book-LicE AND. DEATH-W ATCHES)—THE
First FAMILY oF AMPHIBIOUS NEUROPTERA (PERLIDAE, STONE-FLIES) . 390

CHAPTER XVIII

AMPHIBIOUS NEUROPTERA CONTINUED—ODONATA, DRAGON-FLIES : . 409

CHAPTER XIX

AMPHIBIOUS NEUROPTERA CONTINUED—EPHEMERIDAE, MAY-FLIES ; . 429

CHAPTER XX
NEUROPTERA PLANIPENNIA—SIALIDAE, ALDER-F LIES, SNAKE-FLIES—PANOR-
PIDAE, SCORPION-FLIES—HEMEROBIIDAE, ANT-Lions, LACEWINGS, ETc. 444
CHAPTER XXI
NEUROPTERA CONTINUED —TRICHOPTERA, THE PHRYGANEIDAE OR CADDIS-
Prins. 3 j ; : . : ‘ : ; ’ i wae - 473
CHAPTER XXII
. HyMENOPTERA—HYMENOPTERA SESSILIVENTRES—CEPHIDAE—ORYsSSIDAE—
SIRICIDAE—TENTHREDINIDAE OR SAWFLIES . * “ ‘ . 487
CHAPTER XXIII

HYMENOPTERA PETIOLATA—PARASITIC HYMENOPTERA—CYNIPIDAE OR GALL-

FLIES— PROCTOTRYPIDAE — CHALCIDIDAE — ICHNEUMONIDAE— BRACON-

‘ IDAE — STEPHANIDAE —-- MECALYRIDAE — EVANIIDAE — PELECINIDAE —
TRIGONALIDAE : ; ; ‘ : ; ; A ‘ : . 519

INDEX . : 2 ‘ ‘ ? < . ; ; . : ; Ser

SCHEME: OF THE CLASSIFICATION (RECENT FORMS)
ADOPTED IN THIS BOOK

PROTOTRACHEATA
Peripatus (p. 1)

MYRIAPODA

Order. » Family.

POLYXENIDAE (p. 43).
GLOMERIDAE (p. 48).
SPHAEROTHERIIDAE (p. 43).

CHILOGNATHA (=DIPLOPODA) , 3UUIDAE (p. 43).

~,

BLANJULIDAE (p. 44).
CHORDEUMIDAE (p. 44).
POLYDESMIDAE (p. 44).
POLYZONIIDAE (p. 44).

wT

LITHOBIIDAE (p. 45).
SCOLOPENDRIDAE (p. 45).
ga lala NoroPHILIDAE (p. 45).
GEOPHILIDAE (p. 46).
SCHIZOTARSIA . ; ; . CERMATIIDAE (=ScUTIGERIDAE) (p. 46).
SYMPHYLA. ; , ; . SCOLOPENDRELLIDAE (p. 46),
PAUROPODA .. ‘ P . PAUROPIDAE (p. 47).
INSECTA
Onder Biriaon, Secs) Tea
r [ CAMPODEIDAE (p. 188).
Thysanura JAPYGIDAE (p. 184).
(p. 182) MACHILIDAE (p. 184).
APTERA (p. 180) . i LEPISMIDAE (p. 185).

PopuRIDAE (p. 190).
SMYNTHURIDAE (p. 191).

Collembola

LIPURIDAE (p. 190).
(p. 189)

SCHEME OF INSECTA

Order.

va

ORTHOPTERA |
(p. 198)

L

Division, Series,
or Sub-Order.

Orthoptera
cursoria

Orthoptera

saltatoria )

(Continued on the newt page.)

Family.

BLATTIDAE
(p. 220)

2
MANTIDAE
(p. 242)

PHASMIDAE
(p. 260)

ACRIDIIDAE
(p. 279)

LOcUSTIDAE
(p. 311)

~ | Hetro

Tribe or Sub-Family.

( FORFICULIDAE (p. 202).
HEMIMERIDAE (p. 217).

r Ectobiides.
Phyllodromiides.
Nyctiborides.
Epilamprides.
Periplanetides,
} Panchlorides.
Blaberides.
Corydiides.
Oxyhaloides.
Perisphaeriides,
Panesthiides.
? Geoscapheusides.

Orthoderides.

Amorphoscelides.
Mantides.

| Harpagides.
| Vatides.
Empusides.

‘ Lonchodides.
Bacunculides.
Bacteriides.
Necroscides.
Clitumnides.
Acrophyllides.

; Cladomorphides.
Anisomorphides.

. Phasmides.
Aschipasmides.
Bacillides.

. Phylliides.

Tettigides.
Pneumorides.
Mastacides.
Proscopiides.
Tryxalides.
Oedipodides.
Pyrgomorphides.
: Pamphagides.
Acridiides.

( Phaneropterides.
Meconemides.
Meco) odides.
Prochilides.
Pseudophyllides.
Conocephalides.
Tympanophorides.
- Sagides.
lLocustides.
Decticides.
det ge
Ephippigerides.
3 aides,
Gryllacrides.
_ Stenopelmatides.

:
(
¢

SCHEME OF INSECTA xi
Order. ps drat me ae Family. Tribe or Sub-Family. Group.
Tridactylides,
Gryllotalpides.
oRTHOPTERA | Orthoptera | Guvnuman me
(continued) (continued) J (p. 380) Oecanthides.
Trigonidiides.
\ Eneopterides.
(Mallophaga \ Leiotheides.
(p. 345) Philopterides.
EMBIIDAE (p. 351).
Pseudo-
TERMITIDAE (p. 356).
endo tora | Tzmarti (p. 390).
; PERLIDAE (p. 398). é Fe
omphinae,
Cordulegasterinae.
Anisopterides Aeschninae.
areca cent : ODONATA Corduliinae.
“ \ . 409) Libellulinae.
tica (P wat:
Zygopterides ror eam
\ EPHEMERIDAE (p. 429).
( SIALIDAE Sialides.
(p. 444) { Raphidiides.
eeeny Bs PANORPIDAE (p. mes eae tease
: yrmeleonides (p. 45
Ascalaphides f Holophthalmi.
(p. 459) \ Schizophthalmi.
Neuroptera Nemopterides (p. 462),
planipennia HEMEROBIDAE | Mantispides (p. op Oe
(p. 453) ,
P Hemerobiides Nymphidina.
(p. 465) Osmylina.
A Hemerobiina.
Chrysopides (p. 469).
L ‘ Coniopterygides (p. 471).
Phryganeides (p. 480).
Limnophilides (p. 481).
; _| Sericostomatides (p. 482).
Trichoptera unyeraies Leptocerides (p. 482).
(p- ) Hydropsychides (p. 482).
Rhyacophilides (p. 483).
i \ Hydroptilides (p, 484).
( CEPHIDAE (p. 504),
apres i ORYSSIDAE (p. 506).
fonnk SSL!) SIRICIDAE (p. 507).
in TENTHREDINIDAE (p. 510).
- CYNIPIDAE (p. 523).
PROCTOTRYPIDAE (p. 538).
HYMENOPTERA : CHALCIDIDAE (p. ate .
(p. 487) ICHNEUMONIDAE (p. 551).
sag ae ) Braconipag (p. 558).
pane “f SrEPHANIDAR (p. 561).
ata (part) MEGALYRIDAE (p. 562).
EVANIIDAE (p. 562).
PELECINIDAE (p. 563).

L
(To be continued in Vol. VI.)

\ TRIGONALIDAE (p. 564).

PERIPA’

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_ SEDGWICK, M.. FR R.
v of Trinity College,

,

CHAPTER I
PERIPATUS

INTRODUCTION —- EXTERNAL FEATURES —— HABITS ——- BREEDING —
ANATOMY — ALIMENTARY CANAL—-NERVOUS SYSTEM—THE
BODY WALL— THE TRACHEAL SYSTEM — THE MUSCULAR
SYSTEM -~— THE VASCULAR SYSTEM——THE BODY CAVITY —
NEPHRIDIA——GENERATIVE ORGANS——DEVELOPMENT——SYNOPSIS
OF THE SPECIES—-SUMMARY OF DISTRIBUTION.

THE genus Peripatus was established in 1826 by Guilding}! who
first obtained specimens of it from St. Vincent in the Antilles.
He regarded it as a Moiluse, being no doubt deceived by the
slug-like appearance given by the antennae. Specimens were
subsequently obtained from other parts of the Neotropical region
and from South Africa and Australia, and the animal was vari-
ously assigned by the zoologists of the day to the Annelida
and Myriapoda. Its true place in the system, as a primitive
member of the group Arthropoda, was first established in 1874
by Moseley,? who discovered the tracheae. The genus has been
monographed by Sedgwick, who has also written an account of
the development of the Cape species.* A bibliography will be
found in Sedgwick’s Monograph.

1 L. Guilding, ‘‘ Mollusca caribbaecana: an Account of a New Genus of Mollusca,”

Zool. Journ. vol. ii. 1826, p. 443, pl. 14 ; reprinted in Isis, vol. xxi. 1828, p, 158, pl. ii.
2 H. N. Moseley, “On the Structure and Development of Peripatus capensis,” Phit.

Trans. clxiv. pls. lxxii.-lxxv. pp. 757-782 ; and Proc. KR. S, xxii. pp. 344-350, 1874.
- 3 A, Sedgwick, ‘‘A Monograph of the Genus Peripatus,” Quart. Journ. of Mie.
Science, vol. xxviii., and in Studies from the Morphological Laboratory of the Uni-
versity of Cambridge, vol. iv. Cf. also p. 23 n.

4 A. Sedgwick, ‘‘A Monograph of the Development of Peripatus capensis,”

Studies from the Morphological Laboratory of the University of Cambridge, vol. iv.

4. PERIPATUS CHAP.

There can be no doubt that Peripatus is an Arthropod, for it
possesses the following features, all characteristic of that group,
and all of first-class morphological importance: (1) The presence
of appendages modified as jaws; (2) the presence of paired lateral
ostia perforating the wall of the heart and putting its cavity in
communication with the pericardium; (3) the presence of a vas-
cular body cavity and pericardium (haemocoelic body cavity) ;
(4) absence of a perivisceral section of the coelom. Finally, the
tracheae, though not characteristic of all the classes of the
Arthropoda, are found nowhere outside that group, and constitute
a very important additional reason for uniting Peripatus with it.

Peripatus, though indubitably an Arthropod, differs in such
important respects from all the old-established Arthropod classes,
that a special class, equivalent in rank to the others, and called
Prototracheata, (Onychophora), has had to be created for it.
This unlikeness to other Arthropoda is mainly due to the Anne-
lidan attinities which it presents, but in part to the presence of
the following peculiar features: (1) The number and diffusion of
the tracheal apertures; (2) the restriction of the jaws to a single
pair; (3) the disposition of the generative organs; (4) the tex-
ture of the skin; and (5) the simplicity and similarity of all ae
segments of the body behind the head.

The Annelidan affinities are superficially indibagell in so
marked a manner by the thinness of the cuticle, the dermo-
muscular body wall, the hollow appendages, that, as already
stated, many of the earlier zoologists who examined Peripatus
placed it amongst the segmented worms; and the discovery that
there is some solid morphological basis for this determination
constitutes one of the most interesting points of the recent work
on the genus. The Annelidan features are: (1) The paired
‘nephridia in every segment of the body behind the first two
(Saenger, Balfour *) ; (2) the presence of cilia in the generative
tracts (Gaffron). It is true that neither of these features are
absolutely distinctive of the Annelida, but when taken in con-
junction with the Annelidan disposition of the chief systems of
organs, viz. the central nervous system, and the main vascular
trunk or heart, may be considered as indicating affinities in that

1 F. M. Balfour, ‘‘The Anatomy and Development of Peripatus capensis,” edited.
by Professor H. N. Moseley and A. Sedgwick, Quart. Journ. Mic. Sci. xxiii. pp.
213-259, pls. xiii.-xx, 1883.

I 4 EXTERNAL FEATURES Ss

direction. Peripatus, therefore, is zoologically of extreme interest
from the fact that, though in the main Arthropodan, it possesses
features which are possessed by no other Arthropod, and which
connect it to the group to which the Arthropoda are in the
general plan of their organisation most closely related. It must,
therefore, according to our present lights, be regarded as a very
primitive form; and this view of it is borne out by its extreme
isolation at the present day. ~Peripatus stands absolutely alone
as a kind of half-way animal between the Arthropoda and Anne-
lida. There is no gradation of structure within the genus; the
species are very limited in number, and in all of them the
peculiar features above mentioned are equally sharply marked.

Peripatus, though a lowly organised animal, and of remark-
able sluggishness, with but slight development of the higher
organs of sense, with eyes the only function of which is to enable
it to avoid the light—though related to those animals most re-
pulsive to the aesthetic sense of man, animals which crawl upon
their bellies and spit at, or poison, their prey—is yet, strange to
say, an animal of striking beauty. The exquisite sensitiveness
and constantly changing form of the antennae, the well-rounded
plump body, the eyes set like small diamonds on the side of the
head, the delicate feet, and, above all, the rich colouring and
velvety texture of the skin, all combine to give these animals an
aspect of quite exceptional beauty. Of all the species which I
have seen alive, the most beautiful are the dark green individuals
of Capensis, and the species which I have called Balfowri.
-These animals, so far as skin is concerned, are not surpassed in
the animal kingdom. I shall never forget my astonishment and
delight when on bearing away the bark of a rotten tree-stump
in the forest on Table Mountain, I first came upon one of these
animals in its natural haunts, or when Mr. Trimen showed me in
confinement at the South African Museum a fine fat, full-grown
female, accompanied by her large family of thirty or more just-
born but pretty young, some of which were luxuriously creeping
about on the beautiful skin of their mother’s back.

External Features.

The anterior part ofthe body may be called the head, though
it is not sharply marked off from the rest of the body (Fig. 1).
The head carries three pairs of appendages, a pair of simple eyes,

6 PERIPATUS | CHAP.

and a ventrally placed mouth. The body is elongated and
vermiform ; it bears a number of paired appendages, each termi-
nating in a pair of claws, and all exactly alike. The number
varies in the different species. The anus is always at the

posterior end of the body, and the generative opening is on the
ventral surface just in front of the anus; it may be between the
legs of the last pair (Fig. 2), or it may be behind them. There
is in most species a thin median white line extending the whole
length of the dorsal surface of the body, on each side of which

Pr

Fic. 2.—Ventral view of hind-end of Fic. 3.—Ventral view of the. head of P.

P, Novae-Zealandiae. (After Sedg- capensis. (After Sedgwick.) ant, An-
wick.) g, Generative opening; a, tennae ; or.p, oral papillae; FZ, first
anus. leg; 7, tongue.

the skin pigment is darker than elsewhere. The colour varies
considerably in the different species, and even in different indi-
viduals of the same species. The ventral surface is nearly always
flesh-coloured, while the dorsal surface has a darker colour. In the

i EXTERNAL FEATURES 7

South African species the colour of the dorsal surface varies from
a dark green graduating to a bluish gray, to a brown vary-
ing to a red orange. The colour of the Australasian species
varies in like manner, while that of the Neotropical species (S.
American and W. Indian) is less variable. The skin is thrown
into a number of transverse ridges, along which wart-like papillae
are placed. The papillae, which are found everywhere, are specially
developed on the dorsal surface, less so on the ventral. Each
papilla carries at its extremity a well-marked spine.

The appendages of the head are the antennae, the jaws and
the oral papillae.

The antennae, which are prolongations of the dorso-lateral
parts of the head, are ringed, and taper slightly till near their
termination, where they are slightly enlarged. The rings bear a
number of spines, and the free end of the antennae is covered by
a cap of spiniferous tissue like that of the rings.

The mouth is at the hinder end of a depression called the
buccal cavity, and is surrounded by an annular tumid lip, raised
into papilliform ridges and bearing a few spines (Fig. 3). Within
the buccal cavity are the two jaws. They are short, stump-like,
muscular structures, armed at their free extremities by a pair of
cutting blades or claws, and are placed one on each side of the
mouth. In the median line of the buccal cavity in front is
placed a thick muscular protuberance, which may be called
the tongue, though attached to
the dorsal instead of to the
ventral wall of the mouth (Fig.
3). The tongue bears a row of
small chitinous teeth. The jaw-
claws (Figs. 4 and 5), which re-
semble in all essential points
the claws borne by the feet, and ,
like these are thickenings of the P!% fle Jaw: Per ete
cuticle, are sickle-shaped. They — pensis. (After pensis. (After
have their convex edge directed B#") ap fo
forwards and their concave or cutting edge turned backwards.
The inner cutting plate (Fig. 4) usually bears a number of cutting
teeth. The jaws appear to be used for tearing the food, to which
the mouth adheres by means of the tumid suctorial lips. The
oral papillae are placed at the.sides of the head (Fig. 3). The

8 PERIPATUS CHAP.

ducts of the slime-glands open at their free end. They possess
two main rings of projecting tissue, and their extremities bear
papillae irregularly arranged.

The ambulatory appendages vary in number. There are
seventeen pairs in P. capensis and eighteen in P. Balfouri,
while in P. jamaicensis the number varies from twenty-nine to
forty-three pairs. They consist of two main divisions, which we
may call the leg and the foot (Figs. 6 and 7). The leg (7) has the
form of a truncated cone, the broad end of which is attached to
the ventro-lateral wall of the body, of which it is a prolonga-
tion. It is marked by a number of rings of papillae placed

Fic. 6.—Ventral view of last leg of a Fic. 7.—Leg of P. capensis seen from the
male P. capensis. (After Sedg- front. (After Sedgwick.) jf, Foot; Z, leg;
wick.) f, Foot; J, leg; p, spini- p, spiniferous pads.
ferous pads. The white papilla
on the proximal part of this leg is
characteristic of the male of this
species.

transversely to its long axis, the dorsal of which are pigmented

like the dorsal surface of the body, and the ventral like the

ventral surface. At the narrow distal end of the leg there are
on the ventral surface three spiniferous pads, each of which is

continued dorsally into a row of papillae. .

The foot is attached to the distal end of the leg. It is
slightly narrower at its attached extremity than at its free end.

It bears two sickle-shaped claws and a few papillae. The part

of the foot which carries the claws is especially retractile, and is

generally found more or less telescoped into the proximal part.

The legs of the fourth and fifth pairs differ from the others in

z ; HABITS 9

the fact that the proximal pad is broken up into three, a small
central and two larger lateral. The enlarged nephridia of these
legs open on the small central division.

_ The males are generally rather smaller and fewer in number —
than the females. In those species in which the number of legs
varies, the male has a smaller number of legs than the female.

a Habits.

They live beneath the bark of rotten stumps of trees, in the
erevices of rock, and beneath stones. They require a moist
atmosphere, and are exceedingly susceptible to drought. They
avoid light, and are therefore rarely seen. They move with
great deliberation, picking their course by means of their
antennae and eyes. It is by the former that they acquire a
knowledge of the ground over which they are travelling, and by
the latter that they avoid the light. The antennae are extra-
ordinarily sensitive, and so delicate, indeed, that they seem to be
able to perceive the nature of objects without actual contact.
When irritated they eject with considerable force the contents of
their slime reservoirs from the oral papillae. The force is sup-
plied by the sudden contraction of the muscular body wall. They
can squirt the slime to the distance of almost a foot. . The slime,
which appears to be perfectly harmless, is extremely sticky, but
._ it easily comes away from the skin of the animal itself.

I have never seen them use this apparatus for the capture of
prey, but Hutton describes the New Zealand species as using it
for this purpose. So far as I can judge, it is used as a defensive
weapon; but this of course will not exclude its offensive use.
They will turn their heads to any part of the body which is being
irritated and violently discharge their slime at the offending
object. Locomotion is effected entirely by means of the legs,
-with the body fully extended.

Of their food in the natural.state we know little; but it is
probably mainly, if not entirely, animal. Hutton describes his
specimens as sucking the juices of flies which they had stuck
down with their slime, and those which I kept in captivity
eagerly devoured the entrails of their fellows, and the developing
young from the uterus. They also like raw sheep's liver. They
move their mouths in a suctorial manner, tearing the food with
their jaws. They have the power of extruding their jaws from

Io PERIPATUS CHAP.

the mouth, and of working them alternately backwards or for-
wards. This is readily observed in individuals immersed in water.

Breeding.

All species are viviparous. It has lately been stated that
some of the Australian species are normally oviparous, but this has
not been proved. The Australasian species come nearest to laying
egos, inasmuch as the eggs are large, full of yolk, and enclosed
in a shell; but development normally takes place in the uterus,
though, abnormally, incompletely developed eggs are extruded.

The young of P. capensis are born in April and May. They
are almost colourless at birth, excepting the antennae, which are
vreen, and their length is 10 to 15 mm. A large female will
produce thirty to forty young in one year. The period of gesta-
tion is thirteen months, that is to say, the ova pass into the
oviducts about one month before the young of the preceding year
are born. They are born one by one, and it takes some time
for a female to get rid of her whole stock of embryos; in fact,
the embryos in any given female differ slightly in age, those next
the oviduct being a little older (a few hours) than those next the
vagina. The mother does not appear to pay any special attention
to her young, which wander away and get their own food.

There does not appear to be any true copulation. The male
deposits small, white, oval spermatophores, which consist of small
bundles of spermatozoa cemented together by some glutinous
substance, indiscriminately on any part of the body of the female.
Such spermatophores are found on the bodies of both males and
females from July to January, but they appear to be most nume-
' rous in our autumn. It seems probable that the spermatozoa
-make their way from the adherent spermatophore through the
body wall into the body, and so by traversing the tissues reach the
ovary. The testes are active from June to the following March.
From March to June the vesiculae of the male are empty. _ It is
probable that spermatophores are formed in other species.

There are no marked sexual differences, but in some species
some of the legs of the male, often the last or penultimate, bear
a small white papilla on the ventral surface (Fig. 6).

Whereas in the Cape species embryos in the same uterus are
all practically of the same age (except in the month of April,
when two broods overlap in P. capensis), and birth takes place at
a fixed season; in the Neotropical species the uterus, which is

I ALIMENTARY CANAL 11

always pregnant, contains embryos of different ages, and births
probably take place all the year round.

In all species of Peripatus the young are fully formed at
birth, and differ from the adults only in size and colour.

ANATOMY
The Alimentary Canal (Fig. 8).

The buccal cavity, as explained above, is a secondary forma-
tion around the true mouth, which is at its dorsal posterior end.
It contains the tongue and the jaws, which have already been

-al
orp
ods
8.0 eg? yf
- Y / A \ ee . . .
phi WBS 7. Fic. 8.—Peripatus capensis dissected so as to show

the alimentary canal, slime glands, and salivary
glands. (After Balfour.) The dissection is viewed
pan 3. from the ventral side, and the lips (Z) have been
cut through in the middle line behind and pulled
outwards so'as to expose the jaws (7), which have
sld--.-- been turned outwards, and the tongue (7’) bearing

a median row of chitinous teeth, which branches
behind into two. The muscular pharynx, extend-
ing back into the space between the first and second
pairs of legs, is followed by a short tubular oeso-
phagus. The latter opens into the large stomach with
plicated walls, extending almost to the hind end of
the animal. The stomach at its point of junc-
tion with the rectum presents an §-shaped ventro-
dorsal curve. A, Anus; at, antenna; /.1, F.2,
first and second feet; 7, jaws; JZ, lips; oe,
oesophagus ; or.p, oral papilla; ph, pharynx; R,
rectum ; s.d, salivary duct; s.g, salivary gland ;
sl.d, slime reservoir; sl.g, portion of tubules of
slime gland; st, stomach; 7, tongue in roof of
mouth.

described, and into the hind end of it there opens ventrally by a
median opening the salivary glands (sg). The mouth leads into
a muscular pharynx (ph), which is connected by a short oeso-
phagus (oe) with a stomach (st). The stomach forms by far the

To PERIPATUS CHAP,

largest part of the alimentary canal. It is a dilated soft-walled
‘tube, and leads behind into the short narrow rectum (2), which
opens at the anus. There are no glands opening into the
alimentary canal.

Nervous System.

The central nervous system consists of a pair of supra-
oesophageal ganglia united in the middle line, and of a pair of
widely divaricated ventral cords, continuous in front with the
supra-oesophageal gangha (Fig. 9).

The ventral cords at first sight appear to be without gangli-
onic thickenings, but on more careful examination they are
found to be enlarged at each pair of legs (Fig. 9). These enlarge-
ments may be regarded as imperfect ganglia. There are, there-

Fig. 9.—-Brain and anterior part of the ventral nerve-

cords of Peripatus capensis enlarged and viewed
))) _ etn from the ventral surface. (After Balfour.) The
Win. paired appendages (@) of the ventral surface of the
brain are seen, and the pair of sympathetic nerves
(sy) arising from the ventral surface of the hinder
part. From the commencement of the oesopha-
geal commissures pass off on each side a pair of

commissures between the ventral nerve-cords are
placed close together ; immediately behind them
the nerve-cords are swollen, to form the ganglionic
enlargements from which pass off to the oral
papillae a pair of large nerves on each side (orm).
Behind this the cords present a series of enlarge-
ments, one pair for each pair of feet, from which a
pair of large nerves pass off on each side to the feet
(pn). atn, Antennary nerves; co, commissures
between ventral cords; d, ventral appendages of
brain ; #, eye; en, nerves passing outwards from
ty--- Fg.l ventral cord ; F.g.1, ganglionic enlargements from

~ which nerves to feet pass off ; jn, nerves to jaws ;
org, ganglionic enlargement from which nerves to
oral papillae pass off ; ovn, nerves to oral papillae ;
pc, posterior lobe of brain; pn, nerves to feet ;
sy, sympathetic nerves.

co

fore, as many pairs of ganglia as there are pairs of legs. There
is in addition a ganglionic enlargement at the commencement of
the oesophageal commissures, where the nerves to the oral papillae
are given off (Fig. 9, org).

The ventral cords are placed each in the lateral compart-

ments of the body cavity, immediately within the longitudinal.

layer of muscles. They are connected with each other, rather
like the pedal nerves of Chiton and the lower Prosobranchiata,
by a number of commissures. These commissures exhibit a

a

nerves to the jaws (Jn). The three anterior

——

X

I NERVOUS SYSTEM AND BODY WALL > 13

fairly regular arrangement from the region included between the
first and the last pair of true feet. There are nine or ten of them
between each pair of feet. They pass along the ventral wall of
the body, perforating the ventral mass of longitudinal muscles.
On their way they give off nerves which innervate the skin.

Posteriorly the two nerve-cords nearly meet immediately in
front of the generative aperture, and then, bending upwards, fall
into each other dorsally to the rectum. They give off a series
of nerves from their outer borders, which present throughout
the trunk a fairly regular arrangement. From each ganglion
two large nerves (pn) are given off, which, diverging somewhat
from each other, pass into the feet.

From the oesophageal commissures, close to their junction
with the supra-oesophageal ganglia, a nerve arises on each side
which passes to the jaws, and a little in front of this, apparently
from the supra-oesophageal ganglion itself, a second nerve to the
jaws also takes its origin.

The supra-oesophageal ganglia (Fig. 9).are large, somewhat
oval masses, broader in front than behind, completely fused in
the middle, but free at their extremities. Each of them is pro-
longed anteriorly into an antennary nerve, and is continuous
behind with one of the oesophageal commissures. On _ the
ventral surface of each, rather behind the level of the eye, is
placed a hollow protuberance (Fig. 9, d), of which I shall say
more in dealing with the development. About one-third of: the
way back the two large optic nerves take their origin, arising
laterally, but rather from the dorsal surface (Fig. 9). Each of them
joins a large ganglionic mass placed immediately behind the retina.

The histology of the ventral cords and oesophageal commis-
sures is very simple and uniform. They consist of a cord almost
wholly formed of nerve-fibres placed dorsally, and of a ventral
‘layer of ganglion cells.

The Body Wall.

The skin is formed of three layers.
(1) The cuticle.
(2) The epidermis or hypodermis.
(3) The dermis.
The cuticle is a thin layer. The spines, jaws, and claws are
special developments of it. Its surface 1s not, however, smooth,

—

14 PERIPATUS CHAP. —

but is everywhere, with the exception of the perioral region,
raised into minute secondary papillae, which in most instances
bear at their free extremity a somewhat prominent spine. The
whole surface of each of the secondary papillae just described is

in its. turn covered by numerous minute spinous tubercles. |

The epidermis, placed immediately within the cuticle, is
composed of a single layer of cells, which vary, however, a good
deal in size in different regions of the body. The cells excrete
the cuticle, and they stand in a very remarkable relation to the
secondary papillae of the cuticle just described. Each epidermis
cell is in fact placed within one of these secondary papillae, so
that the cuticle of each secondary papilla is the product of a
single epidermis cell. The pigment which gives the characteristic
colour to the skin is deposited in the protoplasm of the outer ends
of the cells in the form of small granules.

At the apex of most, if not all, the primary wart-like papillae
there are present oval aggregations, or masses of epidermis cells,
each such mass being enclosed in a thickish capsule and bearing a
long projecting spine. These structures are probably tactile organs.
In certain regions of the body they are extremely numerous ; more
especially is this the case in the antennae, lips, and oral papillae.
On the ventral surface of the peripheral rings of the thicker
sections of the feet they are also very thickly set and fused together
so as to form a kind of pad (Figs. 6 and 7). In the antennae
they are thickly set side by side on the rings of skin which give
such an Arthropodan appearance to these organs in Peripatus.

The Tracheal System.

The apertures of the tracheal system are placed in the depres-
sions between the papillae or ridges of the skin. Each of them
leads into a tube, which may be called the tracheal pit (Fig. 10),
the walls of which are formed of epithelial cells bounded towards
the lumen of the pit by a very delicate cuticular membrane con-
tinuous with the cuticle covering the surface of the body, The
pits vary somewhat in depth ; the pit figured was about 0°09 min.
It perforates the dermis and terminates in the subjacent muscular
layer.

Internally it expands in the transverse plane and from the
expanded portion the tracheal tubes arise in diverging bundles.
Nuclei similar in character to those in the walls of the tracheal

I TRACHEAL, MUSCULAR AND VASCULAR SYSTEM 15

pit are placed between the tracheae, and similar but slightly more
elongated nuclei are found along the bundles. The tracheae are
minute tubes exhibiting a faint transverse striation which is prob-
ably the indication of a spiral fibre. They appear to branch, but

Fie. 10.—Section through a tracheal
pit and. diverging bundles of
tracheal tubes taken transversely
to the long axis of the body.
(After Balfour.) tr, Tracheae,
showing rudimentary spiral fibre ;
tr.c, cells resembling those lining
the tracheal pits, which occur at
intervals along the course of the
tracheae ; ¢r.o, tracheal stigma ;
tr.p, tracheal pit.

only exceptionally. The tracheal apertures are diffused over the
surface of the body, but are especially developed in certain regions.

The Muscular System.

The general muscular system consists of—(1) the general
wall of the body; (2) the muscles connected with the mouth,
pharynx, and jaws; (3) the muscles of the feet ; (4) the muscles
of the alimentary tract.

The muscular wall of the body is formed of—(1) an external
layer of circular fibres; (2) an internal layer of longitudinal
muscles,

The main muscles of the body are unstriated and divided into
fibres, each invested by a delicate membrane. The muscles of the
jaws alone are transversely striated.

The Vascular System.

The vascular system consists of a dorsal tubular heart with
paired ostia leading into it from the pericardium, of the pericar-
dium, and the various other divisions of the perivisceral cavity
(Fig. 14, D). As in all Arthropoda, the perivisceral cavity is a
haemocoele ; 7.e. it contains blood and forms part of the vascular
system. The heart extends from close to the hind end of the
body to the head.

16 PERIPATUS CHAP.

The Body Cavity.

The body cavity is formed of four compartments—one central,
two lateral, and a pericardial (Fig. 14, D). The former is by far
the largest, and contains the alimentary tract, the generative
organs, and the slime glands. It is lined by a delicate endo-
thelial layer, and is not divided into compartments nor traversed
by muscular fibres. The lateral divisions are much smaller than
the central, and are shut off from it by the inner transverse band —
of muscles. They are almost entirely filled with the nerve-cord
and salivary gland in front and with the nerve-cord alone behind,
and their lumen is broken up by muscular bands. They further
contain the nephridia. They are prolonged into the feet, as is the
embryonic body cavity of most Arthropoda. The pericardium con-
tains a peculiar cellular tissue, probably, as suggested by Moseley,
equivalent to the fat-bodies of insects.

Nephridia.

In Peripatus capensis nephridia are present in all the legs.
In all of them (except the first three) the following parts may
be recognised (Fig. 11) :—

(1) A vesicular portion opening to the exterior on the ventral -

surface of the legs by a narrow. passage.

(2) A coiled portion, which is again subdivided into several

sections.

(3) A section with closely packed nuclei ending by a some-

what enlarged opening. :

(4) The terminal portion, which consists of a thin-walled

vesicle.

The last twelve pairs of these organs are all constructed in a
very similar manner, while the two pairs situated in the fourth
and fifth pairs of legs are considerably larger than those behind,
and are in some respects very differently constituted.

It will be convenient to commence with one of the hinder
nephridia. Such a nephridium from the ninth pair of legs is
represented in Fig. 11. The external opening is placed at the
outer end of a transverse groove at the base of one of the legs,
while the main portion of the organ lies in the body cavity in
the base of the leg, and extends into the trunk to about the level

I : NEPHRIDIA 17

of the outer edge of the nerve-cord of its side. The external
opening (0.8) leads into a narrow tube (s.d), which gradually
dilates into a large sac (s). The narrow part is lined by small
epithelial cells, which are directly continuous with and perfectly
similar to those of the epidermis. The sac itself, which forms a
kind of bladder or collecting vesicle for the organ, is provided
with an extremely thin wall, lined with very large flattened cells.
The second section of the nephridium is formed by the coiled
tube, the epithelial lining of which varies slightly in the different
parts. The third section (s.0.¢), constitutes the most distinct
portion of the whole organ. Its walls are formed of columnar
cells almost filled by oval nuclei, which absorb colouring matters
with very great avidity, and thus render this part extremely
Fig. 11.—Nephridium from the
9th pair of legs of P. capensis.
o.s, External opening of seg-
mental organ; p.f, internal
opening of *nephridium into
the body cavity (lateral com-
partment) ; s, vesicle of seg- ©
mental organ; s.c.l, s.¢.2,
8.€.3, 8.¢.4, successive regions
of coiled portion of nephri-
dium; s.0.¢, third portion of
nephridium broken off at p.f

from theinternal vesicle, which
is not shown.

conspicuous. The nuclei are arranged in several rows. It ends
by opening into a vesicle (Fig. 14, D), the wall of which is so
delicate that it is destroyed when the nephridium is removed
from the body, and consequently is not shown in Fig. 11.

The fourth and fifth pairs are very considerably larger than
those behind, and are in other respects peculiar. The great mass

of each organ is placed behind the leg on which the external

- opening is placed, immediately outside one of the lateral nerve-
cords. The external opening, instead of being placed near the
base of the leg, is placed on the ventral side of the third ring
(counting from the outer end) of the thicker portion of the leg.
It leads into a portion which clearly corresponds with the collect-
ing vesicle of the hinder nephridia. This part is not, however,
dilated into a vesicle. The three pairs of nephridia in the three
foremost pairs of legs are rudimentary, consisting solely of a
vesicle and duct. The salivary glands are the modified nephridia
of the segment of the oral papillae.

VOL. V C

18 PERIPATUS

Generative Organs.

Ma.e.—tThe male organs (Fig. 12) consist of a pair of testes
(te), a pair of vesicles (v), vasa deferentia (v.d), and accessory
glandular tubules (f/). All the above parts le in the central
compartment of the body cavity. In P. capensis the accessory
glandular bodies or crural glands of the last (17th) pair of legs
are enlarged and prolonged into an elongated tube placed in the

lateral compartment of the body cavity (a.g).
The right vas deferens passes under both nerve-cords to join

Fic. 12.—Male generative organs of Peripatus capensis, viewed from the dorsal surface.
(After Balfour.) a.g, Enlarged crural glands of last pair of legs ; ¥'.16, 17, last pairs
of legs ; f, small accessory glandular tubes ; y, common duct into which the vasa
deferentia open ; te, testis; v, seminal vesicle ; v.c, nerve-cord ; v.d, vas deferens.

the left, and form the enlarged tube (p), which, passing beneath

the nerve-cord of its side, runs to the external orifice. The

enlarged terminal portion possesses thick muscular walls, and
possibly constitutes a spermatophore maker, as has been shown to
be the case in P. V. Zealandiae, by Moseley. In some specimens

a different arrangement obtains, in that the left vas deferens

passes under both nerve-cords to join the right.

FEMALE.—The ovaries consist of a pair of tubes closely ap-
plied together, and continued posteriorly into the oviducts. The
oviducts, after a short course, become dilated into the uteruses,
which join behind and open to the exterior by a median

a | GENERATIVE ORGANS AND DEVELOPMENT 19

7

opening. The ovaries always contain spermatozoa, some of which
project through the ovarian wall into the body cavity. Sperma-
tozoa are not found in the uterus and oviducts, and it appears
probable that they reach the ovary directly by boring through
the skin and traversing the body cavity In the neotropical
species there is a globular receptaculum seminis opening by two
short ducts close together into the oviduct, and there is a small
receptaculum ovorum with extremely thin walls opening into the
oviduct by a short duct just in front of the receptaculum seminis.
The epithelium of the latter structure is clothed with actively
moving cilia. In the New Zealand species there is a receptaculum
seminis with two ducts, but the receptacula ovorum have not
been seen.

There appear to be present in most, if not all, the legs some
accessory glandular structures opening just externally to the
nephridia. They are called the crural glands. |

DEVELOPMENT.

As stated at the outset, Peripatus is found in three” of the
great regions, viz. in Africa, in Australasia, and in South America
and the West Indies. It is a curious and remarkable fact that
although the species found in these various localities are really
closely similar, the principal differences relating to the structure
of the female generative organs and to the number of the legs,
they do differ in the most striking manner in the structure of
the ovum and in the early development. In all the Austral-
asian species the egg is large and heavily charged with food-
yolk, and is surrounded by a tough membrane. In the Cape
species the eggs are smaller, though still of considerable size ; the
yolk is much less developed, and the egg membrane is thinner
‘though dense. In the neotropical species the egg is minute
and almost entirely devoid of yolk. The unsegmented uterine
ovum of P. Novae-Zealandiae measures 1°5 mm. in length by *8 mm.
in breadth; that of P. capensis is 56 mm. in length; and that
of P. Trinidadensis ‘(04 mm. in diameter. In correspondence
with these differences in the ovum there are differences in the
early development, though the later stages are closely similar.
But unfortunately the development has only been fully worked

1 See Whitman, Journal of Morphology, vol. i. 2 See below, p. 24.

20 PERIPATUS | CHAP.
¢.

vut in one species, and to that species—P. capensis—the follow-
ing description refers. The ova are apparently fertilised in the
ovary, and they pass into the oviducts in April and May. In
May the brood of the preceding year are born, and the new ova,
which have meanwhile undergone cleavage, pass into the uterus.
There are ten to twenty ova in each uterus. The segmentation
is peculiar, and leads to the formation of a solid gastrula, consisting
of a cortex of ectoderm nuclei surrounding a central endodermal
mass, which consists of a much-vacuolated tissue with some

Fic. 13.—A series of embryos of P. capensis. The hind end of embryos B, C, D is
uppermost in the figures, the primitive streak is the white patch behind the blasto-
pore. (After Sedgwick.) A, Gastrula stage, ventral view, showing blastopore.
B, Older gastrula stage, ventral view, showing elongated blastopore and primitive
streak. ©, Ventral view of embryo with three pairs of mesoblastic somites, dumib-
bell-shaped blastopore and primitive streak. D, Ventral view of embryo, in which
the blastopore has completely closed in its middle portion, and given rise to two
openings, the embryonic mouth and anus. The anterior pair of somites have
moved to the front end of the body, and the primitive groove has appeared on the
primitive streak. E, Side view of embryo, in which the hind end of the body has.
begun to elongate in a spiral manner, and in which the appendages have begun.
At, antenna ; d, dorsal projection ; p.s, preoral somite. F, Ventral view of head of
embryo intermediate between E and G. The cerebral grooves are wide and shallow..
The lips have appeared, and have extended behind the openings of the salivary
glands, but have not yet joined in the middle line. At, antennae; c.g, cerebral
groove ; 7, jaws ; j.s, swelling at base of jaws ; LZ, lips ; M, mouth ; o7.p, oral papillae ;
0.8, opening of salivary gland. G, Side view of older embryo with the full number
of appendages, to show the position in which the embryos lie in the uterus,

irrecularly-shaped nuclei. The endoderm mass is exposed at one
point—the blastopore (gastrula mouth). The central vacuoles
of the endoderm now unite and form the enteron of the embryo,
and at the same time the embryo elongates into a markedly oval
form, and an opacity—the primitive streak—-appears at the hind
end of the blastopore (Fig. 13,B). This elongation of the embryo
is accompanied by an elongation of the blastopore, which soon
becomes dumb-bell shaped (Fig. 13, C). At the same time the
mesoblastic somites (embryonic segments of mesoderm) have made

—<— so

nd a alee eh

a a

ie DEVELOPMENT 21

‘their appearance in pairs at the hind end, and gradually travel for-
ward on each side of the blastopore to the front end, where the
somites of the anterior pair soon meet in front of the blastopore (Fig.
13,D). Meanwhile the narrow middle part of the blastopore has
closed by a fusion of its lips, so that the blastopore is represented
by two openings, the future mouth and anus. A primitive groove
makes its appearance behind the blastopore (Fig. 13, D). At
this stage the hind end of the body becomes curved ventrally
into a spiral (Fig. 13, E), and at the same time the appendages
appear as hollow processes of the body wall, a mesoblastic
somite being prolonged into each of them. The first to appear
are the antennae, into which the praeoral somites are prolonged.
The remainder appear from before backwards in regular order,
viz. jaw, oral papillae, legs 1-17. The full number of somites
and their appendages is not, however, completed until a later
stage. The nervous system is formed as an annular thickening
of ectoderm passing in front of the mouth and behind the anus,
and lying on each side of the blastopore along the lines of the
somites. The praeoral part of this thickening, which gives rise to
the cerebral ganglia, becomes pitted inwards on each side (Fig. 13,
F,¢g). These pits are eventually closed, and form the hollow
ventral appendages of the supra-pharyngeal ganglia of the adult
(Fig. 9, d). The lips are formed as folds of the side wall of the
body, extending from the praeoral lobes to just behind the jaw
(Fig. 13, F, Z). They enclose the jaws (j), mouth (Jf), and
opening of the salivary glands (0.s), and so give rise to the buccal
cavity. The embryo has now lost its spiral curvature, and
becomes completely doubled upon itself, the hind end being in
contact with the mouth (Fig. 13, G). It remains in this position
until birth. The just-born young are from 10-15 mm. in length

_ and have green antennae, but the rest of the body is either quite

_ white or of a reddish colour. This red colour differs from the
colour of the adult in being soluble in spirit.

The mesoblastic somites are paired sacs formed from the
anterior lateral portions of the primitive streak (Fig. 13, C).
As they are formed they become placed in pairs on each side of
the blastopore. The somites of the first pair eventually obtain a
position entirely in front of the blastopore (Fig. 13, D). They
form the somites of the praeoral lobes. The full complement of
somites is acquired at about the stage of Fig. 13, E. The relations

22 : PERIPATUS ; CHAP.

of the somites is shown in Fig. 14, A, which represents a transverse
section taken between the mouth and anus of an embryo of the
stage of Fig. 13, D. The history of these somites is an exceed-
Setly. interesting one, and may be described shortly as follows :—

They divide into two parts—a ventral part, which extends into

Fig. 14.—A series of diagrams of transverse sections through Peripatus embryos to
show the relations of the coelom at successive stages. (After Sedgwick.) A, Early
stage: 1, gut; 2, mesoblastic somite ; no trace of the vascular space; endoderm
and ectoderm in contact. B, Endoderm has separated from the dorsal and ventral
ectoderm. The somite is represented as having divided on the left side into a
dorsal and ventral portion: 1, gut; 2, somite ; 3, haemocoele. ©, The haemocoele
(3) has become divided up into a number of spaces, the arrangement of which is
unimportant. The dorsal part of each somite has travelled dorsalwards, and now
constitutes a small space (triangular in section) just dorsal to the gut. The ventral
portion (2’) has assumed a tubular character, and has acquired an external opening.
The internal vesicle is already indicated, and is shown in the diagram by the thinner
black line: 1, gut; 2’, nephridial part of coelom; 3, haemocoele ; 3’, part of
haemocoele which will form the heart—the part of the haemocoele on each side of
this will form the pericardium ; 4, nerve-cord. D represents the conditions at
the time of birth; numbers as in C, except 5, slime glands. The coelom is re-
presented as surrounded by a thick black line, except in the ee which forms the
internal vesicle of the uephridium,

the appendage, and a dorsal part (Fig. 14, B). The ventral part
acquires an opening to the exterior just outside the nerve-cord,
and becomes entirely transformed into a nephridium (Fig. 14,
D, 2’). The dorsal part shifts dorsalwards and diminishes rela-
tively in size (Fig. 14, C). Its fate differs in the different parts

I SPECIES : 23

of the body. In the anterior somites it dwindles and disappears,
but in the posterior part it unites with the dorsal divisions of
contiguous somites of the same side, and forms a tube—the
generative tube (Fig. 14, D, 2). The last section of this tube
retains its connexion with the ventral portion of the somite, and
so acquires an external opening, which is at first lateral, but soon
shifts to the middle line, and fuses with its fellow, to form the
single generative opening. The praeoral somite develops the
rudiment of a nephridium, but eventually entirely disappears.
The jaw somite also disappears; the oral papilla somite forms
ventrally the salivary glands, which are thus serially homologous
with nephridia. The perivisceral cavity of Peripatus is, as in all
Arthropoda, a haemocoele. Its various divisions develop as
a series of spaces between the ectoderm and endoderm, and
later in the mesoderm. The mesoderm seems to be formed
entirely from the proliferation of the cells of the mesoblastic
somites. It thus appears that in Peripatus the coelom does not
develop a perivisceral portion, but gives rise only to the renal
and reproductive organs.

APPENDIX!
Preripatus, Guilding

Soft-bodied vermiform animals, with one pair of ringed antennae, one
pair of jaws, one pair of oral papillae, and a varying number of claw-bearing
ambulatory legs. Dorsal surface arched and more darkly pigmented than
the flat ventral surface. Skin transversely ridged and beset by wart-like
spiniferous papillae. Mouth anterior, ventral; anus posterior, terminal.
Generative opening single, median, ventral, and posterior. One pair of
simple eyes. Brain large, with two ventral hollow appendages; ventral
cords widely divaricated, without distinct ganglia. Alimentary canal simple,
uncoiled. Segmentally arranged, paired nephridia are present. Body cavity
is continuous with the vascular system, and does not communicate with the
- paired nephridia. Heart tubular, with paired ostia. Respiration by means
of tracheae. Dioecious; males smaller and generally less numerous than
females. Generative glands tubular, continuous with the ducts. Viviparous.
Young born fully developed. They shun the light and live in damp places
beneath stones, leaves, and bark of rotten stumps. ~ They eject when irritated
a viscid fluid through openings at the apex of the oral papillae. Distribu-

1 Cf., in addition to the works quoted on pp. 3,4: A. Willey, ‘‘ Peripatus novae-
britanniae,” in Zoological Results, i., Cambridge, 1898 ; L. Bouvier, ‘‘ Cont. & l'histoire
des Péripates américains,” Ann. Soc. Entomol. de France, \xviii., 1899; W. F.
Purcell, ‘‘ Anatomy of Opisthopatus cinctipes,” Annals of the S. African Museum,
ii. 1900. R. Evans, Quart. J. Micr. Sci. xliv., 1901, pp. 473, 539.

24 PERIPATUS CHAP.

tion: South Africa (Cape Colony, Natal, and the Gaboon), New Zealand,
Australia and Tasmania, New Britain, South and Central America and the
West Indies, the Malay Peninsula [and Sumatra ?}.

The genus Peripatus, so far as adult conformation is concerned, is a very
homogeneous one. It is true, as was pointed out by Sedgwick, that the species
from the same part of the world resemble one another more closely than
they do species from other regions, but recent researches have shown that
the line between them cannot be so sharply drawn as was at first supposed,
and it is certainly not desirable in the present state of our knowledge to
divide them into generic or subgeneric groups, as has been done by some zoolo-
gists! The colour appears to be highly variable in species from all regions ;
it is perhaps more constant in the species from the Neotropical region than
in those from elsewhere. The number of legs tends to be variable whenever
it exceeds 19 pregenital pairs ; when the number is less than that, it is usually,
though not always, constant. More constant points of difference are the form
of the jaws, the position of the generative orifice, the presence of a recepta-_
culum seminis and a receptaculum ovorum, the arrangement of the primary
papillae on the distal end of the feet, and above all the early development.

South African Species.— With three spinous pads on the legs and feet,
with two primary papillae on the anterior side and one on the posterior
side ; outer jaw with one minor tooth at the base of the main tooth, inner
jaw with no interval between the large tooth and the series of small ones ;
last fully developed leg of the male with enlarged crural gland opening on a
large papilla placed on its ventral surface ; coxal organs? absent ; the nephri-
dial openings of the 4th and 5th pairs of legs are placed in the proximal
spinous pad. Genital opening subterminal, behind the last pair of fully devel-
oped legs; oviduct without receptacula seminis or receptacula ovorum; the ter-
minal unpaired portion of the vas deferens short. Ova of considerable size, but
with only a small quantity of yolk. The embryos in the uterus are all nearly of
the same age, except for a month or two before birth when two broods overlap.

The following species are aberrant in respect of these characters: Peri-
patus (Opisthopatus) cinctipes, Purcell (Cape Colony and Natal), presents a few
Australasian features ; there is a small receptaculum seminis on each oviduct,
some of the legs are provided with well-developed coxal organs, the feet
have one anterior, one posterior, and one dorsal papilla, and the successive
- difference in the ages of the embryos in the uterus, though nothing like that
found in the Neotropical species, is slightly greater than that found in other
investigated African species. Several pairs of legs in the middle region of
the body are provided with enlarged crural glands which open on a large
papilla. Male with four accessory glands, opening on each side of and behind
the genital aperture. P. thollont Bouvier, Equatorial West Africa (Gaboon)
shows some Neotropical features; there are 24 to 25 pairs of legs, the

1 The following genera or subgenera have been proposed: Peripatus for the
Neotropical species, Peripatoides for the Australasian, Peripatopsis and Opisthopatus
for the African, Paraperipatus for the New Britain species, and Loperipatus for the
Malay species.

2 Coxal organs are furrows on the ventral surface of some of the legs, with tumid
lips and lined by smooth non-tuberculate epithelium. It appears that they can be
everted.

I SPECIES ; 25

genital opening is between the penultimate legs, and though there are only
three spinous pads, the nephridial openings of the 4th and 5th legs are
proximal to the 3rd pad, coxal organs are present, and the jaws are on the
Neotropical type; the oviducts have receptacula seminis. The following
South African species may be mentioned: P. capensis Grube, with 17 (rarely
18) pairs of claw-bearing legs; P. balfourt Sedgw., with 18 (rarely 19) pairs ;
P. moseleyt Wood-M., with 20 to 24 pairs,

Australasian Species.—With 14, 15, or 16 pairs of claw-bearing ambu-
latory legs, with 3 spinous pads on the legs, and nephridial opening of the
4th and 5th legs on the proximal pad ; feet with one anterior, one posterior,
and one dorsal primary papilla; inner jaw without diastema, outer with or
without a minor tooth. Last leg of the male with or without a large white
papilla on its ventral surface for the opening of a gland; marked papillae
for the crural glands are sometimes present on other legs of the male; well-
developed coxal glands absent. Genital opening between the legs of the last
pair ; oviducts with receptacula seminis, without receptacula ovorum ; the ter-
minal portion of the vas deferens long and complicated ; the accessory male glands
open between the genital aperture and the anus, near the latter. Ova large
and heavily charged with yolk and provided with a stoutish shell. The uterus
appears to contain embryos of different ages. Specimens are recorded from
West Australia, Queensland, New South Wales, Victoria, and New Zealand.

The Australasian species are in some confusion. The number of claw-
bearing legs varies from 14 to 16 pairs, but the number most often found is
15. Whether the number varies in the same species is not clear. There
appears to be evidence that some species are occasionally or normally oviparous,
and in the supposed oviparous species the oviduct opens at the end of a papilla
called from its supposed function an ovipositor, but the oviparity has not yet
been certainly proved as a normal occurrence. Among the species described
may be mentioned P. leuckarti Sanger, P. insignis Dendy, P. oviparus Dendy,
P. viridimaculatus Dendy, P. novae-zealandiae Hutton, but it is by no means
certain that future research will maintain these. Mr. J. J. Fletcher indeed is of
opinion that the Australian forms are all varieties of one species, P. leuckartt.

Neotropical Species.— With 3 to 5 spinous pads on the legs, nephridial
opening of the 4th and 5th legs usually proximal to the third pad, and
feet either with two primary papillae on the anterior side and one on the
posterior, or with two on the anterior and two on the posterior; outer jaw
with small minor tooth or teeth at the base of the main tooth, inner jaw
with diastema. A variable number of posterior legs of the males anterior to

the genital opening with one or two large papillae carrying the openings
of the crural glands; well developed coxal organs present on most of the
legs. The primary papillae usually divided into two portions. Genital
opening between the legs of the penultimate pair; oviduct provided with
receptacula seminis and ovorum; unpaired part of vas deferens long and
complicated ; accessory organs of male opening at the sides of the anus. Ova
minute, with little food-yolk ; embryos in the uterus at very different stages
of development. The number of legs usually if not always variable in the same
species ; the usual number is 28 to 32 pairs, but in some species 40 to 43
pairs are found. The Neotropical species appear to fall into two groups:
(1) the so-called Andean species, viz., those which inhabit the high plateaux
or Pacific slope of the Andes; in these there are 4 (sometimes 5) pedal

26 PERIPATUS - CHAP. I

papillae, and the nephridial openings of the 4th and 5th legs are on the 3rd
pad ; and (2) the Caribbean species, viz. the remaining Neotropical species,
in which there are 3 papillae on the foot and the nephridial openings of
the 4th and 5th legs are between the 3rd and 4th pads. The Andean species
are P. eisenit Wh., P. tuberculatus Bouvier, P. lankestert Bouv., P. quitensis
Schm., P. corradi Cam., P. cameranot Bouv., and P. balzant Cam.

Of the remaining species, which are the majority, may be mentioned, P.
edwardsit Blanch., P. jamaicensis Gr. and Cock., P. trinidadensis Sedgw.,
—P. torquatus Ken., P. imthurmi Scl.

New Britain Peripatus.—With 22 to 24 pairs of claw-bearing legs,
with three spinous pads on the legs, and nephridial openings of legs 4 and 5
(sometimes of 6 also) on the proximal pad; feet with one. primary papilla on
the anterior, one on the posterior side, and one on the dorsal side (median
or submedian) ; outer jaw with a minor tooth, inner jaw without diastema ;
crural glands absent ; well-developed coxal organs absent. Genital opening
subterminal, behind the last pair of legs; oviduct with receptaculum seminis,
without receptaculum ovorum; unpaired part of vas deferens very short ;
accessory glands two, opening medianly and dorsally. Ova small, -1 mm. in
diameter, with little yolk; the embryos are provided with large trophic
vesicles (Willey). Embryos in the uterus of very different ages and probably
born all the year round.

But one species known, P. novae-britanniae Willey.

Sumatran! Peripatus.—Peripatus with 24 pairs of ambulatory legs, and
4 spinous pads on the legs. The primary papillae of the Neotropical character,
with conical bases. Generative opening between the legs of the penultimate
pair. Feet with only two papillae. Single species. P. sumatranus Sedgw.

Peripatus from the Malay Peninsula.2— With 23 to 25 pairs of claw-
bearing legs, 4 spinous pads on the legs, and nephridial openings of legs 4
and 5 in the middle of the proximal pad or on its proximal side; feet with 2
primary papillae, one anterior and one posterior ; outer jaw with 2, inner jaw »
with 2 or 3 minor teeth at base of main tooth separated by a diastema from
the row of small teeth; crural glands present in male only, in the two pairs
of legs preceding the generative opening; coxal organs present. Genital
opening between the penultimate legs; oviduct with receptacula seminis and
ovorum ; unpaired part of vas deferens long; male accessory glands two, —
opening medianly between the legs of the last pair. Ova large with much
yolk and thick membrane, like those of Australasian species; embryos with
slit-like blastopore, and of very different ages in the same uterus, probably
born all the year round. The species are P. weldoni Evans, P. horsta Evans,
and P. butlert Evans. It will thus be seen that the Malay species while
resembling the Neotropical species in the generative organs, differ from these
in many features of the legs and feet, in the important characters furnished
by the size and structure of the ovum, and by the early development.

1 The existence of this species is doubtful. The description of it was taken
from a singe specimen. The evidence that this specimen was found in Sumatra is
not conclusive.

2 I am indebted to Mr. R. Evans and the Editors of the Quart. J. Mier.
Sci. for permission to see proofs of Mr. Evans’ papers in vol. xliv. of that
journal.

‘MYRIAPODA: te |

RY be, ri :

F. G. SINCLAIR, M.A. — / he
(wormerty F, G. HEATHCOTE) |
‘Trinity College, Cambridge. ;

s .
¢ . 3 i oO

CHAPTER II

MYRIAPODA

INTRODUCTION —— HABITS—— CLASSIFICATION STRUCTURE—— CHILO-
GNATHA—CHILOPODA —— SCHIZOTARSIA —- SYMPHYLA— PAUR-
OPODA——EMBRYOLOGY——PALAEON TOLOGY.

TRACHEATA With separated head and numerous, fairly similar
segments. They have one pair of anterinae, two or three ‘pairs
of mouth appendages, and numerous pairs of legs.

The Myriapoda are a class of animals which are widely
distributed, and are represented in almost every part of the
globe. Heat and cold alike seem to offer favourable conditions
for their existence, and they flourish both in the most fertile
and the most barren countries.

They have not attracted much notice until comparatively
recent times. Compared with Insects they have been but little
known. The reason of this is not hard to find. The Myriapods
do not exercise so much direct influence on human affairs as
do some other classes of animals; for instance, Insects. They
include no species which is of direct use to man, like the silk-
worm or the cochineal insect, and they are of no use to him as
food. It is true that they are injurious to his crops. For instance,
the species of Millepede known as the “ wire worm” ! is extremely
harmful; but this has only attracted much notice in modern
times, when land is of more value than formerly, and agricul-
ture is pursued in a more scientific manner, and the constant
endeavour to get the utmost amount of crop from the soil has
caused a minute investigation into the various species of
animals which are noxious to the growing crop. The species of

1 Not to be confused with the larva of Elater lineatus, also known as “ wire-worm.”

30 MYRIAPODA’ CHAP. .

Myriapoda best known to the ancients were those which were
harmful to man on account of their poisonous bite.

Some writers have supposed that the word which is trans-
lated “mole” in the Bible (Lev. xi. 30) is really Scolopendra
(a genus of Centipede), and, if this is so, it is the earliest men-
tion of the Myriapods. They were rarely noticed in the classical
times; almost the only mention of them is by A®lian, who says
that the whole population of a town called Rhetium were driven
out by a swarm of Scolopendras. Pliny tells us of a marine Scolo-_
pendra, but this was most probably a species of marine worm.

Linnaeus included Myriapods among the Insects; and the
writers after him till the beginning of this century classed them
with all sorts of Insects, with Spiders, Scorpions, and even among
Serpents. It was Leach who first raised them to the importance
of a separate class, and Latreille first gave them the name
of Myriapoda, which they have retained ever since.

Myriapods are terrestrial animals, crawling or creeping on
the ground or on logs of wood, or even under the bark of trees.
There is, however, a partial exception to this; various naturalists
have from time to time given descriptions of marine Centipedes.
These are not found in the sea, but crawl about on the shore,
where they are submerged by each tide. A Geophilus of this
sort has been found in Jersey by Mr. Sinel,’ thus living a semi-
aquatic life. Professor F. Plateau, experimenting on the effect of
immersion on the Geophilidae, found that they could exist in sea
water from twelve to seventy hours, and in fresh water from six
to ten days. They thus offer a striking example of the power that _
their class possess of existing under unfavourable circumstances.

With regard to their habits the different species differ very
considerably. On the one hand we have the Chilopoda, or
Centipedes, as they are called in this country, active, swift, and
ferocious ; living for the most part in dark and obscure places,
beneath stones, logs of wood, and dried leaves, etc., and feeding
on living animals. On the other hand, we have the Chilognatha,
or Millepedes, distinguished by their slow movements and .
vegetable diet; inoffensive to man, except by the destruction
they occasion to his crops, and having as a means of defence no
formidable weapon like the large poison claws of the Centipedes,
but only a peculiarly offensive liquid secreted by special glands

1 See Nature, xli., 1890, p. 104.

II HABITS AND DISTRIBUTION 31

known by the unpleasant though expressive name of “stink glands,”
or by the more euphonious Latin name of glandulae odoriferae.
As a general rule the larger species of Myriapods are found
in the hotter climates, some of the tropical species being very
large, and some, among the family of the Scolopendridae, extremely
poisonous ; and it is even said that their bite is fatal to man.
If, however, the Centipede is sometimes fatal to man, it does

Fic. 15.—Scolopendra obscura. (From ©. L. Koch, Die Myriapoden.)

not always have it its own way, for we read of man making
food of Centipedes. It is hard to believe that any human being
could under any circumstances eat Centipedes, which have been
described by one naturalist as “a disgusting tribe loving the
darkness.” Nevertheless, Humboldt informs us that he has seen
the Indian children drag out of the earth Centipedes eighteen
inches long and more than half an inch wide and devour them.

Fic. 16.—Chordewma sylvestre. Lisp C. L. Koch, Die Myriapoden.)

This, I believe, is the only account of human beings using
the Myriapoda as food, if we except the accounts of the religious
fanatics among the African Arabs, who are said to devour Centi-
pedes alive; though this is not a case of eating for pleasure, for
the Scolopendras are devoured in company with leaves of the
prickly pear, broken glass, etc., as a test of the unpleasant things
which may be eaten under the influence of religious excitement.

32 MYRIAPODA CHAP.

A cold climate, however, is not fatal to some fairly large
species of Centipedes. A striking instance of this came under
my own observation some years ago. In 1886 I was travelling
in the island of Cyprus—the “ Enchanted Island,” as Mr. Mallock —
calls it in his book written about the same time—with the
intention of observing its natural history. This island consists
of a broad flat country crossed by two mountain ranges of con-
siderable height, thus offering the contrast of a hot climate in
the plains and a cold climate in the mountains. On the plain
country I found among the Myriapoda that the most common
species were a large Scolopendra and a large Lithobius. The
Scolopendra was fairly common, living for the most part under |
large stones, and it was a pleasant task to search for them in a
ruined garden near Larnaca.

This garden was made for the public, and is situated about a —
quarter of a mile from the old town of Larnaca. It has been
suffered to fall into decay, and is now quite neglected. Mr.
“Mallock has described many beautiful scenes in his book, but I
think he could have found few more beautiful than this old
garden with its deserted gardener’s house, now a heap of ruins,
but overgrown with masses of luxuriant vegetation, with beauti-
ful flowers peeping out here and there as if charitably endeavour-
ing to hide the negligence of man, and to turn the desolation
into a scene of beauty. I got several prizes in this garden, but
found the Myriapods were principally represented by the species
I have mentioned. |

After leaving Larnaca I rode across the plain country
through blazing heat, which was rapidly parching up the ground
to a uniform brown colour. At every stopping-place I found
the same species of Scolopendra and of Lithobius. After a few
days I began to get up among the mountains of the northern
range, and the burning heat of the treeless plain was gradually
exchanged for the cool shade of the pine-trees and the fresh air
of the mountains. As I ascended higher and higher the tem-
perature grew cooler till I reached the top of Mount Troodos, the
ancient Olympus. Here in the month of May the snow still
lingered in white patches, and the air was clear and cold. I
remained on the top of Troodos for a week, whilegl made a close
examination of the fauna to.be found fiere. I was much
surprised to find the identical species of Scolopendra and

u HABITS AND DISTRIBUTION 33

Inthobius with which I had become acquainted in the heat of
the low country, quite at home among the snow, and as common
as in, what I should have imagined to be, the more congenial
climate. Nor were they any the less lively. Far from exhibit-
_ ing any sort of torpor from the cold, the first one which I
_ triumphantly seized in my forceps wriggled himself loose and
_ fastened on my finger with a vigour which made me as anxious
to get rid of him as,I had formerly been to secure him. How-
_ ever, he eventually went into my collecting box.

On the whole, we may say that the Chilopoda are most
_ largely represented in the hotter climates, where they find a
- more abundant, diet in the rich insect life of the tropical and
_ semi-tropical countries. The more brightly-coloured Myriapods,
too, are for the most part inhabitants of the warmer countries.
The ease with which they are introduced into a country in the
earth round plants, and in boxes of fruit, may account to a great
extent for the wide distribution of the various species in
different countries. Mr. Pocock, who examined the Myriapods
brought back from the “ Challenger ” Expedition, informs us that
of ten species brought: from Bermuda, four had been introduced
from the West Indies. There is no doubt that animals which
can bear changes of temperature and deprivation of food, and
even a short immersion in the water, are well calculated to be
introduced into strange countries in many unexpected ways. |

As might be expected from a class of animals so widely
distributed, Myriapods show an almost infinite variety of size
and.colour. We find them so small that we can hardly see
them with the naked eye, as in the case of the tiny Polyxenus,
the Pauropidae, and the Scolopendrellidae. We also find them
more than six inches in length, as the larger species of Scolo-
pendridae. I am afraid we must dismiss as an exaggeration an
‘account of Centipedes in Carthagena a yard in length, and more
than six inches in breadth. The giver of this account— Ulloa
—informs us that the bite of this gigantic serpent-like creature
is mortal if a timely remedy be not applied. It is certainly
extremely probable that the bite of a Centipede of this size would
be fatal to any one. Some Centipedes are short and broad, and
composed of few segments, as Glomeris ; some are long and thin,
with more than a hundred segments, as Geophilus. They may be
beautifully coloured with brilliant streaks of colour, as in some

VOL. V D

34 MYRIAPODA CHAP.

of the Julidae or Polydesmidae, or may be of a dull nse rusty
iron colour, or quite black.

One of the strangest peculiarities found among Myriapadl is
that some of them (eg. Geophilus electricus) are phosphorescent.
As I was walking one summer evening near my home in
Cambridgeshire I saw what I thought was a match burning.
Looking more closely, I saw it move, and thinking it was a
glow-worm I picked it up, and was surprised to find that it was
a Geophilus shining with a brilliant phosphorescent light. I let
it crawl over my hand, and it left a bright trail of light behind
it, which lasted some time. I have been told that this species
is common in Epping Forest; also in Cambridgeshire.’

Besides G. electricus, G. phosphoreus has been described as
a luminous species by Linnaeus, on the authority of a Swedish
sea captain, who asserted that it dropped from the air, shining
like a glow-worm, upon his ship when he was sailing in the
Indian Ocean a hundred miles from land.

What the use of this phosphorescence may be is not Enotes with
any degree of certainty. It may be either a defence against
‘einen, or else a means of attracting the two sexes to one another.

The places which the Myriapods select for their habitation
vary as much as their colour and size, though, with a few excep-
tions, they chose dark and obscure places. A curious species of
Myriapod is Pseudotremia cavernarum (Cope), which is found in
certain caves in America. The peculiar life it leads in these
caves seems to have a great influence on its colour, and also
affects the development of its eyes. Mr. Packard’s account
of them is worth quoting: “Four specimens which I collected
in Little Wyandotte cave were exactly the same size as
those from Great Wyandotte cave. They were white tinged,
dusky on the head and fore part of the body. The eyes are
black and the eye-patch of the same size and shape, while the
antennae are the same.

“Six specimens from Bradford cave, Ind. (which is a small
grotto formed by a vertical fissure in the rock, and only 300 to
400 yards deep), showed more variation than those from the two
Wyandotte caves. They are of the same size and form, but
slightly longer and a little slenderer. ... The antennae are
much whiter than in those from the Wyandotte caves, and the

! See L. Jenyns’ Observations in Nat. Hist. London, 1846, p. 296.

II: HABITS AND DISTRIBUTION 35

head and body are paler, more bleached out than most of the
Wyandotte specimens... . It thus appears that the body is
most bleached and the eyes the most rudimentary in the Bradford
eave, the smallest and most accessible, and in which consequently
there is the most variation in surroundings, temperature, access of
light and changed condition of air. Under such circumstances
as these we should naturally expect the most variation.”

A strong contrast to these animals is afforded us by the
Scutigeridae (Schizotarsia). They are unknown in this country,
but abound in some of the Mediterranean countries and in parts
of Africa. They remind one strongly of spiders, with their long

Fic. 17.—Cermatia (Scutigera) variegata. (From C. L, Koch, Die Myriapoden. )

legs and their peculiar way of running on stones and about the
walls of houses.

Some years ago I was in Malta, and I used to go and watch
them on the slopes outside Valetta, where they were to be found
in great numbers. They used to come out from beneath great
‘stones and run about rapidly on the ground or on the stones and
rubbish with which the ground was covered, now and again
making a dart at some small insect which tempted them, and
seemingly not minding the blazing sun at all. As might be
expected from their habits, their eyes, far from being rudi-
mentary, like those of the cave-living Pseudotremia, or absent

1 « 4 Revision of the Lysiopetalidae, a family of the Chilognath Myriapoda, with

a notice of the genus Cambala,” by A. S. Packard, junior, Proc. Amer, Phil. Soc.
xxi. 1884, p. 187.

36 MYRIAPODA CHAP.

like those of the Polydesmidae, or of our own Cryptops, are
highly developed, and form the only example among the
Myriapods of what are known as facetted eyes. The Scutigeridae
are also remarkable among Myriapods for the possession of a
peculiar sense-organ which is found in no other Myriapod.

The Myriapods most numerous in our own country are
Lithobius and Julus. nthobius, which will be described later on,
may be found in almost any garden under dried leaves, stones,
etc. Julus, the common wire-worm, is found crawling on plants
and. leaves and under the bark of trees, and does a good deal of.
damage in a garden. Polydesmus is also frequently found in
great numbers, and usually a great many of them together.
Glomeris is also found, though it is not so common as the first
two mentioned animals. Geophilus is also common, and especially
in the south of England. Scolopendridae are only represented
by a single genus, Cryptops, which is not very common, though
by no means rare. The best place to find them is in manure
heaps. ‘The animals of this species are small compared to most
Scolopendras, and have the peculiarity of being without any eyes.

Scutigera is unrepresented in this country. One was found
in Scotland some years ago by Mr. Gibson Carmichael, but was
shown to have been imported, and not bred in the place.

The means of defence possessed by these animals also differ
very much in the different species of Myriapods. In the.
Centipedes the animals are provided with a powerful weapon in
the great poison claws which lie just beneath the mouth, and
which are provided with large poison glands, which supply a
fluid which runs through a canal in the hard substance of the
claw and passes into the wound made by the latter. The effect
of this fluid is instantaneous on the small animals which form
the food of the Centipedes. I have myself watched Lithobius in
this country creep up to a blue-bottle fly and seize it between the
poison claws. One powerful nip and the blue-bottle was dead, as
if struck by lightning. I have also seen them kill worms and also
other Lithobius in the same way. When another Lithobius is
wounded by the poison claws it seems to be paralysed behind
the wound. The Millepedes, on the other hand, have no such
offensive and defensive weapon. They rely for protection on the
fluid secreted by the stigmata repugnatoria (or glandulae odori-
jferae) mentioned before. This fluid has been shown to contain

oe HABITS, BREEDING 37

prussic acid, and has a very unpleasant odour. Most of the
Millepedes are provided with these glands; but in the cave
Myriapods mentioned before, the animals have not to contend
against so many adversaries, and these glands almost disappear.
Other Myriapods defend themselves by means of the Jong and
stiff bristles with which they are pro-

vided, eg. the little Polyxenus. This
means of defence seems to have been
more common among the fossil Myria-
pods than among those still living.
Variations in the shape and size of the
limbs are numerous,as might beexpected F1¢-18.—Polyxenus lagurus (From
: , C. L. Koch, Die Myriapoden).
in so large a class of animals. One of

the most curious of such variations is found in a Centipede of the
Scolopendra tribe, called Hucorybas, in which the last limbs are
flattened out and provided with paddle-shaped lobes. The use
of these is unknown, but it is probable that they are concerned
in some way with the breeding habits of the animal. The
habits of the Myriapods connected with their breeding are most
interesting, but have been very insufficiently investigated. There
is no doubt that a full inquiry into all such habits would be of
great interest, and would help to answer some of the problems
which are still unsolved in these forms. My own observations
refer to two forms—Julus terrestris among the Millepedes, and
Lithobius forficatus among the Centipedes. Julus terrestris is
one of the most common of the English Millepedes, and can be
easily obtained. I kept them in large shallow glass vessels with
a layer of earth at the bottom, and thus was able easily to
watch the whole process. They breed in the months of May,
June, and July. The female Ju/us when about to lay her eggs
. sets to work to form a kind of nest or receptacle for her eggs.
She burrows down into the earth, and at some distance below
the surface begins the work. She moistens small bits of earth
with the sticky fluid secreted by her salivary glands, which
become extraordinarily active in the spring. She works up
these bits of earth with her jaws and front legs till they are of
a convenient size and shape, and places them together. When
complete, the nest is shaped like a hollow sphere, the inside
being smooth and even, while the outside is rough and shows
the shape of the small knobs of earth of which it is composed.

38 MYRIAPODA CHAP.

She leaves a small opening in the top. The size of the whole
nest is about that of a small nut. When she is ready to lay her
eggs she passes them through the hole in the top, and usually
lays about 60 to 100 eggs at a time. The eggs, which are very
small, are coated with a glutinous fluid which causes them to
adhere together. When they are all laid she closes up the
aperture with a piece of earth moistened with her saliva; and
having thus hermetically sealed the nest, she leaves the whole to
its fate. The eggs hatch in about twelve days. |

A German naturalist, Dr. Verhoeff, has lately found that the
males of some Julidae undergo certain changes in the form of the
legs and other organs in autumn and spring. These changes are
probably connected with the breeding of the animal, and remind
us of the changes undergone during the breeding season by salmon
among the fishes.

Julus breed very readily if carefully attended to and well
supplied with food. If they cannot obtain the food they like
they will not breed so well. I found that sliced apples with
leaves and grass formed the best food for them.

The process in the case of Zithobius is much harder to watch.
Lithobius is not so plentiful as Julus terrestris, and the animals
are more impatient of captivity, more shy in their habits, and do
not breed so readily.

In January 1889 I was given the use of a room in the New
Museums at Cambridge, and was allowed to fit it up as I liked,
so that I was able to try the effect of different degrees of light
and darkness, and of different degrees of warmth. I succeeded
in observing the whole process. The female Zithobius is
furnished with two small movable hooks at the end of the
under surface of the body close to the opening of the oviduct.
These small hooks have been observed by many naturalists, but
their use has, so far as I know, never been described before.
They play an important part in the proceedings following the
laying of the egg. The time of breeding in Lithobius is rather
later than in Julus, and begins about June and continues till
August. There are first of all some convulsive movements of the
last segments of the body, and then in about ten minutes the
egg appears at the entrance of the oviduct. The egg is a
small sphere (about the size of a number five shot), rather
larger than that of Julus, and is covered with a sticky slime

o

. ieee HABITS, BREEDING 39

secreted by the large glands inside the body, usually called the
accessory glands. When the egg falls out it is received by
the little hooks, and is firmly clasped by them. This is
the critical moment in the existence of the JLithobius into
which the egg is destined to develop. If a male Lithobius sees
the egg he makes a rush at the female, seizes the egg, and at
once devours it. All the subsequent proceedings of the female
seem to be directed to the frustration of this act of cannibalism.
As soon as the egg is firmly clasped in the little hooks she
rushes off to a convenient place away from the male, and uses
her hooks to roll the egg round and round until it is completely
covered by earth, which sticks to it owing to the viscous material
with which it is coated; she also employs her hind legs, which
have glands on the thighs, to effect her purpose. When the
operation is complete the egg resembles a small round ball of
mud, and is indistinguishable from the surrounding soil. It is
thus safe from the voracious appetite of the male, and she leaves
it to its fate. The number of eggs laid is small when compared
with the number laid by. Julus.

The food in the case of ZLithobius consisted of worms and
blue-bottles, which were put alive into the glass vessel containing
the Lithobius. I tried raw meat chopped up, but they did not
thrive on it in the same way that they did on the living animals.
I also put into their vessel bits of rotten wood containing larvae
of insects, ete.

I have succeeded in bringing back some specimens of Polydesmus
alive from Madeira, and in getting them to breed in this country
—of course in artificial warmth—and their way of laying eggs
and making a nest resembles that of Julus. Geophilus has one
eurious habit in connexion with the fertilisation of the female.
The male spins a web and deposits in the middle of it a single
spermatophore, and the female comes to the web to be fertilised.
The Scolopendridae are said to bring forth their young alive, but
I think the evidence for this is unsatisfactory. What have
been taken for the young Scolopendrae are perhaps the large
spermatophores of the male, which are not unlike a larval Myria-
pod in size and shape. I have never been able to observe the
process of breeding in this family. I have had the spermatophores
sent me from Gibraltar as “eggs,” but a little examination soon
showed me their real character.

40 MYRIAPODA CHAP.

The mode of progression in the Myriapods differs considerably,
as might be expected in a class in which the number of legs
varies to such an extent. The swiftest among them are the
Scutigeridae with their long spider-like legs. The Scolopendridae
are also able to move with considerable rapidity, and are also
able to move tail forward almost as well as in the ordinary
manner. Where there are such a number of legs it becomes a
curious question as to the order in which the animal moves
them; and though several people have endeavoured to find this
out, the number of legs to be moved and the rapid movements
have rendered accurate observation impossible.

Some years ago Professor E. Ray Lankester tried to study the
order in which the legs of Centipedes moved, and came to the
conclusion (recorded in an amusing letter in Nature, 23rd May
1889) that if the animal had to study the question itself, it
would not get on at all. He finishes his letter with the follow-
ing verses :—

A Centipede was happy quite

Until a toad in fun

Said, ‘‘ Pray which leg moves after which ?”
This raised her doubts to such a pitch,

She fell exhausted in the ditch,

Not knowing how to run,

The progression of Millepedes is much slower than that of
the Centipedes, and it is remarkable that when the animal is in
motion a sort of wave runs down the long fringe-like row of feet.
I have endeavoured to make out this motion, but have never
been able to understand it satisfactorily. My belief was that
“the feet were moved in sets of five.

This wave-like peculiarity of motion is described in a curious
old book, An Essay towards a Natural History of Serpents.
Charles Owen, D.D. London, 1742: “The Ambua, so the
natives of Brazil call the Millepedes and the Centipedes, are
serpents. Those reptiles of thousand legs bend as they crawl
along, and are reckoned very poisonous. In these Multipedes the
mechanism of the body is very curious; in their going it is
observable that on each side of their bodies every leg has its
motion, one regularly after another, so that their legs, being
numerous, form a kind of undulation, and thereby communicate
to the body a swifter progression than one could imagine where

II NAMES FOR MYRIAPODS 4I

so many short feet are to take so many short steps, that follow
one another rolling on like the waves of the sea.”
Before proceeding to the classification of Myriapods, which

will form the next part of this account, a few words on the

common names for them may not be without interest.

In English we have the names Centipede and Millepede,
and the Continental nations have similar names implying the
possession of a hundred or a thousand legs, as the German
“ Tausendfiisse ” and the French “ Millepieds.” Of course these
are general words, simply implying the possession of a great
number of legs. But we have also among the peasantry a name
for Centipedes which conveys a much more accurate idea of the
number. The people of the eastern counties (I daresay the
term is more widely spread) call them “ forty legs.” This is not
quite accurate, but as Lithobius has 17 legs on each side, and

Scolopendra (Cryptops is the English species) has 21 on each side,

it is a better approximation than Centipede. But another
country has a still more accurate term. I found some Scolo-
pendra in Beyrout, and asked my native servant what he called
them. He gave them what I afterwards found was the common
Arab name for them, “‘arba wal ‘arbarin,” forty-four legs. Now
the Scolopendras, which in hotter climates are the chief representa-

-tives of the Centipedes, have actually forty-two legs, or, if the

poison claws are counted, forty-four. In looking up the Arab
term for Centipede I came across a curious description given of

_ them by Avicenna, the great Arabian physician: “This is an

animal known for its habit of going into ears. For the most part
it is a palm’s length” [about four inches, which is the average
length of many species]. “ On each side of the body it has twenty-
two feet, and moves equally well either backwards or forwards.”

With regard to its alleged habit of going into ears, the
learned Arabian has evidently made a false imputation on the
character of our animal, and has probably relied too much on the
stories told him. He has also exaggerated in stating that it
goes equally well either backwards or forwards. Some Centi-
pedes can go backwards very easily and well, though not so well
as forwards. Perhaps he preferred examining dead specimens,
which afford an easy opportunity of counting their legs, to experi-
menting with living animals, which might have resented liberties
taken with them.

42 MYRIAPODA CHAP,

The Persians have several words for them, less accurate than
the Arabs and more like our own terms. For instance, they call
them “Hazarpa,” or thousand feet, like our Millepedes; also
“Sadpa,” or hundred feet, equivalent to our Centipedes. Another
term resembles our common term before mentioned, “ Chehlpa,”
forty feet. A more figurative term is “tasbih dud,’ a worm
resembling a rosary with a hundred beads; this word is trans-
lated in Richardson’s Persian Dictionary as “a venomous insect
having eight feet and a piked tail.”

Classification of the Myriapoda.

Two of the principal writers on the classification of the
Myriapods are Koch and Latzel, both of whom have classified
the whole group. I do not wish for a moment to undervalue
the many authors who have done excellent work on the classifi-
cation of different groups and families, but I wish here to give
an outline of a classification of the whole class, and I naturally
have recourse to the authors who have treated the subject as a
whole. | |

Koch’s two works, the System der Myriapoden: and Die
Myriapoden, cover the whole range of the class, and his divisions
are clearly marked out and are easily understood, but both works
are comparatively old. He does not include the Scolopendrellidae
or the Pauropidae, which are now included by all naturalists in
the Myriapoda. Latzel is a more recent writer, and though his
work is entitled Zhe Myriapods of the Austro-Hungarian Empire,*
he gives much information about Myriapods not found in
Europe, and his work is fairly entitled to be considered as
embracing the whole class. He divides the Myriapods into four
Orders, including the Scolopendrellidae and Pauropidae. On the
whole, I think it will be better here to take the classification of
Koch, and to add to it the two Orders before mentioned, viz.
Symphyla containing one family the Scolopendrellidae, and Pauro-
poda with one family the Pauropidae.

The Orders are as follows :—

1 C. L. Koch, System der Myriapoden. Regensberg, 1847.
2 C. L. Koch, Die Myriapoden. Halle, 1863.

3 Latzel, Die Myriapoden der Cisterreichisch-Ungarischen Monarchie. Wien,
1880.

I CLASSIFICATION 43

Order I. CHILOGNATHA (= DIPLOPODA).

Antennae short, 6, 7, or 8 joints. Eyes congregate, simple,
or none. Body rings consisting of dorsal scute, two pleurae, 2
or 4 laminae pedigerae. Odoriferous glands mostly present.
Genital orifice in male and female placed between 2nd and 3rd
segment. In male, auxiliary copulatory organs in last segment
or on 7th, 7th and 8th, or 8th.

Suborder 1. PsrLapsocnatHa. Body having no auxiliary copulatory

organs or odoriferous glands.
Family 1. Polyxenidae. (Fig. 18, p. 37.)

Antennae 8 joints. Somites 11, last with bundle of setae. 13 pairs of legs,

Male with penis.
Family 2. Glomeridae.
12 tergites. 17 pairs of legs. Ocelli in single row.

Fic. 19.—Glomeris marginata. (From C. L. Koch, Die Myriapoden.)

Family 3. Zephroniidae.
13 tergites. 21 pairs of legs. Eyes crowded together in a cluster.

Fic. 20.—Sphaerotherium grossum. (From C. L. Koch, Die Myriapoden.)

Family 4. Julidae.

Body cylindrical. More than 30 body rings) Many eyes crowded
together in a cluster. Odoriferous glands always present.

Fic. 21.—Julus nemorensis. (From C. L. Koch, Die Myriapoden.)

44 MYRIAPODA CHAP.

Family 5. Blanjulidae.

Thin cylindrical body with more .than 30 body rings. Eyes either
absent or in a simple row beneath the edge of the forehead.

Latin

Fia. 22.—Blanjulus guttulatus. (From C. L. Koch, Die Myriapoden. )
Family 6. Chordewnidae,

Resemble the Polydesmidae (Fam. 7), but the head is longer and less rounded
in the forehead. The antennae are placed more at the side of the head.
Eyes small and numerous, ina cluster. Somites 30 or 32. ° (Fig. 16).

Family 7. Polydesmidae,

Body cylindrical, with a lobe or keel on the posterior part of the upper
surface of the body ring. Somites 19 or 20. No eyes.

Fic, 23.—Polydesmus collaris. (From C. L. Koch, Die Myriapoden.)

Suborder 2. ConopognatHa. Family 8. Polyzoniidae:

Head small, eyes few or none. Mouth-parts degenerate, adapted for
sucking. Pieural scutes free or coalesced. Laminae pedigerae free. Somites

30 to 108. Ist, and 2nd somites with one pair of feet. 3rd or Ist and

2nd apodous. Foramina repugnatoria present, Auxiliary copulatory organ
in 7th somite.

Order II. CHiLopopa (or SYNGNATHA).

Antennae with many joints, at least 14. Only one pair of
legs to each body ring. The genital opening on the last ring
of the body. Bases of the legs widely separate.

There are four families in this Order :—

II CLASSIFICATION

45

Family 1. Lithobicdae.
Body short and depressed. Eyes many or few; or a single ocellus on
each side. Antennae many joints but shorter than body. Number of

Fic. 25.—Lithobius erythrocephalus. (From C. L. Koch, Die Myriapoden.)
spiracles fewer than pairs of feet. Strong anal legs. Number of somites 15.
} Family 2. Scolopendridae.

- Body elongate. Ocelli on each side 4, 2, or none. Antennae 17 to 23

joints, much shorter than body. Spiracles fewer than pairs of feet. Anal
legs long and strong, number of legs 21 or 23. (Fig. 15, p. 31.)

Family 3. Notophilidae.
Body very long. Somites 100 to 170. No eyes, Maxillary palps very

Fic. 26.—Notophilus taeniatus. (From C. L. Koch, Die Myriapoden.)

thick. Compact or very short limbs.

Terminal point of last limb without
claw.

46 MYRIAPODA CHAP,

Family 4. Geophilidae.
Body very long; legs 13 to 173 pairs. No eyes. Antennae 14 joints,

Ba

Fia. 27.—Geophilus longicornis. (From C. L. Koch, Die Myriapoden.)

shorter than body. Spiracles fewer than pairs of legs. Anal pleurae coxi-
form.

Order III. ScuIzoTARSIA.

The tarsi of all the legs multiarticulate. The eyes facetted.
Peculiar sense organ beneath the head.

Family 1. Scutigeridae.

Body short and strong. Antennae very long and thin. Facetted eyes.
No spiracles, but stomata in back. (Fig. 17, p. 35.)

Order IV. SYMPHYLA.

Body small, 12 segments, which according to Schmidt equal
22 primary segments. One pair of tracheae opening in the head.
Genital opening before coxae of 4th pair. 1st and 2nd segments
with one pair of legs, rest with a pair and parapodia. Ovaries
beneath the gut. A head artery and a dorsal vessel with ostia
and alary muscles.

Family 1. Scovopendrellidae.
With the characters of the Order.

" STRUCTURE 47

Order V. PAUROPODA:

Body 12 somites, 8 of which fuse to double somites, 7 pairs of
legs. 1st and anal legs with 5 joints, rest 6 joints. Antennae
branched. No tracheae or vascular system. Ovary below gut,
testis above. Genital opening in 3rd somite.

Family 1. Pawropidae.
With long legs.
Family 2. Eurypawropidae.
With short legs.

The Structure of the Myriapoda.

Having now given a short view of the classification of the
Class, I will proceed to give a general account of their structure,
the variations in which have led to the divisions into the various
Orders and Families. Their structure shows resemblances to
several widely different classes of animals. One cannot help

being impressed with their likeness to the Worms, at the same

time they have affinities with the Crustaceans, and still more
with the Insects. In the latter class the likeness of the Thy-
sanuridae to Scolopendrella and Pauropus have induced a cele-

_ brated Italian anatomist, Professor Grassi, to claim the former as

the ancestors of the Myriapoda.

Myriapods have a body which is segmented, as it is termed ;
that is, composed of a number of more or less similar parts or
segments joined together.

One of the most important characteristics which distinguish
Myriapods from other Arthropoda is the fact that they possess
on the posterior segments of the body true legs which are
jointed and take part in locomotion. The head is in all cases
quite distinct from the body, and may be regarded as a number
of segments fused together into one mass. Their heads are
always provided with a single pair of antennae and mouth
appendages, consisting of an upper lip, a pair of mandibles or
jaws, and one to two pairs of maxillae. The mandibles resemble
those of Insects, and are strongly toothed. In the Chilognatha
a pair of maxillae are fused so as to form a single oval appendage.
In the Chilopoda they each consist of a single blade bearing a

48 MYRIAPODA CHAP.

short palp or feeler. The mouth parts may have the forms
known as chewing, biting, or suctorial (Polyzonium) mouth
appendages. ;

With the exception of the terminal segment, and in many
cases the first or the seventh, each segment bears one or two
pairs of limbs. These may be very idug, as in Seutigera, or very
short, as in Polyxenus. They may be attached close to one
another near the ventral middle line of the body, or may
have their bases far apart from each other, as in the Chilopoda.
The exoskeleton or external armour is composed of chitin
(Chilopoda) or of chitin with calcareous salts deposited in it
(Chilognatha).

Their internal structure has a great likeness to that of
Insects.

The general position of the internal organs may be seen from ~
Fig. 28, which shows a Lithobius dissected so as to exhibit the
digestive and nervous systems.

The digestive canal, which is a straight tube, extends through-
out the whole length of the body, and terminates in the last
segment of the body. It may be divided into the ee
parts :—

1. A narrow oesophagus, beginning with the mouth or bisael

cavity, and receiving the contents of two or more
salivary glands (d).

2. A wide mesenteron or mid-gut (x) extending throughout
almost the whole length of the body.

3. A rectum which at its junction with the mid-gut receives
the contents of two or four Malpighian tubes (g, h) which
function as kidneys. Their function was for a long

" time unknown, but the discovery of crystals of uric
acid in them placed the matter beyond doubt.

The heart has the form of a long pulsating dorsal vessel
which extends through the whole length of the animal. It is”
divided into a number of chambers, which are attached to the
dorsal wall of the body, and are furnished with muscles of a
wing-like shape, which are known as the alary muscles, and
which govern its pulsations. The chambers are furnished with
valves and arteries for the exit of the blood, and slits known as
ostia for the return of the blood to the heart. The blood enters .
the chambers of the heart from the body cavity through the

1 STRUCTURE 49

ostia, and passes out through the arteries to circulate through
' the organs of the body and to return by the ostia.

The two figures below (Figs. 29 and 30) show the position of
the arteries and the ostia in a single segment of the body. The
heart is too small and delicate to be seen with the naked eye; it

es

Fic. 28.—Lithobius dis-
sected. (After Vogt
and Yung.) .

a, antennae.

6, poison claws.

c, brain.

d, salivary glands.
é, legs.

J, nerve cord.

g, Malpighian tube.
h, Malpighian tube.
7, vesicula seminalis.
js accessory gland,
k, accessory gland,
Z, testis. «

m, thigh gland.

n, digestive tube.

therefore requires the aid of the microscope. <A freshly-killed
animal was therefore taken and prepared in the manner known
to all microscopists, and extremely thin slices or sections cut
horizontally from its back. One of these sections cut the whole
length of the heart in one segment, which was accordingly drawn
under the microscope (Fig. 29), and shows a longitudinal hori-

VOL. V E

50 MYRIAPODA CHAP. —

zontal section through the whole length of the heart in a single
segment, with the two ostia at each end of the segment and the |
two arteries in the middle.

The arteries, when they leave the body, pass into masses of
fatty tissue on either side of the heart, and the other figure (Fig. .
30) is intended to show the artery leaving the heart and penetrating
into the fatty tissue. The figure is taken from the same section
as the former one, but is much more highly magnified, so as to
show more detail. The delicate coats of the heart are shown,
the artery being covered with a clothing of large cells.

—
)
° ©
i is]
Art—
©
8
a)
Sake ost

Fic, 29.—Heart of Fic. 30. — Heart of Julus terrestris showing structure of

Julus _ terrestris artery (Art.) and external coat of heart (ezt.c), also fat body

showing ostia (ost) (F), highly magnified. Ht, The cavity of the heart. The

and arteries (Art) circular muscle fibres which surrounds the heart are shown

magnified. just below the external coat (ext.c) ogl, Oil globules of the
fat body. .

Myriapods breathe by means of tracheae, with the exception of
~ the Scutigeridae, which have an elementary form of lung which
resembles that of spiders, and will be mentioned further on.
These tracheae, as in Insects, are tubes lined with chitin, which
is arranged in spiral bands. The tracheae open to the exterior
by openings called stigmata, through which they receive the
external air, which passes into the main tracheal tubes and into
their ramifications, and thus effects the aeration of the blood.
The nervous system of the Myriapods consists, as in Insects,
of a brain, which may be more or less developed, a circum-
oesophageal ring embracing the oesophagus, and a ventral chain
of ganglia, and in some cases (Newport) of a system of visceral -

a. STRUCTURE 51

nerves. With the nervots system we may mention the sense
organs, the eyes, which are present in most cases, though
wanting, as has been already stated, in many groups. They are
usually present as clusters of ocelli or eye spots closely packed
together, or (in Sewtigera) as peculiarly formed facetted eyes. The
sensory hairs on the antennae must be reckoned as sense organs,
as also the tufts of sense hairs on the head of Polyxenus. Seuti-
gera has also a peculiar sense organ beneath the head, consist-
ing of a sac opening on the under side of the head full of
slender hairs, each of which is connected at its base with a nerve
fibre. Except the eyes, the Myriapod sense organs have usually
the form of hairs or groups of hairs connected with nerve fibres,
which communicate with the central nervous system.

Fic. 31.—Under side of the head
of Seutigera coleoptrata, with
sense organ. eo, Opening of
sense organ to the exterior ;
0, sense organ shown through Fia, 32.-—Highly magnified section through head

the chitin; m, mouth; oc, of Polyxenus lagurus, showing sense organ.
eye; mal, maxilla ; f, furrow in ext.cut, external cuticle; ¢, tube surrounding
the chitin. (Heathcote, Sense base of sense hair; gang.c, ganglion cell.
organ in Seutigera coleoptrata. ) (Heathcote, Anatomy of Polyxenus lagurus. )

These two sense organs are shown in Figs. 31 and 32.
Fig. 31 shows the under side of the head of Seutigera (Fig.
17), with the position of the sense organ and its opening.
Fig. 32 is part of a section through the head of Polyaenus with
two of the sense hairs. Each spine or sense hair fits into a cup
in the chitin of the head ; and the lower or internal part, which
is divided from the upper or external part by a rim, is joined to
a ganglionic nerve cell (gang.c.).

The Myriapods are of separate sexes, and the generative
organs in both cases usually have the form of a long unpaired

52 , MYRIAPODA CHAP.

tube, which in the male is connected with accessory glands, and
in the female is usually provided with double receptacula
seminis. The: generative openings usually lie near the base of
the second pair of legs (Chilognatha), or at the posterior end of
the body (Chilopoda). In the Chilognatha there is usually in the
male an external copulatory organ at the base of the seventh Par
of legs, remote from the genital opening.

The preceding account of the anatomy of the Myriapods has
shown us the general characteristics of the whole group. I shall
now take each of the five Orders into which the class is divided
in the classification adopted in this account, and endeavour to
explain the differences in anatomy which have led to the estab-
lishment of the Order. The first Order with which we have to
do is that of the Chilognatha, which includes a large number of
Myriapods; no less than eight families, some of them including
a great number of forms.

Order I. Chilognatha.

The Chilognatha differ from other Orders in the shape of the
body. This is in almost all cases, cylindrical or sub-cylindrical,
instead of being more or less flattened as in the other Orders.

The body, as in all other Myriapods, is composed of segments,
but in the Chilognatha these segments are composed, in almost
all cases, of a complete ring of the substance of which the
exoskeleton (as the shell of the animal is called) is composed. —
This substance is in the case of the Chilognatha chitin (a kind
of horny substance, resembling, for instance, the outer case of a
beetle’s wing), containing a quantity of chalk salts and colouring
-matter; the substance thus formed is hard and tough. In other
Orders a chitin of the exoskeleton is without chalky matter
and is much more flexible. The length of the body, as may be
seen from the classification, may be either very long, as in Julus,
or very short, as in Glomeris.

The next anatomical character distinctive of the Order is
the form of the appendages. First, the antennae. These are, as
a general rule, much shorter than in the Chilopods, never
reaching the length of half the body. They are, as a rule, club-
shaped, the terminal half being thicker than the half adjoining
the body.

ie STRUCTURE OF CHILOGNATHA 53

The next appendages to be mentioned are the mouth parts.
These differ in form from those of the other Orders, and their

‘differences are connected very largely with the fact that the

Chilognatha live on vegetable substances. Their mouth parts
are adapted for chewing, except in the case of the Polyzoniidae,
the eighth family of the Order, in which, according to Brandt,
the mouth parts are adapted for sucking, and are prolonged
into a kind of proboscis. The mouth parts of the Chilognatha
consist of—
(1) An upper lip. A transversely-placed plate, which is fused
with the rest of the head.
(2) A pair of powerful mandibles or jaws adapted for mastica-
tion, and moved by powerful
muscles. jf and g in Fig. 33
shows these mandibles, while
the rest of the figure consti-
tutes the broad plate (No. 3).
(3) A broad plate covering the under
part of the head and partially

enclosing the mouth. This Fis. 338.— Mouth parts of

; Chilognatha. (From C. L.
structure, which, as we shall Koch, Die System der
afterwards. see, is formed by Afyriapoden.) f and 9,

the fusion of two appendages
which are distinct .in_ the
animal when just hatched, has
been called the deutomalae,
the jaws receiving the name of

The mandibles. The parts
marked a, 0, c, d, e are
firmly united and consti-
tute the broad plate No. 3.
They have received the
following names—a, }, In-
ternal stipes; c, external
stipes; d, malellae; e,
hypostoma.

protomalae.

After the mouth parts we come to the legs. We first notice
the fact that the bases of the legs in each pair are closely
approached to one another. They are so set into the body that
the basal joints, or, as they are called, the coxal joints, nearly
touch. This is the case in almost all Chilognatha, except in the
Polyxenidae, and it is a fact connected with some important
features in the internal anatomy. Then we have the peculiarity
in the Chilognatha which has formed the basis of most classifi-
cations which have placed these animals in a group by themselves.
This is the possession in most segments of two pairs of legs.
This characteristic has caused the group to be called by some
naturalists Diplopoda. As a general rule, the first four segments

54 - °' 7° “MYRIAPODA CHAP.

have only three pairs of legs between them, one of them being
without a pair of legs. This legless or apodal segment is
usually the third. From the fifth segment to the end of the
body all the segments have two pairs of legs each. The legs are
shorter than those of the Chilopods, and are all nearly equal in
size. This is not the case in the other Orders. The legs are
commonly wanting in the seventh segment of the male, and are
replaced by a copulatory organ. This peculiarity is related to
the different position of the generative openings in the Chilo-
_gnatha. Another anatomical feature peculiar to the Chilognatha
is the possession of the stink glands—the glandulae odoriferae
before mentioned. This, however, is a character which does not
hold for all the Chilognatha, since the Polyxenidae have none of
these glands. All the other families, however, possess them,
except ‘the Chordeumidae.

As regards the internal anatomy of the Chilognatha, the
digestive rane differs.mainly in the glands which susp it with
secretions. It receives the saliva from two long tubular salivary
glands, which open at the base of the four-lobed plate which has
been mentioned as the third of the mouth appendages. The
secretion of these glands is used, as has already been said, in the
“process of preparing the nest for the eggs. We cannot fail to
be reminded of a similar function of salivary glands in those
swallows, which prepare the nests of which bird’s-nest soup is
made with the secretion of the salivary glands. Another feature
in the form of the digestive tube is that in many cases, if not in
all, it is marked with constrictions which correspond with the

segments of the body.

The heart in the Chilognatha is not such a highly developed
organ as in the other Orders. The muscles which have already
been mentioned as the alary muscles (or wing-shaped muscles)
are not so highly developed, and consist for the most part of a
few muscular fibres. The muscular walls of the heart, which
consist of three layers, have the muscles less strongly developed,
and are in general adapted for a less energetic circulation.

The tracheae, which open into the stigmata, as has already .
been said, branch into tufts of fine tubes, but the ramifications of
these tufts never join (or anastomose, as it is called), and con-
sequently we never get, as in the other Orders, long tracheal
trunks running along the body.

aa _, STRUCTURE OF CHILOGNATHA 55

The xervous system, in addition to the existence of the
visceral nerve system described by Newport, shows a marked
peculiarity in the form of the ventral ganglionic chain. As
has already been said, the nerve system consists of a brain or
mass of ganglia fused together and connected with the ventral
nervous cord by a collar of nervous substance surrounding the
oesophagus, and generally known as the cirewmoesophageal collar.
The ventral nerve cord is a stout cord of nervous substance
passing along the whole length of the animal, and situated below
(or ventral to) the digestive tube and the generative system.
This cord is enlarged at certain points, and these enlargements or
swellings are called ganglia, while from the ganglia pass off
nerves which supply the different organs of the body. In the
Chilognatha the cord has a compressed appearance as if the
ganglia were pressed into one another in such a way that it is
very hard to distinguish any ganglia at all. If we use the
microscope and examine sections cut transversely through the
cord, we see that it is not a simple cord. Even if we examine
the nerve cord with a simple lens, we see that a furrow runs
longitudinally down it, and the use of the compound microscope
shows us that this furrow represents a division into two cords in
such a way that the single stout cord as it appeared to the naked
eye is in reality two cords running side by side, and so com-
_ pressed together that the substance is partly fused together.
The Paglia too are double, being swellings of the two cords and
not a siigle enlargement on a single sont As we shall see in
the other Orders, this arrangement constitutes a characteristic
distinction.

The generative organs consist of a long tubular ovary or testis
lying along almost the whole length of the body and placed
between the digestive organ and the nervous system. Near its
exit from the body the long tube divides into two short tubes,
the oviducts in the female or the vasa deferentia in the male.
These ducts open in the third segment of the body, unlike
those of Myriapods belonging to other Orders. The accessory
glands present in most other Myriapods are not present in the
Chilognatha.

The general arrangement of the organs of the Chilognatha
may be seen from Fig. 34, which represents a transverse section
through the body of Polyzenus (Fig. 18). A comparison of

56 MYRIAPODA ve CHAP.

these two figures (Figs. 34 and 18) will show the position of the
organs mentioned in this account. The heart is shown with
the suspensory and alary muscles attached.

Ree.sen.

ori.alct.

gne. fre.

Fic. 34.—Transverse section through Polyxenus lagurus: g.n.c, f.n.c, ganglionic and
fibrous parts of nerve cord; Rec.sen, receptaculum seminis; ori.dct, oviduct ;
Spmzoa, spermatoza. (From Heathcote, Anatomy of Polyxenus lagurus. )

Order II. Chilopoda.

The shape of the body differs from that of the Order which
has been just described (Chilognatha), inasmuch as it is not
cylindrical but flattened, the back, however, being more ‘arched
than the ventral surface. In this respect, however, it cannot be
said to differ from the other Orders which we have yet to describe.

The segments are not formed by a single ring of the
exoskeleton, which in this Order is formed of chitin, and is tough
and flexible rather than hard and strong; but of two or three
plates which form a covering to the segment. The back is
covered by a large plate known as the tergum, the sides by two,
plates known as pleura, and the ventral part by a plate called
the sternum. The pleura and sternum are, however, in most cases
fused together or indistinguishable. In this, as in most of the .
anatomical peculiarities, there is a much greater difference
between the two Orders Chilopoda and Chilognatha than between

a: | STRUCTURE OF CHILOPODA 57

_ the Chilopoda and the other three Orders which have still to be

described.

_ The Chilopoda have only one pair of appendages to each

segment of the body instead of two pairs like the Chilognatha.
The antennae of the Chilopoda are as a rule very long, and

* are always longer than in the Chilognatha which we have just

deseribed. They differ from those of the Schizotarsia (the third
Order, which will be the next to be described) in having the
basal joints nearer together; in other words, they are differently
placed on the head. They differ from those of the Pauropoda
(the fifth Order) in being straight and not branched. As a rule
the antennae of the Chilopoda taper towards the extremity.

A B c
Fic. 35.—Mouth parts of Lithobius (Latzel). A, Head of Lithobiws seen from the
~ under surface after removal of poison claws: a, second maxilla; 0, c, the two
shafts of the first maxilla, B, One of the mandibles. ©, The two poison
claws.

The mouth parts are more numerous than in the Order we

have just described (the Chilognatha). They consist of—

1. An upper lip. This is a transverse plate as just described
in the case of the Chilognatha, but it is not always
fused with the rest of the head. It is also usually
composed of three pieces, two lateral and a middle piece.

2. A pair of jaws or mandibles, which are not of so simple a
form as those of the Chilognatha, but rather resemble
those of some of the Crustacea.

3 and 4. Two pairs of appendages called maxillae resem-
bling feet, but used to aid the act of eating instead
of locomotion. They are very different in different
Chilopods, but are mostly slender and weak and usually
provided with feelers (or palps) growing out of the
main stem.

58 . mee MYRIAPODA cHap.

5. The next pair of sana are the first pair of the legs
of the body, which are also metamorphosed to serve
a function different from the ambulatory function of
the other limbs. These are the poison claws, and the
possession of these forms another distinction between
the Order we are now discussing and that. of the Chilo-
gnatha. At the same time the third Order, that of the
Schizotarsia, has poison claws, so that this feature does
not separate the Chilopoda from all the other Orders.
These poison claws are large curved claws connected
with poison glands, the secretion of which flows through
a canal which opens near the point.

The /egs are longer than those of the Chilognatha, but not so
long as those in the next Order to be described (the Schizotarsia).
Their number is very various, from 15 pairs in Lithobius to 173
in the Geophilidae. Latzel notes a curious point in the number
of the legs in this Order, namely, the number of pairs of legs is
always an uneven one. There are always one pair to each seg-
ment. The last pair of. legs is always longer than the other
pairs, and this is a peculiarity of the Order.

The digestive tube resembles that of the other Orders, but
the salivary glands are not long and tubular but short (Fig. 28,
d). It is, moreover, not snankee with constrictions correspeaaam
with the segments of the body.

The ° Petheal system or the system of respiration may be
said to be more highly developed in this Order than in any
other. The tracheal branches anastomose with one another (that
is, the branches join), and in some cases form long tracheal stems
running along the body almost for its whole length. The number
of the tracheal openings or stigmata varies and does not correspond
with the number of segments.

The nervous system differs considerably from that in the
Order Chilognatha; it resembles that in the Schizotarsia, and
differs again from that in the other two Orders, Symphyla and
Pauropoda. The brain shows some differences from other Orders
chiefly in the development of the different lobes which are con-
nected with the sense organs, the eyes and antennae, for instance ;
but the most marked difference is in the ventral ganglionic cord.
First, the ganglionic swellings are much more clearly marked
than in the Chilognatha. Secondly, the first three ganglia differ

yp tt STRUCTURE OF SCHIZOTARSIA 59

from the others in being nearer to one another and forming a:
single mass when seen by the naked eye, though when examined
by the aid of a microscope we can see all the different parts are
there. Thirdly, the division into two.cords mentioned in the
Chilognatha is carried to a much greater extent. The ganglia in
each segment can be seen plainly to be double, and the cords
connecting the ganglia are two in number. We can plainly see
that the ventral nervous system of the Chilopoda consists of two
cords lying parallel to one another, and each having a ganglionic
enlargement in every segment. Whether a visceral nervous
system is present in the group is doubtful.

The eighth family of the Chilognatha, the Polyxenidae, show
an approach to the Chilopod nervous system.

a The generative system differs chiefly in the opening of the
genital apparatus at the end of the body instead of in the third
segment; though this difference only separates. the Order from
the Chilognatha and not from the other Orders. They also have
two pairs of large accessory glands (as they are called) connected

_ with the genital openings. |

‘J
¥
a
e
.
‘

Order III. Schizotarsia.

The third Order of Myriapods, the Schizotarsia, show a much
greater resemblance to the Chilopoda than to the first Order, the
Chilognatha. There are, however, important differences to dis-
tinguish them from all the other Orders.

The shape of the body is short, thick,and very compact. The
composition of the individual segments resembles that found in
Chilopoda rather than that of Chilognatha.

The antennae are very long, longer than in any of the
Chilopods, and are composed oh a great number of very small

joints. The mouth parts show a greater length and slenderness
| than do those of the other Orders “mentiosied: as yet. They con-
sist of— |
1. An upper lip partly free, but fused at the sides with the
rest of the head. The upper lip is in three parts, as in
the Chilopoda, but with the middle. part very small and
the lateral pieces large.
2. A pair of jaws or meinaables. These are provided not only

with teeth, as in the other Myriapods, but also with a

sort of comb of stiff bristles.

60 MYRIAPODA CHAP,

3 and 4. Two pairs of maxillae or foot jaws distinguished by
their length and slenderness.

5. The poison claws long, slender, and not sharply curved.
The bases of the poison claws hardly fused together and
short.

The respiratory system in the Schizotarsia differs focal that in
all other Myriapods in the fact before mentioned, that they
breathe by means of lungs and not by tracheae. There are, as
before mentioned, eight dorsal scales in these animals; each dorsal
scale except the last bears one of the peculiar organs which I
have called lungs. At the hinder end of the scale there is a slit
which leads into an air sac, from which a number of short tubes
project into the blood in the space round the heart and serve to
aerate it before it enters the heart. The heart, therefore, sends
aerated blood to the organs, while in the tracheal-breathing
Myriapods the blood is aerated in the organs themselves by
means of tracheae. 3

The poison claws are followed by segments bionstbire fifteen pairs |
of true ambulatory legs. These are covered by eight large dorsal
plates, increasing in size from before to the middle of the body,
the middle plate being the largest, and then diminishing in size.

The nervous system resembles that of the Chilopoda, but there
is a special pair of nerves which supply the sense organ, which
has. been mentioned as peculiar to the Order. The ventral nerve
cord shows a very clear division into two, the ganglia of the two
cords being almost entirely separate. The first few, ganglia are
fused, as has been mentioned in the Chilopoda.

The digestive tube resembles that of the Chilopoda. The legs
are very long and slender, and the joints are beset with bristles.
Both sexes have small hook-like appendages at the sides of the
genital openings.

The eyes have already been mentioned as being more highly
developed than in other classes, in correspondence with the more
active habits of the animal. The generative organs open at the
hind end of the body, as in Chilopoda.

The heart is highly developed, quite as much so as the
Chilopod heart, the alary muscles being strong and broad, and
the arteries being quite as perfect as those in any Myriapod.
The muscular coats which govern the pulsations by their con-
tractions are powerful and well developed.

STRUCTURE OF SYMPHYLA 61

,
x

Order IV. Symphyla.

We next come to one of the last two Orders which have

a been recently added to the Myriapoda. These little animals

have a great resemblance to the Thysanura among the Insects,

and especially to Campodea among the Thysanura. It will be

_ well, therefore, to begin our account with a few of the reasons
which have induced naturalists to include them among the
_ Myriapods rather than among the Thysanura.

1, Campodea has three pairs of mouth appendages, while

_ Scolopendrella has only two.

2. Scolopendrella has broad plates covering the back, not only
on the anterior (thoracic) segments, but on the whole
body.

3. The terminal appendages of Scolopendrella differ from
those in Campodea.

4. Scolopendrella has a sense organ which is absent in
Campodea.

5. Campodea breathes by means of three stigmata in the

- anterior part of the body. The stigmata of Scolopen-
drella are hard to see, and are not in the same position.

6. Scolopendrella has twelve pairs of legs, and Campodea, like
all Insects, has only three.

I will now go on to an account of their anatomy. The body
is small and slender, and is covered with a delicate shell or exo-
skeleton of chitin, which is so thin as to be almost transparent.

The antennae are long, and are composed of many joints of
equal size.

The mouth parts consist of—

1. An upper lip.
2. A pair of mandibles.
3. A pair of maxillae.

The seoments are not all of equal size. Some are larger than
others, The larger and smaller segments are arranged alter-
nately, and the smaller do not bear legs. As before stated, there
are twelve leg-bearing segments.

At the end of the body there are two hook-like appendages

_ which are pierced by a canal, through which is poured the secretion

of a pair of glands. Near the sides of these appendages are a pair
of sense organs, consisting of long hairs connected with nerves.

62 MYRIAPODA CHAP.

The digestive canal is a long straight tube passing through
the length of the body. In the middle it is much enlarged, so
as to form a stomach with a glandular coat. Posterior to the
stomach the digestive tube receives the contents of two Mal-
pighian tubes which act as kidneys.

The tracheal system consists of a single pair of stigmata on
the under surface of the head, and the tracheae connected with
them.

Order V. Pauropoda.

The Pauropoda, which form the fifth Order of Myriapods, are
as yet very imperfectly known. Pawropus was discovered by Sir |
John Lubbock, and its discovery was announced by him in 1866.
He found this little Centipede in his kitchen garden among some
Thysanura, and at first considered it as a larval form, but
continued observation showed that it was a mature creature.
He described it as a small, white, bustling, intelligent little
creature about 5; inch in length.

The antennae are very curious and highly characteristic of
the Order. They resemble those of Crustacea rather than those
of Myriapoda. Each antenna is composed in the following
manner. First there is a shaft of four joints. From the fourth
joint of this shaft spring two branches; one of these two
branches is narrower than the other, and ends in a long thin
bristle composed of a great number of joints. The other and
broader branch bears two such bristles, and between them a small
pear-shaped or globular body, the function of which is unknown.

The mouth parts consist of two minute pairs of appendages,
the anterior pair toothed and the posterior pointed. The body
‘is rather narrower in front; the segment behind the head has
one pair of legs, the second, third, fourth, and fifth behind the
head two each. The posterior legs are the longest; the genital
organs open at the base of the second pair of legs, between these
and the third pair. The manner of breathing is as yet unknown,
tracheae not having been discovered.

Pauropus at first looks most like a Chilopod, but differs from
that Order—

1, In the form of the antennae.

2. In the absence of poison claws and in the form of the

mouth parts.

‘ovum is a small sphere of living trans-

EMBRYOLOGY ~ 63

3. The opening of the generative organs being in the front
part of the body.
It differs from Chilognatha in the following respects :—
- 1. The legs are not of equal length, the posterior legs
being the longest, as in Chilopods.
2. The mouth parts differ from those of Chilognaths
almost as much as from those of Chilopods.
3. The form of the antennae.
Only a few Pauropoda have been discovered as yet.

Embryology.

The preceding account of the anatomy of Myriapods would be
incomplete without some reference to the wonderful manner in

which the different organs of the body are built up; the whole

of the complex organism proceeding by a gradual and regulated
process of development from a simple cell called the ovum derived
from the female body, and united with a cell from the male body
(called the spermatozoon). I hope to be able to give my readers
some idea of the interest which the pursuit of the difficult study
of embryology adds to anatomy, by offering us a key to the inter-
pretation of the relations between our knowledge of the forms at
present living on the earth and those which, we learn from
Palaeontology, have inhabited our planet in past ages.

Like all living creatures with which we are acquainted, the
starting-point of Myriapod life is the ovum,
as it is called. This ovwm is a cell resem- |
bling the cells of which the body of all /;
living animals are built up, and which
may be compared to the bricks of which
a building is composed. This cell or

| ., Fic. 36.—Young ovum of
parent substance called protoplasm, and it — yudus terrestris: nucl,

is nucleated—that is, it contains a small nucleolus; nw, nucleus ;
, R, first appearance of

spot of denser protoplasm called the . yolk; F, follicle cells.

nucleus, and within that a still smaller

spot of still more dense protoplasm called the nucleolus. In the

process of impregnation the ovum unites with the male cell, and

the cell so formed is called the impregnated ovum. This ovum

has the property of dividing into two cells, each resembling the

64 | MYRIAPODA CHAP.

parent cell from which it is derived; each of these cells has, like
the parent cell, the same property of dividing into two more, and
so on. Thus from this continual process of division or reprodue-
tion of every living cell, the materials are provided for the
building up of the body.

The regularity of the process of the division of the ovum, or,
as it is called, segmentation of the ovum, is interfered with by
the presence of food yolk. The cells formed by the process of
cell division just described need nourishment, and this nourish-
ment is supplied to them by the food yolk formed in the body
of the ovum before the process of segmentation begins. It is
easy to understand that this yolk, which is not alive like the

I Yily
ity LI Oo"

{> 7 A =< y ip
SOsScores
RY
ie Py A

Fic. 87.—Later stage: nw,
nucleolus ; ¢.p, nucleus ;
y.sp, yolk spherules ; ch,
shell.

cells, cannot divide like them, and therefore the segmentation of
the ovum in Myriapods is irregular, as it is called.

I will now go back a little and describe what happens to the
ovum before the process of segmentation iscomplete. It increases
in size and forms the supply of food yolk which is to provide the
uutriment of the ovum. Then after impregnation the egg-shell
is formed round it, and it becomes what we know as the egg.
This egg is not a perfect sphere, but is oval (in most Myriapods)
in shape. The egg is laid, and the process of segmentation begins
shortly after it is laid, as has already been described.

When it has been laid for about 36 hours, if we take an egg
and, after proper preparation, cut it into thin slices known to

FORMATION OF THE EGG: 65

scopists by the name of sections, and examine it by means
f the microscope, we shall see that segmentation, has resulted in
: is. Just beneath the egg-shell there is a thin layer of cells,
ne cell thick, which completely surrounds the egg. Inside
is coat of cells is the food yolk, with a few cells scattered
bo in it at rare intervals, something like the raisins in a
um-pudding.
"With the next process the formation of the young Myriapod
nay be said to begin. A strip along the’ length of the oval-
shaped egg is thickened, and this thick mass of cells represents
the future ventral surface of the animal. The rest of the thin
ee er of cells: already mentioned just below the shell will form
the shell or exoskeleton of the future animal. The thick strip
of cells at the ventral surface has by this time split into
layers, so that, resorting to our microscope again, a section through
“the short axis of the oval-shaped. egg—a transverse section—
- will show us— |
1. The egg-shell.
2. A layer of cells completely surrounding the egg, thin
everywhere but on the ventral surface. This layer is
known to embryologists as the epiblast. The thick
part of the epiblast on the venttat surface gives rise to
the nervous system.
3 and 4. Two layers of cells connected in the middle, along
the line of the thick strip, but separate elsewhere, and
a ~ not extending round the whole of the inside. These
; layers constitute what is: known asthe mesoblast, and
give rise to the muscles and most of ‘the internal
organs.
5. The scattered cells in the yolk, They’ at are novi as the
hypoblast and give rise to the digestive canal. 5
After this point is reached the formation of the organs
Been. The segments are formed in order from before back-
wards. First the head, then the next segment, and so on.
4 When the number of segments with which the animal will be
hatched are formed, another process begins, and the tail end of
= - he animal, which can already be distinguished, is bent towards
the head. This is a process that takes place in many animals
besides Myriapods, and is called the formation of the ventral
_ flexure. Shortly after this the animal bursts the shell and comes
VOL. V F

.

66 MYRIAPODA CHAP.

into the outer world. The various processes may be understood
by reference to the Figs. 36, 37, 38, 39, which are succes-
sive stages in the development of a Chilognath. Figs. 37, 38,
are thin slices through the shorter diameter of the egg, which, as

Fic. 38. — Transverse section
through next stage: mk,
keel-like mass of cells from
which the mesoblast is pro-
duced ; ec, epiblast. (From
Heathcote, Post. Emb. Dev.
of Julus terrestris; Phil.
Trans, vol. 179, 1888, B.)

before mentioned, is an oval in shape. Fig. 39 is a section
through the longer diameter of an egg in a more advanced stage
of development, in fact just about to burst the shell. The body
of the future animal is marked by constrictions, the future
segments. Some of the organs are already formed, as the brain

Fic. 39. — Longitu-
dinal section
through later stage:
Segs. 2, 3, etc., seg-
ments ; Ceph. Seg,

head; mes, meso-
blast ;en,hypoblast;

Q)

=e st,futuremouth; pr,

future anus ; mesen,

50° 6, gut; mem.ex, as in

® eee en. Fig. 41, (From

& Oy } eS r) Heathcote, Post.

Beceeies mesen. Emb. Dev. of Julus
Loe® eee? terrestris. )

and the digestive tube, the openings of which will form the
mouth (st) and the anus (pr).

Myriapods are hatched at different stages of development.
The Chilognatha have only three appendages, which are so
little developed that they are only small shapeless stumps, while

u FORMATION OF THE YOUNG ANIMAL 67

the Chilopoda have the full number of legs in some cases; in
others only a small number of legs, but yet more than the three
pairs of legs of the Chilognatha, and fully developed instead of
stump-like. The eyes are usually developed late in the life of
the young animal. The bursting of the egg-shell is assisted in
some Myriapods by a special kind of spike on the back part of
the head.

The Fig. 40 shows a young Chilognath which has just burst
the shell and come into the outer world. ya
Tt is still surrounded with a membrane a
which has been formed by its skin or
epiblast within the egg. One eye-spot has
been formed.

Fig. 41 shows a longitudinal section
through the young Chilognath shown in 2,
Fig. 40, and the next (Fig. 42) a transverse Fic. 40.—Young Julus ter-
section through the same. In comparing sg ay ccc
the two Figs. 41 and 42 it must be remembered that they are

ir yy
« ii Yili

a

Oe

Xx) : <u
rh
NK

Fic. 41.—Longitudinal section through late stage : Sup.oe.gl, First appearance of brain ;
st, mouth ; pr, anus ; mesen, gut; 2, nerve cord; n.gang, nerve ganglion ; mem.ex,
membrane surrounding the animal; v./, ventral flexure ; mes, mesoblast cells,
(Heathcote, Post. Emb. Dev. of Julus terrestris.)

sections in different planes through the animal shown in Fig. 40,
and therefore they only show a small portion, a thin slice, of the

organs.

68 MYRIAPODA CHAP,

The first appearance of the mouth appendages has been
already mentioned, and these are shown in Fig. 43, where the

Fic. 42.—G, gut; Malp.T, Malpighian tube ; N.C, nerve cord; 7r.J, deep invagina-
tion by which the tracheae are formed ; y.s, yolk spherules still present ; Z, first
appearance of legs; S.S, part of mesoblast. (Heathcote, Post. Emb. Dev. of
Julus terrestris. )

small stumps that later on change to jaws are shown. The
figure shows the head of a young Chilog-
nat seen from the lower side, and the
second ,pair of stumps fuse together
later on and-.produce the broad plate
already mentioned as the characteristic
mouth appendage of the Order.
-- After the animal is hatched it has
‘ , . still, in the case of most Myriapods
Fic, 43.—Under surface of the (those which are not hatched with all
read of a young Julus ter-
restris: pro.m, rudimentary the segments complete), to undergo a
jaws; Dewees, ‘caduneiety Sieve development, and in particular
mouth plate ; an, antennae.
the eyes are still unformed. The pro-
cess of development of the eye has only been followed out as yet
in the Chilognatha, and in only one form, Ju/us, and is so curious
that a short account may be of interest here. The develop-
ment of the eye begins (in Julus) on the fourth day after hatch-
ing, and continues until the animal is full grown. A single

ai FORMATION OF THE YOUNG ANIMAL 69

ocellus or eye-spot appears first, and the rest are added one by
one until the full number are reached.

The first appearances connected with the formation of the
eye take place in the cellular layer just beneath the chitinous

_ exoskeleton. This layer, called the hypodermis, plays an im-
portant part in the organisation of the animal. It forms the
inner layer of what we may call the skin of the animal, and the

cells of which it is composed secrete the chitin of which the
shell or exoskeleton of the animal is composed, and which is
moulted every year.

The first process in the formation of the eye-spot is the
thickening of the hypodermis beneath the chitin, just in the
place where the eye will come.
At the same time the cells of
this thickened mass of hypoder-

_ mus secrete a quantity of pigment
of a dark red brown colour,
Next the cells of the thick mass
-of hypodermis begin to separate
from one another in such a way
‘that a vesicle is formed. This

_ yesicle is hollow inside, and the
thick walls are formed from the 42»
eells of the thickened hypodermic
mass. This can be seen from
Fig. 44, which represents a
section through an ocellus when

it is partly formed. From this
vesicle the eye is formed.

The wall of the vesicle near-

| est the exoskeleton gives rise to Fic. 44.—Section through eye when first
the lens of the eye, while the forming: Hyp, hypodermis; Ln, lens ;
: F.W.V, front wall of optic vesicle ;
other walls of the vesicle form 4,4,.1, back wall of vesicle; cap,
the retinal parts of the eye. capsule.

The cells from the brain grow out

and form the optic nerve connecting the retina with the brain.
The whole eye spot is covered internally by a thin membrane,
formed not from the hypodermis but by cells from the inside of

_ the body (mesoblast cells).

In the Chilognatha, the first Order of Myriapods, the young

76. MYRIAPODA , CHAP.

animal leaves the egg with three pairs of appendages; the first
have already the form of antennae, the second will form the
jaws, but have not yet taken their proper form, while the third
pair will fuse together and alter their shape so as to form the
curious plate that has already been mentioned as forming the
second pair of mouth appendages. Behind the mouth append-
ages will come the first three pairs of legs. The whole young
animal on leaving the egg is enveloped in two membranes.
These membranes are secreted by the outside layer of cells in
the same way that the shell or exoskeleton of the animal will be
eventually formed, and represent the first two moults of the
animal, which continues to moult its shell every year through-
out life.

Of the Chilopoda, the second Order of Myriapods, all the
families leave the egg-shell with the full number of legs, with
the exception of the Lithobiidae, which have seven pairs of legs
including the poison-claws. The Schizotarsia, the third Order,
also have seven pairs of legs when hatched.

The legs make their appearance not one by one but in
batches (in Julus terrestris in batches of five). The addition of
legs and segments to the body takes place, not at the end of the
body, but between the end segment and the penultimate.

This is a short sketch of the gradual development of the
Myriapoda from the ovum to the fully-grown animal. It is, I
am aware, a short and insufficient account of all the beautiful
processes by which the different organs take their rise, but space
is insufficient here, and too much detail would be out of place in
a work of this nature, which only aims at giving an outline
sketch of the group, which shall be intelligible to the general
reader who has not made a special study of such matters.
Before leaving the subject, however, I must mention a few
of the points of interest which are to be learned from the
examination of the course of development which has been
sketched here. One of the greatest puzzles in the natural
history of the Order Chilognatha has always been the double
segments, as they are called; that is, in fact, the possession of
two pairs of legs to each segment, which is, as we have already
said, a distinguishing characteristic of the Order. As we have
seen, the Chilognatha at an early stage of existence do not
possess this characteristic, which is only peculiar to the adult

tei i res .2

ou GENERAL EMBRYOLOGY 71

and half-grown forms. Now what does this mean? Does each
double segment in the full-grown Millepede represent two
segments which have become fused together, or is each double
segment, so called, a real segment resembling the segments
present in the other Orders (for instance, Chilopoda), which has
grown an extra pair of legs? Both these views have been
advocated by distinguished naturalists. Neither of them is, in

‘my opinion, quite right when viewed in the light cast on the

subject by recent 1 tetpgbeae into the life history of the

— Chilognatha.

A close examination into the minutiae of the growth of the

different organs has shown us that the double characters of the

double segments are more deeply seated than was imagined.
The circulatory system, the nerve cord, and the first traces of
segmentation in the mesoblast all show this double character,
and the only single part about the segment is the broad plate
covering the segment. Now in some of the most ancient of the
fossil Myriapods this broad plate shows traces of a division, as if —

it were in reality two plates fused together. We have also to

consider that the life history of the Chilognatha allows us to
believe that the peculiar cylindrical shape of the body shown in
the greatest degree in the Julidae is attained by the unequal
development of the dorsal and ventral surfaces of the body; the
ventral surface being compressed together till it is extremely
narrow, and the dorsal surface, as it were, growing round it till
the originally dorsal surface forms almost a complete ring round
the body. ‘Taking all this into consideration, we are justified, in
my opinion, in concluding that each double segment in the

_ Chilognatha is not two segments fused together, nor a single
. segment bearing two pairs of legs, but is two complete segments

perfect in all particulars, but united by a large dorsal plate
which was originally two plates which have been fused together,

-and which in most Chilognatha surrounds almost the whole of

two segments in the form of a ring.

Again in the Chilopoda we see that a great distinctive feature
that separates them from the Chilognatha is the character of the
ventral nerve cord, the cord being double and not single, a
character connected with the fact that the bases of the legs are
widely separated from one another, and not closely approached
to each other, as in the Chilognatha. As we before said, a more

72 MYRIAPODA ~~ CHAP,

minute anatomical examination showed us that this difference
was not so great as appeared at first sight, the cord showing
traces of a duplication. Well, are these traces superficial, or do
they represent a state of affairs more or less similar to that in
the Chilopoda? Embryology helps us to answer this question
also. In the early stages of the Chilognatha we find that the
nerve cord has exactly the form of that in Chilopoda, showing us
that the appearances in the anatomy had led us to a right con-
clusion, and giving us a valuable confirmation of our views.
These two examples will serve to show the kind of interest
which attaches to embryology. |

Palaeontology.

We have seen that embryology enables us to look at the
structure of the Myriapods from a new standpoint, and to correct
and supplement the knowledge gained from an examination of
the adult animal. In the same way a study of the forms of
Myriapods which have become extinct on the globe, and have
been preserved to us in a fossil form, gives a further opportunity
of considering the relations of one form to another, and again of
the relations of our group to other groups of animals now exist-
ing on the earth. Myriapod fossils have been found in strata of
great antiquity. The oldest of such fossils must have been
among the first land animals. The figure below shows a fossil
Myriapod found in America, belonging to the Order of the
Protosyngnatha which are only found in the Palaeozoic strata.
It is a good example of the manner in which Myriapods were
protected by bundles of bristles in the same way as_ the
Polyxenus of the present time.

The oldest fossil Myriapods which have been discovered at
the present time are two species which have been found in the
Old Red Sandstone in Scotland. To realise the antiquity of these
Myriapods, it will be worth while recalling the typical fossils
found in the Old Red Sandstone, so as to see what the contem-
poraries of these ancient Myriapods were like. Among the plants
there were Algae, Ferns, and Conifers, belonging to the lower
‘divisions of the plant tribe. Among the animals there were
Sponges, Corals, Starfish, Worms, Shell-fish, and Fishes, but none
of the more highly organised of the animal or vegetable tribe

’

..
i:
»

11 | | PALAEONTOLOGY 73

had appeared on the earth. The Myriapods of the Old Red
Sandstone, as has been before said, differ considerably from those
of the present day, and as we proceed towards the species found
in the more recent strata we find them more and more like the
ones at present living, till we get to the Polyxzenus and other
species found in amber, which are hardly to be distinguished
from living forms.

The next oldest fossil Myriapods are found in the coal
measures, when both the animal and vegetable kingdoms were

represented by more numerous and more specialised forms. The

fossil fauna of this period is characterised by the number of
gigantic Amphibia, many remains of which have been found.
The great forests and the abundant vegetation of this time must
have been favourable to: the existence of our class, and accord-
ingly we find no less than 32 species of fossil Myriapods. Of

Fic. 45.—Palaeocampa an-
thrax. (After Zittel.)
From Mazon Creek,
Illinois.

these most have been found in America, some in Great Britain,
and some in Germany. One well-preserved fossil of Yylobius
sigulariae was found by Dr. Dawson in America in the stump of
a tree in the remains of a fossil forest. The eyes, head, and
legs were plainly seen under the microscope. All these fossils
belong to the earliest or Palaeozoic period.

The figure below (Fig. 46) shows a fossil also from the coal
formations of Illinois, America, belonging to the family of the
Euphoberiidae mentioned further on. It shows a nearer approach
to the Julidae of the present time. The limbs, however, were of
very curious shape, and may possibly have been adapted to loco-
motion in water as well as on land, and the small supposed
branchiae on the ventral surface shown in Fig. 46, B, may possibly
have been an arrangement to render respiration in the water
possible.

74, MYRIAPODA CHAP.

In the secondary period the Myriapods were scantily repre-
sented, or, at any rate, geologists have failed to find their fossils.
The class is represented by a single specimen found in the chalk
in Greenland. This fossil, which has been included in the
Julidae under the name of Julopsis eretacea, may perhaps belong
to the Archipolypoda. ,

Passing on to the Tertiary or Recent period, we find the
Myriapods again numerous, and more nearly resembling those
living at the present time. They belong mostly to the Chilo-
gnatha and Chilopoda. They have been found in the fresh-water
gypsum of Provence in France, the brown coal of Germany, and
the green river formations of America. Several have been found
in amber.

Fossil Myriapods have been divided into four Orders, two

\
vi \) Fic. 46.—Acan-
AOA therpestes major.
(After Zittel.)
Mazon Creek,

America. A,
The whole
animal; _ B,

branchiae on
the ventral sur-
face.

of which coincide with the Orders of living Myriapods; the
differences between the fossils and the living Myriapods having
been held insufficient to warrant the establishment of a new
Order. These two Orders are the Chilopoda and the Diplopoda
or Chilognatha (Diplopoda is another name used by some writers
for the group which we have hitherto called Chilognatha). The
other two Orders have sufficient differences from living forms to
render it necessary to include them in separate Orders.
The fossil Myriapods, then, are arranged as follows :—

Order I. Protosyngnatha.

Order II. Chilopoda.

Order III. Archipolypoda.

Order IV. Chilognatha (or Diplopoda).

The following table will show the species that have been dis-
covered in the different strata :—

=

|
a
r;
“a
-

II PALAEONTOLOGY 76

Devoniam, or ; ;
Old Red Sandstone aiepaues eh -Archipelypoda.

1 species Protosyngnatha
31 species Archipolypoda

as (Rothliegendes of Germany), 4 specimens belonging to the
Julidae or Archipolypoda,

Carboniferous 4

{ Archipolypoda or

Cretaceous, . 1 species ) Chilognatha

17 species Chilopoda
Oligocene < . : Diplopoda
sah i \ (Chilognatha)

f Diplopoda

Miocene, . 1 species | (Chilognatha)

I will now give a short account of the different Orders, and
the fossil forms which are included in them.

Order I. Protosyngnatha.

This Order is represented by a single fossil (Fig. 45), dis-
covered in the coal at Mazon Creek, Illinois, America, by Meek
and Worth. It differs greatly from any of those in existence at
the present day. The body is cylindrical, and composed of
ten segments. The cephalic appendages (that is, the antennae
and mouth parts) are inserted into a single unsegmented cephalic
mass (the head). Each segment hohe the head bears a single
dorsal. and ventral plate of equal breadth and length. The
limbs are placed in these plates with a wide space between the
base of each leg and that of the opposite one of the pair. Along
the back, bundles of bristles are arranged in longitudinal rows.

Order II. Chilopoda.

The fossil forms of this Order resemble those of the Chilopoda
of the present day. The oldest of them are found in amber.
The following families have been found :—

Lithobiidae. Several species have been found in amber.

Scolopendridae. One species in amber, several species in

later Tertiary formations.

Geophilidae. Three species in amber.

Two species resembling the Schizotarsia of the present day
have been found in amber.

76 MYRIAPODA CHAP. —

Order ITI. Archipolypoda.

The most numerous of the fossil families. With a few
exceptions, all the Palaeozoic (that is, the oldest) Myriapods belong
to this Order. The Carboniferous Archipolypoda seem to be
much more numerous in the coal of America than in that of
England. They resemble for the most part the Myriapods of
the present day, except that all the segments without exception
bear legs.

The families are three in number.

Family 1. Archidesmidae.

Resemble the Polydesmidae of the present day. Two species have been:
found by Page in the Old Red Sandstone of Forfarshire. He named them
Kampecaris, One found by Peach in the same formation is called Archi-
desmus.

Family 2. EHuphoberiidae.

They show some resemblance to the Julidae of the present day, but the
‘dorsal scutes, or plates of the back, are more or less perfectly divided into
two divisions corresponding with the pairs of legs, The following are the
principal fossils of this family :—
Acantherpestes. Found by Meek and Worth in the coal at Mazon Creek
in America (Fig. 46),
Euphoberia, About 12 species found at the same place as the last
named.
Amylispes. Found by Scudder, Mazon Creek, America.
Eileticus. Scudder, Mazon Creek, America.

Family 3. Archijulidae.
The dorsal plates nearly consolidated, but the division still apparent.
Fossil forms are—
Trichijulus. Scudder, Mazon Creek, America.
‘Xylobius. Dawson. Found in the coal in Nova Scotia. Two species
found at Mazon Creek, America.

Order IV. Chilognatha.

Families corresponding to those of the present day. The
oldest specimens come from the chalk in Greenland; most of the
others from amber. |

Family 1. Glomeridae. One form, G. denticulata, has been found in
amber,

Family 2. Polydesmidae. Two species in amber.

Family 3. Lysiopetalidae. A number of species, amongst which are 6
Craspedosoma, mostly from amber.

II GENERAL CONCLUSIONS 77

Family 4. Julidae. A number of species of this family have been
found, some in amber, some in other Tertiary strata. Amongst the latter a
probable example of Julus terrestris, living at the present time.

Family 5. Polyxenidae. Five species have been found in amber.

Now that we have considered the structure of the Myriapods
and the groups into which they are subdivided or classified, we
may proceed to consider what position they hold in the house-
hold of nature. That they present certain features of similarity
to other classes has been already mentioned, and that this is the.
fact cannot be doubted when we look back at the way in which
they have been classified in the works of early writers. For
example, Lamarck, the great French naturalist, classifies them
with spiders in his well-known work, La Philosophie Zoologique,
under the name. of Arachnides antennistes. Cuvier, the com-
parative anatomist, unites them with the Insects, making them
the first Order, while the Thysanura is the second. We have
already seen that one Order of Myriapods, the Symphyla, bears
a great resemblance to the Thysanura. The English naturalist
Leach was the first to establish Myriapods as a class, and his
arrangement has been followed by all naturalists after his time.
But while their peculiarities of structure and form are sufficiently
marked to separate them as a class, it cannot be denied that the
older naturalists were right to recognise that they have many

- essential characteristics in common with other classes of animals.

And recent investigations have emphasised this fact. For in-
stance, let us consider the recent ‘discoveries of the Orders of
Symphyla and Pauropoda, Orders which, while bearing so
many of the characters of Myriapods that naturalists have
agreed to place them in that class, yet resemble in many
important points the Insect Order of Thysanura. This seems to
justify Cuvier in claiming the close relationship for them that
he did.

Recent investigations have also brought out more prominently
the resemblances to the Worms. Of late, considerable atten-
tion has been directed to Peripatus (see pp. 1-26), and the resem-
blances to the Myriapods in its anatomy and development are
such that Latzel has actually included it in the Myriapods as
an Order, Malacopoda. Now Peripatus also shows resemblances
to the annelid Worms, and thus affords us a connexion to the
Worm type hardly less striking than that to the Insect. This

78 MYRIAPODA CHAP.

resemblance to the Worms, which Myriapods certainly bear, was
noticed by the ancient writers, and as they had for the most
part only external appearances to consider, they pushed this
idea to extremes in actually including some of the marine
Worms (Annelida) among the Centipedes. Pliny talks of a
marine Scolopendra as a very poisonous animal, and there is little
doubt that he meant one of the marine worms. - An old German
naturalist, Gesner, in a very curious book published in 1669 gives
an account of an annelid sea-worm which he calls Scolopendra
marina, and which is in all probability the sea Scolopendra
which Pliny mentions. From Gesner’s account it seems to have ~
been used as a medicine (externally only). “The use of this
animal in medicine. The animal soaked in oil makes the hair
fall off. So do its ashes mixed in oil.” It was also pounded up
with honey.

This idea of Centipedes living in water survived among later
naturalists. Charles Owen, the author before quoted, mentions .
them as amphibious in 1742. “The Scolopendra is a little
venomous worm and amphibious. When it wounds any, there
follows a blueness about the affected part and an itch all over
the body like that caused by nettles. Its weapons of mischief
are much the same with those of the spider, only larger; its
bite is very tormenting, and produces not only pruriginous pain
in the flesh, but very often distraction of mind. These little
creatures make but a mean figure in the ranks of animals, yet
have been terrible in their exploits, particularly in driving
people out of their country. Thus the people of Rhytium, a
city of Crete, were constrained to leave their quarters for them
(Aelian, lib. xv. cap. 26).”

Myriapods have been considered to bear resemblances to the
Crustacea, and this to a certain extent is true, though only to a
certain extent, the resemblances being confined to the more
general characteristics that they share with other groups of
animals,

Of late years attempts have been made fo speculate about the
origin of the Myriapods—that is, to endeavour to obtain by means
of investigation of their anatomy, embryology, and palaeontological
history, some idea of the history of the group. Such attempts at
research into the phylogeny, as it is called, of a group must be
more or less speculative until our knowledge is much greater than

eae fas GENERAL CONCLUSIONS 79

=

it is at present. But such inquiries have their value, and the
‘schemes of descent and phylogenetic trees, at any rate, indicate a
real relation to different groups, even if they do not provide us
with a real and actual history of the animals.

There have been two main theories about the descent of the
Myriapoda. One of these derives them directly from the Insecta
through the forms known as the Thysanura, which resemble in

such a degree the Myriapod Orders of Symphyla and Pauro-
_ poda. The other theory holds that the Myriapods, as well as the
Insecta, have been derived from some ancestor bearing a resem-
blance to Peripatus. In other words, one theory claims that the
relationship of Myriapoda to Insecta is that of father and son;
the other that the relationship between the two is that of
brother to brother. The arguments by which these theories are
respectively supported consist for the most part of an analysis of
the different characters of the anatomy and embryology and the
determination of the most primitive among them. For example,
the supporters of the theory that the Thysanura are the most
nearly allied to the Myriapod ancestor lay great weight on the fact
that some Myriapods are born with three pairs of legs only, and
they compare this stage in the life history of the Myriapeda to the
-metamorphosis and larval stage of Insects. For the supporters

_. of this view the Orders of Symphyla and Pauropoda are the

most primitive of the Myriapods. On the other hand, the
followers of the other theory do not allow that the characters
in which the Myriapods are like Insects are primitive ones, but
they lay more stress on the characters found in the early
development, such as the character of the process of the forma-
_ tion of the body segments, the mesoblastic segmentation, and the
origin of the various organs of the body.
It may be easily understood that such differences in the
estimation of the primitive characters of the embryology of a
- group may arise. Embryology has been compared by one of the
greatest of modern embryologists to “an ancient manuscript with
many of the sheets lost, others displaced, and with spurious
passages interpolated by a later hand.” What wonder is it that
different people examining such a record should come to different
conclusions as to the more doubtful and difficult portions of
it. It is this very difficulty which makes the principal interest
in the study, and although our knowledge of the language in

80 MYRIAPODA CHAP. II

which this manuscript is written is as yet imperfect, still we
hope that constant study may teach us more and more, and
enable us to read the great book of nature with more and more
ease and certainty. _

If any of my readers should wish for a more full account of
the natural history of this group I must refer them to the
following works, which I have used in compiling the above
account. In the first of these there is an excellent bibliography
of the subject :-—

Latzel, Die Myriapoden der Oesterreichisch-Ungarischen Monarchie, Wien,
1880.

Zittel, Handbuch der Palaeontologie, 1 Abth, II. Bd., Leipzig, 1881-1885.

Korschelt and Heider, Lehrbuch der vergleichenden Entwicklungsgeschichte
der wirbellosen Thiere, Jena 1891.

Some later work of Scudder on Palaeontology must be mentioned. He
establishes a family Gerascutigeridae, with a genus Latzelia. Also a family
Eoscolopendridae in which he includes Hizleticus, also a genus Palenarthrus
in which is placed a scolopendriform Chilopod. A new genus Ilyodes also
chilopodiférm. Amylispes, he thinks, may be allied to Glomeridae. Trichi-
julus must be given up. A new species of Acantherpestes. More species of
Euphoberia. 2 new species of Xylobius were discovered in coal.

Pocock divides the Diplopoda into 3 orders: ONIscoMORPHA, with families
Glomeridae and Zephroniidae ; HELMINrHOMORPHA, with suborders Juloidea,
Chordeumoidea, Polydesmoidea ; and LimacomorpHa, with family Glomeri-
desmidae.

The systematic position of Symphyla and Pauropoda has been the subject
of much discussion. Pocock places Symphyla in a Class and Kenyon places
Pauropoda in a Suborder.

Many naturalists believe that Chilopoda should be united with Hexapoda.
There is no room for a discussion of the point, but I must refer my readers
to Pocock, Zool. Anzeiger, xvi. 1893, p. 271; Kingsley, Tufts Coll. Studies,
No. 1, 1894, p. 15; Bollman,' Bull. U.S. Nat. Mus., No. 46, 1893, where
they will find the arguments for this view.

For further information on Pauropoda and Symphyla, see P. Schmidt,
Zetschr. wiss. Zool. lix., 1895, p. 486; Kenyon, Tufts Coll. Studies, No. 4,
1895, p. 77. :

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CHAPTER III

_ CHARACTERISTIC FEATURES OF INSECT LIFE—SOCIAL INSECTS—
____-DEFINITION OF THE CLASS ZVSECTA—COMPOSITION OF INSECT
SKELETO | :
HEAD—APPENDAGES OF THE MOUTH—-EYES—-THORAX—
__——s&ENTOTHORAX——LEGS——WINGS——ABDOMEN OR HIND BODY—
___._ SPIRACLES—SYSTEMATIC ORIENTATION.

' -Iyszers form by far the larger part of the land animals of the
world; they outnumber in species all the other terrestrial animals
‘together, while compared with the Vertebrates their numbers are
. ~ simply enormous. Yet they attract but little attention from the
B _ ordinary observer, this being probably primarily due to the small
ize of the individual Insect, which leads the unreflecting to treat
| - the creature as of little importance. “It can be crushed in a
moment” is perhaps the unformulated idea that underlies the
_ almost complete neglect of knowledge concerning Insects that
_ prevails even in the educated classes of society. The largest
_ Insects scarcely exceed in bulk a mouse or a wren, while the
- smallest are almost or quite imperceptible to the naked eye, and
is yet the larger part of the animal matter existing on the lands of
_ the globe is in all probability lccked up in the forms of Insects.
- Taken as a whole they are the most successful of all the forms of
_ terrestrial animals.
a _ In the waters of the globe the predominance of Insect life
z ise appears. In the smaller collections of fresh water many
~ Insects find a home during a portion of their lives, and some few
contrive to pass their whole existence in such places; but of the
_ larger bodies of fresh water they invade merely the fringes, and
~ they make only the feeblest attempt at existence in the ocean ;
the genus Halobates containing, so far as we know, the sole Insects

ee”

8 4 INSECTS CHAP.

that are capable of using the ocean as a medium of existence at —
a distance from the shore.

It will probably be asked, how has it come about that creatures
so insignificant in size and strength have nevertheless been so
successful in what we call the struggle for existence? And it is
possible that the answer will be found in the peculiar relations
that exist in Insects between the great functions of circulation
and respiration; these being of such a nature that the nutrition
of the organs of the body can be carried on very rapidly and very
efficiently so long as a certain bulk is not exceeded. |

Rapidity of growth is carried to an almost incredible extent
in some Insects, and the powers of multiplication—which may
be considered as equivalent to the growth of the species—even
surpass the rapidity of the increase of the individual; while, as
if to augment the favourable results attainable by the more usual
routine of the physiological processes, “metamorphosis ” has been
adopted, as a consequence of which growth and development can
be isolated from one another, thus allowing the former to go on ~
unchecked or uncomplicated by the latter. A very simple

calculation will show how favourable some of the chief features

of Insect life are. Let it be supposed that growth of the
individual takes time in proportion to the bulk attained, and let
A be an animal that weighs one ounce, B & creature that weighs.
ten ounces, each having the power of producing 100 young when
full grown; a simple calculation shows that after the lapse of a
time necessary for the production of one generation of the larger ~
creature the produce of the smaller animal will enormously out-
weigh that of its bulkier rival. Probably it was some considera-
tion of this sort that led Linnaeus to make his somewhat para-
doxical statement to the effect that three flies consume the
carcase of a horse as quickly as a lion.’

Astonishing as may be the rapidity of the physiological pro-
cesses of Tndeche the results attained by them are, it must be —
admitted, scarcely less admirable: the structures of the Insect’s
body exhibit a perfection that, from a mechanical point of view, is
unsurpassed, while the external beauty of some of the creatures
makes them fit associates of the most delicate flowers or no mean
rivals of the most gorgeous of the feathered world. The words

1 Tres muscae consumunt cadaver equi, aeque cito ac leo, Syst, Nat., ed. xii. ref.
I, pt. 2, p.- 990.

SOCIAL INSECTS 85

a Linnaeus, “ Natura in minimis maxime miranda,” are not a
i mere rhetorical effort, but the expression of a simple truth. Saint
_ Augustine, too, though speaking from a point of view somewhat
remote from that of the great Swedish naturalist, expressed an
7 idea that leads to a similar conclusion when he said, “ Creavit in
_ coelum angelos, in terram vermiculos ; nec mash in illis nec minor
in istis ” (see note on p. 565).
| The formation of organised societies by some kinds of Insects
_ isa phenomenon of great interest, for there are very few animals
_ except man and Insects that display this method of existence.
| — as to some of these societies will be given when we
_ treat of the Termitidae, and of the Hymenoptera Aculeata; but
we will take this opportunity of directing attention to some patna
4 Bcf general interest in connexion with this subject. In Insect
societies we find that. not only do great numbers of separate
individuals live together and adopt different modes of industrial
: action in accordance with the position they oceupy in the
é association, but also that such individuals are profoundly modified
} in the structures of their body and in their physiological
_ processes in such ways as to specially fit them for the parts they
epee to play. We may also see these societies in what may be
considered different stages of evolution; the phenomena we are
alain to being in some species anche less marked than they
are in others, and these more primitive kinds of societies being
composed of a smaller number of individuals, which are also much
~ less different from one another. We, moreover, meet with complex
’ societies exhibiting some remarkably similar features among
Insects that are very different systematically. The true ants
_ and the white ants belong to groups that are in structure and in
_ the mode of growth of the individual essentially dissimilar, though
_ their social lives are in several important respects analogous,
It should be remarked that the phenomena connected with the
social life of Insects are still only very imperfectly known; many

PB tichty important points being quite obscure, and our ideas being
4 i too much based on fragments gathered from the lives of different
species. The honey bee is the only social Insect of whose economy
we have anything approaching to a wide knowledge, and even in
_ the case of this Insect our information is neither so complete nor
so precise as is desirable.

The various branches of knowledge connected with Insects

A

86 INSECTS CHAP.

are called collectively Entomology. Although entomology is
only a department of the great science of zoology, yet it is in
practice a very distinct one; owing to its vast extent few of
those who work at other branches of zoology also occupy them-
selves with entomology, while entomologists usually confine’
themselves to work in the vast field thus abandoned to them.

Before passing to the consideration of the natural history and
structure of the members of the various Orders of Insects we will.
give a verbal diagrammatic sketch,if we may use such an expression,
with a view to explaining the various terms that are ordinarily
used. | We shall make it as brief as possible, taking in succession
(1) the external structure, (2) internal structure, (3) development of
the individual, (4) classification.

In the course of this introductory sketch we shall find it
necessary to mention the names of some of the Orders of Insects
that will only be explained or defined in subsequent pages. We
may therefore here state that the term “Orthoptera” includes
grasshoppers, locusts, earwigs, cockroaches; “ Neuroptera”’ com-~
prises dragon-flies, May-flies, lacewings, stone-flies and caddis-flies ;
to the “ Hymenoptera” belong bees, wasps, ants, sawflies, and a
host of little creatures scarcely noticed by the ordinary observer :
“ Coleoptera” are beetles; “ Lepidoptera,” butterflies and moths ;
“ Diptera,” house-flies, blue-bottles, daddy-longlegs, and such ;
“ Hemiptera” or “ Rhynchota” are bugs, greenfly, ete.

Class Insecta: or Insecta Hexapoda.

Definition —Insects are small animals, having the body divided
-into three regions placed in longitudinal succession—head, thorax,
and abdomen: they take in air by means of tracheae,a system of
tubes distributed throughout the body, and opening externally by
means of orifices placed at the sides of the body. They have six
legs, and a pair of antennae; these latter are placed on the head,
while the legs are attached tothe thorax, or second of the three great
body divisions; the abdomen has no true legs, but not infrequently
has terminal appendages and, on the under surface, protuberances
which serve as feet. Very frequently there are two pairs of
wings, sometimes only one pair, in other cases none: the wings
are always placed on the thorax. Insects are transversely seg-
mented—that is to say, the body has the form of a succession of

STRUCTURE | 87

_ rings; but this condition is in many cases obscure; the number
4 of these rings rarely, if ever, exceeds thirteen in addition to the
head and to a terminal piece that sometimes exists. Insects usually
_ change much in appearance in the course of their growth, the
_ annulose or ringed condition being most evident in the early part
of the individual’s life. The legs are usually elongate and
apparently jointed, but in the immature condition may be alto-
‘ gether absent, or very short; in the latter case the jointing ‘is
obscure. The number of aainhed legs is always six.

External Structure.

The series of rings of which the external crust or skeleton of
F Insects is composed exhibits great modifications, not only in the
: various kinds of Insects but even in the different parts of the
- same individual, and at successive periods of its development ;
so that in the majority of mature Insects the separate rings are
| airy distinguished only in-the hind body or abdomen. The
; total number of the visible rings, segments, somites, or arthromeres,
_ as they are variously called by different writers, is frequently
_ thirteen in addition to the head. This latter part is considered
to be itself composed of the elements of several rings, but mor-
| ~_ phologists are not yet agreed as to their number, some thinking
_ this is three while chars place it as high as seven; three or four
q Bieing perhaps, the figures at present most in favour, though
- Viallanes, who has recently discussed’ the subject, considers
six, the number suggested by Huxley, as the most probable.
_ Cholodkovsky is of a similar opinion. However this may be,
_ the three rings behind the head constitute the thorax, which is
4 - always largely developed, though, like the head, its segmenta-
tion is usually very much obscured by unequal development of
different parts, or by consolidation of some of them, or by both
_ of these conditions. The third great division of the body, the
abdomen, is also usually much modified by one or more of the
_ terminal segments being changed in form, or even entirely with-
_ drawn into the interior of the body. The existence of ten
segments in the hind body can, however, be very frequently actually
. demonstrated, so that it is correct to speak of ten as the normal

r ret.
1 4nn. Sci. Nat. (7) iv. 1887, p. 111.

88 INSECTS CHAP.

It is no reproach to morphologists that they have not yet.
agreed as to the number of segments that may be taken as
typical for an Insect, for all the branches of evidence bearing on
the point are still imperfect. It may be well, therefore, to state
the most extreme views that appear to be at all admissible.
Hagen’.has recently stated the opinion that each thoracic segment
consists really of three segments—an anterior or wing-bearer, a
middle or leg-bearer, and a posterior or stigma-bearer. There
seems to be no reason for treating the stigma as being at all of

g
i
Ny
bsg nccnweunnaee

re

y
Ke os

>
“< ,
Ss

Fic. 47—Diagram of exterior of insect: the two vertical dotted lines indicate the
divisions between H, head; T, thorax; and A, abdomen: a, antenna; 0, labrum ;
c, mandible ; d, maxillary palpus ; e, labial palpus ; /, facetted eye ; g, pronotum ;
h, mesonotum ; 7, metanotum ; &, wings; J, to /,), abdominal segments ; m, the
internal membranous portions uniting the apparently separated segments ; m, cerci ;
o, stigma; py, abdominal pleuron bearing small stigmata; 9g), go, g3, pro-, meso-,
meta-sterna ; 7,, mesothoracic episternum ; s}, epimeron, these two forming the
mesopleuron ; 7, S,, metathoracic episternum and epimeron; ¢, coxa; v, trochanter ;
w, femur; x, tibia; y, tarsus ; z, gula.

the nature of an appendage, and the theory of a triple origin for
these segments may be dismissed. There are, however, several facts
that indicate a duplicity in these somites, among which we may
specially mention the remarkable constancy of two pleural pieces
on each side of each thoracic segment.. The hypothesis of these
rings being each the representative of two segments cannot there-
fore be at present considered entirely untenable, and in that case
the maximum and minimum numbers that can be suggested
appear to be twenty-four and eleven, distributed as follows :—

1 Stettin. Ent. Zeit. 1, 1889, p. 165.

STRUCTURE 89

Maximum. Minimum.
Head F ‘ 4, 3
Thorax. / Pre 3
Abdomen . . wll 5

_ Total . 24 11

} ealthdugh it is not ‘ecebabts that ultimately so great a difference
/ of these figures indicate will be found to prevail, it is certainly
ab present premature to say that all Insects are made up of the
| same number of primary segments.
_ A brief account of the structure of the integument will be
found in the chapter dealing with the post-embryonic develop-
_ ment.
_ The three great regions of the Insect body are functionally as
_ well as anatomically distinct. The head bears the most important
a Bor the sense organs, viz. the antennae and ocular organs ; it includes
a a greater of the nerve-centres, and carries the mouth as well
_ as the appendages, the trophi, connected therewith. The thorax
is chietly devoted to the organs of locomotion, bearing externally
___ the wings and legs, and including considerable masses of muscles,
: 4 as well as the nerve centres by which they are innervated ; through
_ the thorax there pass, however, in the longitudinal direction,
~ those structures by which the unity of the organisation is com-
cto, viz. the alimentary canal, the dorsal vessel or “ heart” for
i D distributing the nutritive fluid, and also the nerve cords. The
_ abdomen includes the greater part of the organs for carrying on
a the life of the individual and of the species; it also frequently
bears externally, at or near its termination, appendages that are
doubtless usually organs of sense of a tactile nature.

Tn the lower forms of Insect life there is little or no actual in-
~ ternal triple division of the body; but in the higher forms such
_ separation becomes wonderfully complete, so that the head may
communicate with the thorax only by a narrow isthmus, and the
thorax with the abdomen only by a very slender link. This .
x ee eement is carried to its greatest extreme in the Hymenoptera
- Aculeata. It may be looked on as possibly a means for separating
the nutrition of the parts included in the three great body
_ divisions.

4 Along each side of the body extends a series of orifices for the
admission of air, the stigmata or spiracles; there are none of
these on the head, but on each side of most of the other segments

2

i
os

4

90 , SEGMENTS CHAP.

there is one of these spiracles. This, however, is a rule subject
to many exceptions, and it is doubtful whether there is ever a
spiracle on the last abdominal segment. Even in the young stage
of the Insect the number of these stigmata is variable; while
in the perfect Insect the positions of some of the stigmata may be
much modified correlatively with the unequal development or
consolidation of parts, especially of the thorax when it is highly
modified for bearing the wings. |

The segments of the Insect are not separate parts connected
with one another by joints and ligaments; the condition of the
Insect crust is in fact that of a continuous long sac, in which
there are slight constrictions giving rise to the segments, the
interior of the sac being always traversed from end to end by a
tube, or rather by the invaginated ends of the sac itself which
connect with an included second sac, the stomach. The more
prominent or exposed parts of the external sac are more or less
hard, while the constricted parts remain delicate, and thus the
continuous bag comes to consist of a series of more or less hard
rings connected by more delicate membranes. This condition is

Fig. 48—Tillus elongatus, fully distended larva.

readily seen in distended larvae, and is shown by our figure 48
which is taken from the same specimen, whose portrait, drawn
during life, will be given when we come to the Coleoptera, family |
Cleridae. The nature of the concealed connexions between the
apparently separate segments of Insects is shown at m, Fig. 47,
p. 88.

As the number of segments in the adult Insect corresp6nds— ~
except in the head—-with the number of divisions that appear
very early in the embryo, we conclude that the segmentation of
the adult is, even in Insects which change their form very greatly
during growth, due to the condition that existed in the embryo ;
but it must not be forgotten that important secondary changes
occur in the somites during the growth and development of
the individual. Hence in some cases there appear to be more
than the usual number of segments, e.g. Cardiophorus larva,
and in others the number of somites is diminished by amal-

STRUCTURE 91

— or by the extreme reduction in size of some of the
‘Besides the division of the ecaee into consecutive segments,
4 pethict feature is usually conspicuous; the upper part, in many
‘a segments, being differentiated from the lower and the two being
. — connected together by intervening parts in somewhat the same sort
. of way as the. segments themselves are connected. Such.a differen-
_ tiation is never visible on the head, but may frequently be seen in
_ the thorax, and almost always in the abdomen. A dorsal and a
) _ ventral aspect are thus separated, while the connecting bond on
4 either side forms a pleuron. By this differentiation a second form
p of symmetry is introduced, for whereas there is but one upper and
_ one lower aspect, and the two do not correspond, there are two
x lateral and similar areas. This bilateral symmetry is conspicuous
in nearly all the external parts of the body, and extends to most
. of the internal organs. The pleura, or lateral regions of the
_ sac, frequently remain membranous when the dorsal and ventral
aspects are hard. The dorsal parts of the Insect’s rings are
a :. “also called by writers terga, or nota, and the ventral parts
4 -sterna..

___ ‘The appendages of the body are —(1) a pair of antennae ; (2)
the trophi, constituted by three pairs of mouth-parts; (3) three
pairs of legs; (4) the wings'; (5) abdominal appendages of various
a Kinds, but usually jointed. Before considering these in detail we
shall do well to make ourselves more fully acquainted with the
: Be piementary details of the structure of the trunk.

In the adult Insect the integument or crust of the body is
_ more or less hard or shell-like, sometimes, indeed, very hard, and
on ‘examination it will be seen that besides the divisions into
‘segments and into dorsal, ventral, and pleural regions, there are
=a a indicating the existence of other divisions, and it will be
found that by dissection along these lines distinct pieces can be
readily separated. Each hard piece that can be so separated is
- called a sclerite, and the individual sclerites of a segment have
received names from entomotomists. The sclerites are not really

o- '* The wings, by many morphologists, are not included in the category of
_ “appendages”; they apparently, however, differ but little in their nature from
_ legs, both being outgrowths of the integument; the wings are, however, always
___ post-embryonic in actual appearance, even when their rudiments can be detected in
_ the larva. No insect is hatched from the egg in the wing-bearing form.

92 HEAD CHAP.

quite separate pieces, though we are in the habit of speaking of
them as if such were the case. If an Insect be distended by
pressure from the interior, many of the sclerites can be forced
apart, and it is then seen that they are connected by delicate
membrane. ‘The structure is thus made up of hard parts meeting
one another along certain lines of union—sutures—so that the
original membranous continuity may be quite concealed. In
many Insects, or in parts of them, the sclerites do not come into
apposition by sutures, and are thus, as it were, islands of hard
matter surrounded by membrane. . A brief consideration of some
of the more important sclerites is all that is necessary for our
present purpose: we will begin with the head.

The head is most variable in size and form; as a part of its
surface is occupied by the eyes and as these organs differ in
shape, extent, and position to a surprising degree, it is not a
matter for astonishment that it is almost impossible to agree as
to terms for the areas of the head. Of the sclerites of the head
itself there are only three that are sufficiently constant and
definite to be worthy of description here. These are the clypeus,
the epicranium, and tlie gula. The clypeus is situate on the
upper surface of the head-capsule, in front; it bears the labrum
which may be briefly described as a sort of flap forming an upper
lip. The labrum is usually possessed of some amount of mobility.
The clypeus itself is excessively variable in size and form, and
sometimes cannot be delimited owing to the obliteration of the
suture of connexion with the more posterior part of the head;
it is rarely or never a paired piece. Occasionally there is a

more or less distinct piece
interposed between the
clypeus and the labrum,
and which is the source
of considerable difficulty, as
it may be taken for the

i clypeus. Some authors call
Fre. 49.—Capsule of head of beetle, Harpalus the clypeus the epitie but

caliginosus : A, upper ; B, under surface: a, it is better to use this latter

dypenss 2 gpicraninn: «, pofoeaniim ; term for the purpose of indi
men’; g, submentum ; h, cavity for insertion cating the part that is imme-
eh ast diately behind the labrum,

whether that part be the clypeus, or some other sclerite; the

‘inal i + -s

z oS. HEAD 93

term is very convenient in those cases where the structure cannot
Be, or has not been, satisfactorily determined morphologically.
= tn Figure 50 the parts usually visible on the anterior
aspect of the head and its appendages are shown so far as these
latter can be seen when the mouth is closed ; in the case of the
Insect here represented the bases of the mandibles are ecreatly
~~ seen (gy), while their apical portions are
entirely covered by the labrum, just
below the lower margin of which the
tips of the maxillae are seen, looking
as if they were the continuations of the
Be riandiblen

a The labrum is a somewhat perplex-
. ing piece, morphologists being not yet
agreed as to its nature; it is usually
_ placed quite on the front of the head,
and varies extremely in form; it is es
3 nearly always a single or unpaired hee aya: me leader 3
Be ‘piece ; the French morphologist Chatin epicranium; 6, compound
considers that it is really a paired Sake Pisce Ligh nats
structure. . g, base of mandible ; 4, max-_
ee the gula (Fig. 49,B d,and Fig 47, tis) P'sbesof manila.
_ #) is a piece existing in the middle

longitudinally of the under-surface of the head; in front it
pears the mentum or the submentum, and extends backwards
to the great occipital foramen, but in some Insects the gula
is in front very distant from the edge of the buccal cavity.
_ The epicranium forms the larger part of the head, and is con-
sequently most inconstant in size and shape ; it usually occupies
the larger part of the upper - surface, and is reflected to the
-_under-surface to meet the gula. Sometimes a transverse line
exists (F ig. 49, A) dividing the epicranium into two parts, the
_ posterior of which has been called the protocranium; which,
however, is nota good term. The epicranium bears the antennae ;
these organs do not come out between the epicranium and the
clypeus, the foramen for their insertion being seated entirely in
_ the epicranium (see Fig. 50). In some Insects there are traces of
5 the epicranium being divided longitudinally along the middle
line. When this part is much modified the antennae may
appear to be inserted on the lateral portions of the head, or even

94 INSECTS CHAP.

on its under-side; this arises from extension of some part of the
epicranium, as shown in Fig. 49, B, where h, the cavity of
insertion of the antenna, appears to be situate on the under-
surface of the epicranium, the appearance pee due to an
infolding of an angle of the part.

There is always a gap in the back of the head for the passage
of the alimentary canal and other organs into the thorax; this
opening is called the occipital foramen. Various terms, such as
frons, vertex, occiput, temples, and cheeks, have been used for
designating areas of the head. The only one of these which is of
importance is the gena, and even this can only be defined as the
anterior part of the lateral portion of the head-capsule. An
extended study of the comparative anatomy of the head-capsule
is still a desideratum in entomology. The appendages of the head
that are engaged in the operations of feeding are frequently
spoken of collectively as the trophi, a term which includes the
labrum as well as the true buccal appendages.

The appendages forming the parts of the mouth are paired,
and consist of the mandibles, the maxillae, and the labium, the
pair in this latter part being combined to form a single body.
The buccal appendages are frequently spoken of as gnathites.
The gnathites are some, if not all, of them composed of apparently
numerous parts, some of these being distinct sclerites, others
membranous structures which may be either bare or pubescent—
that is, covered with delicate short hair. In Insects the mouth
functions in two quite different ways, by biting or by sucking.
The Insects that bite are called Mandibulata, and those that suck
Haustellata. In the mandibulate Insects the composition of the
gnathites is readily comprehensible, so that in nearly the whole
of the vast number of species of that type the corresponding ©
parts can be recognised with something like certainty. This,
however, is not the case with the sucking Insects ; in them the
parts of the mouth are very different indeed, so that in some
cases morphologists are not agreed as to what parts really
correspond with some of the structures of the Mandibulata. At
present it will be sufficient for us to consider only the mandibulate
mouth, leaving the various forms of sucking mouth to be~
discussed when we treat of the Orders of Haustellata in detail.

The upper or anterior pair of gnathites is the mandibles,
(Fig. 50, 9). There is no part of the body that varies more than

fa

mm | MOUTH-PARTS _ oe

does the mandible, even in the mandibulate Insects. It can
searcely be detected in some, while in others, as in the male stag-
beetle, it may attain the length of the whole of the rest of the
body; its form, too, varies as much as its size ; most usually,
however, the pair of mandibles are somewhat of the form of
eallipers, and are used for biting, cutting, holding, or crushing
_ purposes. The mandibles are frequently armed with processes

spoken of as teeth, but which must not be in any way confounded

with the teeth of Vertebrates. The only Insects that. possess an

~ articulated tooth are the Passalidae, beetles armed with a rather

large mandible bearing a single mobile tooth among others that
are not so. Wood Mason and Chatin consider the mandibles to

Fic. 51. — Mandibles,
maxillae, and labium
of Locusta viridis-
sima; A, mandibles ;
B, maxillae (lateral
parts) and Jlabium
(middle parts) united :
a, cardo; b, stipes ;
c, palpiger ; d, max.
palp. ; ¢, lacinia; /,
galea; g,submentum ;
h, mentum; 7%, pal-
piger ; %, labial pal-
pus; 7, ligula; m,
paraglossa (galea); ,
lacinia ; 0, lingua.

be, morphologically, jomted appendages, and the latter authority
states that in the mandible of Embia he has been able to distin-
guish the same elements as exist in the maxillae. In aculeate
Hymenoptera the mandibles are used to a considerable extent
for industrial purposes.

The maxilla is a complex organ consisting of numerous pieces,
viz. cardo, stipes, palpiger, galea, lacinia, palpus. The galea and
lacinia are frequently cailed the lobes of the maxilla. The
maxilla no doubt acts as a sense organ as well as a ‘mechanical
apparatus for holding; this latter function being subordinate to
the other. In Fig. 68, p. 122, we have represented a complex
maxillary sense-organ.

The labium or lower lip has as its basal portion the un-

96 INSECTS | CHAP.

divided mentum, and closes the mouth beneath or behind,
according as the position of the head varies. In most Insects
the labium appears very different from the maxilla, but in many
cases several of the parts corresponding to those of the maxilla
can be clearly traced in the labium.
The mentum is an undivided, frequently very hard, piece,
continuous with either the submentum or the gula, and anterior
to this are placed the other parts, viz.
the labial palpi and their supports, the
palpigers; beyond and between these
exists a central piece (Fig. 52, B, e),
about whose name some difference of
opinion prevails, but which may be called
the ligula (languette of French authors),
and on each side of this is a paraglossa.
In the Orthoptera the single median
piece —the ligula of Coleopterists — is
represented by two divided parts. In
some Insects (many Coleoptera) there is
interposed between the mentum and the
palpigers a piece called the hypoglottis
(Fig. 52, B, 6). It is not so well ascer-
tained as it should be, that the pieces of
the lower lip bearing the same names in
different Orders are in all cases really
homologous, and comparison suggests that -
Fig. 52.—Maxilla and lower the hypoglottis of Coleoptera may pos-
lip of Coleoptera. A, Max- . " : ‘
illa of Passalus: a, cardo: Sibly represent the piece corresponding
saan ; idee ps ae to the mentum of Orthopterists, the so-
rior lobe or lacinia; f, Called mentum of beetles being in that
outer or superior lobe or ease the submentum of Orthopterists.
galea: B, Labium of Har- : &
palus caliginosus: a, men- There is another part of the mouth
bam 5 0 hyposlottis; © to which we may call special atten-
palpiger (support of the : .
labial palp); d, palp; e, tion, as it has recently attracted more
Aigule 5. fy: Dante hones attention than it formerly did; it is a
membranous lobe in the interior of the mouth, very conspicuous
in Orthoptera, and called the tongue, lingua, or hypopharynx ;
it reposes, in the interior of the mouth (Fig. 51, 0), on the
middle parts of the front of the labium; it is probably not
entirely lost in Coleoptera, but enters into the composition of the

STRUCTURE 97

lex middle part of the lip by amalgamation with the para-
ae. It has recently been proposed to treat this lingua as the
" ogical equivalent of the labium or of the maxillae, g giving

remains to be proved ; * the view is apparently suggested chiefly
b by the structure of the mouth of Hemimerus, a very rare and
‘most peculiar Insect that has not as yet been sufficiently studied.
: ats the maxillae and labium are largely used by taxonomists
in the systematic arrangement of the mandibulate Insects, we
sive a figure of them as seen in Coleoptera, where the parts,
though closely amalgamated, can nevertheless be distinguished.
Phie Fig. 52 should be compared with Fig. 51.

a In speaking of the segments of the body we pointed out
th they were not separate parts but constituted an uninter-
; Br ted whole, and it is well to remark here that this is also
true of the gnathites. Although the mouth parts are spoken of
? as Beerete pieces, they really form only projections from the
| body wall. Fig. 51, B, shows the intimate connexion
; “that exists between the maxillae and labium; the continuity
of the mandibles with the membrane of the bhocal cavity is
ee of very easy demonstration.

_ The head bears, besides the pieces we have considered, a pair
EG ‘antennée. These organs, though varying excessively in form,
are always present in thé adult Insect, and exist even in the
% naj ority of young Insects. They are very mobile, highly sensitive
_ organs, situate on or near the front part of the head. The
antennae arise in the embryo from the procephalic lobes, the
orphological import of which parts is one of the most difficult
“poi connected with Insect embryology.

The eyes of Insects are of two sorts, simple and compound.
dt The simple éyes, or ocelli, vary in number from one to as many
as eighteen or twenty; when thus numerous they are situated in
g oups on each side of the head. In their most perfect form, as
- found in adult aculeate Hymenoptera, in Orthoptera and Diptera,
— 0ce are usually two or three in number, and present the
pe pearance of small, perfectly transparent lenses inserted in the
integument. In their simplest form they are said to consist of
some masses of pigment in connexion with a nerve.

<The compound, or facetted, eyes are the most remarkable of all

1 See on this subject, p. 217.
VOL. V H

98 EYES _ CHAP.

the structures of the Insect, and in the higher and more active
forms, such as the Dragon-flies and. hover-
ing Diptera, attain a complexity and deli-
cacy of organisation that elicit the highest
admiration from every. one who studies
them. They are totally different in
structure and very distinct in function
from the eyes of Vertebrata, and are
seated on very large special lobes of the
brain (see Fig. 65), which indeed are
so large and so complex in structure
that Insects may be described as possess-
ing special ocular brains brought into
relation with the lights, shades, and
movements of the external world by a
remarkably complex optical apparatus.
This instrumental part of the eye is
Fig. 53. —Two ommatidia from called the dioptric part in contradistinc-
the eye of Colymbetes fus- ,. Sha ?
cus,x 160. (After Exner,) t10n from the percipient portion, and con-
a, Cornea; 6, crystalline gists of an outer corneal lens (a, Fig. 53),
cone ; ¢, rhabdom; 4d,
fenestrate membrane with Whose exposed surface forms one of the
D scionca: venes facets of the eye; under the lens is placed
pigment. tye the crystalline cone (b), this latter being
borne on a rod-like object (c), called the
rhabdom. There are two layers of pigment, the outer (e),
called the iris-pigment, the inner (/), the retinal- pigment ;
underneath, or rather we should say more central than, the
rhabdoms is the fenestrate membrane (d), beyond which - there
is an extremely complex mass of nerve- fibres; nerves also
penetrate the fenestrate membrane, and their distal extremi-
ties are connected with the delicate sheaths by one of which
each rhabdom is surrounded, the combination of sheath and
nerves forming a retinula. Each set of the parts above the fene-
strate membrane constitutes an ommatidium, and there may be
‘many of these ommatidia in an eye; indeed, it is said that the
eye of a small beetle, Mordella, contains as many as 25,000
ommatidia. As a rule the larvae of Insects with a complete
metamorphosis bear only simple eyes. In the young of.Dragon-
flies, as well as of some other Insects having a less perfect meta-
morphosis, the compound eyes exist in the early stages, but they

HEAD AND THORAX -99

salled the tentorium, whose chief office apparently is to protect
Be brain. It is different in kind according to the species. The
ud shows a remarkable and unique relation to the following
: ents. It is the rule in Insect structure that the ass g of a

bos 70 rds, each segment receives within it the front of the one
: behind it. Though this is one of the most constant features of
Insect anatomy, it is departed from in the case of the head,
se which may be either received into, or overlapped by, the
a eee! following it, but never itself overlaps the latter. There
_is perhaps but a single Insect (Hypocephalus, an anomalous beetle)
os in which the relation between the head and
‘ thorax can be considered to be at all similar
to that which exists between each of the
other segments of the body and that follow-
ing it; and even in Hypocephalus it is only
2 posterior angles of the head that over- 4 4
ee the thorax. Although the head usually y,, 54 — Extended head
appears to be very closely connected with — and front of thorax of
2 a beetle, Huchroma: a,
‘the thorax, and is very frequently in re- hack of head; 0, front
par ose received to a considerable extent-within of: spe pe ar
“the latter, it nevertheless enjoys great cervical sclerites.

: - freedom of motion; this is obtained by

means of a large saenbrana, capable of much corrugation, and
BY iM which there are seated some sclerites, so arranged as to fold
~ together and occupy little space when the head is retracted, but
which help to prop and support it when extended for feeding or
vi other purposes. These pieces are called the cervical sclerites or
hiss They are very largely developed in Hymenoptera, in
many Coleoptera, and in Blattid, and have not yet received from
te natomists a sufficient amount of attention. Huxley suggested

hat they may be portions of head segments.

i
q

Thorax.

The thorax, being composed of the three consecutive rings
behind the ead: falls naturally into three divisions—pro-, meso-,

100 THORAX "ea

and metathorax. These three segments differ greatly in their
relative proportions in different Ifsects, and in different stages
of the same Insect’s life. In their more highly developed con-
ditions each of the three divisions is of complex structure, and.
the sclerites of which it is externally made up are sufficiently
constant in their numbers and relative positions to permit of
their identification in a vast number of cases; hence the sclerites
have received names, and their nomenclature is of practical
importance, because some, if not all, of these parts are made use
of in the classification of Insects. Each division of the thorax
has an upper region, called synonymically dorsum, notum, or
tergum; an inferior or ventral region, called sternum; and on
each side a lateral region, the pleuron. These regions of each of
the three thoracic divisions are further distinguished by joining
to their name an indication of the segment spoken of, in the
form of the prefixes pro-, meso-, and meta-; thus the pronotum,
prosternum, and propleura make up the prothorax. The thoracic
regions are each made up of sclerites whose nomenclature is due
to Audouin.! He considered that every thoracic ring is com-
posed of the pieces shown in Fig. 55, viz. (1) the sternum (B’,
a), an unpaired ventral piece; (2) the notum (A), composed of
four pieces placed in consecutive longitudinal order (A’), and
named praescutum (a), scutum (0), scutellum (c), and post-scutel-
lum (d@); (3) lateral pieces, of which he distinguished on each
side an episternum (B’, c),epimeron (¢), and parapteron (d), these
together forming the pleuron. We give Audouin’s Figure, but we
cannot enter on a full discussion of his views as to the thorax ;
. they have become widely known, though the constancy of the
parts is not so great as he supposed it would prove to be. Some-
times it is impossible to find all the elements he thought should be
present in a thoracic ring, while in other cases too many sclerites
exist. As a rule the notum of the meso- and metathoraces is
in greater part composed of two pieces, the scutum and the
scutellum; while in the pronotum only one dorsal piece can be
satisfactorily distinguished, though a study of the development
may show that really two are frequently, if not usually, present.
On the other hand, one, or more, of the notal sclerites in some
cases shows evidence of longitudinal division along the middle.
The sternum or ventral piece, though varying greatly in form, is

1 Ann. Sci. Nat. I. 1824, p. 97, ete.

THORAX IOI

: le most constant element of a thoracic segment, but it has
_ sometim<s the appearance of consisting of two parts, an anterior
and a posterior. The pleuron nearly always consists quite
_ evidently of two parts, the episternum, the more anterior and
_ inferior, and the epimeron.'' The relations between these two
_ parts vary much; in some cases the episternum is conspicuously
r _ the more anterior, while in others the epimeron is placed much
a above it, and may extend nearly as far forwards.as it. It may
_ be said, as a rule, that when the sternum extends farther back-

r wards than the notum, the epimeron is above the episternum,

a J 4
4 Fie. 55.—Mesothorax of Dytiscus, after Audouin. A, notum; A’, pieces of the notum

ii’ Separated: a, praescutum ; 6, scutum; c¢, scutellum ; d, post-scutellum: B, the
_ Sternum and pleura united ; B’, their parts separated: a, sternum; c, episternum ;

d, parapteron; e, epimeron.
as in many Coleoptera; but if the sternum be anterior to the
- notum, then the episternum is superior to the epimeron, as in
_ dragon-flies. We would here again reiterate the fact that these
_ “pieces” are really not separate parts, but are more or less in-
_ durated portions of a continuous integument, which is frequently
entirely occupied by them; hence a portion of a sclerite that in
_ one species is hard, may in an allied form be wholly or partly
membranous, and in such case its delimitation may be very
_ evident on some of its sides, and quite obscure on another.
1 See also Fig. 47 (p. 88). :

102 THORAX CHAP.

The parapteron of Audouin does not appear to be really a
distinct portion of the pleuron; in the case of Dytiscus it is
apparently merely a thickening of an edge. Audouin supposed
this part to be specially connected with the wing-articulation,
and the term has been subsequently used by other writers in
connexion with several little pieces that exist in the pleural
region of winged Insects.

The prothorax is even more subject to variation in its
development than the other divisions of the thorax are. In the
_ Hymenoptera the prosternum is disconnected from the pronotum
and is capable, together with the first pair of legs, of movement
independent of its corresponding dorsal part, the pronotum,
which in this Order is always more or less completely united
with the meso-thorax ; in the Diptera the rule is that the three
thoracic segments ‘are closely consolidated into one mass. In
the majority of Insects the prothorax is comparatively free, that
is to say, it is not so closely united with the other two thoracic
segments as they are with one another. The three thoracic
rings are seen in a comparatively uniform state of development
in a great number of larvae; also in the adult stages of some
Aptera, and among winged insects in some Neuroptera such as the
Embiidae, Termitidae, and Perlidae. In Lepidoptera the pro-
notum bears a pair of erectile processes called patagia; though
frequently of moderately large size, they escape observation, being
— covered with scales and usually closely adpressed to the sides of
the pronotum.

The two great divisions of the body—the mesothorax and
the metathorax—are usually very intimately combined in winged —
Insects, and even when the prothorax is free, as in Coleoptera,
these posterior two thoracic rings are very greatly amalgamated.
In the higher forms of the Order just mentioned the meso-
sternum and mesopleuron become changed in direction, and form
as it were a diaphragm closing the front of the metasternum.
The meso- and meta-thorax frequently each bear a pair of wings.

We have described briefly and figured (Fig. 55) the sclerites
of the mesothorax, and those of the metathorax correspond fairly
well with them. In addition to the sclerites usually described
as constituting these two thoracic divisions, there are some small
pieces at the bases of the wings. Jurine discriminated and
named no less than seven of these at the base of the anterior

| THORAX 103

wing of a Hymenopteron. One of them becomes of considerable
size and importance in the Order just mentioned, and seems
to be articulated so as to exert pressure on the base of the
costa of the wing. This structure attains
its maximum of development in a genus
(?nondescript) of Scoliidae, as shown in Fig.
56. The best name for this sclerite seems
to be that proposed by Kirby and Spence,
tegula, Some writers call it paraptére, hypo-
ptere, or squamule, and others have termed
it patagium; this latter name is, however,
inadmissible, as it is applied to a process of
the prothorax we have already alluded to. Fro, 56... Head. and
To complete our account of the structure thorax of fossorial
Bat, ; wasp from Bogota: ¢,
of the thorax it is necessary to mention cer- tegula;d, baseof wing.
tain hard parts projecting into its interior,
but of which there is usually little or no trace externally. <A
large process in many Insects projects upwards from the sternum
in a forked manner. It was called by Audouin the entothorax ;
some modern authors prefer the term apophysis. Longitudinal
partitions of very large size, descending from the dorsum into
the interior, also exist; these are called phragmas, and are of
great importance in some Insects with
perfect flight, such as Hymenoptera,
Lepidoptera, and Diptera. There is no
phragma in connection with the prono-
tum, but behind this part there may
be three. A phragma has the appear-
ance of being a fold of the dorsum; it
“Fic. 57,—Traneverse section of SCrVeS a8 an attachment for muscles,
skeleton of metathorax of and may probably be of service in
cts one mes other ways. More insignificant projec-
metasternum ; c, phragma; tions into the interior are the little
ee dane. ten pieces called apodemes (Fig. 57, e);
Ealbe) articulation, (After these are placed at the sides of the
thorax near the wings. The apophyses
are no doubt useful in preserving the delicate vital organs from
shocks, or from derangement by the muscular movements and
the changes of position of the body.
The’ appendages of the thorax are (a) inferior, the legs; (4)

tuk

104 LEGS CHAP.

superior, the wings. The legs are always six in number, and ‘are
usually present even in larvae, though there exist many apodal.
larvae, especially in Diptera. The three pairs of legs form one
' of the most constant of the characters of

Insects. They are jointed appendages and
consist of foot, otherwise tarsus ; tibia, femur,
trochanter, and coxa; another piece, called
trochantin more or less distinctly separated
from the coxa, exists in many Insects. The
legs are prolongations of the body sac, and
are in closer relation with the epimera and
with the episterna than with other parts
of the crust, though they have a close
relation with the sternum. If we look at
the body and leg of a neuropterous Insect
(Fig. 58) we see that the basal part of the
leg—the coxa—is apparently a continua-
tion of one of the two pleural pieces or of
both; in the latter case one of the prolonged
pieces forms the coxa proper, and the tip
of the other forms a supporting piece,
which may possibly be the homologue of
Fic. 58.—Hind leg of Pan- the trochantin of some Insects. In some
onpa.: a, episternum ; @, Orthoptera, especially in Blattidae, and in

epimeron ; 0, coxa; 0’, 28 : * a

coxal fold of epimeron; Termitidae, there is a transverse chitinised

php a fen femurs fold interposed between the sternum and

the coxa, and this has the appearance of

being the same piece as the trochantin of the anterior legs of
Coleoptera.

Beyond the coxa comes the trochanter; this in many
Hymenoptera is a double piece, though in other Insects it is
single; usually it is the most insignificant part of the leg. ‘The
femur is, on the whole, the least variable part of the leg; the
tibia, which follows-it, being frequently highly modified for
industrial or other purposes. The joint between the femur and
the tibia is usually bent, and is therefore the most conspicuous
one in the leg; it is called the knee. The other joints have not
corresponding names, though that between the tibia and the
tarsus is of great importance. The spines at the tip of the tibia,
projecting beyond it, are called spurs, or calcares. The tarsus or

ee,

FEET | 105

— fo “is s extremely variable; it is very rarely Bhat: but may
Py es ist of only one piece—joint, as it is frequently called }—
af any larger number up to five, which may be considered
characteristic number in the higher Insect forms. The
rminal joint of the tarsus bears normally a pair of claws;
tween the claws there is frequently a lobe or process,
¥ according to circumstances very varied in different Insects,
~ ealled empodium, arolium, palmula, plantula, pseudonychium,
s Bice pulvillus. This latter name should only be used in those
_ eases in which the sole of the foot is covered with a dense
bo pubescence. The form of the individual tarsal joints and the
alia or vestiture of the lower surface are highly variable.
_ The most remarkable tarsus is that found on the front foot of the
~ male Dytiscus.

It has been suggested that the claws and the terminal append- —
age of the tarsus ought to be counted as forming a distinct joint ;
__ hence some authors state that the higher Insects have six joints
" a to the feet. These parts, however, are never counted as
*Y separate joints by systematic entomologists, and it has recently
been stated that they are not such originally.

____ The parts of the foot at the extremity of the last tarsal oink
g proper are of great importance to the creature, and vary greatly
é in different Insects. The most constant part of this apparatus
__ is a pair of claws, or a single claw. Between the two claws
_ there may exist the additional apparatus referred to above. This
in some Insects—notably in the Diptera—reaches a very complex
development. We figure these structures in Pelopaeus spinolae,
a fossorial Hymenopteron, remarking that our figures exhibit the
_ apparatus in a state of retraction (Fig. 59). According to the
nomenclature of Dahl and Ockler? the plate (0) on the dorsal
aspect is the pressure plate (Druck-Platte), and acts as an agent
_ of pressure on the sole of the pad (C, e); ¢ and d on the
= underside are considered to be extension-agents; c, extension-
plate; d, extension-sole (Streck-Platte, Streck- Sohle). These
__agents are assisted in acting on the pad by means of an elastic
___ bow placed in the interior of the ‘latter. The pad (e) is a very
remarkable structure, capable of much extension and retraction ;

1 In entomological language the piece between each two joints of an appendage
is itself called a joint, though segment is doubtless a better term.
2 Arch. f. Naturgeschichte, lvi. 1890, p. 221.

106 FEET CHAP.

when extended it is seen that the pressure plate is bent twice at
a right angle so as to form a step, the distal part of which runs
along the upper face of the basal part of the pad; the apical
portion of this latter consists of two large lobes, which in repose, as
shown in our Figure (/), fall back on the pad, something in the
fashion of the retracted claws of the cat, and conceal the pres-
sure-plate.

The mode in which Insects are able to walk on smooth
perpendicular surfaces has been much discussed, and it appears
highly probable that the method by which this is accomplished
is the exudation of moisture from the foot; there is still, how-
ever, much to be ascertained before the process can be satisfactorily

Fic. 59.—Foot of Pelopaeus, a
fossorial wasp: A,tarsus entire ;
B, terminal joint, upper side ;
C, under side. a, claw; 3B,
base of pressure-plate ; c, ex-
tension - plate ; d, extension-
sole; e, pad; 7, lobe of pad
retracted.

comprehended. The theory to the effect that the method is the
pressure of the atmosphere acting on the foot when the sole is
in perfect apposition with the object walked on, or when a
slight vacuum is created between the two, has apparently less to
support it.

The legs of the young Insect are usually more simple than
those of the adult, and in caterpillars they are short appendages,
and only imperfectly jointed. If a young larva, with feet, of
a beetle, such as Crioceris asparagi be examined, it may be seen
that the leg is formed by protuberance of the integument,
which becomes divided into parts by simple creases; an observa-
tion suggesting that the more highly developed jointed leg is
formed in a similar manner. This appears to be really the case,

IIL WINGS 107

for the actual continuity of the limb at the chief joint—the
knee—can be demonstrated in many Insects by splitting the
outer integument longitudinally and then pulling the pieces a
little apart; while in other. cases even this is not necessary,
the knee along its inner face being membranous to a consider-
able extent, and the membrane continuous from femur to tibia.

_ Turning to the wings, we remark that there may be one or
two pairs of these appendages. When there is but one pair it is
nearly always mesothoracic, when there are two pairs one is invari-
ably mesothoracic, the other metathoracic. The situation of the
wing is always at the edge of the notum, but the attachment
varies in other respects. It may be limited to a small spot, and
this is usually the case with the anterior wing; or the attachment
may extend for a considerable distance along the edge of the
notum, a condition which frequently occurs, especially in the case
of the posterior wings. The actual connexion of the wings
with the thorax takes place by means of strong horny lines
in them which come into very close relation with the little
pieces in the thorax which we have already described, and which
were styled by Audouin articulatory epidemes. There is
extreme variety in the size, form, texture, and clothing of the
wings, but there is so much resemblance in general characters
amongst the members of each one of the Orders, that it is usually
possible for an expert, seeing only a wing, to say with certainty
what Order of Insects its possessor belonged to. We shall allude
to these characters in treating of the Orders of Insects.

Each wing consists of two layers, an upper and a lower, and
between them there may be tracheae and other structures,
especially obvious when the wings are newly developed. It has
‘been shown by Hagen that the two layers can be separated
when the wings are recently formed, and it is then seen that
each layer is traversed by lines of harder matter, the nervures.
These ribs are frequently called wing-veins, or nerves, but as
they have no relation to the anatomical structures bearing those
names, it is better to make use of the term nervures. The
strength, number, form and inter-relations of these nervures
vary exceedingly; they are thus most important aids in the
classification of Insects. Hence various efforts have been made
to establish a system of nomenclature that shall be uniform
throughout the different Orders, but at present success has not

108 WINGS - CHAP.

attended these efforts, and it is probable that no real homology
exists between the nervures of the different Orders of Insects.
We shall not therefore discuss the question here. We may,
however, mention that German savants have recently distin-
guished two forms of nervures which they consider essentially
distinct, viz. convex and concave. These, to some extent, alter-
nate with one another, but a fork given off by a convex one is
not considered to be a concave one. The terms convex and con-
cave are not happily chosen; they do not refer to the shape of
the nervures, but appear to have been suggested by the fact that
the surface of the wing being somewhat undulating the convex
veins more usually run along the ridges, the concave veins along
' the depressions. The convex are the more important of the two,
being the stronger, and more closely connected with the articula-
tion of the wing.

The wings, broadly speaking, may. be said to be three-
margined: the margin that is anterior when the wings are
extended is called the costa, and the edge that is then most
distant from the body is the outer margin, while the limit that
lies along the body when the wings are closed is the inner
margin. | |

The only great Order of Insects provided with a single pair
of wings is the Diptera, and in these .the metathorax possesses,
instead of wings, a pair of little capitate bodies called halteres or
poisers. In the abnormal Strepsiptera, where a large pair of
wings is placed on the metathorax, there are on the mesothorax
some small appendages that are considered to represent the
anterior wings. In the great Order Coleoptera, or beetles, the
anterior wings are replaced by a pair of horny sheaths that close
together over the back of the Insect, concealing the hind-wings,
so that the beetle looks like a wingless Insect: in other four-
winged Insects it is usually the front wings that are most
useful in flight, but the elytra, as these parts are called in
Coleoptera, take no active part in flight, and it has been
recently suggested by Hoffbauer? that they are not the homo-
logues of the front wings, but of the tegulae (see Fig. 56), of other
Insects. In the Orthoptera the front wings also differ in con-
sistence from the other pair over which they lie in repose, and
_ are called tegmina. There are many Insects in which the wings

1 Zeitschr. wiss. Zool. liv. 1892, p. 579.

ABDOMEN 109

in a more or less rudimentary or vestigial condition, though
2 never used for purposes of flight.
‘The abdomen, or hind body, is the least modified part of the
body, though some of the numerous rings of which it is composed
nay be extremely altered from the usual simple form. Such
ange takes place at its two extremities, but usually to a much
er extent at the distal extremity than at the base. This
at r part is attached to the thorax, and it is a curious fact
that in many Insects: the base of the abdomen is so closely
connected with the thorax that it has all the appearance of.
g@ a portion of this latter division of the body; indeed
sometimes difficult to trace the real division between the
tw parts. In such cases a further differentiation may occur,
and the part of the abdomen that on its anterior aspect
is intimately attached to the thorax may on its posterior
ect be very slightly connected with the rest of the abdomen.
der such circumstances it is difficult at first sight to recognise
eal state of the case. When a segment is thus transferred
1 the abdomen to the
athorax, the part is
ed a median segment.
- most remarkable
jan segment exists in
se Hymenoptera which
e a stalked abdomen,
a similar though less

rect condition exists in fe Re lobrt i
‘. Fic. 60.—Simple abdomen of Japyx contrast
aig Insects. When such with the highly modified one of an ant, Crypto-

a union occurs, it is usually —cerus (B). The segments are numbered from
a before backwards.
t complete on the dorsal

mos
‘surface, and the first ventral plate may almost totally disappear :
uch an alteration may involve a certain amount of change in
_ the sclerites of the next segment, so that the morphological deter-
_ mination of the parts at the back of the thorax and front of the
_ abdomen is by no means a simple matter. A highly modified
hind-body exists in the higher ants, Myrmicidae. In Fig. 6 0
| contrast the simple abdomen of Japyx with the highly modi-
fied state of the same part in an ant.

_ Unlike the head and thorax, the abdomen is so loosely knitted
~ together that it can undergo much expansion and contraction. .

I1O ABDOMEN CHAP.

This is facilitated by an imbricated arrangement of the plates, and
by their being connected by means of membranes admitting of
much movement (Fig. 47, m,p. 88). In order to understand the
structure of the abdomen it should be studied in its most dis-
tended state; it is then seen that there is a dorsal and a ventral
hard plate to each ring, and there is also usually a stigma; there
may be foldings or plications near the line of junction of the
dorsal and ventral plates, but these margins are not really distinct
pieces. The pleura, in fact, remain membranous in the abdominal
region, contrasting strongly with the condition of these parts in
the thorax. The proportions of the plates vary greatly; some-
times the ventral are very large in proportion to the dorsal, as is
usually the case in Coleoptera, while in the Orthoptera the reverse
condition prevails.

Cerci or other appendages frequently exist at the extremity
of the abdomen (Fig. 47, n, p. 88); the former are sometimes
like antennae, while in other cases they may be short com-
pressed processes consisting of very few joints. The females of
many Insects possess saws or piercing instruments concealed
within the apical part of the abdomen; in other cases an
elongate exserted organ, called ovipositor, used for placing the
egos in suitable positions, is present. Such organs consist, it is
thought, either of modified appendages, called gonapophyses, or
of dorsal, ventral, or pleural plates. The males frequently bear
within the extremity of the body a more or less complicated
apparatus called the genital armour. The term gonapophysis is
at present a vague one, including stings, some ovipositors, por-
tions of male copulatory apparatus, or other structures, of which
the origin is more or less obscure.

The caterpillar, or larva, of the Lepidoptera and some other
Insects, bears a greater number of legs than the three pairs we
have mentioned as being the normal number in Insects, but the
posterior feet are in this case very different from the anterior,
and are called false legs or prolegs. These prolegs, which are
placed on the hind body, bear a series of hooks in Lepidopterous
larvae; but the analogous structures of Sawfly larvae are destitute
of such hooks.

Placed along the sides of the body, usually quite visiblé in
the larva, but more or less concealed in the perfect Insect, are
little apertures for the admittance of air to the respiratory

Sara | SPIRACLES _ Ill

system. They are called spiracles or stigmata. There is
extreme variety in their structure and size; the largest and most
remarkable are found on the prothorax of Coleoptera, especially in
the groups Copridae and Cerambycidae.

The exact position of the stigmata varies greatly, as does also
their number. In the Order Aptera there may be none, while
the maximum number of eleven pairs is said by Grassi* to be
attained in Japyx solifugus : in no other Insect have more than
ten pairs been recorded, and this number is comparatively rare.
Both position and number frequently differ in the early and
later stages of the same Insect. The structure of the stigmata
is quite as inconstant as the other points we have mentioned are.

The admission of air to the tracheal system and its confine-
ment there, as well as the exclusion of foreign bodies, have to be
provided for. The control of the air within the system is,
according to Landois? and Krancher,* usually accomplished by
means of an occluding apparatus placed on the tracheal trunk a
little inside of the stigma, and in such case this latter orifice
serves chiefly as a means for preventing the
intrusion of foreign bodies. The occluding
apparatus consists of muscular and mechanical
parts, which differ much in their details in
different Insects. Lowne supposes that the
air is maintained in the tracheal system in a
compressed condition, and if this be so, this
apparatus must be of great importance in the
Insect economy. Miall and Denny‘ state Fic. 61.—Membranous
that in the anterior stigmata of the cock- Pare Detween pre.
roach the valves act as the occluding agents, a beetle Huchroma,
muscles being attached directly to the inner 9'°y;"§ “TENE ar

a, hind margin of
‘face of the valves, and in some other Insects — pronotum; 0, front
ef ‘ leg ; c, front margin
the spiracular valves appear to act partially of mesonotum ; d,
by muscular agency, but there are many Pase of elytra; 4
. ; ; . inesosternum.
stigmata having valves destitute of muscles.
According to Lowne® there exist valves in the blowfly at the
entrance to the trachea proper, and he gives the following as the

arrangement of parts for the admission of air :—there is a spiracle

1 Mem. Acc. Lincei Rom. (4) iv. 1888, p. 554.
* Zeitschr. wiss. Zool. xvii. 1867, p. 187. 8 Zool. Anz. iii. 1880, p. 584.
4 The Cockroach, 1886, p. 151. 5 Anatomy of the Blowfly, 1893, p. 362

II2 ‘INSECTS | CHAP. —

leading into .a chamber, the atrium, which is limited inwardly _
by the occluding apparatus; and beyond this there is a second —
chamber, the vestibule, separated from the tracheae proper by a
valvular arrangement. He considers that the vestibule acts as a
pump to force the air into the tracheae.

Systematic Orientation.

Terms relating to position are unfortunately used by writers
on entomology in various, even in opposite senses. Great
confusion exists as to the application of such words as base, apex,
transverse, longitudinal. We can best explain the way in
which the relative positions and directions of parts should be
described by reference to Figure 62. The spot 3 represents an
imaginary centre, situated between the thorax and abdomen, to
which all the parts of the body are supposed to be related. The
Insect should always be described as if it were in the position
shown in the Figure, and the terms used should not vary as the
position is changed. The creature is placed with ventral surface
beneath, and with the appendages extended, like the Insect itself,
in a horizontal plane. In the Figure the legs are, for clearness,
made to radiate, but in the
proper position the anterior pair
should be approximate in front,
and the middle and hind pairs
directed backwards under the
body. The legs are not to be
treated as if they were hanging
from the body, though that is
the position they frequently
actually assume. The right and
left sides, and the upper and
lower faces (these latter are
frequently also spoken of as
sides), are still to retain the
same nomenclature even when

terms of position. A, apex; B, base: the position of the specimen is

1, tibia ; 2, last abdominal segment ; 3, reversed. The base of an organ

ideal centre, ; ' .

is that margin that is nearest
to the ideal centre, the apex that which is most distant.

ORIENTATION — | 113

F ig. 62, where 1 indicates the front tibia, the apex
ler than the base (B) ; ; in. the antennae the apex

; tring to the axis chad fron Spells back-
1 transverse to that going across, 7.¢. from side to side.

CHAPTER IV

ARRANGEMENT OF INTERNAL ORGANS——MUSCLES——NERVOUS SYSTEM
—GANGLIONIC CHAIN—BRAIN—-SENSE-ORGANS——ALIMENTARY
CANAL — MALPIGHIAN TUBES — RESPIRATION — TRACHEAL
SYSTEM—-FUNCTION OF RESPIRATION—-BLOOD OR BLOOD-
CHYLE——-DORSAL VESSEL OR HEART——FAT-BODY——OVARIES—
TESTES——PARTHENOGENESIS——GLANDS.

THE internal anatomy of Insects may be conveniently dealt with
under the following heads :—(1) Muscular system; (2) nervous

SO ees Bo.

Le k;

Fic. 63.—Diagram of arrangement of some of the internal organs of an Insect : a, mouth ;
6, mandible; c, pharynx; d, oesophagus; e, salivary glands (usually extending
further backwards); /, eye; g, supra-oesophageal ganglion; h, sub-oesophageal
ganglion ; 7, tentorium; j, aorta; k,, kj, kz, entothorax; J/,-/,, ventral nervous
chain; m, crop; ”, proventriculus ; 0, stomach; py, Malpighian tubes; qg, small
intestine ; 7, large intestine ; s, heart ; ¢, pericardial septum ; uw, u, ovary composed
of four egg-tubes ; v, oviduct ; w, spermatheca (or an accessory gland): 2, retractile
ovipositor ; y, cercus ; z, labrum.

system ; (3) alimentary system (under which may be included
secretion and excretion, about which in Insects very little is
known); (4) respiratory organs; (5) circulatory system ; 6) fat-
body ; (7) reproductive system.

CHAP. IV | MUSCLES | 115

%

Many of the anatomical structures have positions in the body
that are fairly constant throughout the class. Parts of the
respiratory and muscular systems and the fat-body occur in most
of the districts of the body. The heart is placed just below the
- dorsal surface ; the alimentary canal extends along the middle
from the head to the end of the body. The chief parts of the
nervous system are below the alimentary canal, except that the
brain is placed above the beginning of the canal in the head.
The reproductive system extends in the abdomen obliquely from
above downwards, commencing anteriorly at the upper part and
terminating posteriorly at the lower part of the body cavity.

In Fig. 63 we show the arrangement of some of the chief
organs of the body, with the exception of the muscular and
respiratory systems, and the fat-body. It is scarcely necessary
to point out that the figure is merely diagrammatic, and does not
show the shapes and sizes of the organs as they will be found in
any one Insect.

Muscles.

The muscular system of Insects is very extensive, Lyonnet *
having found, it is said, nearly 4000 muscles in the caterpillar
of the goat-moth; a large part of this number are segmental
repetitions, nevertheless the muscular system is really complex,
as may be seen by referring to the study of the flight of dragon-
flies by von Lendenfeld.” |

The minute structure of the muscles does not differ essentially
from what obtains in Vertebrate animals. The muscles are
aggregations of minute fibrils which are transversely striated,
though in variable degree. Those in the thorax are yellow or
pale brown, but in other parts the colour is more nearly white.
The muscles of flight are described as being penetrated by
numerous tracheae, while those found elsewhere are merely
surrounded by these aerating tubules.

The force brought into play by the contractions of Insect muscles
is very great, and has been repeatedly stated to be much superior
to that of Vertebrate animals; very little reliance can, however, be

1 Lyonnet, Traité anatomique de la Chenille qui ronge le bois de Saule. La
_ Haye, 1762. On p. 188 he says that he found 1647 muscles, without counting
those of the head and internal organs of the body. He puts the number found in

the human body at 529.
* SB. Ak. Wien, Abth. 1, lxxxiii. 1881, pp.' 289-376.

116 INSECTS CHAP.

placed on the assumptions and calculations that are supposed to
prove this, and it is not supported by Camerano’s recent researches.’

Some of the tendons to which the muscles are attached are
very elaborate structures, and are as hard as the chitinous
skeleton, so as to be like small bones in their nature. <A very
elaborate tendon of this kind is connected with the prothoracie
trochantin in Coleoptera, and may be readily examined in Hydro-
philus. It has been suggested that the entothorax is tendinous in
its origin, but other morphologists treat it, with more reason, as
an elaborate fold inwards of the integument.

Nervous System.

Insects are provided with a very complex nervous system,
which may be treated as consisting of three divisions :—(1) The
oe os system ; (2) the ventral, or ganglionic chain; (3) an
accessory sympathetic system, or
XS am systems. All these divisions
are intimately connected. We
will consider first. the most ex-
tensive, viz. the ventral chain.

This consists of a series of small
masses of nervous matter called
ganglia which extend in the
longitudinal direction of the
body along the median line of
the lower aspect, and are con-
nected by longitudinal .commis-
sures, each ganglion being joined
to that following it by two
threads of nervous matter. Each
of the ganglia of the ventral
chain really consists of two
ganglia placed side by side and
connected by commissures as
well as cellular matter. In
Fic. 64.—Cephalic and ventral chain of larvae some of the ganglia may
gunele: A. anya of Chiron: B be contiguous, so that the com-
missures do not exist. From

the ganglia motor nerves proceed to the various parts of the

1 Mem. Ace. Torino (2), xliii. 1898, p. 229..

Iv NERVOUS SYSTEM 117

body for the purpose of stimulating and co-ordinating the
contractions of the muscles. The number of the ganglia
in the ventral chain differs greatly in different Insects, and
even in the different stages of metamorphosis of the same
species, but never exceeds thirteen. As this number is that
of the segments of the body, it has been considered that each
segment had primitively a single ganglion. Thirteen ganglia for
the ventral chain can, however, be only demonstrated in the
embryonic state ; in the later stages of life eleven appears to be
the largest number that can be distinguished, and so many as
this are found but rarely, and then chiefly in the larval stage.
The diminution in number takes place by the amalgamation or
coalescence of some of the ganglia, and hence those Insects in
which the ganglia are few are said to have a highly concentrated
nervous system. The modes in which these ganglia combine are
very various; the most usual is perhaps that of the combination
of the three terminal ganglia into one body. Asarule it may be
said that concentration is the concomitant of a more forward posi-
tion of the gangha. As a result of this it is found that in some
cases, as in Lamellicorn beetles, there are no ganglia situate in
the abdomen. In the perfect state of the higher Diptera, the
thoracic and abdominal ganglia are so completely concentrated
in the thorax as to form a sort of thoracic brain. In Fig. 64
we represent a very diffuse and a very concentrated ganglionic
chain; A being that of the larva of Chironomus, B that of the
imago of Hippobosca. In both these sketches the cephalic gangha
as well as those of the ventral chain are shown.

Turning next to the cephalic masses, we find these-in the
_ perfect Insect to be nearly always two in number: a very large
and complex one placed above the oesophagus, and therefore
called the supra-oesophageal ganglion; and a smaller one, the
sub- or infra-oesophageal, placed below the oesophagus. The
latter ganglion is in many Insects so closely approximated to
the supra-oesophageal ganglion that it appears to be a part
thereof, and is sometimes spoken of as the lower brain. In
other Insects these two ganglia are more remote, and the infra-
oesophageal one then appears part of the ventral chain. In
the embryo it is said that the mode of development of the
supra-oesophageal ganglion lends support to the idea that it
may be the equivalent of three ganglia; there being at one

118 NERVOUS SYSTEM ; CHAP.

time three lobes, which afterwards coalesce, on each side of the
mouth. This is in accordance with the view formulated by
Viallanes! to the effect that this great nerve-centre, or brain,
as it is frequently called, consists essentially of three parts, viz.
a Proto-, a Deuto-, and a Trito-cerebron. It is, however, only
proper to say that though the brain and the ventral chain of
ganglia may appear to be one system, and in the early embryonic
condition to be actually continuous, these points cannot be con-
sidered to be fully established. Dr. L. Will has informed us?”
that in Aphididae the brain has a separate origin, and is only
subsequently united with the ganglionic chain. Some authorities
say that in the early condition the sub-oesophageal ganglion is
formed from two, and the supra-oesophageal from the same number
of ganglia; the division in that case being 2 and 2, not 3 and 1, as
Viallanes’ views would suggest. The inquiries that are necessary ~
to establish such points involve very complex and delicate in-
vestigations, so that it is not a matter of surprise that. it cannot
yet be said whether each of these views may be in certain cases
correct. The supra- and sub-oesophageal ganglia are always
intimately connected by a commissure on each side of the
oesophagus ; when very closely approximated they look like one
mass through which passes the oesophagus (Fig. 66, A). The
large supra-oesophageal ganglion supplies the great nerves of
the cephalic sense-organs, while the smaller sub-oesophageal |
centre gives off the nerves to the parts of the mouth. From
the lower and anterior part of the supra-oesophageal ganglion a
nervous filament extends as a ring round the anterior part of the
oesophagus, and supplies a nerve to the upper lip.’ This structure
is not very well known, and has been chiefly studied by Lienard,* .
who considers that it will prove to be present in all Insects.
Whether the two cephalic ganglia be considered as really part
of a single great ganglionic chain, or the reverse, they are at any
rate always intimately connected with the ventral ganglia. We
have already stated that the two cephalic masses are themselves
closely approximated in many Insects, and may add that in
some Hemiptera the first thoracic ganglion of the ventral chain
is amalgamated into one body with the sub-oesophageal ganglion,

1 Bull. Soc. Philom, Paris (7), xi. 1887, p. 119, etc., and C. R. civ. 1887, p. 444.
2 Zool. Jahrbuch. Anat. iii. 1888, p. 276. 3 Kolbe, Hinfiihrung, 1893, p. 411.
4 Arch. de Biol. i. 1880, p. 381.

4

Te a ere Se

—-

Iv BRAIN 119

and further that there are a few Insects in which this iatter
centre is wanting. If the cephalic ganglia and ventral chain be
looked on as part of one system, this may be considered as
composed originally of seventeen ganglia, which number has
been demonstrated in some embryos.

The anatomy of the supra-oesophageal ganglion is very
complex ; it has been recently investigated by Viallanes’ in the
wasp (Vespa) and in a grasshopper (Caloptenus italicus). The
development and complication of its inner structure and of some
of its outer parts appear to be proportional with the state of
advancement of the instinct or intelligence of the Insect, and
Viallanes found the brain of the grasshopper to be of a more
simple nature than that of the wasp.

Fic. 65.—Brain of Worker Ant
of Formica rufa. (After
Leydig, highly magnified. )
Explanation in text.

Brandt, to whom is due a large part of our knowledge of
the anatomy of the nervous system in Insects, says that the
supra-oesophageal ganglion varies greatly in size in various
Insects, its mass being to a great extent proportional with the
development of the compound eyes; hence the absolute size is
not a criterion for the amount of intelligence, and we must
rather look to the complication’ of the structure and to the
development of certain parts for an index of this nature. The
drone in the honey -bee has, correlatively with the superior
development of its eyes, a larger brain than the worker, but the
size of the hemispheres, and the development of the gyri
cerebrales is superior in the latter. In other words, the mass of

1 Ann. Sci. Nat. Zool. (7) ii. 1887, and iv. 1887.

120 NERVOUS SYSTEM CHAP.

those great lobes of the brain that are directly connected with
the faceted eyes must not be taken into account in a considera-
tion of the relation of the size and development of the brain to
the intelligence of the individual. The weight of the brain in
Insects is said by Lowne to vary from +45 to yop of the
weight of the body.

Figure 65 gives a view of one side of the supra-oesophageal
ganglion of the worker of an ant——¥Formica rufa,—and is
taken from Leydig, who gives the following elucidation of it:
A, primary lobe, a, homogeneous granular inner substance, 0,
cellular envelope; 2, stalked bodies (gyri cerebrales), a, b, as
before; c, presumed olfactory lobes, ¢, inner substance, d, gang-

Fic. 66. — Stomato - gastric
nerves of Cockroach: A,
with brain in situ, after
Koestler ; B, with the
brain removed, after Miall
and Denny: s.g, supra-
oesophageal ganglion ; 0,
optic nerve; a, antennary
nerve; f.g, frontal gang-
lion; oe, oesophagus; ¢,
connective; p.g, paired
ganglia ; vg, crop or ven-
tricular ganglion; 7, re-
current nerve.

lionic masses; D, ocular lobes, ¢, 7, g, 4, various layers of the
same; £, origin of lateral commissures; F, median commissure
in interior of brain; @, lower brain (sub-oesophageal ganglion) ;
H, ocelli; J, faceted eye.

Besides the brain and the great chain of ganglia there exists
an accessory system, or systems, sometimes called the sym-
pathetic, vagus, or visceral system. Although complex, these
parts are delicate and difficult of dissection, and are consequently
not so well known as is the ganglionic chain. There is a con-
necting or median nerve cord, communicating with the longi-
tudinal commissures of each segment, and itself dilating into
ganglia at intervals; this is sometimes called the unpaired
system. There is another group of nerves having paired ganglia,

get ee |

Sm PP tein

ee oe ip Obie

Order,

IV SENSES 121

starting from a small ganglion in the forehead, then connecting
with the brain, and afterwards extending along the oesophagus
to the crop and proventriculus (Fig. 66). This is usually called
the stomatogastric system. The oesophageal ring we have already
spoken of.

By means of these accessory nervous systems all the organs
of the body are brought into more or less direct relation with
the brain and the ganglionic chain.

Our knowledge of these subsidiary nervous systems is by
no means extensive, and their nomenclature is very unsettled ;
little is actually known as to their functions. °

Organs of Sense.

Insects have most delicate powers of perception, indeed they
are perhaps superior in this respect to the other classes of
animals. Their senses, though probably on the whole. analogous
to those of the Vertebrata, are certainly far from corresponding
therewith, and their sense organs seem to be even more different
from those of what we call the higher animals than the functions
themselves are. We have already briefly sketched the structure
of the optical organs, which are invariably situate on the head.
This is not the case with the ears, which certainly exist in one

legs below the knee, or at the base of the abdomen. Notwith-
standing their strange situation, the structures alluded to are
undoubtedly auditory, and somewhat approximate in nature to the
ear of Vertebrates, being placed in proximity to the inner face of
a tense membrane; we shall refer to them when considering the
Orthoptera. Sir John Lubbock considers—no doubt with reason

-.—that some ants have auditory organs in the tibia. Many

Insects possess rod-like or bristle-like structures in various parts
of the body, called chordotonal organs; they are considered by
Graber‘ and others to have auditory: functions, though they are
not to be compared with the definite ears of the Orthoptera.

The other senses and sense organs of Insects are even less
known, and have given rise to ane perplexity; for though many
structures have been detected that may with more or fess prob-
ability be looked on as sense organs, it is difficult to assign a

1 Zool. Anz. iv. 1881, p. 452.

122 SENSES

CHAP.

particular function to any of them, except it be to the sensory
hairs. These are seated on various

parts of the

2)

body. The chitinous

covering, being a dead, hard substance,
has no nerves distributed in it, but it
is pierced with orifices, and in some of
these there is implanted a hair which
at its base is in connexion with a
nerve; such a structure may pos-
sibly be sensitive not only to contact
with solid bodies, but even to vari-

Fig, 67. Longitudinal section of OUS kinds of vibration. We give a
portion of caudal appendage of figure (Fig. 67) of some of these hairs

Acheta domestica (after Vom

Rath): ch, chitin ; hyp, hypo- on the caudal appendage of a cricket,
dermis ; , nerve; h', integu- after Vom Rath. The small hairs on |

mental hairs, not sensitive ; h*,

ordinary hair ; 4%, sensory hair; he outer surface of the chitin in this
ht, bladder-like hair ; sz, sense- figure have no sensory function, but
each of the others probably has; and

these latter, being each accompanied by a different structure,

cell.

must, though so closely approximated,
be supposed to have a different function ;
but in what way those that: have no
direct connexion with a nerve may act
it is difficult to guess.

The antennae of Insects are the seats
of a great variety of sense organs, many
of which are modifications of the hair,
pit and nerve structure we have described
above, but others cannot be brought
within this category. Amongst these
we may mention the pits covered with
membrane (figured by various writers),
perforations of the chitin without any
hair, and membranous bodies either con-
cealed in cavities or partially protruding
therefrom.

Various parts of the mouth are also

of apex of palpus of Pieris
brassicae: sch, scales ; ch,
chitin ; hyp, hypodermis ;
m, nerve; sz, sense cells ;
sh, sense hairs. (After
Vom Rath.)

the seats of sense organs of different kinds, some of them of a
compound character; in such cases there may be a considerable
number of hairs seated on branches of a common nerve as figured

ALIMENTARY SYSTEM 123

oy Vom Rath? on. the apex of the maxillary palp of Locusta
wiredissima, or a compound organ such as we represent in Fig. 68
aay be located in the interior of the apical portion of the ae
The functions of the various structures that have been
ected are, as already remarked, very difficult to discover.
i. Rath thinks the cones he describes on the antennae and palpi
are organs of smell, while he assigns to those on the maxillae,
lower lip, epipharynx, and hypopharynx the réle of taste organs,
but admits he cannot draw any absolute line of distinction
between the two forms. The opinions of Kraepelin, Hauser, and
~ Will, as well as those of various earlier writers, are considered in
‘Sir John Lubbock’s book on this subject.”

7a

Alimentary and Nutritive System.

The alimentary canal occupies the median longitudinal axis
of the body, being situated below the dorsal vessel, and above the
ventral nervous chain; it extends from the mouth to the opposite
extremity of the body. It varies greatly in the different
kinds of Insects, but in all its forms it is recognised as con-
sisting essentially of three divisions: anterior, middle, and pos-
terior. The first and last of these divisions are considered to be
of quite different morphological nature from the middle part,.
or true stomach, and to be, as it were, invaginations of the
_ extremities of a closed bag; it is ascertained that in the embryo
these invaginations have really blind extremities (see Fig. 82,
_p. 151), and only subsequently become connected with the middle
_ part of the canal. There are even some larvae of Insects in which
the posterior portion of the canal is not opened till near the close
_ of the larval life; this is the case with many Hymenoptera, and
it is probable, though not as frequently stated certain, that the
ocelusion marks the point of junction of the proctodaeum with
_ the stomach. The anterior and posterior parts of the canal are
_ formed by the ectoderm of the embryo, and in embryological and
_ morphological language are called respectively the stomodaeum
and proctodaeum ; the true stomach is formed from the endoderm,

1 Zeitschr. wiss. Zool. xlvi. 1888, pl. xxxi.
j 2 On the Senses; Instincts, and Intelligence of Animals, with special reference to
_ Insects. Vol. LXV. International Scientific Series, 1888.

124 ALIMENTARY SYSTEM. CHAP.

and the muscular layer of the whole canal from the meso-
derm.

The alimentary canal is more complex anatomically than it is
morphologically, and various parts are distinguished, viz. the
canal and its appendicula; the former consisting of oesophagus,

crop, gizzard, true stomach, and an
“intestine divided into two or more

parts. It should be remarked that
though it is probable that the mor-
phological distinctions. correspond to

a great extent with the anatomical
_ lines. of demarcation, yet this has

not been sufficiently ascertained : the

ay origin of the proctodaeum in Musca
i; is indeed a point of special difficulty,
— | and one on which there is consider-
Sf 4 able diversity of opinion. In some
AS | Hemiptera the division of the canal

Z \ wy into three parts is very obscure,

Se so that it would be more correct, as
HU Dufour says, to define it as consist-
J ing in these Insects of two main
divisions—one anterior to, the other
4 posterior to, the insertion of the Mal-
| -pighian tubes. | .
V It should be borne in mind that
# () the alimentary canal is very different
in different Insects, so that the brief
general description we must confine
N . :
ourselves to will not be found to
Fic. 69. -— Digestive system of ] Fetamtorie << T
Xyphidria camelus (atter Du- apply Satistactorlly to any one in-
four): a, head capsule; 3, sal- sect. The oesophagus is the part be-
ivary glands ; c, oesophagus; d, , . ; ll
crop; ¢, proventriculus; f, chyle, hind the mouth, and is usually narrow,
or true stomach ; g, small intes- ag jt has to pass through the most
tine; A, large intestine; 7, Mal- .
pighian tubes ; %, termination of Important nervous centres ; extremely
body. variable in length, it dilates behind
to form the crop. It may, too, have a dilatation immediately
behind the mouth, and in such case a pharynx is considered to
exist. The crop is broader than the oesophagus, and must be
looked on as a mere dilatation of the latter, as no line of

oy ALIMENTARY SYSTEM 125

=o ———-- =

demarcation can be pointed out between the two, and the crop
may be totally absent.
_ In some of the sucking Insects chides is a lateral diverticulum,
having,a stalk of greater or less length, called the sucking-
_ stomach; it is by no means certain that the function this name

implies is: correctly assigned to the organ. :
_ The gizzard or proventriculus (French, gésier ; German,
_ Kaumagen) is a small body interposed in some Insects between
the true stomach and the crop or oesophagus. It is frequently
remarkable ‘for the development of its chitinous lining into
__ strong toothed.or ridged processes that look as: if they were well
adapted for the comminution of food. The function of the
proventriculus in. some Insects.is obscure; its structure is used
by systematists in the classification of sata The extremity of
the proventriculus not infrequently projects into the cavity of
the stomach. |

The true stomach, or chylific ventricle (Magen or Mitteldarm

of the Germans), is present in all the post- -embryonic stages of
the Insect’s life, existing even in the imagines of those who
live only for a few hours, and do not use the stomach for any
alimentary purpose. It is so variable in shape and capacity that
no general description of it can be given. Sometimes it is very
elongate, so that it is coiled and like an intestine in shape; it
very frequently bears diverticula or pouches, which are placed on
_ the anterior part, and vary greatly in size, sometimes they are
_ only two in number, while in other cases they are so numerous
_ that a portion of the outside of the stomach looks as if it were
covered with villi. A division of the stomach into two parts
is in some cases very marked, and the posterior portion may, in
certain cases, be mistaken for the intestine; but the position of
_ the Malpighian tubes serves as a mark for the distinction of the
two structures, the tubes being inserted just at the junction of
the stomach with the intestine.

The intestine is very variable in length: the anterior part is
the smaller, and is frequently spoken of as the colon; at the
extremity of the body the gut becomes much larger, so as to

_ form a rectum. There is occasionally a diverticulum or “ caecum ”
connected with the rectum, and in some Insects stink- glands.
In some Hemiptera there is no small intestine, the Malpighian
“tubes being inserted at the junction of the stomach with the

wv
126 ALIMENTARY SYSTEM CHAP.

rectum. The total length of the alimentary canal is extremely
variable ; it is necessarily at least as long as the distance between
the mouth and anal orifice, but sometimes it is five or six
times as long as this, and some of its parts then form coils in
the abdominal cavity.

The alimentary canal has two coats of muscles: a longitudinal
and a transverse or annular. Both coexist in most of its parts.
Internal to these coats there exists in the anterior and posterior
parts of the canal a chitinous layer, which in the stomach is
replaced by a remarkable epithelium, the cells of which are
renewed, new ones growing while the old are still in activity..
We figure’a portion of this structure after Miall and Denny,
and may remark that Oudemans! has verified the correctness of
their representation. . The layers below represent the longi-
tudinal and transverse muscles. |

Fic. 70.—Epithelium of stomach
of Cockroach (after Miall and
Denny): the lower parts indi-
cate the transverse and longi-
tudinal muscular layers.

HIN //
All

SS
ry
! UU Zhe NYA A AAs

In addition to the various diverticula we have mentioned,
there are two important sets of organs connected with the
alimentary canal, viz. the salivary glands and the Malpighian
tubes.

The salivary glands are present in many Insects, but are
absent in others. They are situate in the anterior portion of
the body, and are very variable in their development, being -
sometimes very extensive, in other cases inconspicuous. They
consist either of simple tubes lined with cells, or of branched
tubes, or of tubes dilated laterally into little acini or groups of
bags, the arrangement then somewhat resembling that of a bunch
of grapes. There are sometimes large sacs or reservoirs con-
nected with the efferent tubes proceeding from the secreting
portions of the glands. The salivary glands ultimately discharge
into the mouth, so that the fluid secreted by them has to be

1 Bijd. Dierkunde, 16, 1888, p. 192.

Iv ALIMENTARY SYSTEM 127

bees

‘swallowed in the same manner as the food, not improbably along
with it. The silk so copiously produced by some larvae comes
from very long tubes similar in form and situation to the simple
tubes of the salivary glands.

The Malpighian tubules are present in most Insects, though
they are considered on good authority to be absent in many
Collembola and in some Thysanura. They are placed near the
posterior part of the body, usually opening into the alimentary
canal just at the junction of the stomach and the intestine, at a
spot called the pylorus. They vary excessively in length and in
number,’ being sometimes only two, while in other cases there
may be a hundred or even more of them. In some cases they
are budded off from the hind-gut of the embryo when this is
still very small; in other cases they appear later; frequently
their number is greater in the adult than it is in the young.
In Gryllotalpa there is one tube or duct with a considerable
number of finer tubes at the end of it. There is no muscular
layer in the Malpighian tubes, they being lined with cells which
leave a free canal in the centre. The tubes are now thought, on
considerable evidence, to be organs for the excretion of uric acid
or urates, but it is not known how they are emptied. Marchal
has stated* that he has seen the Malpighian tubes, on extrac-
tion from the body, undergo worm-like movements; he suggests
that their contents may be expelled by similar movements when
they are in the body.

The functions of the different portions of the alimentary
canal, and the extent to which the ingested food is acted on by
their mechanical structures or their products is very obscure, and
different opinions prevail on important points. It would appear
that the saliva exercises a preparatory action on the food, and
that the absorption of the nutritive matter into the body cavity
takes place chiefly from the true stomach, while the Malpighian
tubes perform an excretory function. Beyond these elementary,
though but vaguely ascertained facts, little is known, though
Plateau’s* and Jousset’s researches on the digestion of Insects
throw some light on the subject.

1 For a review of their number see Wheeler, Psyche, vi. 1893, pp. 457, etc.

2 Ann. Soc. Ent. France, \xi. 1892, Bull. p. eclvi.

3 Mem. Ac. Belgique (2), xli. 1875,:and Bull. Ac. Belgique (2), xliv. 1877,
p. 710.

128 RESPIRATION CHAP.

Respiratory Organs.

The respiration of Insects is carried on by means of a system
of vessels for the conveyance of air to all parts of the body; this
system is most remarkably developed and elaborate, and contrasts
strongly with the mechanism for the circulation of the blood,
which is as much reduced as the air system is highly developed,
as well as with the arrangement that exists in the Vertebrates.
There are in Insects no lungs, but air is carried to every part of
the body directly by means of tracheae. These tracheae con-
nect. with the spiracles—the orifices at the sides of the body
we have already mentioned when describing the external struc-
tures —and. the air thus finds its way into the most remote
recesses of the Insect’s body. The tracheae are all intimately
connected. Large tubes connect the spiracles longitudinally,
others pass from side to side of the body, and a set of tracheae
for the lower part of .the body is connected with another
set on the upper surface by means of several descending
tubes. From these main channels smaller branches extend in all
directions, forking and giving off twigs, so that all the organs
inside the. body can be supplied with air in the most liberal
manner. On opening a freshly deceased Insect the abundance of
the tracheae is one of the peculiarities that most attracts the
attention; and as these tubes have a peculiar white glistening
appearance, they are recognised without difficulty. In Insects
of active flight, possibly in some that are more passive, though
never in larvae, there are air-sacs, of more than one kind, con-
nected with the tracheae, and these are sufficiently capacious to
have a considerable effect in diminishing the specific gravity of
the Insect. The most usual situation for these sacs is the basal
portion of the abdominal cavity, on the great lateral tracheal
conduits. In speaking of the external structure we have remarked
that the stigmata, or spiracles, by which the air is admitted
are very various in their size and in the manner in which they
open and close. Some spiracles have no power of opening; while .
others are provided with a muscular and valvular apparatus for
the purpose of opening and closing effectually.

The structure of the tracheae is remarkable: they are elastic
and consist of an,outer cellular, and an inner chitinous layer ;
this latter is strengthened by a peculiar spiral fibre, which gives

IV RESPIRATION ) is

to the tubes, when examined with the microscope, a transversely,
closely striated appearance. Packard considers’ that in some
tracheae this fibre is not really spiral, but consists of a large num-
ber of closely placed rings. Such a condition has not, however,
been recorded by any other observer. The spiral fibre is absent
in the fine capillary twigs of the tracheal system, as well as from
the expanded sacs. The mode of termination of the capillary
branches is not clear. Some have supposed that the finest twigs
anastomose with others; on the other hand it has been said that
they terminate by penetrating cells, or that they simply come
to an end with either open cr closed extremities. | Wisting-

Fig. 71.—Portion of the abdominal part of tracheal system of a Locust (Oedipoda):
a, spiracular orifices ; b, tracheal tubes ; c, vesicular dilatations ; d, tracheal twigs
or capillaries. (After Dufour.)

hausen? states that in the silk-glands the tracheal twigs anas-

_ tomose, and he is of opinion that the fine terminal portions

contain fluid. However this may be, it is certain that all the
organs are abundantly supplied with a capillary tracheal net-
work, or arboreal ramification, and that in some cases the tubes
enter the substance of tissues. Near their terminations they
are said to be 4, to g/5 millimetre in diameter.

We must repeat that such a system as we have just sketched
forms a striking contrast to the imperfect blood-vascular system,
and that Insects differ profoundly in these respects from Verte-
brate animals. In the. latter the blood-vessels penetrate to all

1 American Naturalist, xx. 1886, pp. 438 and 558.

2 Zeitschr. wiss. Zool., xlix. 1890, p. 565.
VOL. V K

130 RESPIRATION CHAP):

the tissues and form capillaries, while the aerating apparatus is
confined to one part of the body; in Insects the blood-circulating
system is very limited, and air is carried directly by complex
vessels to all parts; thus the tracheal system is universally recog-
nised’ as one of the most remarkable of the characters of Insects.

Many Insects have a very active respiratory system, as is shown
by the rapidity with which they are affected by agents like
chloroform; but the exact manner in which the breathing is
carried on is unknown. In living Insects rapid movements of
contraction and expansion of parts of the body, chiefly the
abdomen, may be observed, and these body contractions are some-
times accompanied by opening and shutting the spiracular
orifices: it has been inferred that these phenomena are respira-
tory. Although such movements are not always present, it is
possible that when they occur they may force the air onwards
to the tissues, though this is by no means certain. It is clear
that the tracheal system is the usual means of supplying the
organisation with oxygen, but it appears to be improbable that
it can also act as the agent for removing the carbonaceous pro-
ducts of tissue-changes. It has been thought possible that car-
bonic acid might reach the spiracles from the remote capillaries
by a process of diffusion,’ but it should be recollected that as
some Insects have no tracheal system, there must exist some
other mode of eliminating carbonic acid, and it is possible that
this mode may continue to operate as an important agent of
purification, even when the tracheal system is, as a bearer of air
to the tissues, highly developed. LEisig? has suggested that the
formation of chitin is an act of excretion; if so this is capable
of relieving the system of carbonic acid to some extent. Others
have maintained that transpiration takes place through the deli-
cate portions of the integument. Lubbock*® has shown that
Melolontha larvae breathe “partly by means of their skin.”
The mode in which the carbon of tissue-change, and the
nitrogen of inspiration are removed, is still obscure; but it
appears probable that the views expressed by Réaumur, Lyonnet,
and Lowne* as to inspiration and expiration may prove to be
nearer the truth than those which are more widely current. In

1 See Miall and Denny, Cockroach, p. 158.
* Eisig, Jfon. Capitelliden, 1887, p. 781.
3 Tr. Linn. Soc, London Zool. xxiii. 1860, p. 29. 4 Blowfly, etc. p. 376.

IV RESPIRATION 131

connexion with this it should be recollected that the outer
integument consists of chitin, and is cast and renewed several
times during the life of the individual. Now as chitin consists
largely of carbon and nitrogen, it is evident that the moulting
must itself serve as a carbonaceous and nitrogenous excretion.
If, as is suggested by Bataillon’s researches,’ the condition
accompanying metamorphosis be that of asphyxia, it is probable
that the secretion of the new coat of chitin may figure as an
act of excretion of considerable importance. If there be any
truth in this suggestion it may prove the means of enabling us
to comprehend some points in the development of Insects that
have hitherto proved very perplexing.

Peyron has shown” that the atmosphere extracted from the
bodies of Insects (Melolontha) is much less rich in oxygen than
the surrounding atmosphere is, and at ordinary temperatures
always contains a much larger proportion of carbonic acid: he
finds, too, that as in the leaves with which he makes a comparison,
the proportion of oxygen augments as the protoplasmic activity
diminishes. Were such an observation carried out so as to dis-
tinguish between the air in the tracheal system and the gas in
other parts of the body the result would be still more interesting.

We know very little as to the animal heat produced by
insects, but it is clear from various observations® that the
amount evolved in repose is very small. In different conditions
of activity the temperature of the insect may rise to be several
degrees above that of the surrounding medium, but there seems
to be at present no information as to the physiological mode of
its production, and as to the channel by which the products—
whether carbonic acid or other matters—may be disposed of.

In the order Aptera (Thysanura and Collembola) the tracheal
system is highly peculiar. In some Collembola it apparently
does not exist, and in this case we may presume with greater
certainty that transpiration of gases occurs through the integu-
ment: in other members of this Order tracheae are present ina
more or less imperfect state of development, but the tracheae
ot different segments do not communicate with one another,

1. R. Ac. Sct., exv. 1892, p. 61, and Bull. Sct. France Belgique, xxv. 1893,
. £8.
j * Compt. rend. Ac. Paris, cii. 1886, p. 1339. |

* See Newport, Phil. Trans. 1837, and Lubbock Linn. Trans. xxiii. 1860,
p. 29, etc.

132 RESPIRATION CHAP.

thus forming a remarkable contrast to the amalgamated tracheal
system of the other Orders of Insects, where, even when the
tracheal system is much reduced in extent (as in Coccidae), it is
nevertheless completely unified. Gryllotalpa is, however, said
by Dohrn? to be exceptional in this respect; the tracheae con-
nected with each spiracle remaining unconnected.

Water Insects have usually peculiarities in their respiratory
systems, though these are not so great as might & priori have
been anticipated. Some breathe by coming to the surface and
taking in a supply of air in various manners, but some appar-
‘ently obtain from the water itself the air necessary for their
physiological processes. Aquatic Insects are frequently provided —
with gills, which may be either wing-like expansions of the
integument containing some tracheae (Ephemeridae larvae), or
bunches of tubes, or single tubes (Trichoptera larvae). Such
Insects may either possess stigmata in addition to the gills, or
be destitute of them. In other cases air is obtained by taking
water into the posterior part of the alimentary canal (many
dragon-flies), which part is then provided with special tracheae.
Some water-larvae appear to possess neither stigmata nor gills
(certain Perlidae and Diptera), and it is supposed that these
obtain air through the integument; in such Insects tracheal
twigs may frequently be seen on the interior of the skin. In
the imago state it is the rule that Water Insects breathe by
means of stigmata, and that they carry about with them a supply
of air, sufficient for a longer or shorter period. A great many
Insects that live in. water in their earlier stages and breathe
there by peculiar means, in their perfect imago state live in the
air and. breathe in the usual manner. There are, in both ter-
restrial and aquatic Insects, a few cases of exsertile sacs without
tracheae, but filled with blood (Pelobius larva, Machilis, etc.) ; and
such organs are supposed to be of a respiratory nature, though
there does not appear to be any positive evidence to that effect.

Blood and Blood-Circulation.

Owing to the great complexity of the tracheal system, and to
its general diffusion in the body, the blood and its circulation are
very different in Insects from what they are in Vertebrates, so

1 Zeitschr. wiss. Zool. xxvi. 1876, p. 137.

IV CIRCULATION 133

that it is scarcely conducive to the progress of physiological
knowledge to call two fluids with such different functions by one
name. The blood of Insects varies according to the species, and
in all probability even in conformity with the stage of the life
of the individual. Its primary office is that of feeding the
tissues it bathes, and it cannot be considered as having any aerat-
ing function. It is frequently crowded with fatty substances.
Graber says: “The richness of Insect blood in unsaponified or
unelaborated fat shows in the plainest manner that it is more
properly a mixture of blood and chyle; or indeed we might say
with greater accuracy, leaving out of consideration certain
matters to be eliminated from it, that it is a refined or distilled
chyle.” Connected in the most intimate manner with the blood
there is a large quantity of material called vaguely the fat-
body; the blood and its adjuncts of this kind being called
by Wielowiejski* the blood-tissue. We shall return to the
consideration of this tissue after sketching the apparatus for
distributing the refined chyle, or blood as we must, using the
ordinary term, call it.

There is in Insects no complete system of blood-vessels, though
there is a pulsating vessel to ensure distribution of the nutritive
fluid. This dorsal vessel, or heart as it is frequently called, may
be distinguished and its pulsations watched, in transparent
Insects when alive. It is situate at the upper part of the
body, extending from the posterior extremity, or near it, to the
_ head or thorax, and is an elongate tube, consisting as it were of
a number of united chambers; it is closed behind, except in
some larvae, but is open in front, and has several orifices at the
sides; these orifices, or ostia, are frequently absent from the
front part of the tube, which portion is also narrower, being
called the aorta—by no means a suitable term. Near the lateral
orifices there are delicate folds, which act to some extent as
valves, facilitating, in conjunction with the mode of contraction
of the vessel, a forward movement of the blood. The composition
of the tube, or series of chambers, is that of a muscular layer,
with internal and external membranous coverings, the intima and
adventitia. Olga Poletajewa states* that in Bombus the dorsal

_ vessel consists of five chambers placed in longitudinal succession,

and not very intimately connected, and that there is but little
1 Zeitschr. wiss. Zool. xliii. 1886, p. 512. * Zool. Anz. ix. 1886, p. 13.

134 . CIRCULATION CHAP

valvular structure. In Cimbex she finds a similar arrangement,
but there are ten chambers, and no aorta.

The dorsal vessel is connected with the roof of the body by
some short muscles, and is usually much surrounded by fat-body
into which tracheae penetrate; by these various means it is kept
in position, though only loosely attached; beneath it there is
a delicate, incomplete or fenestrate, membrane, delimiting a sort
of space called the pericardial chamber or sinus; connected with
this membrane are some very delicate muscles, the alary muscles,
extending inwards from the body wall (6, Fig. 72): the curtain
formed by these muscles and the fenestrate membrane is called

Fic. 72. — Dorsal vessel Fic. 73.—Diagram of transverse section

(c), and alary muscles of pericardial sinus of Oedipoda coeru-
(b),of Gryllotalpa (after lescens. (After Graber, Arch. Mikr.
Graber); a, aorta. Anat. ix.) H, heart; s, septum; m,
N.B. — The. ventral muscles—the upper suspensory, the
aspect is here dorsal, lower alary.

and nearly the whole

of the body is removed

to show these parts.
the pericardial diaphragm or septum. The alary muscles are
not directly connected with the heart.

It has been thought by some that delicate vessels exist beyond
the aorta through which the fluid is distributed in definite
channels, but this does not appear to be really the case, although
the fluid may frequently be seen to move in definite lines at some
distance from the heart.

There is still much uncertainty as to some of the details of
the action of the heart, and more especially as to the influence of
the alary muscles. The effect of the contraction of these must
be to increase the area of the pericardial chamber by rendering

IV CIRCULATION . 135

its floor or septum less arched, as shown in our diagram (Fig. 73),
representing a transverse section through the pericardial chamber,
H being the dorsal vessel with m its suspensory muscles, and s its
septum, with m the alary muscles. The contraction of these latter
- would draw the septum into the position of the dotted line, thus
increasing the area of the sinus above; but as this floor or septum
is a fenestrated structure, its contraction allows fluid to pass
through it to the chamber above; thus this arrangement may
be looked on as a means of keeping up a supply of fluid to the
dorsal vessel, the perforated septum, when it contracts, exerting
pressure on the tissues below; these are saturated with fluid,
which passes through the apertures to the enlarged pericardial
chamber.

Some misconception has prevailed, too, as to the function of
the pericardial chamber. This space frequently contains a large
quantity of fat-body—pericardial tissue—together with tracheae,
and this has given rise to the idea that it might be lung-like
in function; but, as Miall and Denny’ have pointed out, this is
erroneous; the tissues in Insects have their own ample sup-
plies of air. It has also been supposed that the alary muscles
cause the contraction of the heart, but this is not directly the
case, for they are not attached to it, and it pulsates after they
have been severed. It has been suggested that the contractions
of this vessel are regulated by small ganglia placed on, or in, its
substance. However this may be, these contractions vary enor-
mously according to the condition of the Insect; they may be -
as many, it is said, as 100 or more in a minute, or they may be
very slow and feeble, if not altogether absent, without the death
of the Insect ensuing. ;

The expulsion of the blood from the front of the dorsal
vessel seems to be due to the rhythm of the contrac-
tion of the vessel as well as to its mechanical structure.
Bataillon says,’ confirming an observation of Réaumur, that at
the period when the silkworm is about to change to the chrysalis
condition, the circulation undergoes periodical changes, the fluid
moving during some intervals of about ten minutes’ duration in
a reversed direction, while at other times the blood is expelled
in front and backwards simultaneously, owing apparently to a
rhythmical change in the mode of contraction of the dorsal vessel.

1 Cockroach, p. 140. 2 Bull. Sci. France Belgique, xxv. 1893, p. 22.

136 FAT-BODY ) CHAP.

As the dorsal vessel consists of a. number of distinct chambers,
it has been suggested that there is normally one of these for
each segment of the body; and it appears that the total number
is sometimes thirteen, which is frequently that of the segments
of the body without the head. The number of chambers differs,
however, greatly, as we have previously stated, and cannot be
considered to support the idea of an original segmental arrange-
ment of the chambers. The dorsal vessel, though in the adult a_
single organ, arises in the embryo from two lateral, widely
- separated parts. which only in a subsequent stage of the embry-
onic development coalesce in the median line. »

Fat-Body.

In discussing the tracheae we remarked on the importance of
their function and on their abundant presence in the body.
Equally conspicuous, and perhaps scarcely less important in fune-
tion, is the fat-body, which on opening some Insects, especially -
such as are in the larval stage, at once attracts attention. It
consists of masses of various size and indefinite form distributed
throughout the body, loosely connected together, and more or
less surrounding and concealing the different organs. The colour
varies according to the species of Insect. This fat-body is much
connected with fine tracheal twigs, so that an organisation extend-
ing throughout the body is thus formed. It may be looked on as _
a store of nutritious matter which may be added to or drawn
on with great rapidity; and it is no doubt on this that many of
the internal parasites, so common in the earlier stages of Insects’
lives, subsist before attacking the more permanent tissues of their
hosts. There is some reason to suppose that the fat-body may
have some potency in determining the hunger of the Insect, for
some parasitised larvae eat incessantly.

The matter extracted from the food taken into the stomach
of the Insect, after undergoing some elaboration—on which point
very little is known—finds its way into the body-cavity of the
creature, and as it is not confined in any special vessels the fat-
body has as unlimited a supply of the nutritive fluid as the
other organs: if nutriment be present in much greater quantity
than is required for the purposes of immediate activity, meta-
morphosis or reproduction, it is no doubt taken up by the fat-

ow ee FAT-BODY 137

body which thus maintains, as it were, an independent feeble life,
subject to the demands of the higher parts of the organisation.
It undoubtedly is very important in metamorphosis, indeed it
is possible that one of the advantages of the larval state may be
found in the fact that it facilitates, by means of the fat-body,
the storage in the organisation of large quantities of material
in a comparatively short period of time. :

A considerable quantity of fat tissue is found in the peri-
cardial sinus, where it is frequently of somewhat peculiar form, and
is spoken of as pericardial cells, or pericardial tissue. Some large
cells, frequently of pale yellow colour, and containing no fat, are
called oenocytes by Wielowiejski. They are connected with the
general fat-body, but are not entirely mingled with it; several
kinds have been already distinguished, and they are. probably
generally present. The phagocytes, or leucocytes, the cells that
institute the process of histolysis in the metamorphosis of
Muscidae, are a form of blood cell; though these cells are
amoeboid some writers derive them from the fat-body. The
cells in the blood have no doubt generally an intimate re-
lation with the fat-body, but very little accurate information has
been obtained as.to these important physiological points, though
Graber has inaugurated: their study.’

Organs of Sex.

The continuation of the species is effected in Insects by means
of two sexes, each endowed: with special reproductive organs. It
has been stated that there are three sexes in some Insects—male,
female, and neuter; but this is not correct, as the so-called
neuters are truly sexed individuals—generally females—though,
as a rule, they are not occupied with the direct physiological
processes for continuing the species.

The offspring is usually produced in the shape of eggs, which
are formed in ovaries. These organs consist of egg-tubes, a cluster
of which is placed on each side of the body, and is suspended,
according to Leydig* and others, to the tissue connected with
the heart by means of the thread-like terminations of the tubes.
The number of egg-tubes varies greatly in different Insects;
there may be only one to each ovary (Campodea), but usually the

2 Biol. Centralbl. xi. 1891, p..212. 2 Acta. Ac. German. xxxiii. 1867, No. 2.

138 OVARIES CHAP.

number is greater, and in the queen-bee it is increased to about
180. In the Queens of the Termitidae, or white ants, the ovaries
take on an extraordinary development; they fill the whole of the
greatly distended hind-body. Three thousand egg-tubes, each con-
taining many hundred eggs, may be found in a Queen Termite, so
that, as has been said by Hagen,’ an offspring of millions in number
is probable. There is considerable variety in the arrangements
for the growth of the eggs in the egg-tubes. Speaking concisely,
the tubes may be considered to be
centres of attraction for nutritive
material, of which they frequently
contain considerable stores. Next
to the terminal thread, of which we
have already spoken, there is a
greater or smaller enlargement of
the tube, called the terminal cham-
ber; and there may also be nutri-
ment chambers, in addition to the
dilatations which form the egg-cham-
bers proper. Korschelt ? distinguishes
three principal forms of egg-tubes, viz.
(1) there are no special nutriment
chambers, a condition shown in Figure
74; (2) nutriment chambers alter-
nate with the egg-chambers, as shown
in our Figure of an egg-tube of
Fic. 74.—Sex organs of female of Dytuscus marginalis ; (3) the ter-
Scolia interrupta (after Dufour); minal chamber takes on an unusual

a, egg-tubes; 0, oviducts; c, ; :
poison glands ; d, duct of acces- development, acting as a large nutri-
con Pe (or spermatheca) ; ¢ ment chamber, there being no other

erminal parts of body. : : , ‘

special nutriment chambers. This

condition is found in Rhizotrogus solstitialis. The arrangements
as to successive or simultaneous production of the eggs in the
tubes seem to differ in different Insects. In some forms, such as
the white ants, the process of egg-formation (oogenesis) attains a
rapidity that is almost incredible, and is continued, it is said, for
periods of many months. There is no point in which Insects
differ more than in that of the number of eggs produced by one

1 Linnaea entomologica, xii. 1858, p. 3138.
2 Zeitschr. wiss. Zool, 1886, xliii. p. 539.

the uterus, near their termination.

Iv OVARIES

139

female.

The egg-tubes are connected with a duct for the con-

veyance of the eggs to the exterior, and the arrangements of

the tubes with regard to the oviduct also vary
much, An interesting condition is found in
Machilis (see Fig. 94, p. 188), where the seven
egg-tubes are not arranged in a bunch, but

‘open at a distance from one another into the

elongated duct. The two oviducts usually unite
into one chamber, called the azygos portion or
There are a
few Insects (Ephemeridae) in which the two ovi-
ducts do not unite, but have a pair of orifices at
the extremity of the body. Hatchett-Jackson
has recently shown’ that in Vanessa io of the
Order Lepidoptera, the paired larval oviducts are
solid, and are fixed ventrally so as to represent

an Ephemeridean stage; that the azygos system

of ducts and appended structures develop separ-
ately from the original oviducts, and that they
pass through stages represented in other Orders

of Insects to the stage peculiar to the Lepi-

doptera. Machilis, according to Oudemans, is a
complete connecting link between the Insects
with single and those with paired orifices.

There are in different Insects more than one
kind of diverticula and accessory glands in con-
nexion with the oviducts or uterus; a recepta-
culum seminis, also called spermatheca, is common.
In the Lepidoptera there is added a remarkable
structure, the bursa copulatrix, which is a pouch
connected by a tubular isthmus with the common

Fic. 75.—Egg-tube

of Dytiscus mar-
ginalis ; €.c, egg-
chamber; %.¢,
nutriment cham-
ber ; ¢.c, terminal
chamber; 44,
terminal thread.
(After Kor-
schelt. )

portion of the oviduct, but having at the same time a separate

_ external orifice, so that there are two sexual orifices, the opening
of the bursa copulatrix being the lower or more anterior.

The

organ called by Dufour in his various contributions glande sébijfique,
is now considered to be, in some cases at any rate, a spermatheca.
The special functions of the accessory glands are still very

obscure.

The ovaries of the female are replaced in the male by a pair
1 Tr. Linn. Soc. London, 2nd ser. ; Zool. vy. 1890, p. 173.

140 MALE-STRUCTURES CHAP.

of testes, organs exhibiting much variety of form. The structure
may consist of an extremely long and fine convoluted tube, packed
into a small space and covered with a capsule; or there may be
several shorter tubes. As another extreme may be mentioned the
existence of a number of small follicles opening into a common
tube, several of these small bodies forming together a testis. As
a rule each testis has its own capsule, but cases occur—very
frequently in the Lepidoptera—in which the two testes are
enclosed in a common capsule; so that there then appears to be
only one testis. The secretion of each testis is conveyed out-
wards by means of a slender tube, the vas deferens, and there are
always two such tubes, even when the two testes are placed
in one capsule. The vasa deferentia differ greatly in their
length in different Insects, and are in some cases many times the
length of the body; they open into a common duct, the ductus
ejaculatorius. Usually at some part of the vas deferens there
exists a reservoir in the form of a sac or dilata-
tion, called the vesicula seminalis. There are
in the male, as well as in the female, frequently
diverticula, or glands, in connexion with the
sexual passages; these sometimes exhibit very
remarkable forms, as in the common cockroach,
but their functions are quite obscure. There
is, as we have already remarked, extreme variety

reproductive apparatus in the male, and there are —
a few cases in which the vasa deferentia do not
unite behind, but terminate in a pair of separate
orifices. The genus Machilis is as remarkable in
the form of the sexual glands and ducts of the
male as we have already mentioned it to be in
the corresponding parts of the female.

Although the internal sexual organs are only
ait: « c, fully developed in the imago or terminal stage
vesicule semin- of the individual life, yet in reality their rudi-
ales; d, extrem-
ity of body with Ments appear very early, and may be detected

_ copulatory ar- from the embryo state onwards through the
mature. (After
Dufour. ) other preparatory stages.

: The spermatozoa of a considerable number of

Insects, especially of Coleoptera, have been examined by Ballo-

Fia. 76.—TZenthredo
cinctag a, a

.

in the details of the structure of the internal

ow | PARTHENOGENESIS 141

witz;* they exhibit great variety; usually they are of extremely
elongate form, thread-like, with curious sagittate or simply
pointed heads, and are of a fibrillar structure, breaking up at
various parts into finer threads.

External Sexual Organs.—The terminal segments of the
body are usually very highly modified in connexion with the

external sexual organs, and this modification occurs in such a

great variety of forms as to render it impossible to give any general
account thereof, or of the organs themselves. Some of these
segments—or parts of the segments, for it may be dorsal plates
or ventral plates, or both—may be withdrawn into the interior,
and changed in shape, or may be doubled over, so that the
true termination of the body may be concealed. The com-
parative anatomy of all these parts is especially complex in
the males, and has been as yet but little elucidated, and as the
various terms made use of by descriptive entomologists are of
an unsatisfactory nature we may be excused from enumerat-
ing them. We may, however, mention that when a terminal
chamber is found, with which both the alimentary canal and the
sexual organs are connected, it is called a cloaca, as in other
animals,

Parthenogenesis.

There are undoubted cases in Insects of the occurrence of
parthenogenesis, that is, the production of young by a female
without concurrence of a male. This phenomenon is usually
limited to a small number of generations, as in the case of the
Aphididae, or even to a single generation, as occurs in the alterna-
tion of generations of many Cynipidae, a parthenogenetic alter-
nating with a sexual generation. There are, however, a few
species of Insects of which no male is known (in Tenthredinidae,
Cynipidae, Coccidae), and these must be looked on as perpetually
parthenogenetic. It is a curious fact that the result of partheno-
genesis in some species is the production of only one sex, which
in some Insects is female, in others male; the phenomenon in the
former case is called by Taschenberg* Thelyotoky, in the latter
ease Arrhenotoky ; Deuterotoky being applied to the cases in
which two sexes are produced. In some forms of partheno-

1 Zeitschr. wiss. Zool. 1. 1890, p. 317. 2 Abh. Ges. Halle, xvii. 1892, p. 365.

142 INSECTS CHAP, IV

genesis the young are produced alive instead of in the form of
eggs. A very rare kind of parthenogenesis, called paedogenesis,
has been found to exist in two or three species of Diptera,
young being produced by the immature Insect, either larva or

pupa.
Glands.

Insects are provided with a variety of glands, some of
which we have alluded to in describing the alimentary canal
and the organs of sex; but in addition to these there are others
in connexion with the outer integument; they may be either
single cells, as described by Miall in Dicranota larva,’ or groups
of cells, isolated in tubes, or pouches. The minute structure
of Insect glands has been to some extent described by Leydig ;?
they appear to be essentially of a simple nature, but their special
functions are very problematic, it being difficult to obtain
sufficient of their products for satisfactory examination.

1 Tr. Ent. Soc. London, 1893, p. 241. 2 Arch. Anat. Phys. 1855 and 1859.

CHAPTER V

DEVELOPMENT

_ EMBRYOLOGY——EGGS——MICROPYLES——FORMATION OF EMBRYO——VEN-
TRAL PLATE——-ECTODERM AND ENDODERM—-SEGMENTATION—
LATER STAGES——DIRECT OBSERVATION OF EMBRYO——METAMOR-
PHOSIS——-COMPLETE AND INCOMPLETE——INSTAR——HYPERMETA-
MORPHOSIS——METAMORPHOSIS OF INTERNAL ORGANS——INTEGU-
MENT——METAMORPHOSIS OF BLOWFLY——-HISTOLYSIS—-IMAGINAL
DISCS——PHYSIOLOGY OF METAMORPHOSIS——-ECDYSIS.

THE processes for the maintenance of the life of the individual
are in Insects of less proportional importance in comparison with
those for the maintenance of the species than they are in Verte-
brates. The generations of Insects are numerous, and the in-
dividuals produced in each generation are still more profuse.
The individuals have as a rule only a short life ; several successive
generations may indeed make their appearances and disappear
in the course of a single year.

Although eggs are laid by the great majority of Insects, a
few species nevertheless increase their numbers by the production
of living young, in a shape more or less closely similar to that
of the parent. This is well known to take place in the Aphi-
didae or green-fly Insects, whose rapid increase in numbers is
such a plague to the farmer and gardener. These and some other
cases are, however, exceptional, and only emphasise the fact that
Insects are pre-eminently oviparous. Leydig, indeed, has found
in the same Aphis, and even in the same ovary, an egg-tube
producing eggs while a neighbouring tube is producing vivi-
parous individuals. In the Diptera pupipara the young are

1 Acta. Ac. German. xxxiii. 1867, No. 2, p. 81.

144 EGGS CHAP.

produced one at a time, and are born in the pupal stage of their
development, the earlier larval state being undergone in the
body of the parent: thus a single large egg is laid, which is
really a pupa. :

The eggs are usually of rather large size in comparison with
the parent, and are produced in numbers varying according to
the species from a few—-15 or even less in- some fossorial
Hymenoptera—to many thousands in the social Insects: some-
where between 50 and 100 may perhaps be taken as an
average number for one female to produce. The whole number —
is frequently deposited with rapidity, and the parent then dies
at once. Some of the migratory locusts are known to deposit
batches of eggs after considerable intervals of time and change
of locality. The social Insects present extraordinary anomalies
as to the production of the eggs and the prolongation of the life
of the female parent, who is in such cases called a queen.

The living matter contained in the egg of an Insect is
protected by three external coats: (1) a delicate interior oolemm ;
(2) a stronger, usually shell-like, covering
called the chorion ; (3) a layer of material
added to the exterior of the egg from
glands, at or near the time when it is _
deposited, and of very various character,
sometimes forming a coat on each egg
and sémetimes a common covering or
capsule for a number of eggs. The egg-
shell proper, or chorion, is frequently
Fic. 77.—Upper or micro. COVered in whole or part with a complex

pylar aspect of egg of minute sculpture, of a symmetrical char-

Vanessa cardui. (After : a le

Scudder. ) acter, and in some cases this is very

highly developed, forming an ornamenta-
tion of much delicacy ; hence some Insects’ eggs are objects of
admirable appearance, though the microscope is of course necessary
to reveal their charms. One of the families of butterflies, the
Lycaenidae, is remarkable for the complex forms displayed by the
ornamentation of the chorion (see Fig. 78, B).

The egg-shell at one pole of the egg is perforated by one or
more minute orifices for the admission to the interior of the
spermatozoon, and it is the rule that the shell hereabouts is
symmetrically sculptured (see Fig. 77), even when it is unorna-

V EMBRYOLOGY 145

mented elsewhere: the apertures in question are called micro-
pyles. They are sometimes protected: by a micropyle apparatus,
consisting of raised processes, or porches: these are developed
to an extraordinary extent in some eggs, especially in those of

Fic, 78.—Eggs of In-
sects: <A, blowfly
(after Henking) ; B,
butterfly, Thecla
(after Scudder); C,
Hemipteron (Redu-
viid).

C

Hemiptera-Heteroptera (see Fig. 78, C). Some of these peculiar
structures have been described and figured by Leuckart.' The
purpose they serve is quite obscure.

Formation of Embryo.

The mature, but unfertilised, egg is filled with matter that
should ultimately become the future individual, and in the
process of attaining this end is the seat of a most remarkable
series of changes, which in some Insects are passed through with
extreme rapidity. The egg-contents consist of a comparatively
structureless matrix of a protoplasmic nature and of yolk, both
of which are distributed throughout the egg in an approximately
even manner. The yolk, however, is by no means of a simple
nature, but consists, even in a single egg, of two or three kinds
of spherular or granular constituents; and these vary much in their
appearance and arrangement in the early stages of the develop-
ment of an egg, the yolk of the same egg being either of a homo-
geneously granular nature, or consisting of granules and larger
masses, as well as of particles of fatty matter; these latter when
seen through the microscope looking sometimes lke shining,
nearly colourless, globules. The nature of the matrix—which term
we may apply to both the protoplasm and yolk as distinguished

1 Miiller’s Arch. Anat, Phys, 1855, p. 90.
VOL; ¥ L

146 EMBRYOLOGY CHAP

from the minute formative portions of the egg—and the changes
that take place in it have been to some extent studied, and
Kowalewsky, Dohrn,’ Woodworth,? and others have given some
particulars about them. The early changes in the formative
parts of the mature egg have been observed by Henking in
several Insects, and particularly in Pyrrhocoris, his observations
being of considerable interest. When the egg is in the
ovary and before it is quite mature-—at the time, in fact,
when it is receiving nutriment from ovarian cells,—it contains
a germinal vesicle including a germinal-spot, but when the
egg is mature the germinal vesicle has disappeared, and there
exists in its place at one portion of the periphery of the egg-
contents a cluster of minute bodies called chromosomes by Henking,
whom we shall follow in briefly describing their changes. The
group divides into two, each of
which is arranged in a rod or
spindle - like manner, and may
then be called a directive rod
or spindle. The outer of these
two groups travels quite to the
periphery of the egg, and there
with some adjacent matter is
extruded quite outside the egg-
contents (not outside the egg-
coverings), being in its aug-
mented form called a polar or
directive body. While this is
u Lf going on the second directive

Fic. 79.—Showing the two extruded polar spindle itself divides into two
bodies P,, P, now nearly fused and re- e :
included, and the formation of the groups, the outer of which is
spindle by junetion of the male ood then extruded in the manner
we have already described in

the case of the first polar body, thus completing the extrusion of
two directive bodies. The essential parts of the bodies that
are successively formed during these processes are the aggregates,
called chromosomes; the number of these chromosomes appears
to be constant in each species; their movements and dispositions
are of a very interesting character, the systems they form in

R 42

| Zeitschr. wiss. Zool. xxvi. 1876, p. 115.
* Scudder, Butterflies of New England, i. 1889, p. 99.

v EMBRYOLOGY 147

the course of their development having polar and equatorial
arrangements. These we cannot further allude to, but may
mention that the extrusion of the directive bodies is only
temporary, they being again included within the periphery of the
egg by the growth and extension of adjacent parts which meet
over and thus enclose the bodies.

The arrangements and movements we have briefly alluded to
have been limited to the unfertilised condition of the egg (we
should rather say, the fertilisimng element has taken no part in
them), and have as their result the union of the chromosomes
existing after the extrusion of the two polar bodies, into a small
body called the female pronucleus or egg-nucleus (Eikern), while
the position of the movements has been an extremely minute
portion of the egg near to its outer surface or periphery. The
introduction of a sperm, or male, element to the egg through
the micropyle gives rise to the formation of another minute body
placed more in the interior of the egg, and called the sperm-
nucleus, The egg-nucleus, travelling more into the interior of
the egg, meets the sperm-nucleus; the two amalgamate, forming
a nucleus or body that goes through a series of changes resulting
in its division into two daughter-bodies. These two again divide,
and by repetitions of such division a large number of nuclei
are formed which become arranged in a continuous manner so
as to form an envelope enclosing a considerable part (if not
quite the whole) of the egg-mass. This envelope is called the
blastoderm, and together with its contents will form the embryo.
We must merely allude to the fact that it has been considered
that some of the nuclei forming the blastoderm arise directly
from the egg-mass by a process of amalgamation, and if this
prove to be correct it may be admitted that some portions of
the embryo are not entirely the result of division or segmentation
of combined germ and sperm-nuclei. Wheeler states? that some
of the nuclei formed by the first differentiation go to form the
vitellophags scattered throughout the yolk. We should also
remark that, according to Henking, the blastoderm when com-
pleted shows at one part a thickening, immediately under
which (7.e. included in the area the blastoderm encloses) are the
two polar bodies, which, as we have seen, were formed by the
germinating body at an earlier stage of its activity. Fig. 79

1 J. Morphol. viii. 1893, p. 81; see also Graber’s table on p. 149.

148 EMBRYOLOGY CHAP,

represents a stage in the development of Pyrrhocoris, showing
the interior of the egg after a body has been formed by the union
of the sperm and egg-nuclei; this body is about to undergo
division or segmentation, and the equatorial arrangement where
this will take place is seen. The two polar bodies P,, P,, after
having been excluded, are nearly reincluded in the egg. 3

The Ventral Plate.

The next important change after the formation of the blastoderm
is the partial detachment of a part of its periphery to become
placed in the interior of the other and larger
portion. The way in which this takes place
will be gathered from the accompanying dia-
grammatic figures taken from Graber: a
thickened portion (@ }) of the blastoderm

(¢ d) at each point of its withdrawal, and
these folds afterwards grow and meet so as
to enclose the thickened portion. The outer
envelope, formed in part by the original
blastoderm and in part by the new growth,
PRR es ak is called the serosa (e f), the inner layer (g) of
caiddieee of the ven. dhe conjoined new folds being termed the
tral plate: A, a, 6 amnion: the part withdrawn to the interior
ventral plate; B, c, ‘ :

d, folds of the blas- and covered by the serosa and amnion is

toderm that form the called the ventral plate, or germinal band

commencement of the : i -

amnion and serosa; (Keimstreif), and becomes developed into the

C, « J, part of the future animal. The details of the withdrawal

serosa ; g, amnion. . .

of the ventral plate to the interior are very
different in the various Insects that have been investigated.

One of the earliest stages in the development is a differentia-
tion of a portion of the ventral plate into layers from which
the future parts of the organisation will be derived. This
separation of endoderm from ectoderm takes place by a_ sort
of invagination, analogous with that by which the ventral plate

itself is formed. A longitudinal depression running along the

middle of the ventral plate appears, and forms a groove or
channel, which becomes obliterated as to its outer face by the
meeting together of the two margins of the groove (except on the

7

becomes indrawn so as to leave a fold —

v EMBRYOLOGY 149

anterior part, which remains open). The more internal layer of
the periphery of this closed canal is the origin of the endo-
derm and its derivatives. Subsequently the ventral plate and
its derivatives grow so as to form the ventral part and
the internal organs of the Insect, the dorsal part being com-
pleted much later by growths that differ much in different
Insects; Graber, who has specially investigated this matter,
informing us‘ that an astonishing multifariousness is displayed.
It would appear that the various modes of this development
do not coincide with the divisions into Orders and Families
adopted by any systematists.

We should observe that the terms ectoderm, mesoderm, and
endoderm will probably be no longer applied to the layers of the
embryo when embryologists shall have decided as to the nature
of the derived layers, and shall have agreed as to names for
them. According to. the nomenclature of Graber” the blasto-
derm differentiates into Ectoblast and Endoblast; this latter
undergoing a further differentiation into Coeloblast and Myoblast.
This talented embryologist gives the following table of the
relations of the embryonic layers and their nomenclature, the

Periblast Ectoblast Part of yolk cells.
(Epiblast, (Ectoderm, outer
blastoderm). layer). Coeloblast
Protoblast. (Endoderm ie nar-
Centroblast Endoblast rower sense).
(Yolk-cells, hypo- or Hypoblast, Darmdriisenblatt.
blast, endoderm inner layer. _
in part of Bal- (Mesoblast of Bal- Myoblast (Meso-
four). four.) derm of most
Mesoderm and endo- authors). Darm-
derm. muskelblatt.

Nussbaum considers * that “there are four layers in the cock-
roach-embryo, viz. (1) epiblast, from which the integument and
nervous system are developed; (2) somatic layer of mesoblast,
mainly converted into the muscles of the body-wall; (3) splanchnic
layer of mesoblast, yielding the muscular coat of the alimentary
eanal; and (4) hypoblast, yielding the epithelium of the mesen-
teron.”

Turning our attention to the origin of the segmentation, that
is so marked a feature of Insect structure, we find that evidence

1 Denk. Ak. Wien, lv. 1888, p. 109, ete. 2 Morph. Jahrb. xiv. 1888, p. 347.
3 In Miall and Denny, Cockroach, p. 188.

150 EMBRYOLOGY CHAP.

of division or arrangement of the body into segments appears
very early, as shown in our Figure of some of the early stages
of development of Zina (a beetle), Fig. 81. In A the segmen-
tation of the ectoderm has not commenced, but the procephalie
lobes (P C) are seen; in B the three head segments are distinct,
while in C the thoracic segmentation has occurred, and that
of the abdomen has commenced. Graber considers that in this
species the abdomen consists of ten segmental lobes, and a
terminal piece or telson. According to Graber’ this is not a

primitive condition, but is preceded by a division into three or

C

Fic. 81.—Early stages of the segmentation of a beetle (Zina): A, segmentation not visible,
1 day ; B, segmentation of head visible ; C, segmentation still more advanced, 2}
days ; PC, procephalic lobes; g', g?, g®, segments bearing appendages of the head ;
th, thorax ; th, th, th®, segments of the thorax ; a!, a®, anterior abdominal.

four parts, corresponding with the divisions that will afterwards

be head, thorax, and abdomen. This primary segmentation, he
says, takes place in the Hypoblast (Endoderm) layer of the ventral
plate; this layer being, in an early stage of the development of
a common grasshopper (Stenobothrus variabilis), divided into
four sections, two of which go to form the head, while the others

become thorax and abdomen respectively. In Zina the primary —

segmentation is, Graber says, into three instead of four parts.
Graber’s opinion on the primary segmentation does not appear
to be generally accepted, and Wheeler, who has studied? the

' Morph. Jahrb. xiv. 1888, p. 345. 2 J. Morphol. viii. 1893, p. 1.

y EMBRYOLOGY 151

embryology of another Orthopteron, considers it will prove
to be incorrect. When the secondary segmentation occurs the
anterior of the two cephalic divisions remains intact, while the
second divides into the three parts that afterwards bear the
mouth parts as appendages. The thoracic mass subsequently
segments into three parts, and still later the hind part of the
ventral plate undergoes a similar differentiation so as to form the
abdominal segments; what the exact number of these may be
is, however, by no means easy to decide, the division being but
vague, especially posteriorly, and not occurring all at once, but
progressing from before backwards.

The investigations that have been made in reference to the
segmentation of the ventral plate do not at present justify us
in asserting that all Insects are formed from the same number
of embryonic segments. The matter is summarised by Lowne, to
the effect that posterior to the procephalic lobes there are three
head segments and three thoracic segments, and a number of
abdominal segments, “rarely less than nine or more than eleven.”
It will be seen by referring to Figure 81 that the segmentation
appears, not simultaneously, but
progressively from the head back-
wards; this of course greatly in-
creases the difficulty of determin-
ing by means of a section the real
number of segments.

The later stages in the develop-
ment of Insects are already proved
to be so various that it would be
impossible to attempt to follow
them in detail; but in Fig. 82 =
We represent a median section th? th
of the embryo of Zygaena jilipen- Fic. 82.—Embryo of a moth (Zygaena)
Mita at the fifth day. a at the fifth day (after Graber): am,

amnion; s, serosa; p, procephalic
well some of the more important lobes ; st, stomodaeum ; pr, procto-
re daeum ; g', g*, g®, the mouth parts
of the general features of the de- or head appendages; th}, th2, th,
velopment at a stage subsequent to — @ppendages of the thoracic segments ;
: k a-a°, abdominal segments ; s.g, sali-

those represented in Fig. 81, A,B, vary gland.

C. The very distinct stomodaeum

(st) and proctodaeum (pv) are seen as inflexions of the external

wall of the body; the segmentation and the development of the

152 EMBRYOLOGY CHAP.

ventral parts of the embryo are well advanced, while the dorsal
part of the embryo is still quite incomplete.

The method of investigation by which embryologists chiefly
carry on their researches is that of dividing the egg after
proper preparation, into-a large number of thin sections, which
are afterwards examined in detail, so as to allow the arrange-
ment to be completely inferred and described. Valuable as this
method is, it is nevertheless clear that it should, if possible,
be supplemented by direct observation of the processes as they
take place in the living egg: this method was formerly used,
and by its aid we may still hope to obtain exact knowledge
as to the arrangements and rearrangements of particles by
which the structures develop. Such questions as whether the
whole formative power in the egg is absolutely confined to

;
\

one or two small centres to-which the whole of the other egg 4

contents are merely, as it were, passive accessories, or whether an
egg is a combination in which some portion of the powers of
rearrangement is possessed by other particles, as well as the
chromosomes, in virtue of their own nature or of their position
at an early period in the whole, can scarcely be settled without
the aid of direct observation of the processes during life.

The importance of the yolk is recognised by most of the -

recent writers. Nussbaum states (oc. cit.) that “scattered yolk-

cells associate themselves with the mesoblast cells, so that the

constituents of the mesoblast have a twofold origin.” Wheeler

finds’ that amoeboid cells—he styles them vitellophags —

traverse the yolk and assist in its rearrangement; he insists on
the importance both as regards quantity and quality of the yolk.

The eggs of some insects are fairly transparent, and the
process of development in them can, to a certain extent, be
observed by simple inspection with the microscope; a method
that was used by Weismann in his observations on the embry-
ology of Chironomus. There is a moth (Limacodes testudo), that

has no objection to depositing its eggs on glass microscope-slides.

These eggs are about a millimetre long, somewhat more than half
that width, are very flat, and the egg-shell or chorion is very thin
and perfectly transparent. When first laid the contents of this
egg appear nearly homogeneous and evenly distributed, a finely
granular appearance being presented throughout; but in twenty-

1 J. Morphol. viii. 1893, pp. 64, 65, and 81.

v EMBRYOLOGY > 153

four hours a great change is found to have taken place. The
whole superficial contents of the egg are at that time arranged in
groups, having the appearance of separate rounded or oval masses,
pressed together so as to destroy much of their globular symmetry.
The egg contents are also divided into very distinct forms, a
granular matter, and a large number of transparent globules,
these latter being the fatty portion of the yolk; these are present
everywhere, though in the centre there is a space where they are
very scanty, and they also do not extend quite to the cireum-
ference. But the most remarkable change that has taken place
is the appearance in the middle of the field of an area different
from the rest in several particulars; it
oceupies about one-third of the width
and one-third of the length; it has a
whiter and more opaque appearance,
and the fat globules in it are fewer in
number and more indistinct. This
area is afterwards seen to be occupied
by the developing embryo, the outlines
of which become gradually more dis-
tinct. Fig. 83 gives an idea of the
appearance of the egg about the middle
period of the development. In warm

weather the larva emerges from this \ :
egg ten or eleven days after it has S55
been deposited. -

The period occupied by the develop- *", ae ae ears
ment of the embryo is very different in the development of the em-
the various kinds of Insects; the blowfly a en ir pat yrodby a
embryo is fully developed in less than

twenty-four hours, while in some of the Orthoptera the embryonic
stage may be prolonged through several months. According to
Woodworth the blastoderm in Vanessa antiopa is complete in
twenty-four hours after the deposition of the egg, and the
involution of the ventral plate is accomplished within three days
of deposition.

Metamorphosis.

The ontogeny, or life history of the individual, of Insects is
peculiar, inasmuch as a very large part of the development takes

154 | METAMORPHOSIS CHAP.

place only late in life and after growth has been completed. Insects
leave the egg in a certain form, and in that condition they con-
tinue—with, however, a greater or less amount of change according
to kind—till growth is completed, when, in many cases, a very great
change of form takes place. Post-embryonic development, or
change of form of this kind, is called metamorphosis. It is not a
phenomenon peculiar to Insects, but exists to a greater or less
extent in other groups of the Metazoa; while simpler post-
embryonic development occurs in nearly all, as in scarcely any
complex animals are all the organs completely formed at the time
the individual becomes possessed of a separate existence. In
many animals other than Insects the post-embryonic development
assumes most remarkable and complex forms, though there are
perhaps none in which the phenomenon is very similar to the
metamorphosis of Insects. The essential features of metamor-
phosis, as exhibited in the great class we are writing of, appear
to be the separation in time of growth and development, and the
limitation of the reproductive processes to a short period at the
end of the individual life. The peculiar phenomena of the post-
embryonic development of the white ants show that there exists
some remarkable correlation between the condition of the repro-
ductive organs and the development of the other parts of the
organisation. If we take it that the post-embryonic physio-
logical processes of any individual Insect are of three kinds,
—growth, development, and reproduction,—then we may say
that in the higher Insects these three processes are almost
completely separated, and go on consecutively, the order being,—
first, growth; second, development; third, reproduction. While,
if we complete the view by including the processes comprised in
the formation of the egg and the development therein, the series
will be—(1) oogenesis, or egg-growth ; (2) development (embry-
onic); (8) growth (post-embryonic); (4) development (post-
embryonic); (5) reproduction.

The metamorphosis of Insects is one of the most interesting
parts of entomology. It is, however, as yet very little known
from a scientific point of view, although the simpler of its
external characters have for many ages past attracted the
attention and elicited the admiration of lovers of nature. It
may seem incorrect to say that little is yet known scientifically
of a phenomenon concerning which references almost innumer-

+ sarees oo ee .

ev | METAMORPHOSIS) * 155

able are to be found in literature: nevertheless the observations
that have been made as to metamorphosis, and the analysis that -
has been commenced of the facts are at present little more than
sufficient to show us how vast and complex is the subject, and
how great are the difficulties it presents.

There are three great fields of inquiry in regard to meta-
morphosis, viz. (1) the external form at the different stages ;
(2) the internal organs and their changes; (3) the physiological
processes. Of these only the first has yet received any extensive
attention, though it is the third that precedes or underlies the
other two, and is the most important. We will say a few words
about each of these departments of the inquiry. Taking first
the external form—the instar. But before turning to this we
must point out that in limiting the inquiry to the post-embryonic
development, we are making one of those limitations that give rise
to much misconception, though they are necessary for the acquisi- *
tion of knowledge as to any complex set of phenomena. If we
assume five well-marked stages as constituting the life of an Insect
with extreme metamorphosis, viz. (1) the formation and growth of
the egg; (2) the changes in the egg culminating in its hatching
after fertilisation; (3) the period of growth; (4) the pupal
changes ; (5) the life of the perfect Insect ; and if we limit our
inquiry about development to the latter three, we are then
shutting out of view a great preliminary question, viz. whether
some Insects leave the egg in a different stage of development to
others, and we are consequently exposing ourselves to the risk
of forgetting that some of the distinctions we observe in the
subsequent metamorphosis may be consequential on differences in
the embryonic development.

Instar and Stadium.

Figs. 84 and 85 represent corresponding stages in the life
of two different Insects, Fig. 84 showing a locust (Aeridium),
and Fig. 85 a white butterfly. In each A represents the
newly-hatched individual; B, the insect just before its perfect
state ; C, the perfect or imago stage. On comparing the two sets
of figures we see that the C stages correspond pretty well as
regards the most important features (the position of the wings
being unimportant), that the A stages are moderately different,

156 ’ METAMORPHOSIS CHAP, »

while the B states are not to be recognised as equivalent condi-
tions. | :

Every Insect after leaving the egg undergoes during the
process of growth castings of the skin, each of which is called

Fic. 84. — Locust
(Acridium per-
egrinum): A,
newly hatched;
B, just -ante-
cedent to last
ecdysis ; C, per-
fect Insect.

4 - —
<= S=

J —
LSS SS =

a moult or ecdysis. Taking for our present purpose five as the
number of ecdyses undergone by both the locust and butterfly,
we may express the differences in the successions of change we
portray in Figs. 84 and 85 by saying that previous to the

Fie. 85.—Butterfly (Pieris) :
A, the newly hatched
young, or larva magnified ;
B, pupa (natural size) just
antecedent to last ecdysis ;
C, perfect Insect.

first eedysis the two, Insects are moderately dissimilar, that the
locust undergoes a moderate change before reaching the fifth
ecdysis, and undergoes another moderate change at this moult, thus
reaching its perfect condition by a slight, rather gradual series of

Vv METAMORPHOSIS fe

alterations of form. On the other hand, the butterfly under-
goes but little modification, remaining much in the condition
shown by A, Fig. 85, till the fourth, or penultimate, ecdysis,
but then suffers a complete change of form and condition, which
apparently is only inferior to another astonishing change that
takes place at the fifth or final moult. The chief, though by no
means the only, difference between the two series consists in the
fact that the butterfly has interposed between the penultimate
and the final ecdyses a completely quiescent helpless condition, in
which it is deprived of external organs of sense, locomotion, and
nutrition ; while in the locust there is no loss of these organs, and
such quiescent period as exists is confined to a short period just
at the fifth ecdysis. The changes exhibited by the butterfly are
called “ complete metamorphosis,’ while this phenomenon in the
locust is said to be “incomplete.” The Insect with complete
metamorphosis. is in its early stage called a larva, and in the
quiescent state a pupa. The adult state in both butterfly and
locust is known as imago or perfect Insect.

The most conspicuous of the differences between Insects with
complete and those with incomplete metamorphosis is, as we
have remarked, the existence in the former of a pupa. The
pupal state is by no means similar in all the Insects that
possess it. The most anomalous conditions in regard to
it occur in the Order Neuroptera. In some members of
that Order—the Caddis-flies for instance—the pupa is at first
quiescent, but becomes active before the last ecdysis; while in
another division—the May-flies—the last ecdysis is not preceded
by a formed pupa, nor is there even a distinct pupal period, but
the penultimate ecdysis is accompanied by a change of form to
the winged condition, the final ecdysis being merely a casting of
the skin after the winged state has been assumed. In the
Odonata or Dragon-flies there is no pupal stage, but the change
of form occurring at the last ecdysis is very great. In those
Insects where the interval between the last two moults is not
accompanied by the creature’s passing into a definite, quiescent
pupa, the individual is frequently called then a nymph; but the
term nymph has merely a distinctive meaning, and is not capable
of accurate definition, owing to the variety of different conditions
covered by the word. Eaton, in describing this term as it is used
for Ephemeridae, says, “Nymphs are young which lead an

158 METAMORPHOSIS CHAP.

active life, quitting the egg at a tolerably advanced stage of

morphological development, and having the mouth-parts formed
after the same main type of construction as those of the adult
insect.” + \

The intervals between the ecdyses are called stadia, the first
stadium being the period between hatching and the first ecdysis.
Unfortunately no term is in general use to express the form of
the Insect at the various stadia; entomologists say, “the form
assumed at the first moult,’ and so on. To avoid this circum-
locution it may be well to adopt a term suggested by Fischer?
and call the Insect as it appears at hatching the first instar,
what it is as it emerges from the first ecdysis the second instar,
and so on; in that case the pupa of a Lepidopteron that assumed
that condition ‘at the fifth eedysis would be the sixth instar, and
the butterfly itself would be the seventh instar.

Various terms are used to express the differences that exist in »

the metamorphoses of Insects, and as these terms refer chiefly to
the changes in the outer form, we will here mention them. As
already stated, the locust is, in our own language, said to have an
incomplete metamorphosis, the butterfly a complete one. The
term Holometabola has been proposed for Insects with complete
metamorphosis, while the appellations Ametabola, Hemimetabola,
Heterometabola, and Paurometabola have been invented for
the various forms of incomplete, or rather less complex, meta-

morphosis. Some writers use the term Ametabola for Insects |
that are supposed to exhibit no change of external form after

quitting the egg, the contrasted series of all other Insects being
then called Metabola. . Westwood and others use the word
Homomorpha for Insects in which the condition on hatching

more or less resembles that attained at the close of the develop-

ment, and Heteromorpha for those in which the form on
emergence from the egg differs much from what it ultimately
becomes.

Hypermetamorphosis.

There are certain unusual changes to which the term
hypermetamorphosis has been applied; these we can here only
briefly allude to.

1 Trans. Linn. Soc., 2nd Series, ‘‘ Zool.” 1888, iii. p. 12.
2 Orthoptera ewropaea, 1853, p. 87.

a me METAMORPHOSIS : 159

Insects that have complete metamorphoses, and are not
supplied with food by their, parents or guardians, are provided
during their larval life with special modifications of extremely
various kinds to fit them for the period of life during which they
are obtaining food and growing. Thus caterpillars possess numer-
ous adaptations to fit them for the period during which they
live on leaves, while maggots have modifications enabling them to
live amongst decomposing flesh. Some larvae are greatly modified
in this adaptive way, and when the adaptations change greatly
during the life of the larva, hypermetamorphosis is said to exist.
As an instance we may mention some beetle larvae that are born
with legs by whose aid they can clmg to a bee, and so get

Fic. 86.—Prepara-
“wh tory stages of
Sitaris humer-
alis; 9, 10, 11,
12, first, second,
third, and fourth
larval instars ;
13, pupa. (After
Lubbock and
Fabre.)

carried to its nest, where they will in future live on the stores
of food the bee provides for its own young. In order that they
may be accommodated to their totally different second circum-
stances, they change their first form, losing their legs, and _be-
coming almost bladder-like creatures, fitted for floating on the
honey without being injured by it. Such an occurrence has
been described by Fabre’ in the case of Sitaris humeralis, and
his figures have been reproduced in Sir John Lubbock’s book on
the metamorphoses of Insects,’ as well as in other works, yet they
are of so much interest that we give them again, especially as the
subject is still only in its infancy ; we at present see no sufticient
reason for the later of these larval states. Little is, we believe,
known as to the internal anatomy of the various instars in these
curious cases.

1 Ann. Sci. Nat. Zool. Ser. iv. vol. vii. 1857, pl. 17. 2 Nature Series, 1874.

160 METAMORPHOSIS CHAP.

There are certain minute Hymenoptera that deposit their
eggs inside the eggs of other Insects, where the beings hatched
from the parasitic eggs subsequently undergo their development
and growth, finding their sustenance in the yolk or embryo con-
tained in the host-egg. It is evident that such a life is very
anomalous as regards both food and the conditions. for respira-
tion, and we consequently find that these tiny egg-parasites go
through a series of changes of form of a most remarkable
character.’ It would appear that in these cases the embryonic
and post-embryonic developments are not separated in the same
way as they are in other Insects. We are not aware that any
term has yet been proposed for this very curious kind of Insect
development, which, as pointed out by Brauer, is doubtless of a
different nature from the hypermetamorphosis of Sitaris.

Changes in Internal Organs.

In relation to the post-embryonic development of the internal
organs of the body there is but little exact generalisation to be
made, the anatomical condition of these organs at the time of
emergence from the egg having been ascertained in but few
Insects. We know that in Holometabolous Insects the internal
anatomy differs profoundly in the larval and imaginal instars.
As to Insects with more imperfect metamorphosis very little
information exists, but it appears probable that in many no ex-

tensive distinctions exist between the newly-hatched and the |

adult forms, except in the condition of the reproductive organs.
Differences of minor -importance doubtless exist, but there is
almost no information as to their extent, or as to the periods at
which the changes occur; so that we do not know to what
extent they may be concentrated at the final ecdysis. In Insects
with perfect metamorphosis the structures of the internal organs
are, as we have said, in many cases totally different ‘in the larval
and imaginal periods of the life; but these changes are far from
being uniform in all Holometabola. The nervous system in
some cases undergoes a great concentration of the ganglia, in
others does not, and important distinctions exist in this respect
even within the limits of a single Order, such as the Coleoptera.

1 See Proctotrupidae subsequently,
2 Verh. Zool.-bot. Ges. Wien, xix. 1869, p. 839.

Vv METAMORPHOSIS 161

Some Insects take the same kind of food throughout their lives,

but many others change totally in this respect, and their organs
for the prehension and digestion of food undergo a corre-
sponding change. Butterflies suck food in the form of liquid
juices from flowers by means of a delicate and long proboscis,

while the young butterfly——the caterpillar—disdains sweets,

and consumes, by the assistance of powerful mandibles, a great
bulk of leaves. Other Holometabola undergo no such total change
of habits; the tiger-beetle, for instance, is as ferocious a con-
sumer of the juices of Insects in its young stage as it is in the
adult condition. Hence Brauer‘ divides Insects, as regards this
point, into three categories. The forms in which both the young
and adult take food by suction he calls Menorhyncha; those in
which both the imago and immature forms feed by mandibles he
calls Menognatha; while his Metagnatha consists of those insects
that take food by jaws when young, but by suction with tubular
mouths when mature. Besides these main divisions there are
some exceptional cases to which we need not here allude, our
present object being to indicate that in the Metagnatha the
digestive organs are of a very different nature in the young and
in the adult states of existence.

The internal organs for the continuance of the species are
known to be present in a rudimentary stage in the embryo, and
it is a rule that they do not attain their full development until
growth has been completed; to this rule there may possibly be
an exception in the case of the Aptera. But little information
of a comparative character exists as to the dorsal vessel and the
changes it undergoes during metamorphosis. There is con-
siderable difficulty in connexion with the examination of this
structure, but it appears probable that it is one of the organs
that changes the least during the process of metamorphosis.

The exact nature of the internal changes that occur during
metamorphosis is almost a modern subject. It is of course a
matter of great difficulty to observe and record changes that go

‘on in the interior of such small creatures as Insects, and when

the phenomena occur with great rapidity, as is frequently the
case in Insect metamorphosis, the difficulty is much increased,
Nevertheless the subject is of such great interest that it has been
investigated with a skill and perseverance that call for the

1 «Syst. Zool. Stud.” SB. Ak. Wien, Abth. 1, xci. 1885, p. 291.
VOL, V M

162 METAMORPHOSIS—IN TEGUMENT _ CHAP.

highest admiration. The greater part of the information ob-
tained refers to a single Insect, the blowfly; and amongst those
who have made important contributions to it we may mention
Weismann,’ Viallanes,? Ganin,® and Van Rees,* and it is at pre-
sent under investigation by Lowne. A good deal, too, is becoming
known about the processes in the case of the silkworm.

Integument and Ecdysis.

The integument consists of a cellular layer, usually called the
hypodermis, situated on a basement membrane. The hypo-
dermis, or layer of chitinogenous cells, excretes a matter which
remains attached to the body, forming the hard outer layer of the
skin. This layer consists of chitin and has no vitality, but
its presence no doubt exerts a very important influence on the
physiological processes of the Insect. The chitinous investment

varies much in thickness and in other properties; in some .

Insects it is hard, even glassy, so as to be difficult to pierce with
a pin, in others it is pliable, and in some very delicate. Chitin
is a substance very difficult to investigate; according to the
recent researches of Krawkow ° it may prove to be of somewhat
variable chemical composition.

After a time the hypodermis excretes a fresh supply of
chitin, and, possibly by the commencement of this process, the
older chitinous investment becomes separated and is shed. The
details have, however, not been ascertained, though their import-
ance has been suggested by Hatchett Jackson.6 The newly
exposed layer of integument is pallid, but afterwards becomes
coloured in a manner varying according to the species, the process
being possibly due to some secondary exudation permeating the
freshly exposed chitin, or modifying some part of its exterior.

Lowne informs us that in the imago of the blowfly the great
majority of the hypodermic cells themselves enter into the com-
position of the chitinous integument; and it is perhaps not a

matter for surprise that the cells should die on the completion of

their functional activity, and should form a part of the chitinous

1 Zeitschr. wiss. Zool. xiv. 1864, p. 187.
2 Viallanes, Ann. Sci. Nat., Series 6, “ Zool.” xiv. 1882.
% Unfortunately in the Russian language. * Zool. Jahrb. Abth. Anat. iii. 1888, p. 1.
5 Zeitschr. Biol., xxix. 1892, p. 177.
5 Trans. Linn. Soc. London, ‘‘ Zoology,” 2nd series, v. 1890, p. 174.

v METAMORPHOSIS 163

investment. Some writers say that the chitinous layer may be
shown to be covered by a delicate extima or outer coat.

The number of ecdyses varies greatly in Insects, but has been
definitely ascertained in only a few forms outside the Order
Lepidoptera. In Campodea Grassi says there is a single frag-
mentary moult, and in many Hymenoptera the skin that is cast
is extremely delicate, and the process perhaps only occurs twice
or three times previous to the pupal stage. In most Insects,
however, ecdysis is a much more important affair, and the whole
of the chitinous integument is cast off entire, even the linings of
_ the tracheae, and of the alimentary canal and its adjuncts being
parted with. Sir John Lubbock observed twenty-three moults
in a May-fly of the genus Cloéon, this being the maximum yet
recorded, though Sommer states? that in Macrotoma plumbea
moulting goes on as long as life lasts, even after the Insect has
attained its full size.

Some Insects get quit of a considerable quantity of matter by
their ecdyses, while in others the amount is comparatively slight.
It has been thought that the moulting is effected in order to
permit of increase of size of the Insect, but there are facts which
point to the conclusion that this is only a factor of secondary
importance in the matter. One of these is that many Insects
make their first ecdysis almost immediately after they leave the
egg; this is the case with the young larva of the blowfly, which,
according to Lowne, moults within two hours of its emergence
from the egg. We have already referred to the important sug-
gestion made by Eisig* that, since chitin is a nitrogenous sub-
stance, the ecdyses may be a means of getting rid of waste
nitrogenous matter; to which we have added that as chitin also
consists largely of carbon, its excretion may be of Importance
in separating carbonaceous products from the blood.

Metamorphosis of Blowfly.

The phenomena of’ metamorphosis are displayed to their
greatest extent in the transformations and physiological processes
of the Muscid Diptera, of which the common blowfly is an

_ + Trans. Linn. Soc. xxv. 1866, p. 491. * Zeitschr. wiss. Zool. xli. 1885, p. 712.
* “Fauna und Flora d. Golfes von Neapel,” Die Capitelliden, 1887, p. 781.

164 METAMORPHOSIS CHAP.

example. We will briefly consider the information that has been
obtained on this. subject. |

The development of the embryo in the egg of the blowfly is
unusually rapid, occupying only a period of twenty to twenty-
four hours. After its first moult the blowfly larva grows rapidly
during a period of about ten to fourteen days, during which it
undergoes moults, the number. of which appears not to be
definitely ascertained. After becoming full-fed the larva loses
its active state, and passes for a period into a condition of com-
parative quiescence, being spoken of in this state as a resting
larva. This quiet period occurs in most full-grown larvae, and
is remarkable for the great variation that may occur in its
duration, it being in many Insects subject to prolongation for
months, in some cases possibly even for years, though in favour-
able circumstances it may be very short. Lowne informs us that
in the blowfly this period of the life is occupied by very great
changes in the internal organs, which are undergoing very exten-
sive processes of destruction and rebuilding. After some days
the outer skin of the resting larva shrivels, and is detached from
the internal living substances, round which it hardens and forms
the sort of cocoon or capsule that is so well known. This
using of the cast larval skin as a cocoon is, however, limited to
certain of the two-winged flies, and perhaps a few other Insects,
and so must be considered an exceptional condition, The capsule
conceals from view a most remarkable state, known to the old
naturalist Réaumur as the “spheroidal condition,’ but called by
more recent writers the pronymph. . The pronymphal state
may be looked on as being to a great extent a return of the
animal to the condition of an egg, the creature becoming an
accumulation of soft creamy matter enclosed in a delicate skin,
This spheroidal condition, however, really begins in the resting
larva,and Van Rees and others think that the delicate membrane
enclosing the substance of the pronymph is really the hypodermis
of the integument of the larva. Although this seems probable,
from the resemblance this condition would in that case present
to the phenomena usual in ecdysis, it is not generally admitted,
and there is much difficulty in settling the point. Lowne is of
a contrary opinion, looking on the limiting membrane as a sub-
sequent formation; he calls it the paraderm. The process of
forming the various organs goes on in the pronymph, till the

Vv METAMORPHOSIS 165

“nymph” has completed its development, the creature having
then again taken on a definite form which apparently corre-
sponds to the pupa of Hymenoptera. Great doubt, however,
exists as to this equivalence, and indeed as to any exact corre-
spondence between the metamorphic stadia of different Insects,
a view which long since was expressed by Sir John Lubbock *
and Packard. The term nymph is used ini this case not because
there is any resemblance to the condition similarly named in
Insects with less complete metamorphosis, but because the term
pupa is applied to the outer case together with the contained
nymph. The transformation of the nymph into the perfect blow-
fly occupies a period very variable according to the temperature.
Histolysis.—The processes by which the internal organs of
the maggot are converted into those of the fly are of two kinds,
—histolysis or breaking down, histogenesis or building up, of
tissue. The intermediary agents in histolysis are phagocytes,
cells similar to the leucocytes or white corpuscles of the blood:
the intermediary agents in histogenesis are portions of tissue
existing in the larval state incorporated with the different organs,
or preserving a connexion therewith even when they are to a
great extent separated therefrom. In this latter case they are
called imaginal discs, though Professor Miall prefers to term them
imaginal folds.” The two processes of histolysis and histogenesis,
though to some extent mutually dependent (for the material to be
built up has to be largely obtained by previous destruction), do not
go on pari passu, though they are to a great extent contemporaneous.
In the resting larva histolysis is predominant, while in the nymph
histogenesis is more extensive. Microscopic observation shows
that the phenomena connected with the histolysis of the mus-
cular tissue are scarcely distinguishable from those of an inflam-
matory process, and Viallanes* dilates on this fact in an instruc-
tive manner. The phagocytes attach themselves to, or enter, the
tissues which are to be disintegrated, and becoming distended,
assume a granular appearance. By this pseudo-inflammatory pro-
cess the larval structures are broken down into a creamy substance ;
the buds, or germs, from which the new organs are to be devel-
oped being exempt from the destruction. These buds, of which
about sixty or upwards have already been detected, undergo

? Trans. Linn. Soc. xxiv. 1863, p. 65. 2 Trans. Linn. Soc. “Zool.” v. 1892, p. 267.
. 3 Ann. Sci. Nat., Series 6, ‘‘ Zool.” xiv. 1882, p. 150.

166 METAMORPHOSIS CHAP,

growth as they are liberated, and so the new creature is formed,
the process of growth in certain parts going on while destrue-
tion is being accomplished in others. Considerable discrepancy
prevails as to the extent to which the disintegration of some
of the tissues is carried.

According to Kowalevsky* it would appear that after the
phagocytes have become loaded with granules they serve as
nutriment for the growing tissues, and he thinks they become
blood-cells' in the imago. The process of histolysis has been

hy af
V Ge jj :
{i}
fi
Wy
Ng =
4 \
?
if EEE
L) {
j ia
\

Fie, 87.—Imaginal discs of Muscidae in process of development: A, Brain and

ventral ganglion of a larva 7 mm. long of M. vomitoria; v, ventral ganglion ;

c, cephalic ganglion; h, head rudiment; ve, portion of: ventral chain; pd,
prothoracic rudiment; vc3, third nerve; md, mesothoracic rudiment: B, meso-
thoracic rudiment, more advanced, iu a pupa just formed of Sarcophaga carnaria,
showing the base of the sternum and folds of the forming leg, the central part (/)
representing the foot: C, the rudimentary leg of the same more advanced ; f, femur;
t, tibia ; /,, 7; tarsal joints: D, two discs from a larva 20 mm. long of Sarcophaga,
attached to tracheae ; msw, mesonotal and wing-rudiment ; m¢, metathoracie rudi-
ment; E, 7, mesothoracic rudiment of a 7 mm. -long larva attached to a tracheal
twig. (After Weismann and Graber. )

chiefly studied in the blowfly, and not much is known of it in
other Insects, yet it occurs to a considerable extent, according to
Bugnion” and others, in the metamorphosis of Lepidoptera.
Indeed it would almost seem that the processes of histolysis
and histogenesis may be looked on as exaggerated forms of the
phenomena of the ordinary life of tissues, due to greater rapidity
and discontinuity of tissue nutrition. |

1 Zool. Anz. viii. 1885, p. 125. 2 Mitt. Schweiz. ent. Ges. viii. 1893, p. 403.

’ ,
‘
Py
«
ee

at a Eee

~ METAMORPHOSIS 167

_ Imaginal Discs.—The imaginal discs are, portions of the
larval hypoderm, detached from continuity with the main body
of the integument, but connected therewith by strings or pedicels
which may be looked on as portions of the basement membrane.
Whether these discs, or histoblasts as they are called by Kiinckel
d’Herculais,’ are distinguished by any important character from
other buds or portions of regenerative tissue that, according to
Kowalevsky,? Korschelt and Heider,? and others, exist in other
parts of the body, does not appear to be at present ascertained.

We give some figures, taken from Weismann and Graber, of
- the imaginal rudiments existing in the
larvae of Muscidae. Although by no means
good, they are the best for our purpose
we can offer to the reader. Other figures
will be found in Lowne’s work on _ the
blowfly now in course of publication.
Weismann’s paper * is now thirty years old,
and, when it was written, he was not aware
of the intimate connexion the rudiments
have with the integument; this has, how-
ever, now been demonstrated by several
observers. Pratt states’ that the formation
of the imaginal discs in Melophagus ovinus
takes place in the later stages of the em-
bryonic development, and after the manner
formerly suggested by Balfour, viz. invagin-
ation of the ectoderm.

Both the regenerative buds and the
‘rudimentary sexual glands are known to be
derived directly from the embryo; neither
of them undergoes any histolysis, so that Fie. 88.— Median longi-
we have in them embryonic structures ‘inal section through

: Seman : fo , larva of blowfly during
which exist in a quiescent condition during _ the process of _histo-
th ‘od i Roy the. } ey . lysis. (After Graber.)

e period in which the larva is growing — fxpjanation in text.
with great rapidity, and which when the

larva has attained its full growth and is disintegrating, then

1 Recherches Org. des Volucelles, 1875, p. 143.
2 Zeitschr. wiss. Zool. xlv. 1887, p. 587.
3 Lehrbuch Entwicklungsgeschichte, Spec. Theil. 1890, p. 875.
* Zeitschr. wiss. Zool. xiv. 1864, p. 187. ° Arch. f. Naturges. lix. 1893, 1, p. 168.

168 METAMORPHOSIS CHAP, Om

appropriate the products of the disintegration so as to’ produce
the perfect fly.

Our Fig. 88, taken from Graber, represents a longitudinal
median section of a full-grown larva of Musca, in which the
processes of metamorphosis are taking place. The position of
some of the more important imaginal rudiments is shown by it:
b', 6, 8, rudiments of the three pairs of legs of the imago; an, of
antennae ; between an and w, rudiment of eye; w, of wings; h, of
halteres ; f, fat-body ; d, middle of alimentary canal; n, ventral
chain; st, stigma; 6, 7, sixth and seventh body segments.

Physiology of Metamorphosis.

Many years ago, Harvey perceived the probable existence of
a physiological continuity between the earlier and later stages
of the Insect’s life. Modern investigation has shown that in the
blowfly a remarkable analogy exists between the conditions of
the pupa and the egg. The outer shell of the pupa corresponds
to the chorion or egg-shell, and the delicate outer membrane of
the pronymph to the oolemn or lining membrane of the egg; the
creamy matter corresponds with the yolk, and the regenerative
buds are analogous to the formative portions of the developing
egg. The process of histolysis as carried out by the phagocytes
of the later life appears also to find a parallel in the vitellophags
of the embryonic life.’ It appears probable that the physio-
logical processes of the post-embryonic metamorphosis may be
essentially a repetition—or an interrupted continuation—of
those of the embryonic period.

The inquiry as to what are the determining causes of the

metamorphic changes of the blowfly and other Insects has as
yet but little advanced. Why does the larva grow up to a

certain period with great rapidity, then cease its appropriating —

power and break up the parts that have been so rapidly and
recently formed? And why do the imaginal buds remain
quiescent till the other tissues are being disintegrated, and
then, instead of sharing the general condition of disintegra-
tion, commence a career of development? To these questions no
satisfactory answer has yet been given, though the remarkable
- studies, already referred to, of Bataillon on the later larval life

1 Wheeler, in J. Morphol. viii. 1893, p. 81.

Ee ee ee ee A ae reer Mn Ee aa i ae OR ae a

METAMORPHOSIS 169

of the silkworm suggest the direction in which knowledge may
be found, for they show that the physiological conditions of the
later larval life are different from those of the earlier life, possibly
as the direct result of the mere aggregation of matter, and the

consequent different relations of the parts of the organism to

atmospheric and aqueous conditions.

If we wish to understand metamorphosis, we must supplement
the old opinion that ecdysis is merely an occurrence to facilitate
expansion, by the more modern conception that it is also an
important physiological process. That shedding the skin is done
solely to permit of enlargement of size is a view rendered unten-
able by many considerations. The integument can increase and
stretch to an enormous extent without the aid of moulting; wit-
ness the queen-termite, and the honey-bearers of the Myrmeco-
cystus ants. Many moults are made when increase of size does
not demand them, and the shedding of the skin at the time of.
pupation is accompanied by a decrease in size. And if moulting

be merely connected with increase of size, it is impossible to see

why Cloéon should require two dozen moults, while Campodea

can do with one, or why a collembolon should go on moulting

during the period of life subsequent to the cessation of growth.
The-attention of entomologists has been chiefly directed to

the ecdyses connected with the disclosure of the pupal and

imaginal instars. Various important transformations may, how-
ever, occur previous to this, and when they do so it is always
in connexion with ecdyses. Caterpillars frequently assume a
different appearance and change their habits or character at a
particular ecdysis; and in Orthoptera each ecdysis is accom-
panied by a change of form of the thoracic segments; this
change is very considerable at one of the intermediate ecdyses.

The assumption of the pupa state is the concomitant of an
ecdysis, and so also is the appearance of the imago; but the
commencement of each of these two stages precedes the ecdysis,
which is merely the outward mark of the physiological processes.
The ecdysis by which the pupa is revealed occurs after the
completion of growth and when great changes in the internal
organs have occurred and are still taking place; the ecdysis by
which the imago appears comes after development has been quite
or nearly completed.

Although the existence of a pupa is to the eye the, most

170 _-—— *_s METAMORPHOSIS CHAP. v.

striking of the differences between Insects with perfect and those
with imperfect metamorphosis, yet there is reason for supposing
that the pupa and the pupal period are really of less importance
than they at first sight appear to be. In Fig. 85 we showed
how great is the difference in appearance between the pupa and
the imago. The condition that precedes the appearance of the
pupa is, however, really the period of the most important change.
In Fig. 89 we represent the larva and pupa of a bee; it will be
seen that the difference between the two forms is very great,
while the further change that will be required to complete
the perfect Insect is but slight. When the last skin of the

Fria. 89.—Larva and pupa of a bee, Xylocopa violacea: A, larva; B, pupa, ventral ©
aspect ; C, pupa, dorsal aspect. (After Lucas.) °

larva of a bee or of a beetle is thrown off, it is, in fact, the
imago that is revealed; the form thus displayed, though colour-
less and soft, is that of the perfect Insect; what remains to be
done is a little shrinking of some parts and expansion of others,
the development of the colour, the hardening of certain parts.
The colour appears quite gradually and in a regular course,
the eyes being usually the first parts to darken. After the
coloration is more or less perfected—according to the species
—a delicate pellicle is shed or rubbed off, and the bee or beetle
assumes its final form, though usually it does not become active
till after a farther period of repose.

CHAPTER VI.

CLASSIFICATION——THE NINE ORDERS OF INSECTS—-THEIR CHARACTERS
—PACKARD’S ARRANGEMENT——BRAUER’S CLASSIFICATION—
CLASSIFICATIONS BASED ON METAMORPHOSIS——SUPER-ORDERS
—THE SUBDIVISIONS OF ORDERS.

Classification.

WE have already alluded to the fact that Insects are the most
numerous in species and individuals of all land animals: it is
estimated that about 250,000 species have been already described
and have had scientific names given to them, and it is considered
that this is probably only about one-tenth of those that really
exist. The classification in a comprehensible manner of such an
enormous number of forms is, it will be readily understood, a
matter of great difficulty. Several methods or schemes have
‘since the time of Linnaeus been devised for the purpose, but we
shall not trouble the reader to consider them, because most of
them have fallen into disuse and have only a historical interest.
Even at present there exists, however, considerable diversity of
opinion on the question of classification, due in part to the fact
that some naturalists take the structure of the perfect or adult

_ Insect as the basis of their arrangement, while others prefer to

treat the steps or processes by which the structure is attained, as
being of primary importance. To consider the relative values of
these two methods would be beyond our scope, but as in practice
a knowledge of the structures themselves must precede an inquiry
as to the phases of development by which the structures are reached;
and as this latter kind of knowledge has been obtained in the
case of a comparatively small portion of the known forms,—the
embryology and metamorphosis having been investigated in but

172 INSECTS CHAP,

few Insects,—it is clear that a classification on the basis of
structure is the only one that can be at present of practical value.
We shall therefore for the purposes of this work make use of an
old and simple system, taking as of primary importance the nature
of the organs of flight, and of the appendages for the introduction
of food to the body by the perfect Insect. We do not attempt to
disguise the fact that this method is open to most serious
objections, but we believe that it is nevertheless at present the
most simple and useful one, and is likely to remain such, at any
rate as long as knowledge of development is in process of
attainment.

Orders.

The great groups of Insects are called Orders, and of
these. we recognise nine, viz. (1) Aptera, (2) Orthoptera, (3)
Neuroptera, (4) Hymenoptera, (5) Coleoptera, (6) Lepidoptera,
(7) Diptera, (8) Thysanoptera, (9) Hemiptera. These names are
framed to represent the nature of the wings; and there is some
advantage in having the Orders named in a uniform and descriptive
manner. The system we adopt differs but little from that
proposed by Linnaeus." The great Swedish naturalist did not,
however, recognise the Orders Orthoptera and Thysanoptera ; and
his order Aptera was very different from ours.

being asked to recall the fact that by a mandibulate mouth we
understand one in which the mandibles, or the maxille, or

both, are fitted for biting, crushing, or grasping food; while the
term suctorial implies that some of the mouth parts are of a
tubular form or are protrusible as a proboscis, which assists, or
protects, a more minute and delicate sucking apparatus :—

1. Aptera (a without, rrepdv a wing). Wingless? Insects ; mouth mandibulate
or very imperfectly suctorial. Metamorphosis very little.

2. Orthoptera (opOds straight, rrepov a wing). Four wings are present, the
front pair being coriaceous (leather-like), usually smaller than the
other pair, which are of more delicate texture, and contract in repose
after the manner of a fan. Mouth mandibulate. Metamorphosis
slight. ;

3.“ Neuroptera (vetpov nerve, rrepdv a wing). Four wings of membranous

1 Syst. Nat. Ed. 12, ref. i. pars ii. p. 536 (by error, 356).

2 It must not be supposed that all wingless Insects fall within the limits of this .

Order.

ail

VI _ THE ORDERS OF INSECTS 173

consistency, frequently with much network ; the front pair not much,
if at all, harder than the other pair, the latter with but little or no
fanlike action in closing,- Mouth mandibulate. Metamorphosis
variable, but rarely slight.

4, Hymenoptera (ipjv membrane, rrepov a wing), Four wings of membranous
consistency ; the front pair larger than the hind, which are always
small and do not fold up in repose. Mouth mandibulate, sometimes
provided also with. a tubular proboscis, Metamorphosis very great.

5. Coleoptera (koXeds sheath, rrepdv a wing). Four wings; the upper pair
shell-like in consistency, and forming cases which meet: together
over the back in an accurate line of union, so as to entirely lose a

° winglike appearance, and to conceal the delicate membranous hind
pair. Mouth mandibulate. Metamorphosis great.

6. Lepidoptera (Aeris scale, trepdv a wing). Four large wings covered with
scales. Mouth suctorial. Metamorphosis great.

7. Diptera (Sis double, rrepdv a wing), Two membranous wings. Mouth
suctorial, but varying greatly. Metamorphosis very great.

8. Thysanoptera (Ovoavos fringe, rrepdv a wing). Four very narrow fringed
wings. Mouth imperfectly suctorial. Metamorphosis slight.

9. Hemiptera (pe half, rrepdv a wing). Four wings; the front pair either
leather-like with more membranous apex, or entirely parchment-like
or membranous. Mouth perfectly suctorial, Metamorphosis usually
slight.

We must again ask the reader to bear in mind that numerous
exceptions exist to these characters in most of the great Orders ;
for instance, wingless forms are not by any means rare in several
of the Orders.

Before remarking further on this system we will briefly
sketch two other arrangements of the Orders of Insects, for which
we are indebted to Packard and Brauer.

Packard’s Classification.

Packard has devoted much attention to the subject, and has
published two or three successive schemes, of which the following
is the most recent:’ the definitions are those of the author
himself, but the information in brackets is given to institute a
concordance with the system we adopt :— -

1. Thysanura. Wingless ; often with a spring (equivalent to our Apftera).
2. Dermaptera. Front wings minute, elytra-like (= Forficulidae, a part of
our Orthoptera).

3. Orthoptera. Wings net-veined ; fore wings narrow, hind wings folded
(=our Orthoptera after subtraction of Dermaptera).

1 American Naturalist, xx. 1886, p. 808.

?

174 INSECTS CHAP, — |

+

4. Platyptera. Four net-veined wings; mouth parts adapted for biting
(= Termitidae and Mallophaga, parts of our Neuroptera).

5. Odonata. Wings net-veined, equal (= Odonata, a division of our
Neuroptera).

6. Plectoptera. Wings net-veined, unequal (= Hphemeridae, a part of our
Neuroptera).

7. Thysanoptera. Mouth beaklike but with palpi (= our Thysanoptera).

8. Hemiptera. Mouth parts forming a beak for sucking. No palpi (=our™
Hemiptera). ;

The above eight Orders form the group AMETABOLA, while the
following eight constitute the METABOLA :— .

9. Neuroptera. Wings net-veined ; metamorphosis complete (=a small part
of our Neuroptera).

10. Mecaptera. Wings long and narrow (fora small part of our Neuroptera;
the Panorpatae of Brauer).

11. Trichoptera. Wings not net-veined (=our division of Newroptera with
the same name). .

12. Coleoptera. Fore wings sheathing the hinder ones (= our Coleoptera).

13. Stphonaptera. Wingless, parasitic. Flea (=a division of Diptera).

14, Diptera. One pair of wings (=our Dvzptera after subtraction of
Siphonaptera).

15. Lepidoptera, Four wings (and body) scaled (= our Lepidoptera).

16, Hymenoptera. Four clear wings; hinder pair small; a tongue (=our
Hymenoptera). . |

Se te on 6 ee

Although this system of the Orders of Insects has some
valuable features it 1s open to very serious objections, to which we
can only briefly allude. The Order Hemiptera with its extensive —
divisions, Heteroptera, Homoptera, Coccidae, and Anoplura exhibit- _
ing great differences in structure and considerable divergence in
metamorphosis, is treated as only equivalent to the little group
Panorpatae (scorpion-flies); these latter being considered a dis-
tinct order, although they are not very different in structure or
metamorphosis from the Orders he calls Neuroptera and Trichop-
tera. The arrangement appears to be specially designed with
the view of making the Orders adopted in it fall into the two
groups Ametabola ‘anid Metabola. The propriety of such a
course is more than doubtful since very few of the Ametabola
are really without metamorphosis, in the wide sense of that term,
while the Metabola include Insects with various kinds of meta- .
morphosis. Indeed if we substitute for the term Ametabola the
more correct expression, “ Insects with little metamorphosis,” and
for Metabola the definition, “Insects with more metamorphosis
but of various kinds,” we then recognise that the arrangement

vI CLASSIFICATION - 175

is, like all others, a quite artificial one, while it is of little
value, owing to the development of so few Insects being hitherto
fully ascertained.

Brauer’s Classification.

Professor Brauer has recently proposed * to adopt 17 Orders
or chief groups of Insects, arranging them as follows :—

I, APTERYGOGENEA (with one order).
1. Synaptera (= Aptera of our system).
IL PreryeocEenra (=all the other Insects of our arrangement).
2. Dermaptera (= Orthoptera, Fam. Forficulidae in our arrangement).
3. Ephemeridae (=a division of Neuroptera in our arrangenient).
4, Odonata (=a division of Neuroptera in our arrangement).
5. Plecoptera (= Neuroptera, Fam. Perlidae in our arrangement).
6. Orthoptera (= our Orthoptera — Forficulidae and + Embiidae).
7. Corrodentia (=the families Termitidae, Psocidae, and Mallophaga, of
our Neuroptera).
8. Thysanoptera (as with us).
9. Rhynchota (= Hemiptera with us).
10. Neuroptera (= the families Hemeroliide and Sialide of our Neuroptera),
11. Panorpatae (=the family Panorpidae of our Neuroptera).
12. Trichoptera (=the division Trichoptera of Neuroptera).
13. Lepidoptera (=as with us).
14. Diptera (= our Diptera — Aphaniptera).
15. Siphonaptera (= Aphaniptera, a division of Diptera with us).
16. Coleoptera (= Coleoptera).
17. Hymenoptera (as with us).

The chief characters on which Brauer bases his system are:
(1) The existence or absence of wings. (2) The condition of the
mouth, and whether it undergoes radical changes.in the ontogeny,
arriving thus at the categories Menognatha, Metagnatha, and
Menorhyncha, as we have mentioned on p. 161. (3) The meta-
morphosis; the grouping adopted being Ametabola, Hemimetabola,
Metabola. (4) The number of the Malpighian tubules ;
Oligonephria, Polynephria. (5) The nature of the wings, the
relative proportions of the thoracic segments, and some other
characters. |

Brauer’s treatise is accompanied by a valuable and in many
respects very sagacious consideration of the generalised char-
acters of the Insecta; as a classification based partly on general-
isations and partly on structures, it is, so far as the present

1 “Syst. Zool. Studien.” §.B. Ak. Wien, xci. 1885, Abth, I. p. 374.

176 CLASSIFICATION CHAP.

condition of our knowledge goes, a good one. But it is of
little value as a practical guide, and as a basis for theoretical
speculation it cannot be treated as of importance, because the
generalisations it makes use of are premature, owing to the small
proportion of the forms that have been examined. And even now
the groups adopted are known to be subject to many exceptions.

Thus it begins by a division of Insecta into. winged and
wingless; but the winged division is made to comprehend an
enormous number of wingless Insects, whole subdivisions of
Orders such as the Mallophaga being placed in the winged series,
although all are without wings. This first division is indeed
entirely theoretical; and if a classification on generalisations
were adopted, it would be more natural to begin with the old
division into Homomorpha and Heteromorpha, and treat the
Order Aptera as the first division of the Homomorpha, while the
Heteromorpha would commence with the Ephemeridae and Odonata,
in which, though the individual in the early part of the ontogeny
is very different from the perfect Insect, there is no marked
division of the later larval and the pupal stages. Brauer’s system
is also defective inasmuch as it takes no account of the embryo-
logical or oogenetic processes, though these are of equal import-
ance with the later phases of the Ontogeny, Even as regards the
division into Orders, it is far from being free from reproach ; for
instance, the separation of the Dermaptera from the Orthoptera,
while Rhynchota remains intact, although including a more
extensive series of heterogeneous forms; the division of the-
Neuroptera into widely separated groups, each of which is treated
as equivalent to the great Orders, such as Coleoptera (in which
Strepsiptera are included), Hymenoptera, and Diptera, is not
reasonable, The association of Mallophaga and Termitidae, while
Dermaptera are separated from Orthoptera, is also undeniably
arbitrary, and other similar disparities are to be seen on
scrutinising the details of the system. 7

On comparing the three arrangements we have outlined, it
will be seen that the chief discrepancies they present come
under two heads: (1) The treatment of the Neuroptera, opinions
differing as to whether these Insects shall be grouped as a single
Order, or shall be divided into numerous Orders; and as to what,
if this latter course be adopted, the divisions shall be. (2) The
treatment of the parasitic groups Mallophaga, Aphaniptera, ete.

VI CLASSIFICATION 177

It must be admitted that whichever of the three systems we
have sketched be adopted, the result is, as regards both these
points, open to criticism. The Order Neuroptera, if we take it
in the broad sense, differs from the other Orders in the greater
variety of metamorphosis exhibited by its members; while if, on
the contrary, it be dismembered, we get a number of groups
of very unequal extent and not distinguished from one another
by the same decisive and important characters as are the other
Orders of which they are considered equivalent. The discrepancy
exists in nature, and can scarcely be evaded by any system. <A
similar observation may be made as to the parasitic groups,
viz. Mallophaga, Anoplura, Aphaniptera, and Strepsiptera. If
these be treated as separate Orders the result is not satisfactory ;
while, if they be associated with the larger groups to which they
are respectively nearest allied, it is almost equally unsatisfactory.

We may mention that Packard and Brauer have in their
treatises discussed the question of super-orders, and have gone so
far as to propose names for them. These two authorities do not
however agree in their conclusions ; and as the names proposed are
of little practical value, and are but rarely met with, we need not
explain them or discuss the comparative merits of the two systems.

The divisions of inferior value to the Order are, after. repeated
scrutiny by many naturalists, becoming of a more satisfactory
character, and notwithstanding various anomalies, may be, many
of them, considered fairly natural.’ Unfortunately entomologists
have not been able to agree on a system of terminology, so that
for these subdivisions terms such as sub-order, series, legion,
section, tribe, ete., are used by different authorities in ways
so various as to cause much confusion. In the following pages
the terms sub-order and series will be used in a somewhat vague
manner, the term sub-order being preferred where the group
appears to be an important one and of a fairly natural character,
while the word series will be adopted when the groups are con-
nected in a conventional manner. The designation “family ”
will be used for groups of subordinate importance ; and as regards
this term we may remark that systematic entomologists are
making genuine efforts to define the “ families ” in an accurate and
comprehensible manner. The endeavour to make these systematic

1 The term natural is here employed in the empirical sense described by Brunner
von Wattenwyl, Nowv. Syst. Blattaires, 1865, p. vii.
VOL, V N

178 _ INSECTS CHAP,

families dependent throughout the Class Insecta on characters of
similar morphological value has, however, scareely been entered
on, and it is perhaps not desirable, seeing how very small a
portion of the Insects of the world have been critically examined,
that much effort should be yet expended on an attempt of
the kind. It must be admitted that the species of Insects should
be obtained before they can be satisfactorily classified, and it is
estimated * that at least nine-tenths of the Insects of the world
are still unknown to entomologists.

Geological Record.—Although Insects have a very long
pedigree, it is as yet a very imperfect one. The remains of
creatures that can be referred to the Class Insecta have been
found, it is said, in Silurian strata; only one or two of these
very early forms are at present known, and the information
about them is by no means satisfactory; if Insects at all—as
to which some doubt exists—they apparently belong to very
different forms, though, like all the earliest fossil Insects, they
are winged. In the strata of the Carboniferous epoch numerous
Insects have been detected, in both Europe and North America.
These earlier Insects are by Scudder called Palaeodictyoptera,
and separated from the Insects around us on the ground that
he considers there existed amongst these palaeozoic Insects no
ordinal distinctions such as obtain in the existing forms, but
that the primeval creatures formed a single group of generalised
Hexapods. Brauer does not accept this view, considering that —
the earlier Insects can be referred to families existing at the
present time and forming parts of the Orthoptera, Neuroptera,
and Hemiptera. The discrepancy between these two authorities
depends to a great extent on the different classifications of existing
Insects that they start from; Scudder treating the wings as of
primary importance, while Brauer assigns to them only a
subordinate value. From the point of view taken in the present
work Scudder’s view appears to be. in the main correct, though
his expression as to the primary fossil Insects forming a single
homogeneous group is erroneous. The Neuroptera, still in exist-
ence, certainly form a heterogeneous group, and it is clear that
the Palaeozoic fossils represent a more diverse assemblage than
the present Neuroptera do,’

' Lord Walsingham, Proc. Ent. Soc. London, 1889, p. lxxx.
2 We may mention that fossil Insects are chiefly determined from their wing-

VI PALAEONTOLOGY 179

In the more recent rocks Insect remains become compara-
tively numerous, and in Mesozoic strata forms that can satisfac-

torily be referred to existing Orders are found, the Palaeodicty-

optera of Goldenberg and Scudder having mostly disappeared ;
the Blattidae or cockroaches do not apparently present any great
discontinuity between their Palaeozoic and Mesozoic forms. The
Tertiary rocks afford us fairly satisfactory evidence to the effect
that Insects were then more numerous in species than they
are at the present day. At Florissant in Colorado the bed
of an ancient lake has been discovered, and vast quantities of
Insect remains have been found in it, the geographical conditions
indicating that the creatures were not brought from a distance,
but were the natural fauna of the locality; and if so we can
only conclude that Insects must have been then more abundant
in species than they are now.

‘Scudder has informed us‘ that not only were Insects abundant
in the Tertiaries, but that their remains indicate conditions of
existence very similar to what we find around us. “Certain
peculiarities of secondary sexual dimorphism accompanying
special forms of communistic life, such as the neuters and workers
in Hymenoptera and the soldiers among the Termitina, are also
found, as would be expected, among the fossils, at least through
the whole series of the Tertiaries)s The same may be said of
other sexual characteristics, such as the stridulating organs of the
Orthoptera, and of peculiarities of oviposition, as seen in the

huge egg-capsules of an extinct Sialid of the early Tertiaries.
The viviparity of the ancient Aphides is suggested, according to

Buckton, by the appearance of one of the specimens from the
Oligocene of Florissant, while some of the more extraordinary
forms of parasitism are indicated at a time equally remote by the
occurrence in amber of the triungulin larva of JJeloe, already
alluded to, and of a characteristic strepsipterous Insect; not only,
too, are the present tribes of gall-making Insects abundant in the
Tertiaries, but their galls as well have been found.”

remains, which are often surprisingly perfect. This is one of the reasons that have
induced us to prefer a classification of Insects in which the nature of the wings is
considered of great value. It would be impossible to refer fossil Insects to groups
that are established on account of the metamorphosis or of the internal structure of
their components, for there is not yet any evidence on cither of these points in the
fossil remains preserved for us by the rocks.

1 Bull. U.S. Geol. Survey, No. 31, 1886, p. 109.

CHAPTER VII

THE ORDER APTERA —— DEFINITION — CHIEF CHARACTERISTICS —
THYSANURA — CAMPODEA—-JAPYX — MACHILIS —- LEPISMA —
DIVERSITY OF INTERNAL STRUCTURE IN THYSANURA—ECTO-
TROPHI AND ENTOTROPHI — COLLEMBOLA — LIPURIDAE —
PODURIDAE——-SMYNTHURIDAE—-THE SPRING THE VENTRAL
TUBE——ABDOMINAL APPENDAGES——PROSTEMMATIC ORGAN—
TRACHEAL SYSTEM ANURIDA MARITIMA——COLLEMBOLA ON
SNOW—LIFE-HISTORIES OF COLLEMBOLA——-FOSSIL APTERA—
APTERYGOGENEA——ANTIQUITY AND DISTRIBUTION OF CAMPODEA.

Order I. Aptera.

Small Insects with weak outer skin, destitute throughout life of
wings or their rudiments, but with three pairs of legs; an-
tennae large or moderate in size.

THE above definition is the only one that can at present be
framed to apply to all the Insects included in our Aptera.
Unfortunately it is far from diagnostic, for it does not enable
us to distinguish the Aptera from the larvae or young indi-
viduals of many Insects of other Orders. There are, however,
certain characters existing in many species of Aptera that enable
their possessors to be recognised with ease, though, as they are
quite wanting in other members, they cannot correctly be in-
cluded in a definition applying to the whole of the Order.

We are thus brought in view of two of the most important
generalisations connected with the Aptera, viz. that these Insects

in their external form remain throughout their life in a condition .

resembling the larval state of other Insects, and that they never-~
theless exhibit extreme variety in structural characters.
The more important of the special characters alluded to above

eHar. VII APTERA 181

as being possessed by some but not by all members of the Order
are (1) a remarkable leaping apparatus, consisting of two
elongate processes at the under side of the termination of the
body ; (2) a peculiar ventral tube, usually seen in the condition
of a papilla with invaginated summit, and placed on the first
abdominal segment (see Fig. 100, p. 194); (3) the scales cover-
ing the body ; (4) the existence of abdominal appendages in the
form of long cerci or processes at the termination of the body, or
of short processes on the sides of the under surface of the abdominal
segments.

Throughout the Order the general shape approximates to
that of a larva; this is shown by the diagrammatic section of
the body of Machilis

(Fig. 90). There isa ee es
succession of rings

differing little from es Hike:
one another, except i

so far as the head is _ Fic. 90.—Section of body of Machilis : 0, ovipositor.
concerned; even the nates Serer

division of thorax from abdomen is but little evident, and
although in some of the forms the three thoracic segments may
differ considerably among themselves, yet they never assume the
consolidated form that they do to a greater or less extent in the
imago stage of the other Orders. Fig. 90 shows the larva-like
structure of the body, and also exhibits the inequalities in size
between some of the dorsal and the corresponding ventral plates.
This phenomenon is here displayed only to a small extent, so
that the true relations of ‘the dorsal and ventral plates can be
readily detected; but in the higher Insects want of correspond-
ence of this fend may be much more extensive.

The respiratory system is in many of these Insects very
inferior in development, and may even be, so far as tracheae and
spiracles are concerned, entirely absent, but in other members of
the Aptera it is well developed. In the other internal organs
there is also great variety, as there is in the external structure.

A brief explanation as to the term Aptera, which we have
adopted as the name of this Order, is necessary. This name was
used by Linnaeus for our Insects, but as he associated with them
various other heterogeneous forms which were afterwards
separated, his “ Aptera” became completely broken up and ceased

182 INSECTS CHAP.

to be recognised as an Order of Insects. The term was, how-
ever, revived by Haeckel and Balfour several years since, and.
applied quite properly to the Insects we have in view. . Subse-
quently Packard and Brauer, recognising the claims of these
Insects to an isolated position, proposed for them the names.
Synaptera and Apterygogenea, and Packard has also used the
term Cinura. There is, however, clearly an advantage in ~
retaining the termination “ptera” for each of the Orders of
Insects; and as the fact that “ Aptera” of Linnaeus included
many Insects is not a sufficient reason for refusing to apply the
term to a portion of the forms he used it for, we may, it is clear,
make use of the Linnaean name with propriety, it being explicitly
stated that the Order does not include by any means all the
apterous forms of Insects. )

The Order includes two sub-orders, viz. (1) Zhysanura, in
which the hind body (abdomen) is composed of ten segments, and
there is no ventral tube on its first segment; and (2) Collembola,
in which the hind body consists of not more than six segments,
the first of which is furnished beneath with a peculiar tube
or papilla.

Thysanura.

Our knowledge of this important sub-order has been re-
cently much increased by the works of Grassi‘ and Oudemans.’
Very little is known, however, of the extra-European forms,
there being great difficulties in the way of collecting and pre-
serving specimens of these Insects in such a way as to render
them available for study and accurate comparison.’ Grassi and
~ Rovelli* recognise four families among the few European species of
Thysanura, viz. Campodeidae, Japygidae, Machilidae, Lepismidae.
Campodeidae is perhaps limited to a single species, only one
having been satisfactorily established, though several descriptions
have been made of what are supposed to be other species.

‘This Insect (Campodea staphylinus) is,so far as external form
goes, well known, from its having been figured in many works
on natural history on account of its having been supposed to be

1 Mem. Acc. Lincei Roma (4), iv. 1888, p. 543, etc., and other preceding memoirs
mentioned therein.

2 Bydr. Dierkunde, xvi. 1888, pp. 147-227.

3 Natural Sicil, ix. 1889, pp. 25, ete.

vil THYSANURA | 183

the nearest living representative of a primitive or ancestral
Insect. The creature itself is but little known even to
entomologists, although it is one of the commonest of Insects
over a large part of Europe. It is numerous in the gardens
and fields «about London and Cambridge, and abounds in damp
decaying wood in the New Forest; if there be only one
species, it must possess an extraoediann capacity for adapting
itself to extremes of climate, as we have found it at midsummer
near the shores of the Mediterranean in company with the sub-
tropical white ants, and within a day or
two of the same time noticed it to be
abundant on the actual summit of Mount
Canigou, one of the higher Pyrenees,
where the conditions were almost arctic,
and it was nearly the only Insect to be
found. The species is said to exist also
in North America and in East India. It
is a fragile, soft Insect of white colour,
bending itself freely to either side like a
Myriapod; the legs are rather long, the
antennae are long and delicate, and the
two processes, or cerci, at the other ex-
tremity of the body are remarkably similar
to antennae. It has no eyes and shuns
the light, disappearing very quickly in the
earth after it has been exposed. If placed
in a glass tube it usually dies speedily,
and is so extremely delicate that it is
difficult to pick it up even with a camel’s
hair brush without breaking it; so that 4£& }
we may fear it to be almost hopeless to 5
get enough specimens from different parts py¢. 91, Campodea staphy-
of the world to learn what differences JUinus. (After Lubbock,
may exist amongst the individuals of this ated
so-called primitive Insect. Meinert, a very able entomologist,
considers that there is really more than one species of Campodea
Campodeidae as a family may be briefly defined as Thysanura
with the trophi buried in the head and with the body terminated
by antenna-like processes. We shall consider some of the ana-
tomical peculiarities of this interesting Insect after we have

184 : APTERA CHAP,

briefly reviewed some of the external characters of the other

Thysanura.

The second family (Japygidae) consists of one genus Japya, of —

which there are, no doubt, several different species in various
parts of the world, such having already been detected in tropical
Africa, in Malasia, and in Mexico, as well as in Madeira and
Europe. The commoner species of the latter continent, Japyx
solifugus, lives in moss or in shady places on the edges of woods.
It possesses a great resemblance to a newly-hatched earwig, and
the writer has found it in France under a stone in company with
a number of the tiny creatures it was so much like. This species
has been found as far north as Paris, but has not been met with

in Britain. ~The family Japygidae is, like the Campodeidae, —

entotrophous, and is distinguished by the body being terminated
behind by a pair of forceps instead of antennary organs. 3

The other two families of Thysanura, Machilidae and Lepis-
midae, are ectotrophous—that is, the parts of the mouth are not
buried in the head, but are arranged in the fashion usual in
mandibulate Insects.

Only one genus of Machilidae is known, but it is no doubt.

very numerous in species, and probably is distributed over
most of the globe. Machilis maritima is common in some
places on the coast of England. Another species (IZ polypoda)
occurs amongst dead leaves in the New Forest, and we have also
observed a species of the genus under the loose stones that

frequently form the tops of the “ dykes” or piled walls in Scotland.

In more southern Europe species of Machilis are commonly met

with on the perpendicular faces of very large stones or rocks, .

over which they glide with wonderful facility. The scales on
the bodies of these rock-inhabiting species form pretty patterns,
but are detached with such facility that it is almost impossible
to obtain specimens in satisfactory condition for examination.

In Machilidae the dorsal plates of the hind body are reflexed
to the under surface so as to form an imbrication covering the
sides of the ventral plates, and the eyes are largely developed ;
by which characters the family is distinguished from the
Lepismidae. The pair of large compound eyes (Fig. 92, O) is a
remarkable feature, being indeed unique in the Aptera. The
structures (0, 0’) that Oudemans considers to be simple eyes have,
in external appearance, a resemblance to the fenestrae of the

i i ntl =

Spica laconic

a
>

eernnenggea Maree har we 29 6

ae ;

VII THYSANURA 185

- Blattidae; Grassi states, however, that not only are they eyes,

but that they are of almost unique structure, being, in fact,
intermediate between simple and compound eyes.

The mode of development of the compound eyes of Machilis
is of considerable interest, but unfortunately very little is known
about it, even the period at which the eyes appear being uncertain.
Judging from analogy with the Orthoptera, we should suppose
them to be present when the Insect leaves the egg, and Oudemans
apparently considers this to be the case, but Bolivar states’ that

Fie. 92.—Head of Machilis mari-
tima (after Oudemans): A, base
of antenna; C, clypeus; /, ver-
tex; P, fold; O, eye; 0, 0’, sup-
posed simple eye; J/, mandible ;

m, maxilla; L, upper lip; 7, lower Fie. 93.—Lepisma cineta. (After
lip; 7, portion of maxillary palp ; Oudemans.) x4. (The line indi-
t, of labial palp. x 20. cates the natural length, )

in the early stages of Machilis the eyes are only simple eyes;
these being replaced by compound eyes in the later life. The
writer has observed very young individuals of, Machilis polypoda,
and found the eyes to be evidently compound.

The remaining family of Thysanura, the Lepismidae, is in
certain respects the most highly developed of the Order. The
covering of scales found on the body is very remarkable in some
of the species, especially in the genus Lepisma (Fig. 93, J.
cincta); the thoracic segments are different from one another

1 Ann. Soc. ent. France, 1892, p. 34.

186 APTERA © s OHAP.

and from those of the abdomen, and the tracheal system is more
highly developed than it is in the Machilidae. Several genera
are known, but only two members of the family have yet been
detected in Britain. One of them (Lepisma saccharina), occurs
only in houses, and is sometimes called the silver fish; it is,
when full grown, less than half an inch long, and is covered with
scales that give it a feebly metallic lustre. Like the other
Thysanura, its movements are very perfect. It is said that it is
occasionally injurious by nibbling paper, but the writer’s observa-
tions lead him to doubt this; its usual food is doubtless farin-
aceous or saccharine matter. Zhermobia furnorum, our other
British Lepismid, has only recently been discovered ; it is found
in bakehouses at Cambridge and elsewhere. The bakers call
these Insects fire-brats, apparently considering them to be fond
of heat. |
Much valuable information as to the anatomy of Thysanura
has been obtained by Grassi and Oudemans, and is of great
interest. Taking four genera, viz. Campodea, Japyx, Machilis,
and Lepisma, to represent the four families constituting the
sub-order, we will briefly enumerate some of the more remarkable
of the characters of their internal anatomy. Campodea has a
very inferior development of the tracheal system; there are three
pairs of spiracles, which are situate on the thoracic region;

the tracheae connected with each spiracle remain distinct,

not uniting with those coming from another spiracle; there are
thus six separate small tracheal systems, three on each side
of the body. Japyx solifugus has eleven pairs of spiracles, of
which four are thoracic; the tracheae are united into one system
on each side by means of lateral tubes; thus there are two
extensive tracheal systems situate one on each side of the body,
there being a single transverse tube, placed near the posterior
extremity, uniting the two lateral systems. In Machalis there
are nine pairs of stigmata, two of them thoracic, seven abdominal ;
the tracheae from each spiracle remain unconnected, so that there
are eighteen separate tracheal systems, some of which are con-
siderably more developed than others. The Lepismidae have
ten pairs of stigmata, and the tracheae connected with them are
completely united into one system by longitudinal and transverse
tubes. Besides these differences there are others, of considerable
importance, in the position of the stigmata.

THYSANURA 187

_ All the Thysanura possess salivary glands. In Campodea

there are about sixteen extremely short Malpighian tubules, or
1 ) Sena glands representing these organs; Japyxz is destitute
' these structures; Machilis maritima has twenty elongate
tubu es; 1n Pee also they are long, and apparently vary in
mber from four to eight in different species. The propor-
tions of the three divisions of the alimentary canal differ’
extremely ; there is a very large proventriculus in Lepisma, but
ot ot in the other families; coecal diverticula are present on the
me rior part of the true Honiadh in Machilis and in Lepisma,
- j are wanting in Campodea and in Japyz.
The dorsal vessel seems not to present any great differences
n the sub-order. Grassi says there are no alary muscles present,
ie Oudemans describes them as existing in Machilis, but as
sing excessively delicate.
i The ventral chain of nerve-ganglia consists in Campodea of
: ne cephalic ganglion, one sub-oesophageal (which clearly
belongs to the ventral series of ganglia), three thoracic, and
seven abdominal. In the other families there are eight instead
of seven abdominal ganglia.
ag structure of the internal sexual organs is very remark-
able in the Thysanura. In Campodea there is one extremely
a ze, Simple tube on each side of the body. In Japys there are
‘seven small tubes on each side, placed one in each of the suc-
cessive abdominal segments, and opening into a common duct.
; _ Machilis there are also seven tubes opening into a common
luct, but the arrangement is no longer a distinctly segmental one.
in Lepisma there are five egg-tubes on each side, the arrange-
aent being segmental in the young state but not in the adult
condition. In Campodea nutrient cells alternate with the eggs
n the tubes, but this is not the case in the other families,
Fi ig. 94 shows the ovaries in three of the Thysanura ; in the draw-
ing representing this part in Machilis (C), one of the two ovaries
is cut away for the sake of clearness.
The male organs in Campodea are very similar in size and
oo to the ovaries, there being a single large tube
n° * 8aC and a short vas deferens on each side of the body. In
yx there is a sac on each side, but it is rendered double by
, coeeum at its base, and there are long and tortuous vasa
entia. In ZLepisma there are three pairs of coeca on each

188 THYSANURA ALS CHAP.

side, segmentally placed and opening into a common duct.
In Machilis there are three retort-shaped sacs on each side open-
ing near one another into a common duct, the vasa deferentia
are elongate, and are very curiously formed, being each double
for a considerable length, and the separated portions connected
at intervals by five transverse commissural ducts.

One of the characteristic features of Insect structure is the —
restriction of articulated legs to the thoracic region. In the

Thysanura there exist ap-

pendages occupying a posi-

tion on the hind body some-

what similar to that of the

legs on the thorax. These

appendages are quite small

bodies, and are placed at the

C hind margins of the ventral

| plates of the abdomen, one

near each side; they are con-

nected by a simple joint to

the sternite and are provided

with muscles. They are

found in Campodea on seg-

ments 2 to 7; in Lepisma

| on 8 and 9, in the allied
Fic. 94.—Ovaries of Thysanura: A, of Cam- Nicoletia on 2 to 9; in Japyx

podea } B, of Jupyx ; C,of Machilis. (After on. dete 7, being, how- —

Grassi and Oudemans. ) ;

ever, more rudimentary than
they are in Campodea. In Machilis they attain perhaps their
greatest development and exist on segments 2 to 9; more-
over, in this genus such appendages occur also on the coxae of
the second and third pairs of thoracic legs. Oudemans thinks
they help to support the abdomen, and that they also assist
in leaping; Grassi considers that they are supporting agents to
some extent, but that they are essentially tactile organs. He
calls them false legs “ Pseudozampe.”

Still more ‘omarion and obscure in function are the vesicles
found near the appendages; we figure a pair after Oudemans,
showing them in the exserted state. In the retracted state the
outer portion of the vesicles is withdrawn into the basal part P
(Fig. 95), so that the vesicles are then only just visible, being

vir | APTERA 189

concealed by the ventral plate. The abdominal appendage is not
retractile. In Machilis there are twenty-two of these vesicles,
arranged either two or four on one ventral plate of the hind
body. They are also present in Campodea, where there are six
pairs. They are usually said to be absent in Japyx and in
Lepisma, but Haase shows' that Japya possess a pair placed
behind the second ventral plate of the abdomen. The vesicles
appear to be exserted by the entrance of blood into them, and to
be retracted by muscular agency. Much difference of opinion
prevails as to their function; it appears probable that they may
be respiratory, as suggested by Oudemans.

The scales found on the bodies of the Ectotrophous Thysanura
may be looked on as modified hairs, and are essentially similar to
those of the Lepidoptera, and they drop off
as readily as do those of the Lepidoptera.

Stummer-Trauntels, who has recently
published * the results of his researches on
the mouth-organs of Thysanura and Col-
lembola, confirms the division of the
Thysanura into Entotrophi and Ectotrophi,
and considers that the Collembola agree
with the former group. The German
author therefore proposes to divide our
Aptera, not into Thysanura and Collembola, gr Aion aaa aa
but into Ectognathi and Entognathi, the cles of Machilis. A,
former group consisting of Machilidae and sion te ig ae
Lepismidae, the latter of Campodeidae, tion; &, muscles. x70.
Japygidae and the various families of
Collembola. We think it far more natural, however, to retain
the older division into Thysanura and Collembola.

Collembola.

The sub-order Collembola, which we have defined on p. 182,
consists of small Insects, many of which possess the capacity of
leaping, or springing suddenly, and when disturbed or alarmed
naturally make use of this means of escaping. Their leaps, how-
ever, appear to be made quite at random, and very frequently do

* Morph. Jahrb. xv. 1889, p. 363. 2 SB. Ak. Wien, c. 1891, Abth. I. p. 216.

190 COLLEMBOLA . CHAP.

not have the result of taking the creature into concealment, and
in such circumstances they may be rapidly and frequently
repeated until the Insect feels itself, as we may suppose, in a
position of safety. Three families may be very readily. dis-
tinguished, viz. (1) Lipuridae, in which no leaping apparatus is

present; (2) Poduridae, a leaping apparatus exists near the ex- —

tremity of the abdomen; the body is subcylindric and evidently
segmented; (3) Smynthuridae, a leaping apparatus exists: the ~
body is sub-globular with comparatively large head and abdomen,
the intervening thoracic region being small; the segmentation of
the body is obscure.

The study of the Collembola is much less advanced than that
of the Thysanura, comparatively little having been added to our
knowledge of the group since Lubbock’s monograph of the
British forms was published by the Ray Society in 1873. Why
the Collembola should be neglected when the Thysanura attract
so much attention is as inexplicable as many other fashions are.

The family Lipuridae consists of a few very small and obscure
Insects of soft consistence. They move slowly, and, owing to the
absence of any leaping power, attract atten-
tion less readily than the other Collembola
do. ‘Two genera are generally recognised,
and they should probably form separate
families ; indeed, in Lubbock’s arrangement
they do so. In one of the genera (Anoura)
the mouth is very imperfect, no mandibles
or maxillae having been detected, while in
the other genus (Lipura) these organs exist.

In the members of the family Poduridae,
including the Degeeriidae of Lubbock, a
saltatory apparatus is present in the form
of avpendages attached to the fifth abdomi-
nal segment (Degeeriides), or to the fourth
Fic, 96.—Lipura bur- (Podurides). These appendages are during

eerie i. (After Lub- Jife flexed beneath the body, but in dead

specimens usually project backwards, having
the appearance of a bifid tail. Poduridae are of elongate form,
somewhat like small caterpillars, and are frequently prettily
marked with variegate colours. Fig. 97 represents an arctic form
closely allied to our native genus Jsotoma.

vit SPRING-TAILS IgI

The peculiar shape of the members of the Smynthuridae is
sufficient for their identification. They possess a very convex
abdomen, and very near to it
a large head, the intervening
chink being occupied by the
small thorax. The segmenta-
tion of the body is not easily
distinguished. Nicolet states
that the thorax consists of
three segments and the abdo-
men of the same number, and
that when the Insect emerges Fic. 97.—Corynothrix borealis: a, ventral
Peer the ege Me, divisions tube ; 6, the spring. (After Tullberg.)
can be perceived. In after life the posterior part of the thorax
becomes amalgamated with the abdomen, so that it is difficult to
trace the divisions, but there appears to be no information as to

- the manner in which this change occurs.
Some of these minute Insects frequent
trees and bushes, and their leaping powers
are very perfect, so that it is difficult to
capture them. The family includes both
the Smynthuridae and the Papiriidae of
Lubbock.

The two most characteristic organs of
the Collembola are the spring and the
ventral tube. The first of these is an
elongate structure attached to the under-
side of the abdomen near its extremity,
either on the penultimate or ante-penulti-
mate segment. It consists of a_ basal
part, and of two appendages attached
thereto. It is carried under the Insect
bent forwards, and is retained in this
position by means of a catch which pro-
jects from the under surface of the third
Fig. 98.—Smynthurus varie. Segment of the body, descending between

Oe, ation Tabs a) the two branches of the spring, and pass-

ing under the extremity of its basal seg-
ment. It is considered that the spring is elastic, is flexed under
the body by muscular action, and, being retained in this position

192 SPRING-TAILS CHAP,

of restraint by the catch, when the latter is removed the spring
extends by reason of its elasticity, and the leap is thus executed.
Whether this is really the exact method of leaping is, however,
doubtful, for Lubbock says that the catch “only exists in certain
genera”; while in its structure it does not appear to be well
calculated to retain in position an organ that by virtue of its
elasticity is constantly exerting a considerable force.

The ventral tube is an anomalous and enigmatic structure.
In the lower forms, such as Lipura or Anurida, it consists merely
of a papilla (Fig. 100, A, a) more or less divided by fissure into two
parts. In the Smynthuridae it is more highly developed, and
protects two long delicate tubes that are capable of being
protruded, as shown in the outline profile of Smynthurus fuscus
(Fig. 99), which is taken from specimens preserved in balsam by
Mr. J. J. Lister, The nature and use
of this ventral tube have given rise to
much discussion. Lubbock considered,
and others have agreed with him, that
it serves to attach the Insect to bodies
to which it may be desirable the Insect
should, when in the perpendicular posi-
tion, adhere. Reuter’ assigns a quite
different function to this singular struc-
Fic. 99.—Smynthurus fuscus, ture, He states that the hairs of the

with exsertile vesicle (a) pro- ;

truded from ventral tube; body are hygroscopic, and that the

0; the eprinp ogre a ces. peculiar claws of the Insect having
collected the moisture from the hairs, the ventral tube becomes
the means of introducing the liquid into the body. These Insects
possess, however, a mouth, and there seems to be no reason why
a complex apparatus should be required in addition to it for so
simple a purpose as the introduction of moisture to the interior of
the body. Haase finds? that Collembola can crawl on glass
without the aid of the ventral tube; he considers its function
to be physiological, and that it may probably be respiratory as it
has been suggested is the case with the vesicles of Thysanura.
The function of the ventral tube is certainly not yet satisfac-
torily elucidated. The vesicles contained in it are said to be
extruded by blood-pressure, and withdrawn by muscular action
in a manner similar to that which we have described as occurring

1 Ent. Tidskr. i. 1880, p. 159. 2 Morphol. Jahrb. xv. 1888, p. 361.

» Se sees s

VII APTERA 193

in the case of the exsertile vesicles of the Thysanura. The pro-

cesses in Smynthurus bear glandular structures at their ex-

tremities. It has been suggested that the ventral tube of Collem-
bola is the homologue of a pair of ventral appendages. The term

Collophore has been applied to it somewhat prematurely, seeing

the doubt that still exists as to its function.

‘Some of the Collembola possess a very curious structure
called the prostemmatic or ante-ocular organ; its nature and
function have been very inadequately investigated. The ocular
organs of the Collembola consist, when they are present, of

isolated ocelli placed at the sides of the head like the corre-

sponding organs of caterpillars; the prostemmate is placed
slightly in front of the group of ocelli, and has a concentric
arrangement of its parts, reminding one somewhat of the com-
pound eyes of the higher Insects. This structure is represented
in Fig. 100, B, C; it is said by Sir John Lubbock to be present
in some of the Lipuridae that have no ocelli, and he therefore
prefers to speak of it as the “ post-antennal ” organ. .

A very characteristic feature in the Collembola is the slight

development of the tracheal system. Although writers are far

from being in accord as to details, it seems that stigmata and
tracheae are usually absent. In Smynthurus there are, however,
according to Lubbock,—whose statement is confirmed by Meinert
and Tullberg,—a pair of stigmata situate on the head below the
antennae, and from these there extends a tracheal system through-
out the body. Such a position for stigmata is almost, if not
quite unique in Insects; Grassi, however, seems to have found
something of the kind existing in the embryo of the bee.

At present only a small number of species of the Order -
Aptera are known; Lubbock recognised about sixty British
species, and Finot sixty-five as found in France. The North
American forms’ have not received so much attention as the
European, and the Aptera of other countries, though they are
probably everywhere fairly numerous, are scarcely known at all. A
few have been described from the Indo-Malayan region and some
from Chili, and the writer has seen species from the West Indian
and Sandwich Islands. All the exotic forms as yet detected are
very similar to those of Europe.

The Thysanura are probably not very numerous in species, and
appear to be in general intolerant of cold. With the Collembola

VOL. V 0

194 APTERA CHAP.

the reverse is the case. They are excessively numerous in
individuals; they are found nearly everywhere on the surface of
the ground in climatic conditions like those of our country,
while no less than sixteen species have been found in Nova
Zembla and one each in Kerguelen and South Georgia. One
_ species, if not more, of Podura, lives on the surface of stagnant
waters, on which the minute creatures may frequently be seen
leaping about in great numbers after being disturbed.

In 1874 the plain of Gennevilliers in France was copiously

irrigated ; in the following year the soil was still very damp, and
there existed numerous pools of stagnant water, on the surface
of which Podura aquatica was developed in such prodigious
quantity as to excite the astonishment of the inhabitants of the
region. :
Accounts have been frequently given of the occurrence on
snow and glaciers of Insects spoken of as snow-fleas, or snow-
worms. These mostly relate to Poduridae, which are sometimes
found in countless number in such situations. The reason for
this is not well understood. According to F. Léw,' on the 17th
of March at St. Jacob in Carinthia, Parson Kaiser observed, on
the occurrence of the first thaw-weather, enormous numbers of a
‘Podura (? Achorutes murorum) on the surface of the snow for an
extent of about half a mile, the snow being rendered black in
appearance by them; eleven days afterwards they were found in
diminished numbers on the snow, but in large quantity on the |
water left by its melting. This account suggests that the
occurrence of the Insects on the snow was merely an incident
during their passage from the land, where they had been
hibernating, to the surface of the water.

One little member of the Lipuridae, Anurida maritima -
(Lipura maritima of Lubbock), has the habit, very unusual for an
Insect, of frequenting salt water. It lives amongst the rocks on —
the shores of the English Channel, between high and low tide-
marks. Its habits have been to some extent observed by
Laboulbéne ? and Moniez*; it appears to be gregarious, and when
the tide is high, to shelter itself against the commotions of the
water in chinks of the rocks and other positions of advan-
tage. When the tide is out the Insects apparently delight to

1 Verh. zool.-bot. Ges. Wien, viii. 1858, p. 564.
2 Ann. Soc. ent. France, 4th ser. iv. 1864, p. 705.
3 Rev. biol. Nord France, ii. 1890, p. 347.

/

@
fh
=
3 a
:

ot ea an Pee og Poet

completely covered with a coat

- touch it. The little creature

vie | APTERA 195

congregate in masses on the surface of the rock pools. This
Anurida can endure prolonged immersion; but both the ob-
servers we are quoting say that it is, when submerged, usually

of air so that the water does not

can, however, it would appear,
subsist for some time in the
pools of salt water, even when
it is not surrounded by its
customary protecting envelope
of the more congenial element.
Its food is said, on very slender
evidence, to consist of the re-

mains of small marine animals, 7,100, Anwida maritima: &, under
such as Molluscs. We repro- prostemmatic organ of young; C, of

duce some of Laboulbéne’s adult. (After Laboulbeéne, )

figures (Fig. 100); the under-surface shows at a the divided pap-
illa of the ventral tube ; B, C represent the peculiar prostemmatic

_ organ, alluded to on p. 193, in its mature and immature states.

Very little information exists as to the life-history of the
Aptera ; as for their food, it is generally considered to consist of
refuse vegetable or animal matter. It is usual to say that they
are completely destitute of metamorphosis, but Tenpleton says of
Lepisma niveo-fasciata that “the young differ so much from the
mature Insect that I took them at first for a distinct species; the
thoracic plates are proportionately less broad, and the first is
devoid of the white marginal band.” As regards the moults, it
would appear that in this, as in so many other points, great
diversity prevails, Grassi stating that in Campodea there is a
single fragmentary casting of the skin; and Sommer informing us
that in Macrotoma plumbea the moults are not only numerous,
but continue, after the creature has attained its full growth,
throughout life. |

A very marked feature of the Aptera is their intolerance of a
dry atmosphere. Although Campodea can exist under very
diverse conditions, it dies very soon after being placed in a dry
closed tube; and the same susceptibility appears to be shared by
all the other members of the Order, though it is not so extreme
in all; possibly it may be due to some peculiarity in the structure

196 APTERA CHAT.

of the integument. So far as tolerance of heat and cold goes,
the Aptera can apparently exist in. any climate, for though some
of the species extend to the Arctic regions, others are peculiar to
the tropics. |

Thysanura are recorded by Klebs and Scudder as occurring
commonly in amber; the latter author has described a fossil,
supposed to be a Lepisma, found in the Tertiary deposits at
Florissant. Scudder has also described another fossil, hkewise
from Florissant, which he considers to form a special sub-order of
Thysanura—Ballostoma—but it is extremely doubtful whether
this anomalous creature should be assigned to the Order at all. A
still older fossil, Dasyleptus lucasii. Brongniart, from the Carbon-
iferous strata in France, is considered to belong to the Order
Aptera, but it must be admitted there is some doubt on this
point.

The interest aroused in the minds of naturalists by the
comparatively simple forms of these purely wingless and therefore
anomalous Insects has been accompanied by much discussion as to
their relations to other Insects, and as to whether they are
really primitive forms, or whether they may perhaps be degenerate
descendants from some less unusual states of Insect-life. Mayer
and Brauer dissociated our Aptera entirely from other Insects,
and proposed to consider the Hexapoda as being composed of two
eroups—(1) the Apterygogenea, consisting of the few species we
have been specially considering ; and (2) the Pterygogenea, includ-
ing all the rest of the immense crowd of Insect forms. They
were not, however, able to accompany their proposed division by
any satisfactory characters of distinction, and the subsequent
‘progress of knowledge has not supported their view, all the best
investigators having found it necessary to recognise the extremely
intimate relations of these Insects with the Orthoptera. Meinert
thought that Lepisma must be included in the Orthoptera ; Grassi
proposes to consider the Thysanura as a distinct division of
Orthoptera ; and Oudemans recognises the close relations existing
between Machilis and Orthoptera proper. Finot includes the
Aptera in his Orthoptéres de la France, and a species of Japyx
has actually been described by a competent entomologist as an
apterous earwig. At present, therefore, we must conclude that
no good distinction has been found to justify the separation of .
“the Aptera from all other Insects.

VII APTERA 197

The taxonomy of the Collembola has not yet been adequately
treated, and it is possible that more grounds will be found
for separating them as a distinct Order from the Thysanura,—a
course that was advocated by Lubbock,—than exist for dividing
these latter from the Orthoptera proper. There are apparently no
grounds for considering the Aptera to be degenerate Insects, and we
may adopt the view of Grassi, that they are primitive, or rather
little evolved forms. It must be admitted that there are not at
‘present any sufficient reasons for considering these Insects to be
“ancient ” or “ancestral.” The vague general resemblance of Cam-
podea to many young Insects of very different kinds is clearly the
correlative of its simple form, and is no more proof of actual
‘ancestry to them than their resemblances inter se are proofs of
ancestry to one another. But even if deprived of its claim to
antiquity and to ancestral honours, it must be admitted that
Campodea is an interesting creature. In its structure one of the
most fragile of organisms, with a very feeble respiratory system,
inadequate organs of sense, only one pair of ovarian tubes, very
imperfect mouth-organs, and a simple alimentary canal, it
nevertheless flourishes while highly-endowed Insects become
extinct. In the suburban gardens of London, on the shores of —
the Mediterranean, on the summits of the higher Pyrenees, in
North America even it is said in the caves of Kentucky, and
in India, Campodea is at home, and will probably always be
with us.

CHAPTER VIII

ORTHOPTERA——-FORFICULIDAE, EARWIGS——HEMIMERIDAE

Order II.—Orthoptera.

Insects with the mouth parts conspicuous, formed for biting, the
Sour palpi very distinct, the lower lip longitudinally divided
in the middle. The tegmina (mesothoracie wings), of parch-
ment-like consistence, in repose closed on the back of the
Insect so as to protect it. The metathoracie wings, of more
delicate consistence, ample, furnished with radiating or
divergent nervures starting from the point of articulation,
and with short cross nervules forming a sort of network;
in repose collapsing like a fan, and more or less completely
covered by the tegmina (except in certain Phasmidae, where,
though the wings are ample, the tegmina are minute, so that
the wings are uncovered). Ina few forms (winged Forfi-
culidae and some Blattidae) the metathoracie wings are, in
addition to the longitudinal folding, contracted by means of
one or two transverse folds. ' The mode of growth of each
individual is a gradual increase of size, without any abrupt
change of form, except that the wings are only fully developed in
the final condition. There is no special pupal instar. Species
in which the wings are absent or rudimentary are numerous.

THE Orthoptera are Insects of comparatively large size. The
Order, indeed, includes the largest of existing Insects, while none |
are so minute as many of the members of the other Orders are ;
three millimetres is the least length known for an Orthopterous
Insect, and there are very few so small, though this is ten times
the length of the smallest beetle. The Order includes earwigs,
cockroaches, soothsayers or praying-insects, stick- and leaf-insects,
grasshoppers, locusts, green grasshoppers, and crickets.

CHAP. VIII ORTHOPTERA 199

The changes of form that accompany the growth of the
individual are much less abrupt and conspicuous than they are
in most other Insects. The metamorphosis is therefore called
Paurometabolous. It has been supposed by some naturalists that
Orthoptera go through a larger portion of their development in
the egg than other Insects do. This does not clearly appear -
to be the case, though. it seems that there are distinctions of a
general character in the embryology; the period of development
in the egg is prolonged, and the yolk is said by Wheeler? to be
more than usually abundant in comparison with the size of the
young embryo. The embryonic development may in tropical
countries be accomplished in three weeks (see Mantidae), but in
countries where winter supervenes, the period may in some
species be extended over seven or eight months.

The external features of the post-embryonic development—a
term that is more convenient in connexion with Orthoptera than
metamorphosis —are as follows: the wings are never present when
the Insect is first hatched, but appear subsequently, and increase
in size at the moults; the form and proportions of the segments
of the Bidy especially of the thorax—undergo much change ;
an alteration of colour occurs at some of the moults, and the
integument becomes harder in the adult condition. Neither
the development of the internal organs, nor the physiological pro-
cesses by which the changes of external form are effected, appear
to have been studied to any great extent.

Many of the Orthoptera do not possess wings fit for flight, and
some species even in the adult state have no trace whatever of such
organs. Flight, indeed, appears to be of minor importance in the
Order; in many cases where the wings exist they are purely musical
organs, and are not of any use for flight. The apterous and the
flightless conditions are not confined to one division of the Order,
but are found in all the families and in many of their sub-
divisions. As the front pair of wings in Orthoptera do not really
carry out the function of flight, and as they differ in several par-
ticulars from the hinder pair, or true wings, it is usual to call
them tegmina.. The musical powers of the Orthoptera are confined
to the saltatorial group of families. The Cursoria are dumb or
nearly so; it is a remarkable fact that also in this latter division
the alar organs, though frequently present, have but little value

1 J. Morphol. viii. 1893, p. 64.

200 . ORTHOPTERA CHAP.

for flight, and are in some cases devoted to what we may call
purposes of ornament or concealment. This is specially the case
in the Phasmidae and Mantidae, where the effectiveness of colour
and pattern of these parts becomes truly astonishing. The
tegmina frequently exhibit an extraordinary resemblance to
vegetable structures, and this appearance is not superficial, for it —
may be seen that the nervures of the wings in their disposition and
appearance resemble almost exactly the ribs of leaves. One of the
most remarkable of the features of Orthoptera is that a great
difference frequently exists between the colours of the tegmina
and of the wings, ze. the front and hind wings; the latter are
concealed in the condition of repose, but when activity is entered
on and they are displayed, the individual becomes in appearance
a totally different creature. In some cases, contrary to what
usually occurs in Insects, it is the female that is most remark-
able; the male in Mantidae and Phasmidae being frequently a
creature of quite inferior appearance and power in comparison
with his consort. The musical powers of the saltatorial
Orthoptera are, however, specially characteristic of the male sex.
There is evidence that these powers are of great importance to
the creatures, though in what way is far from clear. Some parts
of the structures of the body are in many of these musical species
clearly dominated by the musical organs, and are apparently
specially directed to
securing their effici-
ency. We find in some
Locustidae that the
tegmina are nothing
but sound - producing
instruments, while the
pronotum is prolonged

Fic. 101.—Poecilimon afinis 6. Bulgaria. Alar organs to form a hood that
serving only as musical organs. The ear on front protects them without

tibia and aural orifice of prothorax are well shown. ‘ °

encumbering their ac-
tion. In the males of the Pneumorides, where the phonetic organ
is situated on the abdomen, this part of the body is inflated and
tense, no doubt with the result of increasing the volume and quality
of the sound. In the genus Methone (Fig. 185) we find a grass-
hopper whose great hind legs have no saltatorial function, and but
little power of locomotion, but act as parts of a sound-producing

vil 7 THE FAMILIES , 201

instrument, and as agents for protecting some parts of the body
in repose. Further particulars of these cases must be looked for
in our accounts of the different groups.

The eggs of many Orthoptera are deposited in capsules or
cases; these capsules may contain only one egg, or a great many.

The Order includes many species of Insects, though in Britain
it is poorly represented: we have only about forty species, and
this small number includes some that are naturalised. Only a
few of the forty extend their range to Scotland. A revision of
the species found in Britain has recently been made by Mr.
Eland Shaw.’ In continental Europe, especially in the south,
the species become more numerous; about 500 are known as
inhabitants of geographical Europe. In countries where the face
of nature has been less transformed by the operations of man,
’ and especially in the tropical parts of the world, Orthoptera are.
much more abundant.

The lowest number at which the species now existing on the
surface of the earth can be estimated is 10,000. This, however,
is probably far under the mark, for the smaller and more obscure
species of Orthoptera have never been thoroughly collected in
any tropical continental region, while new forms of even the
largest size are still frequently discovered in the tropics.

We shall treat the Order as composed of eight families :—

1. Forficulidae—Tegmina short, wings complexly folded ; body

armed at the extremity with strong forceps.

Series, Cursoria ; |2. Hemimeridae—Apterous: head exserted, constricted behind.
hind legs but | 3. Blattidae—Coxae of the legs large, exserted, protecting
little different the lower part of the body.
from the others. | 4. Mantidae—Front legs very large, raptorial, armed with spines.

5. Phasmidae—Mesothorax ec as compared with the pro-

thorax.

Series, Saltatoria : | 6. Acridiidae—Antennae short, not setaceous, of not more than
hind legs elon- 30 joints, tarsi three-jointed.
gate, formed for } 7. Locustidae—Antennae very long, setaceous, composed of a
leaping, their large number of joints, tarsi four-jointed.
femora usually | g
thickened.

“I

. Gryllidae—Antennae very long, setaceous, tarsi two- or three-
jointed.

The first five of these subdivisions are amongst the. most
distinct of any that exist in the Insecta, there being no con-
necting links between them. The three groups forming the

1 Ent. Mo. Mag. xxv. 1889, and xxvi. 1890.

202 ORTHOPTERA CHAP.

Saltatoria are much more intimately allied, and should, taken
together, probably have only the same taxonomic value as any one
of the other five groups. |
Owing partly to the inherent difficulties of the subject, and

partly to the fragmentary manner in which it has been treated
by systematists, it has been impossible till recently to form any
clear idea of the classification of Orthoptera. During the last
twenty years Henri de Saussure and Brunner von Wattenwyl
have greatly elucidated this subject. The latter of these two
distinguished naturalists has recently published} a revision of the
system of Orthoptera, which will be of great assistance to those
who may wish to study these Insects. We therefore reproduce
from it the characters of the tribes, placing the portion relating
to each family at the end of our sketch thereof.

Fam. I. Forficulidae—Earwigs.

(DERMAPTERA OR DERMATOPTERA OF BRAUER AND OTHERS)

Insects of elongate form, with an imbricate arrangement of the
segments of the body; bearing at
the posterior extremity a pair of
callipers or more distorted instru-
ments. The hind wings (when
present) folded in a complea
manner, and covered, except at their
tips, by a pair of short wing-covers
(tegmina), of a leather-like consist-
ence. Wingless forms are very
numerous. The young is very
similar to the adult.

- Although earwigs are said to be
rare in most parts of the world, yet
| in Europe no Insect is better known

Fic. 102.—Pygidicrana hugeli. than Forficula auricularia, the common

qin earwig, it being very abundant even in
gardens and cultivated places. In certain seasons it not un-
frequently enters our houses, in which case it too often falls a _

1 Ann. Mus. Genova, xxxiii. (1892).

VIL EARWIGS 203

victim to prejudices that have very little to justify them. This
Insect is a good type of the winged earwigs. In the parts of
the mouth it exhibits the structures usual in the Orthoptera ;
there is a large labrum, a pair of maxillae, each provided with two
lobes and a palpus consisting of two very short basal joints and
three longer joints beyond these ; the mandibles are strong, with
curvate pointed extremities; in the lower lip there is a ligula
exposed in front of a very large mentum; it consists of two
pieces, not joined together along the middle, but each bearing on
its lateral edge a palpus with two elongate joints and a short
basal one; this lip is completed by the lingua, which reposes
on the upper face of the part, and completely overlaps and
protects the chink left by the want of union along the middle
line of the external parts of the lip. The antennae are elon-
gate, filiform, and are borne very near the front of the exserted
head. There are rather large facetted eyes, but no ocelli. The
three segments of the thorax are distinct, the prothorax being
quite free and capable of movement independent of the parts
behind it: the meso- and meta-nota are covered by the tegmina
and wings; these latter project slightly from underneath the
former in the shape of small slips, that are often of rather lighter
colour; the wing-covers are short, not extending beyond the
insertion of the hind legs, and repose flat on the back, meeting
together in a straight line along the middle. These peculiar
flat, abbreviated wing-covers, with small slips (which are portions
. of the folded wings) ‘projecting a little from underneath them,
are distinctive marks of the winged Forficulidae.

The legs are inserted far from one another, the coxae being
small; each sternum of the three thoracic segments projects
backwards, forming a peculiar long, free fold, underlapping the
front part of the following segment. The hind body or abdomen
is elongate, and is. formed of ten segments; the number readily
visible being two less in the female than it is in the male.
The segments are fitted together by a complex imbrication,
which admits of great mobility and distension, while offering a
remarkable power of resistance to external pressure: each
segment is inserted far forward in the interior of that preceding
it, and each also consists of separate upper and lower plates that
much overlap where they meet at the sides (see Fig. 103). The
body is always terminated by a pair of horny, pincer-like

204 ORTHOPTERA CHAP.

processes, which are differently shaped according to the sex of
the individual.

The structure of the abdomen in the earwig has given rise to
considerable discussion. In Fig. 103 we reproduce Westwood’s
diagram of it as seen fully distended
in a female specimen; in this state the -
minute spiracles can be detected, though
in the normal condition of the body
they cannot be seen, being placed on
the delicate membranes that connect
the chitinous plates. Westwood’s inter-
pretation of the structure was not, how-
ever, quite correct, as the part which .
he considered to be the first dorsal
plate is really the second; so that the
Frc. 103.—Lateral view of For. Segments numbered 7, 8, 9 in our

sie uenaad snomng’ Sure are really 8,9, 10. ‘The com

spiracles, S$, and the small Mon earwig 18 interesting as exhibit-

Sth and 9th dorsal plates ing in an imperfect state, the union

(7 and 8 in Fig.).

of the first dorsal plate of the abdo-
men with the thorax; a condition which is carried to so
great an extent in the Hymenoptera as to quite obscure the
nature of the parts, and which has consequently given rise to
much perplexity and discussion. We repre-
sent this structure as seen in the common
earwig in Fig. 104, where a represents the
pronotum, ) the mesonotum, ¢ the metanotum,
d the first, f the second abdominal segment ;
e being a delicate membrane of considerable
size that intervenes between the two, and
which is more exposed than are the corre-
sponding membranes connecting the subse- yy, 104,—Dorsal por-
quent rings ; a condition similar to that which tions of the middle
: ‘ ; segments of body of
is found in Cimbex, Cephus, and some other = Forficula auricul- -
Hymenoptera. — aria (tegmina and

wings removed).

On the under surface of the abdomen of the
earwig the full number of 10 plates cannot be superficially dis-
tinguished ; but it is found by dissection that in the female the
short eighth and ninth dorsal rings are joined on the ventral aspect
by a delicate membrane, while the tenth ventral is of a less delicate

VIII . WINGLESS EARWIGS 205

nature, and forms a triangular plate at the base of each half of
the forceps. Between the branches of the forceps there is a per-
pendicular plate, the pygidium of Orthopterists, possibly the
unpaired terminal portion of the body seen in some embryos, and -
called the telson. The pygidium is a separate sclerite, though
it looks as if it were only a portion of the large tenth dessa
plate bent downwards, and in some descriptive works is errone-
ously described as being such.

A very large number of species of Forficulidae have the
organs of flight undeveloped. Fig. 105 represents Chelidura
dilatata, an apterous form that is very com-
mon in the Eastern Pyrenees. The condition
of the meso- and meta-nota—the parts from
which the tegmina and wings are developed,
and to which they are attached when present
—is very remarkable in these forms, and
exhibits much variety. In Fig. 106 we
represent the conditions of these parts in
a few apterous forms. The tegmina or the
segment from which they are developed (0),
are seen in the shape of a plate which may
extend all across the middle and be undi-
vided (No. 4); in which case the appearance indicates entire
absence of the tegmina; these are, on the contrary, evidently present
in the form of slips grafted one to each side of the second thoracic
seoment in Anisolabis (No. 3); or they may look like. short
| broad slips extending all

pee - across the body, and mark-

i) 1 Janes ing off a piece frequently

c = calledascutellum, but which

£ Wo Le is really the mesonotum
a.

(some species of Chelidura,

Fic. 106. —Tegmina and wings cently in part or gg No, 2): ars again, they
invisible) of apterous earwigs. 1, Chelidura sp.;
2, Chelidura dilatata ; 3, Anisolabis moesta.; ae be nearly fr ee teg-

EAcgrerina, 4 Bist tomate ements?» anina, somewhat, similar to

"those of the winged forms ;

this is the case with some species of Chelidura, as represented

by No.1. This last figure is taken from a species from the
Sierra Nevada, apparently undescribed, allied to C. bolivari.

In the cases we are considering no analogous structures exist on

Fic. 105.—Chelidura
dilatata, male. Pyrenees.

206 ORTHOPTERA CHAP.

the metanotum (the part of the body that in the winged forms
bears the wings, and which is marked ¢ in our diagrams, Fig.
106), so that the tegmina are to all appearance less rudimentary ~
(or vestigial) than the wings. The metanotum forms a sort of
flap, called by Fischer? “involucrum alarum”; he considered
the part ‘immediately behind this to be the metanotum; this —
piece is, however, no doubt really part of the abdomen (d in our
Figure). This is apparently the view taken by Brunner.” The ~
structure of these parts is important as bearing on the subject
of the nature and origin of Insects’ wings, a question to which
no satisfactory answer has yet been given. The appearances
we have remarked on are to some extent similar to the con-
ditions existing in the immature state of the organs of flight in
the common earwig (see Fig. 112, p. 212), but whether the
varieties presented by the wingless forms have parallels in the
immature conditions of the various winged forms is quite
uncertain, the life-histories of earwigs being almost unknown.
The developed wings of earwigs are worthy of attention,
both as regards their actual structure and the manner in which
they are folded up in repose. When
expanded they have a shape curiously
suggestive of the human ear. The chief
parts of the wing, as shown in Fig. 107,
A, are a, b, two portions of the horny
piece that forms the scale which covers
the more delicate parts of the wing
when it is folded, and which, according
fia. 1b oes ee ee to Brunner, represents the radial and
auricularia, A, Wing ex- Ulnar fields of the wings of Acridiidae
gern Se ipa iy berks and Locustidae (see Fig. 167); ¢€ is
‘the small apical field limited below
by the vena dividens; d is the vena plicata which runs
along the under side of the scale as far as the apical field,
where it gives off the axillary nerves; e is a vena spuria, or
adventitious vein such as exists in many other Orthoptera
with delicate wings. On the front part of the scale, a, and
on a different plane so that it is not shown in our figure,
there is a very delicate small band which is supposed to repre-

1 Orthoptera Europaea, 1853, pl. vi. f. 4, p. 484.
2 Morph. Bedeut. Seg. Orthopt. 1876, p. 14; and Prod. Orthopt. Europ. 1882, p. 3.

VIII WINGS OF EARWIGS 207

sent the marginal field of the wing of other Orthoptera. There
are, however, grave difficulties in the way of accepting this view
of the earwig’s wing, amongst which we may mention the
position of the vena dividens and its relation to the so-called
radial and ulnar fields of the wing. The wings are remarkable
for their delicacy ; moreover, the way in which they fold up so
as to be packed in the manner shown in B, Fig. 107, is very
interesting, there being, in fact, no other Insects that fold up
their wings in so complicated and compact a fashion as the
earwigs do. The process is carried out somewhat as follows: the
longer radii come a little nearer together, the delicate membrane
between them falling into folds somewhat like those of a paper
fan; a- transverse fold, or turn-over, then occurs at the point
where the radii, or axillary nerves, start from the vena plicata ;
then a second transverse fold, but in a reversed direction, occurs
affecting the wing just close to the spots where the shorter
radial nervures are dilated; then by a contraction close to the
scale the whole series of complex folds and double are brought
together and compressed. ,

It is quite a mystery why earwigs should fold their wings
in this complex manner, and it is still more remarkable that
the Insects very rarely use them. Indeed, though orjicula
auricularia is scarcely surpassed in numbers by any British
Insect, yet it is rarely seen on the wing; it is probable that
the majority of the individuals of this species may never make
use of their organs of flight or go through the complex process
of unfolding and folding them. It should be remarked that no
part of the delicate membranous expanse of the wing is exposed
when the wings are packed in their position of repose; for the
portion that projects from under the tegmina—and which, it
will be remembered, is always present, for when wings exist
in earwigs they are never entirely concealed by the tegmina—
is, it is curious to note, of hard texture, and is frequently coloured
and sculptured in harmony with the tegmen; in fact, one small
part of the wing forms in colour and texture a most striking
contrast to the rest of the organ, but agrees in these respects
with the wing-covers. This condition is seen in Fig. 108,
where B shows the sculpture of the tegmina #, and of the
projecting tips of the wings w. There are numerous other
instances in Orthoptera where one part of a wing or wing-case

208 ORTHOPTERA CHAP.

is exposed and the other part concealed, and the exposed portion
is totally different in colour and texture from the concealed
portion.

The wings of earwigs are attached to the body in a very
unusual manner ;.each wing is continued
inwards on the upper surface of the
metanotum, as if it were a layer of the
integument meeting its fellow on the
‘mesial line; the point of contact forming
two angles scat behind the metanotum.

Some writers have considered that the
tegmina of earwigs are not the homologues
of those of other Orthoptera, but are really
tegulae (cf. Fig. 56, p. 103). We are not
aware that any direct evidence has been
produced in support of this view.

The pair of forceps with which the
body is armed at its extremity forms
another character almost peculiar to the
earwigs, but which exists in the genus
Japyx of the Thysanura. These forceps
> ge age eee syiae vary much in the different genera of the

line of the Insect; B, family ; they sometimes attain a large size

vies eh : shoving th and assume very extraordinary and dis-

similar sculpture, _ torted shapes. They are occasionally used
by the Insects as a means of completing the process of packing
up the wings, but in many species it is not probable that they
can be used for this purpose, because their great size and peculiarly
‘distorted forms render them unsuitable for assisting in a delicate
process of arrangement ; they are, too, always present in the wingless
forms of the family. Their importance to the creature is at
present quite obscure; we can only compare them with the
horns of Lamellicorn Coleoptera, which have hitherto proved
inexplicable so far as utility is concerned. No doubt the
callipers of the earwigs give them an imposing appearance, and
may be of some little advantage on this account; they are not
known to be used as offensive instruments for fighting, but they
are occasionally brought into play for purposes of defence, the
creatures using them for the infliction of nips, which, however,
are by no means of a formidable character.

:
'
‘

a

=

Seal

Vul EARWIG-FORCEPS 209

These forceps are, in the case of the common earwig—and they
have not been studied from this point of view in any other
species—remarkable, because of the great variation in their
development in the male, a character which again reminds us
of the horns of Lamellicorn beetles: in the female they are

comparatively invariable, as is also the
case in the few species of Lamellicornia,
which possess horned females. A and :
B in Figure 109 represent the forceps
A B c

of different males of the common earwig,

C showing those of the other sex. The

subject of the variation of the male

callipers of the earwig has been con-

sidered by Messrs. Bateson and Brind- F109. — Forceps of the
. : : common earwig: A, of large

ley who examined .1000 specimens male; B, of small male;

captured on the same day on one of the ©&% ° female.

Farne islands off the coast of Northumberland ; 583 of these were

mature males, and the pincers were found to vary in length

from about 24 mm. to 9 mm. (A and B in Fig. 109 repre-
sent two of the more extreme forms of this set of individuals.)
Specimens of medium size were not, as it might perhaps have
been expected they would be, the most common; there were,
in fact, only about 12 individuals having the forceps of the
medium length—4#? to 54 mm., while there were no less than
90 individuals having forceps of a length of about 7 mm., and
120 with a length of from 2? to 34. Males with a medium
large length of the organ and with a medium small length
thereof were the most abundant, so that a sort of dimorphism
was found to exist. Similar relations were detected in the
length of the horns of the male of a Lamellicorn beetle examined
by these gentlemen. In the case of the set of earwigs we have
mentioned, very little variation existed in the length of the
forceps in the female sex.

In many earwigs—including F. auricularia—there may be
seen on each side of the dorsal aspect of the true fourth, or of the
fourth and neighbouring segments of the hind body a small
elevation, called by systematists a plica or fold, and on examina-
tion the fold will be found to possess a small orifice on its
posterior aspect. These folds are shown in Figs. 105 and 108;

1 Proc. Zool. Soc. London, 1892, p. 586,
VOL. V P

210 ORTHOPTERA CHAP.

they have been made use of for purposes of classification, though
no functional importance was attached to them. Meinert,
however, discovered’ that there are foetid glands in this
situation, and Vosseler has recently shown? that the folds are
connected with scent-glands, from which proceed, in all pro-
bability, the peculiar odour that is sometimes given off by the
earwig. The forms destitute of the folds, eg. Labidura, are
considered to have no scent glands. There is a very peculiar
series of smooth marks in the earwigs on the dorsal aspect of
the abdominal segments, and these are present in the glandless
forms.as well as in the others.

The internal anatomy has been to some extent investigated

by Dufour and Meinert. Dufour dis-
/ sected F. auricularia and Labidura riparia,
and found® that salivary glands exist in
the latter Insect (called by him Forficula
gigantea), though he was unable to discover
them in the common earwig. According
to Meinert,* there are, however, salivary
glands affixed to the stipes of the maxillae
in / auricularia, while (in addition?) JL.
riparia possesses very elongate glands seated
in the middle or posterior part of the breast.
The alimentary canal is destitute of con-
volutions, but oesophagus, crop, and gizzard
all exist, and the intestine behind the
stomach consists of three divisions. The
Malpighian tubes are numerous, 30 or 40,
and elongate. The respiratory system is
not highly developed. Earwigs—the Euro-
pean species at least—have, as already mentioned, very small
powers of flight; the tracheal system is correspondingly small,
and is destitute of the vesicular dilatations that are so remarkable
in the migratory Locusts.

The three thoracic spiracles’ are readily observed in living

>)
Le,

oy, . F

Yl

=a
AT
— |

Lh ~~
ur)

é =

a
“

Whiz

=

> > EE Be

Fig. 110.—Labidura ripa-
_ gta, male. Europe.

1 Naturhistorisk Tidsskrift, 3rd ser. ii. 1868, p. 475.

2 Arch. mikr. Anat. xxxvi. 1890, p. 565.

3 Ann. Sci. Nat. xiii. 1828, p. 337.

* Naturhistorisk Tidsskrift, 8rd ser. ii. 1868, p. 475.

° Some writers are of opinion that there are only two thoracic spiracles in Insects,
considering the third as belonging really to the abdomen. Looking on the point as

ae a ae Se
¥

obliquely directed lateral part of the

“yII EARWIGS 211

individuals. There are seven pairs of abdominal spiracles, which,
however, are very minute, and can only be found by distending
the body as shown in Fig. 103. The ventral chain consists of
nine ganglia (the sub-oesophageal centre is not alluded to by
Dufour); the three thoracic are equidistant and rather small;
the hindmost of the six abdominal ganglia is considerably larger
than any one of the other five.

The ovaries of Labidura riparia and Forficula auricularia are
extremely different. In Z. riparia there are on each side five
tubes, each terminating separately in an

oviduct. In F& auricularia there is but
one tube on each side, but it is covered
by three longitudinal series of very short
sub-sessile, grape-like bodies, each of the
two tubes being much dilated behind the
point where these bodies cease.

The testes in earwigs are peculiar and
simple; they consist, on each side, of a
pair of curvate tubular bodies, connected
at their bases and prolonged outwards in
the form of an elongate, slender vas de-
ferens. The structures in the males of
several species have been described at
some length by Meinert,’ who finds that
in some species a double ejaculatory duct
exists.

The young is similar to the adult in :
form; in the winged forms it is always pyc, 111.—Ovaries of Labi-
easy to distinguish the adult by the full @ureriparia, A; and For-

; ‘ jficula auricularia, B.
development of the wings, but in the ‘(After Dufour.)
Wingless forms it can only be decided

with certainty that a specimen is not adult by the softer and

weaker condition of the integuments. Scarcely anything appears
to be known as to the life-history, except a few observa-
tions that have been made on the common earwig; Camerano
found? that this Insect has certainly three ecdyses, and possibly

at present chiefly one of nomenclature, we make use of the more usual mode of
expression.

1 As on last page, and also op. cit. v. 1868, p. 278.

2 Bull. Ent. Ital. xii. 1880, p. 46.

212 ORTHOPTERA CHAP.

an earlier one which he failed to notice, and his observa-
tion confirms the vague previous statement of Fischer. The
egos, in the neighbourhood of Turin, are deposited and hatched
in the early spring; in one case they were laid on the 10th
March, and the Insects issuing from them had completed their
growth and were transformed into perfect Insects on the 22nd.
May. In the immature state the
alar structures of the future imago
may be detected. The tegmina-bear-
ing sclerites, ¢, Fig. 112, look then
somewhat like those of some of the
apterous forms (Fig. 106) and, as
shown in A and B, Fig. 112, do not
Fic. 112.—Notal plates from which differ greatly in the earlier and later

arp enna wr stages. The wings, however, change

young, A, and more advanced, B, much more than the tegmina do;

nymph. at first (Fig. 112, A) there is
but little difference between the two, though in the interior of
the wing-flap some traces of a radiate arrangement can be seen,
as shown at W in A, Fig. 112; in a subsequent condition the
wing-pads are increased in. size and are more divided, the appear-
ance indicating that the wings themselves are present and packed
about a centre, as shown in W of B, Fig. 112.

In the young of the common earwig the number of joints? in
the antennae increases with age. Camerano, l.c., says that before -
emergence from the egg there are apparently only 8 joints in the
antennae, and Fischer states that the larvae of -#! auricularia
have at first only 8 antennal joints; later on 12 joints are
commonly found, and, according to Bateson? this number
occasionally persists even in the adult individual. Meinert says *
that the newly hatched Forfiewla has either 6 or 8 joints, and
he adds that in the later portion of the preparatory stage the
number is 12. Considerable discrepancy prevails in books as. to
the normal number of joints in the antennae of the adult /
auricularia, the statements varying from 13 to 15. The latter
number may be set aside as erroneous, although it is, curiously

1 It may be worth while to repeat that “ geal means a piece, and is the
equivalent of ‘‘link” in a chain.

2 Materials for the Study of Variation, 1894, p. 413.

> Naturhist. Tidsskrift, 3rd ser. ii. 1863, p. 474.

LI EE ec RT Lt <A Na aT I

“he

VIII EARWIGS 213

enough, the one given in the standard works of Fischer, Brunner,
and Finot. Meinert gives without hesitation 14 as the number;
Bateson, /.c., found that 14 joints occurred in 70 or 80 per cent
of adult individuals, that 13 was not uncommon, that 12 or 11
occasionally occurred, and that the number may differ in the two
antennae of the same individual. These variations, which seem
at first sight very remarkable, may with probability be con-
sidered as due to the fact that in the young state the number
of joints increases with age, and that the organs are so fragile

- that one or more of the joints is very frequently then lost, the

loss being more or less completely repaired during the subse-
quent development. Thus a disturbing agency exists, so that the
normal number of 14 joints is often departed from, though it
appears-to be really natural for this species. Bateson has also
pointed out that when the normal number of articulations is not —
present, the relative proportions of joints 3 and 4 are much. dis-
turbed. It is, however, probable that the increase in number of
the joints takes place by division of the third or third and fourth
joints following previous growth thereof, as in Termitidae; so
that the variations, as was suggested by Bateson, may be due to
mutilation of the antennae, and consequent incompletion of the
normal form of the parts from which the renovation takes place ;
growth preceding segmentation—in some cases the growth may
be like that of the adult, while the segmentation remains more
incomplete. In the young the forceps of the two sexes differ but
slightly; the form of the abdominal rings is, on the contrary,
according to Fischer, already different in the two sexes in the
early stage.

The common earwig has a very bad reputation with gardeners,
who consider it to be an injurious Insect, but it is probable that
the little creature is sometimes made the scapegoat for damage
done by other animals; it appears to be fond of sweets, for it
often makes its way to the interior of fruits, and it no doubt
nibbles the petals, or other delicate parts of flowers and vegetables.
Camerano, however, states, /.c., that the specimens he kept in
confinement preferred dead Insects rather than the fruits he
offered them. MRiihl considers the earwig to be fond of a car-
nivorous diet, eating larvae, small snails, etc., and only attacking
flowers when these fail. It has a great propensity for concealing

1 Mt. Schweiz. ent. Ges. vii. 1887, p. 310.

214 ORTHOPTERA CHAP.

itself in places where there is only a small crevice for entry, and
it is possible that its presence in fruits is due to this, rather than
to any special fondness for the sweets. This habit of concealing
itself in chinks and crannies in obscure places makes it an easy
matter to trap the Insect by placing pieces of hollow stalks in
the situations it affects; inverted flower-pots with a little hay, -
straw, or paper at the top are also effectual traps. We have
remarked that it is very rarely seen on the wing, and though it
has been supposed to fly more freely at night there is very little
evidence of the fact. Another British species, Labia minor, a
smaller Insect, is, however, very commonly seen flying.

Earwigs have the reputation of being fond of their young, and
Camerano describes the female of the common earwig as carefully
collecting its eggs when scattered, lifting them with its mandibles
and placing them in a heap over which it afterwards brooded,
De Geer! more than a century ago observed a fondness of the
mother for the young. After the eggs were hatched, Camerano’s
individual, however, evinced no interest in the young. A larger
species, Labidura riparia (Fig. 110) is said to move its eggs from
place to place, so as to keep them in situations favourable for
their development.

The name “earwig” is said to be due to an idea that these
creatures are fond of penetrating into the ears of persons when
asleep. Hence these Insects were formerly much dreaded, owing
to a fear that they might penetrate even to the brain. There
does not appear to be on record any occurrence that could justify
such a dread, or the belief that they enter the ears. If they
do not do so, it is certainly a curious fact that a superstition of
the kind we have mentioned occurs in almost every country
where the common earwig is abundant; for it has, in most
parts of Europe, a popular name indicating the prevalence of
some such idea. It is known as Ohren-wurm in German, as
perce-oreille in French, and so on. The expanded wing of the
earwig is in shape so very like the human ear, that one is
tempted to suppose this resemblance may in former ages have
given rise to the notion that the earwig has some connexion with
the human ear; but this explanation is rendered very improbable
by the fact that the earwig is scarcely ever seen with its wings
expanded, and that it is a most difficult matter to unfold them

1 Mem. hist. Insectes, iii. 1773, p. 548.

—
..

Te tk

ig
‘

ON eo

vul EARWIGS 215

artificially, so that it is very unlikely that the shape of the wings
should have been observed by untutored peoples.

The group Forficulidae seems to be most rich in species in
warm and tropical regions; several unwinged species are met
with in the mountainous districts of Europe; indeed, in some
spots their individuals are extremely numerous under stones. In
Britain we have a list of six species, but only two of these are
to be met with; the others have probably been introduced by
the agency of man, and it is doubtful whether more than one
of these immigrants is actually naturalised here. One of these
doubtfully native species is the fine Labidura riparia (Fig. 110),
which was formerly found near Bournemouth. Altogether about
400 species of earwigs are known at the present time, and
as they are usually much neglected by Insect collectors, it is
certain that this number will be very largely increased, so that
it would be a moderate estimate to put the number of existing
species at about 2000 or 3000. None of them attain a very
large size, Psalis americana being one ‘of the largest and
most robust of the family; a few display brilliant colours, and
some exhibit a colour ornamentation of the surface; there are two
or three species known that display a general resemblance to
Insects of other Orders. The remarkable earwig represented in
Fig. 102 (and which appears to be a nondescript form—either
species or variety—closely allied to P. marmoricauda) was found
by Baron von Hiigel on the mountains of Java; the femora in
this Insect have a broad face which is turned upwards instead of
outwards, the legs taking a peculiar position; and it is curious
that this exposed surface is ornamented with a pattern. The
feature that most attracts attention on inspecting a collection of
earwigs is, however, the forceps, and this is the most marked
collective character of the group. These curious organs exhibit
a very great variety ; in some cases they are as long as the whole
of the rest of the body, in others they are provided with tynes ;
sometimes they are quite asymmetrical, as in Anisolabis tasmanica
(Fig. 113); in Opisthocosmia cervipyga, and many others they
are curiously distorted in a variety of ways. The classification
of the earwigs is still in a rudimentary state; the number of
joints in the antennae, the form of the feet, and (in the terres-
trial forms) the shape of the rudimentary wing-cases and wings
being the characters that have been made most use of by syste-

216 ORTHOPTERA : cues

matists; no arrangement into sub-families or groups of greater
importance than genera is adopted.

The only particulars we have as to the embryological develop-
ment of the earwig are due to Heymons. The forceps spring
from the eleventh abdominal segment, and
represent the cerci of other Orthoptera. An —
egg-tooth is found to be present on the
head for piercing the egg-shell. The embryo
reverses its curved position during the de-
velopment, as other Orthoptera have been
observed to do, but in a somewhat different
manner, analogous to that of the Myriapods. —

Several fossil Forficulidae are known;
specimens belonging to a _ peculiar genus
have been described from the Lower Lias of
Aargau and from the Jurassic strata in
Eastern Siberia, but the examples ‘appar-
ently are not in a very satisfactory state of
preservation. In the Tertiary formations earwigs have been
found more frequently. Scudder has described eleven species of
one peculiar genus from the Lower Miocene beds at Florissant in
Colorado; some of these specimens have been found with the
wings expanded, and no doubt that they were fully developed
Forficulidae can exist. The fossil species of earwigs as yet known
do not display so remarkable a development of the forceps as
existing forms do. 7

Brauer and others treat the Forficulidae as a separate Order
of Insects—-Dermaptera—but the only structural characters
that can be pointed out as special to the group are the peculiar
form of the tegmina and hind wings—which latter, as we have
said on p. 206, are considered by some to be formed on essentially
the same plan as those of other Orthoptera—the imbrication of
the segments, and the forceps terminating the body. The develop-
ment, so far aS it is known, is that of the normal Orthoptera.
Thus the Forficulidae are a very distinct division of Orthoptera,
the characters that separate them being comparatively slight,
though there are no intermediate forms. Some of those who treat
the Dermaptera as a sub-Order equivalent to the rest of the
divisions of the Order, call the latter combination Euorthoptera.

1 SB. Ges. naturf. Fr. Berlin, 1893, p. 127.

Fia. 113.—Anisolabis tas-
manica 3.

i vin HEMIMERUS 217

Fam, II. Hemimeridae.

Apterous, blind Insects with easerted head, having a constricted
neck, mouth placed quite inferiorly ; the
thoracic nota large, imbricate. Hind 4’

body elongate, the segments imbricate, the | i is
dorsal plates being large and overlapping 2 =
the ventral; the number of visible seg- ee Ey

ments being different according to sew: Ag ey “)
a pair of long unsegmented cerci at the

extremity. Coxae small, widely separ- ae, “i
ated. Development intra-uterine. ,

Pe ee
eal
In describing the labium of Mandibulata, eRe
_p. 97, we alluded to the genus Hemimerus as x2 Sate
reputed to. possess a most peculiar mouth. — aihy
When- our remarks were made little was mt
_ known about this Insect ; but a very valuable
paper’ by Dr. H. J. Hansen on it has since
appeared, correcting some errors and supply-
ing us with. information on numerous points.
M. de Saussure described the Insect as possess- 5,, 414. — Hemimerus
ing two lower lips, each bearing articulated — hanseni,female. Africa.
palpi, and he therefore proposed to treat (Afer Hansen.)
Hemimerus as the representative of a distinct Order of Insects,
to be called Diploglossata. It now appears that the talented

Fic. 115,—Under side of head and
front of prothorax of Hemimerus.
a, base of antenna ; 6, articulation
of antenna; c, labrum; d, man-
dible; e, condyle of mandible ; /,
articular membrane of mandible ;
g, stipes of maxilla; h, exterior
lobe ; 7, palpus of maxilla ; k, sub-
mentum ; 7, mentum; m, terminal
lobe of labium ; ”, labial palp ; 0,
plate between submentum and ster-
num; p~, prosternum; g, cervical
sclerites. (After Hansen.)

Swiss entomologist was in this case deceived by a bad prepara-
tion, and that the mouth shows but little departure from the
ordinary mandibulate type. There is a large inflexed labrum ;

1 Ent. Tidskr. 1894, p. 65.

218

ORTHOPTERA

CHAP.

the mandibles are concealed by the maxillae, but are large, com-
pressed, and on their inner edge toothed. The maxillae are well
developed, are surmounted by two lobes and bear five-jointed palpi.

Fie. 116.—Foetus of Hemimerus.
(After Hansen.) a, Antenna; 0,
organ from the neck ; ¢, cerci ; d,
membrane (? cast skins).

beneath, as in Coleoptera.

The ligula appears to be broad and
short, and formed of two parts longi-
tudinally divided; the short palpi
consist of three segments. The men-
tum is very large. The lingua is
present in the form of a free pubescent
lobe with a smaller lobe on each
side. The structure of the pleura is
not fully understood; that of the
abdomen seems to be very like the
earwigs, with a similar difference in
the sexes. The cerci are something
like those of Gryllidae, being long,
flexible, and unsegmented. The legs
have rather small coxae, and three-
jointed tarsi, two of which are
densely studded with fine hairs

It is difficult to detect the stigmata,

but Dr. Hansen’ believes there are ten pairs.
The species described by Dr. Hansen as H. talpoides is prob-
ably distinct from that of Walker, though both come from

equatorial West Africa. Dr.
Hansen’s species, which may
be called H. hanseni, has
been found living on the
body of a large rat, Crice-
tomys gambianus ; the In-

sect occurred on a few speci-

mens only of the mammal,
but when found was present
in considerable numbers; it
runs with rapidity among
the hairs and apparently
also springs.
its food is by no means clear.

The nature of Fic. 117.—Hemimerus talpoides. Africa.

(After

de Saussure.) A, Upper; B, under surface.

Not the least remarkable fact in connexion with this peculiar

Insect is its gestation.

The young are borne inside the mother,

ee wite | HEMIMERUS RS 219

eS apparently about six at a time, the larger one being of course
the nearest to the orifice. Dr. Hansen thinks the young

| _ specimens are connected with the walls of the maternal passages
_ by means of a process from the neck of each. But the details of

this and other points are insufficiently ascertained ; it is, indeed,

difficult to understand how, with a process of the kind of which
ses fragment is shown in Fig. 116, d, the Insect could fix itself
after a detachment for change of position. The young is said
to be very like the adult, but with a simpler structure of the

antennae and abdomen. On the whole, it appears probable that

Hemimerus is, as stated by Dr. Hansen, a special family of
Orthoptera allied to Forficulidae ; further information both as to
structure and development are, however, required, as the material
at the disposition of the Swedish entomologist was very small.

CHAPTER Ix

ORTHOPTERA CONTINUED—BLATTIDAE, COCKROACHES
Fam. III. Blattidae—Cockroaches.

Orthoptera with the head deflexed, in repose concealed from above,
being flexed on to the under-surface with the anterior part
directed backwards. All the coxae large, free, entirely cover-
ing the sternal surfaces of the three thoracic segments, as well
as the base of the abdomen. The sternal sclerites of the
thoracic segments little developed, being weak and consisting
of pieces that do not form a continuous exo-skeleton ; tegmina
and wings extremely variable, sometimes entirely absent.
The wings possess a definite anal region capable of fan-like
folding ; rarely the wing is also transversely folded. The
three pairs of legs differ but little from one another. |

Fic. 118. — Heterogamia
aegyptiaca. A, male;
B, female. (After
Brunner.)

THE Blattidae, or cockroaches, are an extensive family of
Insects, very much neglected by collectors, and known to the
ordinary observer chiefly from the fact that a few species have

oe a

CHAP. IX COCKROACHES 221

become naturalised in various parts of the world in the houses of
man. One such species is abundant in Britain, and is the
“black beetle” of popular language; the use of the word beetle
in connexion with cockroaches is, however, entomologically in-
correct. One or two members of the family are also well known,
owing to their being used as the “corpora vilia” for students
commencing anatomical investigation of the Arthropoda; for this
purpose they are recommended by their comparatively large size
and the ease with which an abundant supply of specimens may
always be procured, but it must be admitted that in some respects
they give but a poor idea of Insect-structure, and that to some
persons they are very repulsive.

The inflexed position of the head is one of the most character-
istic features of the Blattidae; in activity it is partially released
from this posture, but the mouth does not appear-to be capable
of the full extension forwards that
is found in other Insects that inflex
the head in repose. The labium
is deeply divided, the lingua forms
a large lobe reposing on the cleft.
The maxillary palpi have two basal
short joints, and three longer
joints beyond these; the labial
palps consist of three joints of
moderate length. The under-
surface of the head is formed in
large part by the submentum,
which extends back to the occipital
foramen.

The front of the head is the
aspect that in repose looks directly
downwards; the larger part of it
is formed by the clypeus, which is Fro. 119.—Under-surface of Peri-
separated from the epicranium planeta australasiae. c, Coxae.
by a very fine suture angulate
in the middle; there is a large many-facetted eye on each
side; near to the eye a circular space serves for the inser-
tion of the antenna; close to this and to the eye there

is a peculiar small .area of paler colour, frequently membranous,

called the fenestra, and which in the males of Corydia and

222 ORTHOPTERA CHAP.

Heterogamia is replaced by an ocellus. The antennae are very
elongate and consist of a large number of minute rings or joints,
frequently about 100. The head is not inserted directly in the
thorax, as is the case in so many Insects; but the front of the
thorax has a very large opening, thus the neck between it and
the head is of more than usual importance; it includes six
cervical sclerites.

The pronotum is more or less like a shield in form, and
frequently entirely conceals the head, and thus looks lke the
most anterior part of the body; usually
it has no marked angles, but in some of
the apterous forms the hind angles are
sharp and project backwards. In contrast
to the pronotum the prosternum is small
and feeble, and consists of a slender lateral
strip on each side, the two converging
behind to unite with a median piece, the
prosternum proper. None of these pieces
of the ventral aspect of the prothorax are
ordinarily visible, the side-pieces being
covered by the inflexed head, and the
median piece by the great coxae. In
some of the winged Blattidae (Blabera, e.g.)
Fic. 120,—Base of front leg there is at the base of each anterior coxa

and portion of prothorax . 3

of Blabera gigantea, a, & Small space covered by a more delicate

SEE ce membrane, that suggests the possibility

epimeron?; d,episternum?; Of the existence of a sensory organ there

oa ehanter? K’pase of (Fig. 120, 2). At the base of—above
femur ; 7, presumed sense and behind—the front coxa the pro-
neue thoracic spiracle is situate.

The meso- and meta-thoracic segments differ but shghtly from
one another; the notal or dorsal pieces are moderately large,
while the sternal or ventral are remarkably rudimentary, and are
frequently divided on the middle line. Connected with the
posterior part of each sternum there is a piece, bent upwards,
called by some anatomists the furca; when the sterna are
divided the furca may extend forwards between them; in other

1 This enigmatic structure is similar in position to the aural orifice of Locustidae
(see Fig. 101); but it is closed by a transparent membrane, whereas the ear orifice
of Locustidae is, as we shall subsequently see, quite open,

‘rae

1x COCKROACHES 223

cases it is so obscure externally as to leave its existence in some

doubt.

The sterna in Blattidae are remarkable for their rudimentary
structure. This is probably correlated with the great develop-
ment of the coxae, which serve as shields to the lower part
of the body. The pieces of the sterna are not only small, but
are also of feeble consistence—semi-membranous, in fact—and
appear like thicker portions of the more extensive and delicate
membrane in which they are situate; they sometimes differ
considerably in the sexes of the same species. The coxae have
very large bases, and between them and the sterna are some
pieces that are grooved and plicate, so that it is not easy to
decide as to their distinctions and homology (Fig. 120). The
second breathing orifice is a slit placed in a horny area in the
membrane between the middle and hind coxae.

The legs are remarkable for the large and numerous spines
borne by the tibiae, and frequently also by the femora:
the trochanters are distinct and of moderate size; the
tarsi are five-jointed, frequently the basal four joints are
furnished with a pad beneath; the fifth joint is elongate,
bears two claws, and frequently between these a_ pro-
jecting lobe or arolium; this process scarcely exists in the
young of Stylopyga orientalis, the common cockroach, though
it is well developed in the adult. The hind body or abdomen
is always large, and its division into rings is very visible, but the
exact number of these that can be seen varies according to age,
sex, species, and to whether the dorsal or ventral surface be
examined. The differences are chiefly due to the retraction and
inflexion of the apical segments; the details of the form of these
parts differ in nearly every species. It is, however, considered
that ten dorsal and ventral plates exist, though the latter are
not so easily demonstrated as the former. The basal segment is
often much diminished, the first dorsal plate being closely con-
nected with the metanotum, while the first ventral may be still
more rudimentary; much variety exists on this point. In the
female two of the ventral terminal plates are frequently inflexed,
so as to be quite invisible without dissection. From the sides of
the tenth segment spring the cerci, flat or compressed processes
very various in size, length, and form, usually more or less
distinctly jointed. Systematists call the seventh ventral plate of the

224 ORTHOPTERA CHAP-

female the “lamina subgenitalis,” or the “lamina subgenitalis
spuria,” the concealed eighth plate being in this latter case con-
sidered the true subgenital plate. In the male this term is
applied to the ventral plate of the ninth segment, the corre-
sponding dorsal plate being called the “lamina supra-analis.”
These terms are much used in the systematic definitions of the _
genera and larger groups. |

The males, in addition to the.cerei alluded to as common to
both sexes, are provided on the hind margin of the lamina
subgenitalis with a pair of slender styles. These are wanting
in the females, but in the common cockroach the young in-
dividuals of that sex are provided, like the male, with these
peculiar organs. M. Peytoureau has described! the mode of
their disappearance, viz. by a series of changes at the ecdyses.
Cholodkovsky, who has examined the styles, considers them
to be embryologically the homologues of true legs.” These
styles are said not to be present in any shape in some species—
Ectobia, Panesthia, ete.; this probably refers only to the adults.
In some cases a Curious condition occurs, inasmuch as one of
the two styles is absent, and is replaced by a notch on the
right side, thus causing an asymmetry—Phyllodromia, Temnop-
teryx, ete. ©

It has been found in several species that there are eight pairs
of abdominal spiracles, making, with the two thoracic, ten pairs
in all. The first of the abdominal spiracles is larger than the
others, and in the winged species may be easily detected by
raising the tegmina and wings, it being more dorsal in position
than those following, which are in some species exposed on the
ventral surface owing to the cutting away of the hind angles of
the ventral plates; but the terminal spiracles are in all cases diffi-
cult to detect, and it is possible that the number may not be the
same in all the species of the family. The cerci exhibit a great
deal of variety. In the species with elongate tegmina and wings
the cerci are elongate, and are like antennae in structure; in
many of the purely apterous forms the cerci appear to be entirely
absent (cf. Fig. 130, Gromphadorhina), but on examination may
be found to exist in the form of a small plate, or papilla scarcely
protuberant. In the males of Heterogamia they are, on the

1 Rev. biol. Nord France, vii. 1894, p. 111.
2 Ann. Nat. Hist. Decr. 6th, ser. x. 1892, p, 433.

p<

Ix WINGS OF COCKROACHES 225

contrary, very like little antennae; in the unwinged females of
this genus they are concealed in a chink existing. on the under-
surface of. the apex of the body.

The alar organs of Blattidae are of considerable interest from
several points of view. They exist in various conditions as
regards size and development, and in some forms are very large ;

each tegmen in some species of the genus Blabera (Fig. 132) may

attain a length of nearly three inches; in other cases wings and
tegmina are entirely absent, and various intermediate conditions
are found. In Fig. 121 we give a diagram of the tegmen or front
wing, A, and the hind wing, B, to explain the principal nervures
and areas. The former are four in BE and, adopting
Brunner’s nomenclature! for
them, are named proceeding
from before backwards medi-
astinal, @; radial, 0; infra-
median. (or ulnar), ¢; and
dividens, d. An adventitious
vein, vena spuria, existing in
the hind wings of certain genera

is marked sp in B. 4: |

The vena dividens is of ——————
great importance, as it marks ee ? ,
off the anal or axillary field,
which in both tegmen and
wing has a different system. of
minor veins from what obtains
inthe rest of the organ; the veins Fic. 121.—Diagram of tegmen, A, and
being in the anterior region Wins. B iy Batiae, Nerrurs: « nett
abundantly branching and dicho- median ; d, dividens ; SP, spuria, Areas:
tomous (Fig. 132), while in the}, melietinal or anginal: 2, scapular

3 3, 3; 4,

anal field there is but little
furcation, though the nervures converge much at the base.. The
mediastinal gives off minor veins towards the front only, the radial
gives off veinlets at first towards the front, but nearer the tip
of. the wings sends off minor veins both backwards and forwards.
The infra-median or ulnar vein is very variable; it is frequently

1 Prod. Orth. europ. 1882, p. 27, and Rev. Syst. Orthopt. 1892, p. 15. Unfortu-
nately de Saussure oe a different nomenclature ; we have preferred Brummer’s as
being more simple... = ._ a ate eet Fea a ee 3

VOL, V Q

226 ORTHOPTERA ' CHAR

abbreviated, and on the whole is of subordinate importance to
the other three. These latter thus form four chief areas or fields,
viz—1, mediastinal or marginal; 2, scapular or radial; 3,
median; and 4, anal. These nervures and divisions may be
traced in a large number of existing and fossil Blattidae, but
there are forms existing at present which it is difficult to reduce
to the same plan. In Luthyrhapha, found in the Pacific Islands,
the hind wings are long and _ project
beyond the tegmina, and have a very
‘peculiar arrangement of the nervures ;
the species of Holocompsa also possess
abnormal alar organs, while the struc-
ture of these parts in Diaphana (Fig.
122) is so peculiar that Brunner
wisely refrains from attempting to
homologise their nervures with those
of the more normal Blattidae. The
alar organs are frequently extremely
different in the two sexes of the same
F1G.122,—Diaphana fiebert. Brazil species of Blattidae, and the hind

A, The Insect, natural size; B, Wing may differ much from the teg-

he beet magnified. men as regards degree of departure

from the normal. So that.it is not
a matter for surprise that the nervures in different genera cannot
be satisfactorily homologised.

But the most peculiar wings in the family are the folded
structures found in some forms of the groups Ectobiides and ~
Oxyhaloides [Anaplectinae and Plectopterinae of de Saussure].
These have been studied by de Saussure,’ and in Fig. 123 we
reproduce some of his sketches, from which it will be seen that in
B and C the wing is divided by an unusual cross-joinut into two
parts, the apical portion being also longitudinally divided into
two pieces a and b, Such a form of wing as is here shown has
no exact parallel in any’of the other groups of Insects, though
the earwigs and some of the Coleoptera make an approach to it.
This structure permits a very perfect folding of the wing in
repose. The peculiarities exhibited have been explained by de
Saussure somewhat as follows. In the ordinary condition of
Orthoptera the axillary or anal field (P) when the wings are

1 Ann. Sci. Nat. Zool. ser, 5, x. 1868, p. 161.

IX | WINGS OF COCKROACHES 227

closed collapses like a fan, and also doubles under the anterior
part (H) of the wing along the line a a, in Fig. 123, A, the result.
being similar to that shown by our Fig. 124. It will be noticed

; in Fig. 123, A, that a small tri-

angular area (¢) exists at the tip
of the wing just where the fold
takes place, so that when the
wing is shut this little piece is
liberated, as shown in #, Fig. 124.
In many Blattidae, eg. Blabera
(Fig. 132), no trace of this little
intercalated piece can be found,
but in others it exists in various
degrees of development interme-
diate between what is shown in
Thorax porcellana (Fig. 123, A)
and in Anaplecta azteca (123, B),
so that a, b of the latter may be
looked on as a greater develop-
ment of the condition shown in A
at ¢. It will be noticed that the
superadded part of the wing of
123, B, possesses no venation,
peri traversed only by the line 5. 125 -<Hing wings of Blathidam A,
along which it folds; but in Thorax porcellana; B, Anaplecta
the wing of Diploptera silpha, aa aye Col stipha, (After
123, C, the corresponding part
is complexly venated. This venation, as Brunner says,! is not
an extension of the ordinary venation of the wing, but is suz
generis, It is curious that though all the degrees of develop-
. ment between A and B exist in various
SS forms of the tribes Ectobiides and Oxyha-
a loides, yet there is nothing to connect the
ye : Be veined apex of Diploptera with the unveined
_ Fie. 124.—Hind wing of
Blatta folded. t, Free One of Anaplecta.
triangular area. (After The internal anatomy of Blattids has
de Saussure. ) ; ; . ;
been investigated in only one or two species.
There are no great peculiarities, but some features of minor
interest exist. The alimentary canal (Fig. 125) is remarkable

1 Nour. Syst. Blattaires, 1865, p. 265. .

228 ORTHOPTERA. CHAP.

on account of the capacious crop, and the small gut-like, chylific
ventricle ; eight elongate pouches are situate on this latter part

Fig. 125.—Alimentary canal of Stylo-
pygaorientalis. (After Dufour.) a,
Head ; 8, salivary glands ; ¢, saliv-
ary reservoir; d, crop; é, diver-

ticula placed below proventriculus ; -

J, stomach ; g, small intestine ; h,
rectum ; 7, Malpighian tubes; 4,
extremity of hind body.

at its junction with the gizzard.

~The Malpighian tubules are
very numerous and delicate; there
are extensive salivary glands and
reservoirs; and on the anterior
part of the true stomach there are
eight caecal diverticula, The great
chain of the nervous system con-
sists in all of eleven ganglia—two
cephalic, three thoracic, and six
abdominal.

- The ovaries in Stylopyga orient-

_alis. consist each of eight egg-tubes,
- placed at the periphery of a common —

receptacle or oviduct, the pair of
receptacles themselves opening. into
a common chamber—the uterus—
which is surrounded by a. much
branching serific or colleterial gland.
In this chamber the egg-case is
formed from. the secretion of the
gland just mentioned. According
to Miall and Denny,’ there is a
spermatheca which opens not into
the uterus but into the cloacal
chamber behind it. Lowne doubts
this diverticulum being a_ true
spermatheca. The manner in which

the eggs are fertilised and their capsule modelled is uncertain.”
The internal reproductive organs of the male are very com-

plex in Stylopyga orientalis ;

each testis consists of a number

(30 to 40) of vesicles placed on a tube which is prolonged to
form the vas deferens. There is a-very peculiar large complex
gland consisting of longer and shorter utricles, opening into the
vesiculae seminales, and forming a “mushroom-shaped gland.” *

1 The Cockroach, p. 170.

? Cf. Duchamp, Rev. Sci. Nat. Montpellier, vii. [21879], p. 423.
’ Huxley, Manual Anat. Invert. Animals, 1877, p. 416. —

Ix 3 COCKROACHES 229

This gland is much larger than the testes proper, which, it is
said, lose early their functional activity in the species in question,
and shrivel. There is another important accessory gland, the
_ conglobate gland of Miall and Denny, opening on a portion of
the external copulatory armour. |

Although some species of Blattidae are domesticated in our
houses, and their bodies have been dissected by a generation of
anatomists, very little is known as to their life histories. The
common “black beetle” of the kitchen is said by Cornelius to be
several years in attaining the adult state. Observations made at
Cambridge by the writer, as well as others now being carried on
there by Mr. H. H. Brindley, quite confirm this view, the extent of
. growth accomplished in several months being surprisingly little,
and the amount of food consumed very small. It is therefore not
improbable that the life of an individual of this species may
_ extend to five years. Phyllodromia germanica, a species that is
abundant in the dwellings of the peoples of north-eastern Europe,
attains its full development in the course of a few months.

We have already alluded to the fact that in the Blattidae the
egos are laid in a capsule formed in the interior of the mother-
Insect. This capsule is a horny case varying much in size and
somewhat less in form in the different species; it is borne about
for some time by the mother, who may not
infrequently be seen running about with it
protruding from the hinder part of the body.
Sooner or later the capsule is deposited in a
suitable situation, and the young cockroaches
emerge; it is said that they are sometimes
liberated by the aid of the mother. Mr.
Brindley has found it very difficult to pro- | ,, Btu Ceation

cure the hatching of the young from their of European Blat-
‘ tidae. A, Ectobialap-
capsules. . ponica; B, Phyllo-
It is known that some Blattidae are dromia germanica;
ae ; C, Het -
viviparous. In the case of one such species, 777 (AfterBr fwd
Panchlora viridis, it appears probable that
the egg-capsule is either wanting, or is: present in only a very
imperfect form.’
On emerging the young Blatta is in general form very similar
to the parent, though usually much paler in colour. After casting

1 Riley, Jnsect Life, iii. 1891, p. 443, and iv. 1891, p. 119.

230 ORTHOPTERA CHAP.

the skin an uncertain number of times—not less than five,
probably as many as seven—it reaches the adult condition, the
changes of outer form that it undergoes being of a gradual nature,
except that at the*last ecdysis the wings—in the case of the
winged species —— make their appearance, and the terminal
segments of the body undergo a greater change of form. What
mutations of shape may be undergone by the thoracic segments
previous to the final production of the wings has not apparently
been accurately recorded, Fischer’s opinion being evidently based
on very slight observation. The little that has been recorded as
to the post-embryonic development since the observations of
Hummel ! and Cornelius ? will be found in the works of Brunner?

According to this latter authority, in the wingless species the .

terminal segments of the body have the same form in the early
stages as they have in the adult state, so that this latter condition
can only be recognised by the greater hardness of the integument.
When tegmina or wings are present in a well-developed form in
a Blattid, it is certain that the Insect is adult; and when there
can be seen at the side of the mesonotum or metanotum a piece,
however small, separated by a distinct suture, it may be correctly
assumed that the individual is an adult of a species having only
rudimentary alar organs. The adult female of the common
Stylopyga orientalis Bice this phenomenon.

The cockroaches are remarkable for the. excessive rapidity
with which they run, or rather scurry, their gait being very
peculiar. The common domestic forms, when alarmed, disappear
with great agility, seeking obscure corners in which to hide
themselves, it being part of their instinct to flee from light.
Hence they are called lucifugous, and are most of them entirely
nocturnal in their activities. In the South of Europe and other
warmer regions many Blattidae may, however, be found on bushes
and foliage in the daytime; these, when alarmed, fall down and
run off with such speed and in so tortuous a manner, that it
is a very difficult matter to seize them. It is recorded that the
males of the genus Heterogamia are attracted by lights, though
their apterous females keep themselves concealed underground in
sandy places.

1 Essais entomologiques, St. Petersburg, 1821.
2 Beitrige zur niheren Kenntniss von Periplaneta orientalis, Elberfeld, 1853.
3 Nouv. Syst. Blattaires, 1865, p. 16, ete. ‘

IX . HABITS OF COCKROACHES 231

We may take this opportunity of alluding to the attraction
that light exerts on Insects. Many species that conceal them-
selves during the daytime and shun light as if it were dis-
agreeable, are at nighf*time so fascinated by it that it is the
cause of their destruction. The quantity of Insects killed in this
way by electric and other bright lights is now enormous; in
many species the individuals immolate themselves by myriads.
It would appear that only nocturnal and winged species are so
attracted. So far as we know, light has no fascination for Insects
except when they are on the wing. The phenomenon is not
understood at present.

The food of Blattidae is believed to be of a very mixed
character, though Brunner considers that dead animal matter is
the natural nutriment of the members of this family. It is well
known that the common cockroach eats a variety of peculiar
substances ; its individuals undoubtedly have the somewhat too
Scoudiaical habit of eating their own cast skins and empty egg-
capsules, but in this they only act like many other much admired
Insects. SS. orientalis is gregarious, and the individuals are
very amicable with one another; small specimens sit on, or run
over the big individuals, and even nestle under them without their
displaying the least resentment. The common cockroach is a
rather amusing pet, as the creatures occasionally assume most
comical attitudes, especially when cleaning their limbs; this they
do somewhat after the fashion of cats, extending the head as far
as they can in the desired direction, and then passing a leg or
antenna through the mouth; or they comb other parts of the
body with the spines on the legs, sometimes twisting and distort-
ing themselves considerably in order to reach some not very
accessible part of the body.

There is very little information extant as to the domestic
Blattidae found in parts of the world outside Europe, but it seems
that there are numerous species that prefer the dwellings of man,
even though they only tolerate the owners. Belt says* “the
cockroaches that infest the houses of the tropics are very wary,
as they have numerous enemies—birds, rats, scorpions, and
spiders; their long trembling antenne are ever stretched out,
vibrating as if feeling the very texture of the air around them ;
and their long legs quickly take them out of danger: Sometimes

1 Naturalist in Nicaragua, 1874, p. 110.

232 ORTHOPTERA CHAP.

I tried to chase one of them up to a corner where on a wall
a large cockroach-eating spider stood motionless looking out for
his prey; the cockroach would rush away from me in the
greatest fear, but as soon as it came wi€hin a foot of its mortal
foe nothing would.-force it onwards, but back it would double,
facing all the danger from me rather than advance nearer to, its
natural enemy.” To this we may add that cockroaches are the
natural prey of the fossorial Hymenoptera of the group Ampuli-

Fic. 127.—Noeticola simoni. A, male; A,, tegmen and rudiment of wing; A,, front
of head; B, female. The cerci are broken, in B the right one is restored in out-
line. (After Bolivar.)

cides, and that these wasps sometimes enter houses in search of
the Insects. -

We have already noticed the considerable difference that
exists in many cases between the sexes of the same species.
This is sometimes carried to such an extent that nothing but
direct observation could make us believe that the males and
females are of one kin. Fig. 118 (p. 220) shows a case of this
kind. Though the young as a rule are excessively similar to the
adults, yet this is by no means invariably the case. In some
of the more amply winged forms, such as blabera, the young is
about as different from the adult as the female of Heterogamia

Vy: Ata

-absurd to talk of elegance in con-

Ix , ELEGANT COCKROACHES 233

is from its male. In Blattidae it is always the case—so far as
is yet known—that when there is a difference as regards the
alar organs between the two sexes, it is the male that has these
structures most developed, and this even when they can be of
little or no use for purposes of flight.

Among the most interesting forms of the family are the two
species of the genus Nocticola, recently discovered by M. Simon
in caves in the Philippine Islands.‘ They are amongst the
smallest of the Orthoptera, the male being scarcely 4 of an
inch long. In the larval state of M. simoni the ocular organs
exist as three ocelli, or facets, on each side of the head, and in
the perfect state the number is increased somewhat, as shown in
Fig. 127, A,. In the second species of the genus the female is
quite blind (the male being still undiscovered). The fenestrae
in Nocticola are absent; the tegmina and wings are totally
wanting in the female (Fig. 127, B), but are present in a very
peculiar condition in the male (Fig. 127, A,). There are other
anomalies in the structure of these cavernicolous Insects, the
cercl being apparently of peculiar structure, and the spines of
the legs more hair-like than usual.
The condition of the eyes is remark-
able; the peculiarity in their de-
velopment is worthy of study.

To those who are acquainted |
with Blattidae only through our
domestic “ black beetle ” it may seem

nexion with cockroaches. Yet there
are numerous forms in which grace
and beauty are attained, and some
exhibit peculiarities of ornamenta-
tion that are worthy of attention.
Corydia petiveriana (Fig. 128) isa
common cockroach in East India. It
has an effective system of coloration,
the under wings and the sides of
the body being vividly coloured with orange yellow; when the
tegmina are closed the upper surface of the body is of a velvet-
black colour, with cream-coloured marks ; these spots are different

1 See Bolivar, Ann. Soc. ent. France, 1892, p. 29.

Fia. 128.—Corydia petiveriana, with
tegmina extended, A ; closed, B.

234 ORTHOPTERA CHAP.

on the two tegmina, as shown in Fig. 128, A, but are so arranged
that when the tegmina are closed (Fig. 128, B) a symmetrical
pattern is produced by the combination of the marks of the two
differently spotted tegmina. It is very curious to notice the
great difference in the colour of the part of the right tegmen
that is overlapped by the edge of the left one; this part of the
tegmen being coloured orange yellow in harmony with the wings.
The result of the remarkable differentiation of the colours of the
two tegmina may be summarised by saying that on the right
one the colour of a part is abruptly contrasted with that of the
rest of the organ, so as to share the system of coloration of the
under-wings and body, while the corresponding part of the other
tegmen,is very differént, and completes the system of symmetrical
ornamentation of the upper surface.

Many other members of the Blattidae have an elegant
appearance, and depart more or less from their fellows in
structural characters, with the result of adding to their graceful
appearance ; in such cases, so far as at present
known, these Insects are brightly coloured.
Thus Hypnorna amoena (Fig. 129) has the
antennae banded in -white, black, and red,
while the overlapping part of the tegmina is
arranged so as to bring the line of junction
between them nearly straight along the middle
line of the body, and thus produce a more
) , symmetrical appearance than we find in other
Fic. 129. — Hypnorna cockroaches. The head in this Insect is not
| pe ake, Central so concealed as usual, and this undoubtedly

merica. Tribe Oxy- ‘

haloides. (After de adds somewhat to the effective appearance of

panera this cockroach. This visibility of the front of
the head in Hypnorna is not, as would be supposed, owing to
its being less inflexed than usual. On the contrary, the head is
quite as strongly inflexed as it is in other Blattidae, but the
part just at the front of the thorax is unusually elongate; so
that the eyes are exposed and the Insect has a larger field of
vision. This interesting Insect belongs to the tribe Oxyhaloides
[Plectopterinae Sauss.], in which group the most highly developed
folded wings occur.

The wingless forms’ never exhibit the grace and elegance
possessed by some of the more active of the winged Blattidae.

Ce al

Ix PECULIAR COCKROACHES 235

One of them, Gromphadorhina portentosa, found in Madagascar
(Fig. 130), is a very robust
Insect, and attains a length
of 78 millim,— somewhat
more than 3 inches. This
Insect has projections on the
thorax that remind us of the
ee me ot wai Peace (Aer fom)"

Little has been yet written as to the resemblances of Blattidae
to other species of their own family, or to other creatures, but it
is probable that such similarities will be found to prevail to a
considerable extent. W. A. Forbes has called attention’ to the
larva of a Blattid from Brazil as being remarkable for its super-
ficial resemblance to an Isopod crustacean. Some of the wingless
forms have a great resemblance to the small rolling-up Myriapods
of the group Glomerides ; Pseudoglomeris
Jornicata, of which we figure the female
(Fig. 131), has received its name from
this resemblance. The females of the 8.
Fia. 131.—Pseudoglomeris for- 4 :

nicata, Q. Burma. Tribe African genus Derocalymma. possess this
Ferisphacriides. _ (After GJlomerid appearance, and have a peculiar
runner, ) aie
structure of the prothorax, admitting of a
more complete protection of the head. Brunner states that the
wingless kinds of Derocalymma roll themselves up like wood-lice. —
In many of the forms of this tribe—Perisphaeriides—the males
are winged, though the females are so like Myriapods. Accord-
ing to de Saussure” the gigantic Megaloblatta rufipes bears an
extreme resemblance in appearance to the large cockroaches of
the genus Blabera.

Some of the species of Holocompsa remind us strongly of
Hemiptera of the family Capsidae; they have an arrangement
of colours similar to what prevails in that group, and their
tegmina and wings which, as being those of Blattids may be
said to be abnormally formed, resemble in texture and the
distribution of the venation those of the Hemiptera. These Insects
are closely allied to Diaphana, of which genus we have figured
a species (Fig. 122).

1 P, ent. Soc. London, 1881, p. 1.
2 Biol. Centr. Amer. Orthopt. 1893, p. 57.

236 ORTHOPTERA CHAP.

There is very little evidence on which to base an estimate
of the number of species of Blattidae existing in the world at
present. Probably the number extant in collections may amount
to 1000 or thereabouts, and the total existing in the world may
be as many as 5000. The species of Blattidae cannot tolerate
cold, and are consequently only numerous in tropical regions.
Europe possesses about twenty species, and in Britain there ‘are only —
three that are truly native; these are all small Insects belonging
to the genus Zetobia, and living out of doors, amongst leaves,
under bushes, and in various other places. We have, however,
several other species that have been introduced by the agency of
man, and these all live under cover, where there is artificial warmth
and they are protected from the inclemencies of the winter season.
The commonest of these forms is Stylopyga orientalis, the “ black
beetle” of our kitchens and bakehouses. This Insect is said to
have been brought to Europe from “ Asia” about 200 years ago,
but the evidence as to its introduction, and as to the country of
which it is really a native, is very slight. It is indeed said * that
S. orientalis has been found in peat in Schleswig-Holstein. Peri-
planeta americana is a larger Insect, and is common in some
places; it is apparently the species that is most usually found
on board ships, where it sometimes multiplies enormously, and
entirely devours stores of farinaceous food to which it obtains
access: it is known that sometimes a box or barrel supposed to
contain biscuits, on being opened is found to have its edible con-
tents entirely replaced by a mass of living cockroaches. Fortu-
nately Periplaneta americana has not spread widely in this country,
though it is found in great numbers in limited localities; one of the
best known of which is the Zoological Gardens in the Regent’s
Park at London. Periplaneta australasiae is very similar to P.
americana, but has a yellow mark on the shoulder of each tegmen.
This has obtained a footing in some of the glass-houses in the
Botanic Gardens at Cambridge and Kew; and it is said to be fairly
well established in Belfast. Another of our introduced domestic
cockroaches is Phyllodromia germanica, a much smaller Insect
than the others we have mentioned. It has only established
itself at a few places in this country, but it is extremely abundant
in some parts of Northern and Eastern Europe. It has been in-
creasing in numbers in Vienna, where, according to Brunner, it is

1 Schiff, Zool. Anz. xvi. 1898, p. 17.

sm

_1 ue 8

1X COCKROACHES 237

displacing Stylopyga orientalis, In addition to these, Lhyparobia
maderae and species of the genus
Blabera have been met with in
our docks, and are possibly always
to be found there. Theyare Insects
of much larger size than those
we have mentioned. We figure
the alar organs of one of these
species of Blabera of the natural
size: the species in this genus
are extremely similar to one an-
other. Blaberae are known in
the West Indies as drummers, it
being supposed that they make a Fic. 132.—Alar organs of Blabera sp. |
noise at night,’ but details in con- A, tegmen ; B, wing.
firmation of this statement are wanting.

It is a remarkable fact that no satisfactory reasons can be
assigned for the prevalence of one rather than another of these
domestic cockroaches in particular localities. It does not, seem

to depend at all on size, or on the period of development, for

the three species Stylopyga orientalis, Periplaneta americana, and
Phyllodromia germanica, which are the most abundant, differ
much. in these respects, and replace one another in particular
localities, so that it does not appear that any one is gaining a
permanent or widespread superiority as compared with another.
There are, however, no sufficient records on these points, and
further investigation may reveal facts of which we are at present
ignorant, and which will throw some light on this subject. We
may remark that Mr. Brindley has found it. more—difficult to
obtain hatching of the young from the egg-capsules of Periplaneta
americana and Phyllodromia germanica at Cambridge, than from
those of Stylopyga orientalis. aS ah we
Although much work has been done on the embryology of
Blattidae, the subject is still very incomplete. The recent memoirs
of Cholodkovsky? on Phyllodromia germanica contain so much of

general interest as to the development of the external parts of the.

body that we may briefly allude to them. The earliest appearance
of segmentation appears to be due to the centralisation of numerous

1 Westwood, Modern Class. Insects, i. 1839, p. 418.
? Zeitschr. wiss, Zool. xlviii. 1889, p. 89;.and Mem. Ac. St. Petersb, xxxviii. No. 5, 1891.

238 ORTHOPTERA CHAP,

cells round certain points in the ventral plate. The segmentation
of the anterior parts is first distinct, and the appearance of the
appendages of the body takes place in regular order from before
backwards, the antennae appearing first; the mandibles, however,
become distinct only subsequent to the maxillae and thoracic
appendages. There are in the course of the development append-
ages to each segment of the body (he counts eleven abdominal
segments); the cerci develop in a similar manner to the anten-—
nae; the first pair of abdominal appendages—at first similar to
the others—afterwards assume a peculiar stalked form. The
abdominal appendages subsequently disappear, with the exception
of the ninth pair, which form the ventral styles, and the
eleventh pair, which become the cerci. The last ventral segment
is said to be formed by the union of the tenth and eleventh
embryonic ventral segments.

As regards their Palaeontological forms Blattidae are amongst
the most interesting of Insects, for it is certain that in the
Carboniferous epoch they existed in considerable number and
variety. A still earlier fossil has been found in the Silurian
sandstone of Calvados; it con-
sists of a fragment (Fig. 133,
A), looking somewhat like an
imperfect tegmen of a Blattid ;
it was described by Brongniart
under the name of Palaeoblat-
tina douviller, and referred by
him, with some doubt, to this
family. Brauer has, however,
expressed the opinion’ that
the fragment more probably
Fic. 133.—A, Tegmen(?) of Palacoblattina belonged to an Insect like the

courte Bot Rotate mandiach- mole-cricket, and in view of

: this discrepancy of authorities
we may be pardoned for expressing our own opinion to the effect
that the relic has no connexion with the Insecta. The figure
given by Scudder” has not, however, so uninsect-like an appear-
ance as that we have copied from Brauer. Whatever may prove
io be the case with regard to Palaeoblattina, it is certain, as we

1 Ann, Hofmus. Wien., i. 1886, p. 104.
* Zittel, Handb. Palacont. 1 Abth. ii. 1885, p. 753.

ed ee
7

Ix FOSSIL COCKROACHES 239.

have already said, that in the Palaeozoic epoch Insects similar to
our existing cockroaches were abundant, their remains being
found in plenty in the coal-measures both of Europe and North
America. Fig. 133, B, shows a fossil tegmen of Etoblattina
manebachensis from the upper Carboniferous beds of Ilmenau
in Germany. It will be noticed that the disposition of the
nervures is very much like that which may be seen in some
of our existing Blattidae (cf. the tegmen of SBlabera, Fig.
132, A), the vena dividens (a) being similarly placed, as is
also the mediastinal vein on the front part of the organ.
The numerous carboniferous Blattidae have been separated as a
distinct Order of Insects by Scudder under the name Palaeo-
blattariae, but apparently rather on theoretical grounds than
because of any ascertained important structural distinctions. He
also divided the Palaeoblattariae into two groups, Mylacridae and
Blattinariae, the former of which was supposed to be peculiar
to America. Brongniart has, however, recently discovered that
in the Carboniferous deposits of Commentry in France Mylacridae
are as common as in America. This latter authority also states
that some of the females of these fossil Blattidae are distinguished
by the presence of an elongate exserted organ at the end of the
body. He considers this to have been an ovi-
positor by which the eggs were deposited in
trees or other receptacles, after a manner that
is common in certain Orthoptera at the present
day. If this view be correct these Carbon-
iferous Insects must have been very different
from the Blattidae of our own epoch, one of
whose marked characteristics is the deposition
of the eggs in a capsule formed in the body of
the parent. 3

In the strata of the secondary epoch re-
mains of Blattidae have also been discovered
in both Europe and America, in Oolitic, Liassic,
and Triassic deposits. From the Tertiary .
strata, on the other hand, comparatively few pig 134.—Front leg
species have been brought to light. A few of Periplaneta

; : australasiae.

have been discovered preserved in amber.

The classification of the Blattidae is attended with considerable
difficulty on account of the numerous wingless forms, and of the

240 ORTHOPTERA CHAP.

extreme difference in the organisation of the two sexes of many
species. It has, however, been brought to a fairly satisfactory
state by the reiterated labours of Brunner von Wattenwyl, and
we reproduce his recently perfected exposition of their characters.
His first division is made by means of a structure which is very -
easily observed, viz. whether the femora are armed with spines,
as in Fig. 154, or not. The terms used in connexion with the
wings and other parts of the body we have already explained.
Brunner’s system is adopted by de Saussure who, however,
proposes to replace the names Ectobiides and Oxyhaloides by
Anaplectinae and Plectopterinae. He also proposes to apply the
generic name Slatta to the Insect that is now so frequently called
Phyllodromia germanica in zoological works. If that view bé
adopted, Brunner’s group Phyllodromiides will be called Blattides.
Table of the tribes of Blattidae, after Brunner :—

1. Femora spiny beneath.?
2. The last ventral plate of the female large, without valves.

3. Supra-anal lamina of both male and female transverse, narrow.
Wings, when present, furnished with a triangular apical field.
Posterior femora unarmed beneath, or armed with two spines on
the anterior margin. Egg-capsules furnished with a longitudinal
suture. Tribe 1. Ecropmpxrs. [Anaplectinae Saussure.]

3’. Supra-anal lamina of each sex more or less produced, triangular,
“or emarginate. Wings, when present, without apical field. Pos-
i terior femora with both edges spiny.

/4, Supra-anal lamina of each sex triangular, not notched. Cerci
-- projecting much beyond this lamina.

5. Pronotum and elytra smooth (%.e. without peculiarity of
surface other than punctuation). The radial nervure of the
wing giving off several parallel branches, pectinate on the
anterior margin (except in the genus Abrodiaeta). Tarsal
joints without pads. Tribe 2. PayLuopRomripEs. [Blattinae
Saussure. |

5. Pronotum and elytra soloweminanie: Radial nervure of the
wings giving off irregular branches on the anterior margin
(ulnar vein many-branched). ‘Tarsal joints furnished with

ee pads, Tribe 3. NycrTiBoRIDEs.

-’ 4’, Supra-anal lamina of males more or less four-sided, with obtuse
angles, of females broad, rounded, or lobed. Cerci not pro-
jecting beyond the lamina. (Tarsal joints with distinct pads.)
Ulnar nervure of the wings giving off parallel branches towards
the vena dividens.. Tribe 4, EPILAMPRIDES.

1 Biol: Centr.-Amer. Orthoptera, 1893.
2 Although the genus Chorisoneura has unarmed femora, it must be placed in this
division. - — ae ee a

ix BLATTIDAE 241

2’. The last ventral plate of the female furnished with valves. Tribe
5. PERIPLANETIDES.! (Fig. 119, Periplaneta australasiae.)
1’. Femora unarmed beneath. (In the tribe Panesthiides the anterior

femora are frequently armed with two spines.)

2. Supra-anal lamina of each sex more or less produced, posterior margin
notched.
3. A distinct pad between the claws. Tribe 6. PANCHLORIDES.
3’. No pad between the claws, or only an excessively small one.

4, Wings with a folded fan-like anal field. Pronotum smooth.
Tribe 7. BuaBeripes. (Fig. 132, Blabera sp. wings.)

4’. Anal field of the wing with a single fold. Pronotum more or
less pilose. Tribe 8. Corypimpes. (Fig. 128, Corydia peti-
veriana. Fig. 118, Heterogamia, aegyptiaca.)

2’, Supra-anal lamina of each sex, short, transverse, posterior margin

- straight or rounded.
3. Subgenital lamina of the male somewhat produced, furnished
with a single style. Tarsal claws with a distinct pad (except in

the genus Paranauphoeta). .

4, Anterior portion of the wings pointed, either the apical field of

; the wing very much produced, or the wings twice as long as
the tegmina, folded in repose. Tribe 9. OxyHaxorpEs. [Plec-
topterinae Saussure.] (Fig. 129, Hypnorna amoena. )

4’, Anterior portion of wing, when present, rounded, with no
apical field. Tribe 10. PERISPHAERIIDES. (Fig. 130, Grom-
phadorhina portentosa ; Fig. 131, Pseudoglomeris fornicata.)

3. Subgenital lamina of males extronely small, without styles. No
pad between claws. ‘Tribe 11. PANESTHIIDES.
To the above tribes another one—GroscaPHEUSIDES—has been recently
added by Tepper,” for an extraordinary Australian Insect of fossorial habits,
with front legs formed somewhat like those of Gryllctalpa.

1 The ‘‘black beetle,” Stylopyga orientalis, belongs to this tribe, as does also
Periplaneta americana.
2 Tr. R. Soc. S. Austral. xvii. 1893, p. 68.

VOL. V R

CHAPTER X

ORTHOPTERA CONTINUED——MANTIDAE—SOOTHSAYERS

Fam. IV. Mantidae—Soothsayers or Praying Insects.

Orthoptera with exserted but deflexed head and elongate prothoraz,
the first pair of legs largely developed, raptorial, the coxae
elongate, free, femora and tibiae armed with spines: second
and third pair of legs simple and similar ; the tarsi five-
jointed, without a pad (arolium) between the claws ; a pair
of jointed cercr near the extremity of the body.

THE Mantidae are an extensive family of Orthoptera, showing
extreme variety in the shapes and outlines of the body, and -
characterised by the very remarkable front legs; the function of
these legs being to seize and hold their prey, which consists of
living Insects, Mantidae being carnivorous and highly voracious.
The labium is deeply divided, each half exhibiting a very |
near approach to the structure of a maxilla; there is a large
membranous lingua reposing on the inner face of the lower lip.
The head is quite free from the thorax, its front part being
deflexed, and even somewhat inflexed, so that the mouth 1s directed
downwards and somewhat backwards: it is very mobile, being
connected to the thorax by a comparatively slender neck, which —
is, however, concealed by the pronotum. There are two large,
prominent eyes, the antennae are frequently very slender, but
they sometimes differ according to sex, and in some genera
are pectinate in the male; just above and between their inser-
tion are three ocelli placed in a triangle, two above, one below ;
between the antennae and the clypeus there is an interval
called the scutellar space. In some forms of Mantidae the
head assumes most extraordinary shapes; the eyes may become

CHAP. X MANTIDAE 243

a

elongate and horn-like; there may be a projection between them
bearing the ocelli, and attaining occasionally a great length; the
scutellar space also may have a remarkable development, the

hc. 1385.—Deroplatys sarawaca, female. Borneo. (After Westwood.)

whole thus forming a peculiar ornamental structure, as in Fig.

156.

The prothorax is elongate, but there are a few genera, e.g.
Eremiaphila, in which it is exceptionally short, and there are
several others in which the elongate form is more or less masked
by foliaceous expansions of the sides. The pronotum shows
near the front a transverse depression or seam, which marks the
position of an internal chitinous ridge. The anterior legs are

244 ORTHOPTERA CHAP.

inserted near the front of the prosternum, which extends less
far forwards than the pronotum does; the posterior part of the
prosternum is very elongate, and is completely separated from
the anterior part by the base of
the coxae and the membranes
attached to them; the pronotum
and sternum are closely connected |
at the sides till near the posterior
part where they diverge, the space
so formed being occupied by a
membrane in which the prothoracice
stigma is situated. The meso-
thorax is as long as_ broad, and
the front wings are attached to
the whole length of the sides; the
vide mesosternum is a triangular piece
Fic. 136.—Head,of Harpax variegatus, pointed behind, and bearing very
seen from_the front. : ; R
: | large side-pieces, to the hinder
portion of which the middle: coxae are attached; these latter are
large and quite free, and repose on the metasternum which they
cover ; the mesothoracic stigma may be detected as a slit situated
on a slight prominence just behind:and.a little below the mem-
branous hind-margin of the tegmen: The metathorax differs
comparatively little in size and structure from the’ mesothorax ;
the membranous hind wings are attached to the sides of the
notum along nearly the whole length of the latter. The abdo-
men is moderately long; in each sex ten dorsal plates may be
detected, and there is a pair of ringed cerci projecting from
beneath the sides of the tenth plate. The number of ventral
plates is more difficult to verify, the first one being much
reduced; eight other plates can be demonstrated in the male
and six in the female. :

The anterior legs are formed in a remarkable manner in the
Mantidae, and are, in fact, the most characteristic feature of the
family. Attached near the front of the thorax there is a very
long coxa, to the apex of which is articulated the triangular
trochanter ; this bears the elongate femur, which is furnished on
its lower face with sharp spines and teeth; the tibia which
follows is much shorter and smaller than the femur; its lower
face bears also an armature of teeth, and it is so articulated with

x | MANTIDAE 245

the femur that it can be ers closed thereon, its teeth
fitting in among those of the femur (Fig.
137, B); the latter has one or more longer
spines overlapping the apical part of the
tibia when contracted. The tarsus is
slender, five-jointed, without pad. The other
two pairs of legs are simple; the hinder
usually a little the longer, and in some
species that possess powers of leaping
(Ameles), with the femora a little thicker
at the base.

The alar organs of the Mantidae are
as regards the nervures and areas fairly
similar to those of the Blattidae, The “gaecag wee ee
tegmina are usually narrow, and exhibit ‘female: A, with tibia

‘ extended and _ tarsus

three well-marked areas; the one in front wanting ; B, more mag-
or external (according as the wing is al eo.
expanded or closed) is the mediastinal mode of closure. —
area; it is usually more elongate and |
occupies a larger portion of the surface of the tegmen than in
Blattidae. The middle area, forming the larger part of the
wing, is occupied by the branches of the. radial and ulnar
nervures. The third area, the anal, possesses a sort of appendage
in the form of a small space of a more delicately membranous
nature at the inner part of the base. The tegmina are often
more or less leaf-like in texture and consistence; this character
is as a rule not very marked, but there are a few species with the
tegmina very like foliage, this being more marked in the female ;
in some, if not in all, of these cases the mediastinal area is con-
siderably increased. One tegmen overlaps the other, as in Blat-
tidae, but to a less extent, and the correlative asymmetry is but
slight: there is frequently a pallid spot close to the main vein
on the principal area, nearer to the base than to the extremity.
The hind wings are more ample than the front, and of much
more delicate consistence; they possess numerous veins converg-
ing to the base; the anterior part of the wing is firmer in con-
sistence, and its veins are more numerously fureate; there are
many. more or less distinct minute cross-veinlets, and an elegant
tinting is not infrequent. They close in a fan-like manner,
transverse folding being unknown in the family.

246 ORTHOPTERA CHAP.

But little has been written on the internal anatomy of the
Mantidae. Dufour has described only very partially that of J
religiosa. The salivary glands are largely developed, salivary
receptacles exist; the alimentary canal possesses eight elongate
coecal diverticula placed on the chylific ventricle; there are
about one hundred Malphigian tubules. In each ovary there
are about 40 egg-tubes, and they are joined at their bases in
clusters of about half a dozen; each cluster has a common sinus ;
these sinuses are placed at intervals along a tube, which is one
of two branches whose union forms the oviduct; there are a
large number of “serific glands” of two kinds in the female.
The testes are unusually complex in their structure.

According to Schindler+ the Malphigian tubes in Mantis are
not inserted, as usual, at the base of the intestine, but on the
intestine itself at about one-third of its length from the base.
There is some doubt about this observation. Schindler considers
the fact, if it be such, unique.

The eggs of the Mantidae are deposited in a singular manner :
the female, placing the extremity of the body against a twig or
stone, emits some foam-like matter in which the eggs are
contained. This substance dries and forms the ootheca; whilst
attaining a sufficient consistence it is maintained in position by
the extremity of the body and the tips of the elytra, and it is
shaped and fashioned by these parts. The eggs are not, as ©
might be supposed, distributed at random through the case, but
are lodged in symmetrically-arranged chambers, though how these
chambers come into existence by the aid of so simple a mode
of construction does not appear. The capsule is hard; it quite
conceals the eggs, which might very naturally be supposed to be
efficiently protected by their covering: this does not, however,
appear to be the case, as it is recorded that they are subject to
the attacks of Hymenopterous parasites. The time that elapses
after the eggs are laid and before they hatch varies greatly
according to circumstances. In France, Mantis religiosa deposits
its eggs in September, but they do not hatch until the following
June; while in E. India the young of another species of MJantis
emerge from the eggs about twenty days after these have been
deposited. Trimen has recorded some particulars as to the
formation of its egg-case by a Mantis in 8. Africa. This

1 Zeitschr. wiss, Zool. xxx. 1878, p. 609, pl. xxxviii. fig. 7.

x : MANTIDAE ; 247

specimen constructed four nests of eggs at intervals of about a
fortnight, and Trimen states that the four were “as nearly as
possible of the same size and of precisely similar shape.” He
also describes its mode of feeding, and says
that it was fond of house-flies, and would
eat “ blue-bottles,” ie. Musca vomitoria, but
if while eating one of the latter a house-fly
were introduced, the “ blue-bottle ” was gener-
ally dropped, even though it might be in
process of being devoured. The young have
to escape from the chambers in which they
are confined in these egg-cases; they do so
in a most curious manner; not by the use
of the feet, but by means of spines directed
backwards on the cerci and legs, so that
when the body is agitated advance is made
in only one direction. The eggs last de-
posited are said to be the first to hatch.
On reaching the exterior the young Mantids

Fic. 138.—Egg-case of

do not fall to the ground, but remain sus-
pended, after the manner of spiders, to the
—ootheca by means of two threads attached to
the extremities of the cerci; in this strange
position they remain for some days until the
first change of skin is effected, after which

Mantis with young

‘escaping: A, the case

with young in their
position of suspension ;
B, cerci magnified,
showing the suspen-
sory threads. (After
Brongniart. )

they commence the activity of their predatory life.

Dr. Pagenstecher has given an account’ of the development
of Mantis religiosa, from which it would appear that the statements
of Fischer and others as to the number of moults are erroneous,
owing to the earliest stages not having been observed. When
the young Mantis emerges from the egg it bears little resemblance
to the future Insect, but looks more like a tiny pupa; the front
legs, that will afterwards become so remarkable, are short and not
different from the others, and the head is in a curious mummy-
like state, with the mouth-parts undeveloped and is inflexed on
the breast: there are, he says, nine abdominal segments. The
first ecdysis soon takes place and the creature is thereafter
recognisable as a young Mantis. Pagenstecher’s specimens at
first would only eat Aphididae, but at a later stage of the

1 Arch. f. Naturgesch. xxx. Band 1, 1864, p. 7.

248 ORTHOPTERA CHAP.

development they devoured other Insects greedily: the number
of ecdyses is seven or eight. The ocelli appear for the first time
when the wing rudiments do so; the number of joints in the
antennae increases at each moult. Dr. Pagenstecher considers
that this Insect undergoes its chief meta-
morphosis immediately after leaving the ‘egg,
the earlier condition existing apparently to
fit the Insect for escaping from the egg-case.
In the immature stage of the Mantidae the alar
organs appear (Fig, 139) as adjuncts of the ~
sides of the meso- and meta- notum, projecting
backwards and very deeply furrowed and
ribbed in a wing-like manner. According to
Fig. 139. — Tegmina Pagenstecher, this wing-like appearance only
(t) and wings (w) of commences in the fifth stadium, but he has
immature Mantis, ; ° eis
E not given particulars of the conditions of
these parts in the preceding instars. According to de Saussure *
the wings of the females of some species remain permanently in
this undeveloped or nymphal state.

The Mantidae, as a rule, have a quiet unobtrusive mien, and
were it not for their formidable
front legs would look the picture of
innocence; they, however, hold these
legs in such manner as to greatly
detract from the forbidding appear-
ance thereof, stretching them out only
partially so as: to give rise to an
appearance of supplication or prayer;?
‘this. effect is increased by their
holding themselves in a semi-erect
position, standing on the hind and
middle legs with the upper parts of
the body directed somewhat for-
wards, hence they are called by
various names indicating prayer or
supplication, and it is said that in
some countries they are considered sacred. Some of the older

Fic. 140.—Jris oratoria, female.
South Europe. Natural size.

1 Biol. Centr. Amer. Orthopt. 1894, p. 160. .
2 Our figures do not exhibit this attitude ; if portrayed in their natural position
in a drawing the front legs would be to a large extent obscured.

ee <—~'d ?
ao ,

LAR eR re ORR

=
i.

— DECEPTIVE MANTIDAE 249

writers went so far as to say that a Mantis would indicate

the road a child should take by stretching out one of its arms

in the right direction. The traveller Burchell, speaking of
a species since described by Westwood under the name of
Tarachodes lucubrans, says: “I have become acquainted with
a new species of Mantis, whose presence became afterwards
sufficiently familiar to me by its never failing, on calm warm
evenings, to pay me a visit as I was: writing my journal, and
sometimes to interrupt my lucubrations by putting out the
lamp. All the Mantis tribe are very remarkable Insects; and
this one, whose dusky sober colouring well suits the obscurity of
night, is certainly so, by the very late hours it keeps. It often
settled on my book, or on the press where I was writing, and
remained still, as if considering some affair of importance, with
an appearance of intelligence which had a wonderful effect in
withholding my hand from doing it harm. Although hundreds
have flown within my power, I never took more than five. I
have given to this curious little creature the name of Mantis
lucubrans ; and having no doubt that he will introduce himself
to every traveller who comes into this country [Southern Africa]
in the months of November and December, I beg to recommend
him as a harmless little companion, and entreat that kindness and
mercy may be shown to him.’ This appearance of innocence
and quietness must have struck all who have seen these Insects

- alive; nevertheless, it is of the most deceptive character, for the

creature’s activity consists of a series of wholesale massacres
carried on day after day, the number of victims it sacrifices being
enormous. The J/antis does not even spare its own kind; it
is well known that the female not unfrequently devours its own
mate. A very different picture to that of Burchell has been
drawn by Potts, who observed the habits of a species in New
Zealand.’ He informs us that when about making an attack it
approaches its intended prey with slow, deliberate movements, its
anterior limbs folded in an innocent fashion, now and then
raising itself or lifting the prothorax in a stealthy quiet manner,
perhaps to judge accurately of its distance; when near enough,
with one swift dart the victim is secured. The prey is held

' The name of the species is not given (7r. NV. Z. Inst. xvi. 1883, p. 114), but
it is probably Orthodera ministralis Fab., an Australian Insect perhaps taken to
New Zealand by miners. Cf. Wood-Mason, Cat. Mantodea, i. 1889, p. 20.

250 ORTHOPTERA CHAP,

firmly in the formidable trap formed by the anterior leg, and is
thus brought near the mouth. The Mantis usually commences
its feast by taking off some portions of the head of its wretched
victim, and displays an absolute indifference to its struggling or
kicking; the mandibles having seized a portion of the food, the
legs holding it move away, thus leaving a fragment in the mouth.
Portions only of a captured Insect are consumed, much being cast
away; and Mr. Potts states that he has seen one of these voracious
creatures kill and devour parts of fourteen small flies within a
very brief space of time. This voracity and waste of animal
food is very remarkable when we recollect that many Insects
have such perfect powers of assimilation that during their whole
period of growth they only consume a mass of food—and that
vegetable—but little larger in size than the bulk they themselves
attain. This fact is well known in the case of Bruchus, Caryo-
borus, and other seed-feeding Insects. Burmeister has stated good
' grounds for believing that some of the larger Mantidae do not
confine themselves to Insect diet, but attack and devour small
Vertebrates." He has given a circumstantial account of a case at
Buenos Ayres, where a small bird was secured by the wingless
female of a large Mantis, which had commenced devouring its
head when the observer took possession of the creature and its
booty. Dubois states? that when a decapitated, but living,
Mantis was suspending itself to a roll of drapery by its four
posterior legs, a person could detach with the fingers the left
anterior leg (of the four) and the right posterior, or conversely
the left posterior and right anterior, without the interference
producing any action on the part of the creature; but if one
of the other legs was also interfered with, which would neces-
sarily have changed the position of the body, then immediately
one of the two unoccupied legs was placed by the creature in a
proper position to assure its stability. This reflex action alto-
gether resembled in appearance a conscious action, and was as
effectually performed.

The combination in Mantidae of voracious and destructive
instincts with helpless and inert attitudes gives rise to the idea that
these latter are adopted for the purpose of deceiving the living
prey and of thus more easily obtaining the means of subsistence.

1 Berlin. ent. Zeitschr. viii. 1864, p. 234.
* Ann. Soc. Linn. Lyon, xi. 1893, p. 205.

x _MANTIDAE 251

It appears, however, more probable that the helpless attitudes
have no such origin, but are due to the structure and form of the
creature. The front legs being wonderfully well formed for
raptorial purposes, have no capacity for locomotion or for support-
ing the Insect in the usual manner, so that the body has to be
borne by the hinder two pairs of legs; at the same time the
raptorial pair of limbs—which, it will be recollected, are of great
size and attached to the anterior part of an unusually long
prothorax—have to be held in such a position as will not derange
the equilibrium maintained by the posterior part of the body ;
moreover, these large raptorial legs are entirely exserted, and
have no trace of any articulatory cavity that might act as a
mechanical aid to their support. Thus they could not be held
extended without great muscular exhaustion; hence we can
well believe that the sedentary and helpless attitudes of the
creature are not the results of any guile.

A Mantis has been recorded as bearing a close resemblance
to a Phasmid of the genus Bacillus and having only small front
legs; it was suggested by Bates’ that the Mantis would probably
be found to feed on the JSacillus. Though the case is of con-
siderable interest, no further information about it has been
_ obtained.

The simplest forms of the family are found in the groups
Amorphoscelides and Orthoderides. From our figure of one of
these (Fig. 141, Mantoidaluteola $), it will
be seen that the peculiarities of the family
can scarcely be detected, the raptorial legs
being very little developed and the prothorax
short. The sexes, too, differ but little in &
these simple forms. Most of them are very &
rare in collections, but Wood-Mason states?
that Amorphoscelis annulicornis is frequently
found about Calcutta on the trunks of Fic. 141. — Mantoida

: aa aoe tie luteola Westw., male.
trees, to the bark of which it is so similar uataruts.
that it is only discovered with difficulty.
In its rapid movements it resembles the cockroaches or Machilis,
more than it does the more differentiated forms of its own

group.

1 Proc. ent. Soc. London, 1867, p. ev.
2 Cat. Mantodea, i. 1889, p. 4.

252 ORTHOPTERA CHAP.

In the genus Pyrgomantis (Fig. 142, P. singularis, female)
the male has the tegmina and wings of normal size, while in
the female they are rudimentary.

The variety of shape and external appearance in this family
is very great; de Saussure considers it to be a mimetic group.
In certain species some parts of the body—more especially the
tegmina—have very much the appearance of foliage, and usually
in such cases this appearance is confined to the female, the males
in this family having, as we have said, the organs of flight more
transparent and colourless : in the former sex the alar organs,

Fic. 142.—Pyrgomantis singularis, Fic. 143.—Outline of Chaeradodis —
female. 8. Africa. (After West- cancellata 9, nymph. (After
wood, ) Wood- Mason. )

when present, are frequently but little adapted for flying. In
some species the prothorax is expanded at the sides (Fig. 135,
Deroplatys sarawaca; and Fig. 143, Choeradodis cancellata), and
in such cases the outline of the natural thorax—if we may use
such an expression—may be detected occupying the middle of
the unusual expansion. The European Mantis religiosa varies
much in colour; in some examples the tegmina are leaf-green,
while in others they are brown or gray. There is some evidence
extant making it probable that in some species the colour of an
individual changes at different times—Colonel Bowker saying of

CEE TE ee nha Tw

x DESERT MANTIDAE 253

‘sure considers that some species of

Harpax ocellata that it “beats the Chameleon hollow in changing
colour.” : .

Some of the species of the old genus Hremiaphila (Fig. 144)
are of very unusual form. De Saus-

this genus are more highly modified
than any other'animals for maintain-
ing ‘their existence in desert regions.
They are said to be found in places
where no vegetation exists, and to
assimilate in appearance with the
sandy soil, the species varying in
colour, so that the individuals agree -
in tint with the soil on which they
dwell. These Insects are referred to
the group Orthoderides, and have a
short prothorax, the alar organs being
unsuited for flight. What they live
on is not actually known; although other Insects are the
natural food of Mantids, it is said that these desert-frequent-
ing species occur in spots where no other Insect life is known
to exist. Lefebvre’ met with these Eremiaphilas in the desert
between the Nile and the Northern Oasis, El Bahryeh, but was
quite unable to discover their mode of subsistence. These
Insects are very rare in collections, and the information we
possess about them is very meagre. .

Mr. Graham Kerr found on the Pilcomayo river a species of
Mantidae living on branches of trees amongst lichens, which
it so exactly resembled that it was only detected by the move-
ment of a limb; it was accompanied by a Phaneropterid grass-
hopper, which bore a similar. resemblance to the lichens. One
of the rarest and most remarkable forms of Mantidae is the
genus Zoxodera, in which the eyes project outwards as: pointed
cones (Fig. 145). These Insects offer an interesting problem
for study, since we are entirely ignorant about them. Brunner
places the Toxoderae in his tribe Harpagides, but with the
remark that “these Insects of antediluvian shapes differ essen-
tially from all other Mantidae.”

. Wood-Mason informs us? that the young of Hymenopus bicornis

1 Ann. Soc. ent. France, 1835, p. 457. 2 P. ent. Soc. London, 1877, p. xxix.

Fic. 144.—Hremiaphila turcica.
(After Westwood.)

254 ORTHOPTERA CHAP.

beautifully simulate blossoms of different colours. And it has

been stated by Dr. Wallace, on the authority of a communication

made to him by Sir Charles Dilke, that a small Mantis found in

Java exactly resembles a pink Orchis-flower, and this species

“was not only said to-

attract Insects, but even

the kind of Insects (but-

terflies) which it allures

and devours was men-

an tioned.” We'do not know

of what species or genus

, this Insect may be, but

| Hymenopus bicornis is a

} peculiar form of the tribe

Harpagides, and has, to-

gether with its younger

state, been figured long

ago by Caspar Stoll in

his quaint and interest-

ing old book.’ Though

| it has very peculiar foli-

\. aceous expansions on the

two hinder pairs of legs,

these dilatations are very

\ different from those seen

in the curious Gongylus

gongyloides, the female

V of which we figure (Fig.

ay ! 146). This latter,accord-
Fic, 145,—Toxodera denticulata, male. Java. ‘ : :

(After Serville. ) ing to the information

we shall quote, is also a

“floral simulator.” Specimens of G. gongyloides were shown to

the members of the Asiatic Society of Bengal in 1877 by Dr. J.

Anderson,? who at the same gave some information about them

which we shall reproduce in full, because, incomplete as it is, it

is apparently almost the sole piece of definite information we

possess as to this curious Insect, or any of its congeners :—
“These Insects all came from the same locality, having been

Wl

~~
Ca

)

NK

}

SSS

SE = =
NY Ss ls =
SESS <

fA
\

SS
Bs

Sg

Ss

1 Afbeeldingen der Spoken en wandelende Bladen, etc., Amsterdam, 1813.
2 P, Asiat. Soc. Bengal, 1877, p. 193.

—

x FLORAL SIMULATORS 255

forwarded to Mr. Buckland by Mr. Larymore of the Central Jail
at Midnapur. Mr. Larymore had procured them from the neigh-
bouring country district, where Santdél women and children had
hunted them out and brought them in, hanging on branches or
twigs of a bush, somewhat like a wild plum-tree. They are also
said to be found upon rose-bushes, and in connexion with this it

Fig. 146.—Gongylus gongyloides, female. East India.

was observed that, in Midnapur, they were known as rose-leaf
Insects, from the circumstance that when the Insect is more
developed and furnished with. wings, the foliaceous appendages
are said greatly to increase in size, and exactly to resemble rose-
leaves. Dr. Anderson, however, was disposed to think that more
than one species might probably occur in the Midnapur district,
and that these Insects with the larger foliaceous expansions might
be distinct from the species now before the Society.

256 ORTHOPTERA CHAP.

“Mr. Buckland had made over these Insects to Dr. Anderson,
and since that time they have been regularly fed upon house-flies -
and grasshoppers; the latter, however, appear to be rather too
strong for them, and they therefore prefer the flies. They have,
been tried with small fragments of plaintain and custard-apple,
which they not only eat, but the juice of which they seem to
suck with considerable avidity, Dr. Anderson, however, thought
that it was the moisture of these fruits that was the chief attrac-
tion to these Insects, for the entire character of their organisation
indicated a raptorial habit.

“Dr. Anderson went on to say that he had succeeded in
identifying the three larger Insects by means of a single dried
specimen in the Indian Museum, which, however, was fully
mature and provided with wings. These remarkable Insects
proved to be the pupae of a peculiar species of Mantis which was
known to Aldrovandus, who figured it more than a century and
a half before the first appearance of the Systema Naturae of
_ Linnaeus, to whom it was known as Gryllus gongylodes, and also
as Mantis gongylodes ; and since the time of Aldrovandus it had
been figured in a variety of works on Natural History, but
apparently in every instance from rhature, and seemingly dried.
specimens, so that the colours of the Insect during life had never
been correctly described.

“So much by way of introduction.to these remarkable pupal
Mantises, the recognised scientific name of which is Gongylus
gongylodes L. 3

“The reason which induced Dr. Anderson to bring them to—
the notice of the Society had now to be pointed out. On looking
at the Insects from above, they did not exhibit any very striking
features beyond the leaf-like expansion of the prothorax and the
foliaceous appendages to the limbs, both of which, like the upper
surface of the Insect, are coloured green, but on turning to the
under surface the aspect is entirely different. The leaf-like ex-
pansion of the prothorax, instead of being green, is a clear, pale
lavender-violet, with a faint pink bloom along the edges of the
leaf, so that this portion of the Insect has the exact appearance
of the corolla of a plant, a floral simulation which is perfected —
by. the presence of a dark, blackish brown spot in the centre,
over the prothorax, and which mimics the opening to the tube of
a corolla. A favourite position of this Insect is to hang head

= FLORAL SIMULATORS 257

downwards among a mass of green foliage, and, when it does so,
it generally remains almost motionless, but, at intervals, evinces a
swaying movement as of a flower touched by a gentle breeze;
and while in this attitude, with its fore-limbs banded violet and
black, and drawn up in front of the centre of the corolla, the
simulation of a papilionaceous flower is complete. The object of
the bright colouring of the under surface of the prothoracic ex-
pansion is evident, its purpose being to act as a decoy to Insects,
which, mistaking it for a corolla, fly directly into the expectant,
serrated, sabre-like, raptorial arms of the simulator. It is no
new fact that many Insects resemble the leaves of plants and
trees, and that they manifest forms and colours which serve to
protect them in the struggle for existence, but so far as Dr.
Anderson had ascertained, this was the first recorded instance of
an Insect simulating the corolla of a flower for the evident
purpose of attracting Insects towards it for its sustenance, It
is even more remarkable than this, for it is a localised adaptation
for such a purpose, a portion of the Insect being so modified in
form and colour that the appearance of the corolla of a plant is
produced, in conjunction with the remainder of the long attenuated
prothorax, which at a distance resembles the flower stem; the
anterior limbs when in repose even adding to and heightening
the deception.”

That we should have no more precise information as to a
large Insect of such remarkable habits and appearance, and one
that has been known to naturalists for upwards of three centuries,
is a matter for regret. Careful observation as to the habits, food,
and variation of these floral simulators, and as to whether they
seek for spots specially suitable to their coloration, would be of
great interest. A European congener of this Insect, Hmpusa
pauperata, has small foliaceous expansions on the legs, but its
habits have not been noticed in detail.

The very curious Insect represented in Fig. 141, Stenophylla
cornigera,is a member of the tribe Vatides; the form of the cerci
at the end of the body is very peculiar. This extremely rare;
if not absolutely unique, Insect is a native of the interior of
Brazil. |

Dufour has recorded that Mantis religiosa possesses the power
of producing a mournful sound by rubbing the extremity of the
body against the wings; it is stated that a hissing sound is

VOL, V )

258 ORTHOPTERA CHAP.

produced by other species, and Wood-Mason has suggested’ that
a special structure exists on the tegmina for the purpose.

There are probably about 600 species of Mantidae known ;
they are distributed over all the warmer parts of the earth, but
there are none in the cooler regions. Europe possesses some twelve
or fourteen species, most of them confined to the Mediterranean
sub-region ; a single species, Mantis religiosa, is frequently found in
Central France, and has been recorded as occurring as far north as:
Havre. Although no species is a native of Britain, it is not

Fic. 147.—Stenophylla cornigera. Brazil. (After Westwood. )

difficult to keep them alive here. Denny records? that an egg-.
case of a Mantis was sent from Australia to England, and that
the hatching of the eggs was completed after its arrival. The
young fed readily on flies, and we are informed that in the —
neighbourhood of Melbourne, where this Jantis is plentiful,
specimens are placed by the citizens on the window-blinds of their
houses, so that the rooms may be cleared from flies by means of
the indefatigable voracity of the Mantis.

The geological record as to Mantidae is very meagre and
Guia tiabictory. The genus Mantis is said to occur in amber,
and Heer has referred to the same genus an ill-preserved fossil
from the upper Miocene beds of Central Europe; a fragment

1 Tr, ent. Soc. London, 1878, p. 263. 2. Ann. Nat. Hist. 8rd ser. xix. 1867, p. 144. .

a
—

x | MANTIDAE 259

of a hind wing found in the Jurassic strata of Siberia has been

assigned to the family; and until recently Lithomantis from the

Carboniferous beds of Scotland was considered to belong to
Mantidae. Scudder, however, has rejected it therefrom, placing it -
in the Neuropteroid division of Palaeodictyoptera, and Brongniart,
adding another species to the genus from the Carboniferous strata
in France, proposed to treat the two as a distinct family, which he
called Palaeomantidae.! This naturalist has, however, since renewed
his study * of these Insects, has become convinced that they have
no relations with existing Mantidae, and has consequently removed
them to the family Plats vtenideas in the Order Neuroptera.

Six tribes of Mantidae are recognised by Brunner and de
Saussure.

Table of the tribes of Mantidae :—

1. Anterior tibiae with the outer edge unarmed beneath or only furnished»

with very minute tubercles. (Pronotum not longer than the anterior
coxae.) Tribe 1. AMORPHOSCELIDES. (Fig. 141, Mantoden luteola.)
1’. Anterior tibiae with the outer edge spinose beneath.

2. Anterior femora having the inner edge armed beneath with equal
spines, or with spines in which only the alternate are smaller.
Antennae of the male simple, rarely unipectinate.

3. Tibiae and also the intermediate and hind femora even above.
4. Legs and body with no lobe-like processes. (Antennae pao
in each sex.)

5. Pronotum not forming any dilatation above the insertion of
the coxae, its lateral margins straight or (in the genus
Choeradodis) strongly dilated with the anterior margin not
rounded. Tribe 2. ORTHODERIDES. (Fig. 142, Pyrgomantis ;
Fig. 143, Choeradodis ; Fig. 144, Eremiaphila turcica.)

5’. Pronotum dilated above the insertion of the coxae, there with
the lateral margins broadened in a round manner, the anterior
margin rounded. Tribe 3. MantipEs. (Fig. 140, Iris oratoria.)

4’. Legs or body furnished with lobes. (Posterior femora or
segments of the body with lobes, or vertex of the head
conically prolonged.) Tribe 4. Harpacipes. (Fig. 136,
Harpasz variegatus ; Fig. 135, Deroplatys sarawaca.)

3’. Tibiae as well as the intermediate and hind femora carinate
above. (Pronotum elongate, with the posterior part, behind the
transverse groove, three times as long as the anterior part.)
Tribe 5. VatTipes. (Fig. 147, Stenophylla cornigera.)

2’. Anterior femora beneath, with the inner edge armed between the
longer teeth with shorter teeth, usually three in number. Antennae

of the male bipectinate. (Vertex conically prolonged.) ‘Tribe 6.

Empusipes. (Fig. 146, Gongylus gongyloides.) ©

1 Bull. Soc. Philomat. (8) ii. 1890, p. 154, _
"? Insectes fossiles des temps primatres, 1894, p. 353.

CHAPTER Xl

ORTHOPTERA CONTINUED——PHASMIDAE—W ALKING-LEAVES
—STICK-INSECTS

Fam. V. Phasmidae—Stick and Leaf Insects.

eHead exserted ; prothorax small, not elongate; mesothorax very
elongate ; the siz legs differing but little from one another,
the front pair not raptorial, the hind pair not saltatorial.
The cerci of the abdomen not jointed, consisting of only one
prece; the tarsi five-jointed. Tegmina usually small, or
entirely absent, even when the wings are present and ample.
The sexes frequently very dissimilar, Absence of alar
organs frequent.

THESE Insects are amongst the most curious of natural objects.
They are frequently of large size, some attaining 9 inches
in length (Fig. 162, Palophus centaurus, one-half natural length).
Their variety of form could scarcely be surpassed; their re-
semblance to products of the vegetable kingdom is frequently
very great: some of the more linear species (Fig. 148, Lonchodes
nematodes) look like sticks or stems of grass; some have a moss-
like appearance, while others resemble pieces of lichen-covered
bark. The members of the tribe Phyllides are leaf-like. A
certain number of other Phasmids are covered with strong
spines, like thorns (Fig. 149). The plant-like appearance is
greatest in the female sex. When there is a difference between
the two sexes as to the organs of flight, these are more fully
developed in the male.

The antennae are usually many-jointed, but the number of
joints varies from 8 to more than 100; the head is exserted ;
the eyes are more or less prominent; ocelli are present in some

long; it is very simple in structure, consisting

‘it is always of large size relatively to the other

CHAP. XI STICK-INSECTS 261 -

eases. The prothorax is always small, and it is a remarkable
fact that it undergoes but little elongation even in those species
that are most linear and clongate in form (see Fig. 148, Lonchodes
nematodes), and that have the meso- and metathoraces extremely

apparently merely of a dorsal and of a sternal
plate, nearly the whole of the side being occupied
by the large space in which the coxae are inserted ;
the edges of the pronotum are not free. The
mesothorax is frequently six times as long as the
prothorax, though in the leaf-like and a few other —
forms it does not possess this great extension ; still

two thoracic segments. This is peculiar inas-
much as in other groups where the mesothorax is
relatively large there are powerful mesothoracic
wings; whereas the Phasmidae are remarkable for
the obsolescence of the mesothoracic alar append-
ages. The middle legs and the tegmina or elytra,
when present, are attached only to the posterior
part of the mesothorax; the notum and the
sternum are separated by two narrow slips on
each side, the epimeron and episternum. The |
metathorax is formed like the mesothorax,
except that the posterior part of the dorsal sur- =~ |
face is considered to consist of the first ventral [
segment consolidated with the posterior part of ‘
the metanotum, the two being distinct enough in
the winged forms. The hind body or abdomen :
is elongated except in the Phylliides; it consists |
of ten dorsal plates; the first frequently looks like
a portion of the metanotum, and is treated as F1>.148.—Loncho-
really such by Westwood, who describes the abdo- MUAer deci,
men as consisting of nine segments. The flat apical _Pelago. (Alter
; estwood. )
appendages are attached behind the tenth dorsal
plate. The ventral plates are similar to the dorsal in arrangement,
except that in the female the eighth plate forms a sort of spoon-like
or gutter-like process to assist in carrying or depositing the eggs, and
that the two following segments are concealed by it, and are some-
times of more delicate texture. The legs vary greatly in the details of

Ni-

262 ORTHOPTERA > CHAP,

their shape: the coxae are short, oval, or round, never .large; the
trochanter is small; the front femora.
often have the basal part narrower
than the apical, and they are fre-
quently so formed that they can be
stretched out in front of the head, —
concealing its sides and outline and.
entirely encasing the antennae.
There is an arolium or cushion
between the claws of the five-
jointed tarsi. The front legs are
frequently longer than the others.
Only a very slight study has been
made of the alar organs of Phas-
midae; but according to Redten-
bacher and Brauer, they differ
greatly from those of Blattidae and
Mantidae, inasmuch as the costal
vein is placed not on the actual
i margin of the wing but in the
‘ field thereof, and in this respect
they more resemble the Orthoptera
saltatoria.

Very little information exists
as to the internal anatomy of the Phasmidae. Many years ago
a memoir of a fragmentary and discursive nature was published
on the subject by J. Miiller,’ but his conclusions require con-
firmation ; the nervous system, according to his account, which
refers to Arumatia ferula, has the anterior ganglia small, the
supra-oesophageal ganglion being apparently not larger than
those forming the ventral chain.

Joly’s more recent memoir on the anatomy of Phylliwm
crurifolium ? is also meagre; he states that the nervous system
resembles that of the locusts (Acridiidae), though there are at
least ten pairs of ganglia—one supra-, one infra-oesophageal, three
thoracic, and five abdominal. He found no salivary glands; the
Malpighian tubules are slender, elongate, and very numerous.
The tracheal system has no air-vesicles. He found no distinction

Fic. 149.—Heteropteryx grayi, male.
‘Borneo. One-half natural size.

1 Acta Ac. German. xii. 1825, pp. 555-672, pls. 1.-liv.
2 Mem. Ac. Sci. Toulouse, series 7, iii. pp. 1-30.

se

xr PHASMIDAE 263

of crop and proventriculus, but the true stomach appears to consist

of two different parts, the anterior being remarkably uneven

externally, though destitute of coeca, while on the posterior part
there are peculiar vermiform pronterss There are eighteen or
twenty tubes in each ovary.

When the young Insect is in the egg, ready for emergence,
the meso- and meta-thorax are not remarkably elongate, so that
the femora are not very far
apart, but by the time the crea-
ture has fairly emerged from the
prison of its embryonic life the
thoracic segments have attained
their usual proportions; much
expansion of the body takes place
as the Insect leaves the egg, so.
that it appears a marvel how it
could have been contained therein;
this expansion affects the parts
of the body unequally.

_ The records as to the post-
embryonic development of Phas-
midae are very scanty, but indi-
cate great differences in the
length of time occupied by it.
Bacillus patellifer is said to
moult several times, Diaphero-
mera femorata only twice. This
latter > ee becomes full iprtaies Fia.150.—Aschipasma catadromus, female.
in six weeks, while, according Sumatra. Natural size. (After West-
to Murray,’ Phylliwm scythe i in
required fifteen or sixteen months for growth, and did not
moult until ten months after hatching; the number of
ecdyses in the case of the Phylliwum was three. At cach
ehange of skin an immediate increase in.size, similar to that we
have noticed as occurring on leaving the egg, takes place; each
limb on being freed becoming about a fourth longer and larger
than the corresponding part of the envelope from which it has

just been withdrawn. After the second moult of Phyllium the

tegmina and wings made their appearance, but remained of very
1 Edinburgh Philosoph. Journ. January 1856.

264 ORTHOPTERA 7 CHAP.

small size until after the third moult, when they suddenly shot out
to their full size; they came out of little cases about a quarter of
an inch long, and in the course of a
few minutes attained their full size
of about two and a half inches of
length. In the apterous species the
difference between the young and
adults in external characters is very
slight. — ;
Phasmidae are very sensitive to
cold; both in North America and
Australia their lives are terminated —
by the occurrence of frost. They
are all vegetable feeders, the canni-
balism that has been attributed to
them by several writers being prob-
ably imaginary. They are, how-
ever, excessively voracious, so that a
pair will destroy a great quantity
of foliage; they are consequently
in some parts of the world classed
amongst injurious Insects. In Fiji
tT _ and the Friendly Islands, Lopaphus
Fie. 151.—Ceroys saevissima. Brazil. .
(After Westwood. ) cocophagus eats the cocoa-nut foliage
and causes a scarcity of food, so that —
it becomes a matter of necessity to destroy these Insects, One
writer has gone so far as to attribute the occurrence of cannibal
habits amongst the inhabitants of some of these islands to the want
of food caused by the ravages of this Insect. Some, if not all, of
the Phasmidae have the habit of ejecting a stinking fluid, that is
said to be very acrid, and occasionally, when it strikes the eye, to
cause blindness; this liquid comes from glands placed in the
thorax. Some Phasmidae are much relished as food by birds;
Napheromera femorata is sucked by several bugs as well as eaten
by birds, and another species is recorded to have harboured
Ichneumon-flies in its body without suffering any apparent incon-
venience from their presence or from their emergence. Not-
withstanding the great amount of food they consume and their
want of activity, they produce comparatively few eggs. From
twelve to twenty or thirty is frequently mentioned as about the

XI EGGS OF PHASMIDAE 265

number, but in the case of Diapheromera femorata Riley speaks
of upwards of one hundred. These eggs are not deposited in any
careful way, but are discharged at random, simply dropping from
the female; the noise caused by the dropping of the eggs of
MNapheromera femorata from the trees on which the Insects are
feeding to the ground is said to resemble the pattering of rain-
drops. The eggs of this
species-often remain till
the second year before
they hatch. The eggs
in the Phasmidae gen-
erally are of a most
remarkable nature, and
nearly every one who

; h k A B C D
mentions them Speaks Pye, 152.—Eggs of Phasmidae: A, Lonchodes duiven-
of their extreme resem- bodi ; B, Platycrania edulis ; C, Haplopus grayi ;

blance to seeds. Gdoldi2 D, Phyllium siccifolium. (After Kaup.)

has suggested that this is for the purpose of deceiving Ichneumons ;
it 1s, however, on record that the eggs are actually destroyed by
Ichneumons. It is worthy of notice that the eggs are-shed like
seeds, being dropped loosely and, as we have said, remaining on
the ground or elsewhere, sometimes for nearly two years, without
other protection than that they derive from their coverings.
Each egg is really a capsule containing an egg, reminding us thus
of the capsule of the Blattidae, which contains, however, always
a number of eggs. Not only do the eggs have a history like that
of seeds, and resemble them in appearance, but their capsule in
minute structure, as we shall subsequently show, greatly resembles
vegetable tissue. The egg-capsule in Phasmidae is provided
with a lid, which is pushed off when the Insect emerges (Fig.
157). This capsule induced Murray to suppose that the egg
contained within is really a pupa, and he argued therefrom that
in the Orthoptera the larval stages are passed in the egg, and
that the Insect after its emergence should be looked on as an
active pupa that takes food.

The individuals of this group of Insects possess the power of
reproducing a lost hmb; and Scudder, who has made some experi-
ments as to this,” states that if a leg be cut off beyond the

1 Zool. Jahrb. Syst. i. 1886, p. 724.
2 P. Boston Soc. xii. 1869, p. 99.

266 - ORTHOPTERA CHAP.

trochantero-femoral articulation, the parts remaining outside of
this joint are dropped before the next. moult, and are afterwards
renewed either as a straight short stump in which the articula-
y tions are already observable, or as a
miniature leg, the femur of which is

| . straight and the tibia and tarsus

Ly # i curved into a nearly complete circle ;

f 3 in the former case, the leg assumes at
Va \ the next moult the appearance that
\ \ it has in the second ease; this latter
‘ form is always changed at the succeed-
ing moult into a leg resembling the
normal limb in every respect except-
ing size, and the absence of the fourth
tarsal joint (Fig. 153). If the leg
be removed nearer to the body than
the trochantero-femoral articulation
the limb is not replaced.

The sexes are frequently ex-
tremely different; the female is usually
very much larger than the male.
This latter sex often possesses wings
when they are quite wanting in the
other sex; the resemblance to por-
tions of plants is often very much
greater in the female than it is in
the male.

We have pointed out that the
) tegmina or upper wings are usually

of small size or absent (Fig. 150,
Aschipasma catadromus), even in the

species where the lower wings are

‘ very largely developed ; in such cases
4 the latter organs are folded in a
Sita SAS, agelte reg pegs complicated, fan-like manner, and
front leg has been renewed. repose on the back, looking as if

Senegal. (After Westwood.) ’ :

they were really the tegmina (Fig.
159, Calvisia atrosignata); this appearance, moreover, is in some
species enhanced much by the fact that the part of the wing
which is outermost in the folded state is quite differently

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—_
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rE

XI LEAF-INSECTS 267

coloured from the rest of the organ. The colour of the body in
many Phasmidae is said to be very variable, and if the tints be
owing to chlorophyll or other plant juices, finding their way amongst
the Insect-tissues, this is readily understood; in Diapheromera
the young Insect is brownish on hatching, becomes green after
feeding, and turns brown again when the leaves do so. The
ocelli, too, are saia to be very variable, and M‘Coy goes so far
as to state’ that they may be either present or absent in different
individuals though of the same species and sex,—a statement so
remarkable as to require minute examination, though it is to some
extent confirmed by the remarks of other entomologists.

The resemblance presented by different kinds of Orthoptera
to leaves is so remarkable that it has attracted attention even in
countries where Natural History is almost totally neglected; in
many such places the inhabitants
are firmly convinced that the
Insects are truly transformed
leaves, by which they understand
a bud developing into a leaf and
subsequently becoming a walking-
leaf or Insect. To them the
change is a kind of metamor-
phosis of habit ; it grew as a leaf
and then took to walking It
is usually the tegmina that dis-
play this great resemblance to
vegetable structures, and there is
perhaps no case in which the
phenomenon is more marked than
it is in the genus Phyllium, the
members of which occur only in
the tropical regions of the Old
World, where they extend from =
Mauritius and the Seychelles to ee tacod
the Fiji Islands—possibly even
more to the East—and have, it would appear, a peculiar penchant
for insular life. The genus Phyllivm constitutes by itself the
tribe Phylliides. Although the characters and affinities of this

1 Prod. Zool. Victoria, Decade vii. 1882, p. 34.
2 See de Borre, CR. Soc. ent. Belgique, xxvii. 1883, p. exliii.

268 ORTHOPTERA _ CHAP.

group have been only very inadequately investigated, it will
probably prove to be a very distinct and isolated one. The
species are not well known, but are probably numerous, and the
individuals are believed not to be rare, though the collections of
entomologists are very badly supplied with them. The resem-
blance of the tegmina or front wings to leaves is certainly of
the most remarkable nature. During the early life the Insect
does not possess the tegmina, but it is said then to adapt itself
to the appearance of the leaves it lives on, by the positions it

Fic. 155.—Phyllium scythe, male. Sylhet. (After Murray.)

assumes and the movements’ it makes. When freshly hatched
it is of a reddish-yellow colour: The colour varies at different
periods of the life, but “always more or less resembles a leaf.”
After the young Insect has commenced eating the leaves it speedily
becomes bright green; and when the metamorphosis is completed
the female Insect is possessed of the leaf-like tegmina shown in
Figs. 154, 156. Before its death the specimen described by
Murray passed “through the different hues of a decaying leaf.”
Brongniart has had opportunities of observing one of these leat-
Insects, and has, with the aid of M. Becquerel, submitted their
colouring matter to spectral analysis,” with the result of finding

1 See Murray, Edinburgh New Philosophical Jowrnal, January 1856.
2 CR. Ac. Paris, exviii. 1894, No. 24, p. 1299.

XI LEAF-INSECTS 269

that the spectrum exhibits slight distinctions from that of solu-
tions of chlorophyll, but does not differ from that of living
leaves. Mr. J. J. Lister when in the Seychelles brought
away living specimens of Phyllium; and these becoming short
of food, nibbled pieces out of one another just as they might
have done out of leaves. The Phasmidae are purely vegetable
feeders, and these specimens did not seriously injure one another,
but confined their depredations to the leaf-like appendages and
expansions.

The males of this genus are totally different from the females ;
the foliaceous tegmina being replaced by appendages that are not
leaf-like, while the posterior wings, which are large and conspicu-
ous parts of the body, have no leaf-like appearance (Fig. 155),

In the female Phyllium the hind wings are not present,
being represented by a minute process (Fig. 156, B). The
tegmen of the female Phyllium is, from various points of view,
a remarkable and exceptional structure. it is the rule that
when there is in Insects a difference between the alar organs of
the two sexes it is the male that has them largest; this is the
case in Phylliwm so far as the hind wings are concerned, but in
the fore-wings the rule is departed from, the leaf-like tegmina of
the female being very much larger than the rudimentary wing-
covers of the male. In Phasmidae it is the rwe that the tegmina
are atrophied, even when the hind wings are largely developed.
This is the case in the male of Phyllvum, but in the female this
normal condition is re- ,
versed. Although the alar
organs of Phasmidae have
received hitherto but a small
amount of attention, it is
probable that the female
tegmen of Phyllium is as
peculiar morphologically as
2 ee Fic. 156.—Alar organs and one side of thorax of
it is in other respects. In

x Phyllium crurifolium: A, tegmen; B, rudi-

Fig. 156 we give an accur- ment of wing; C, pronotum; D, anterior
‘.' f th division of mesonotum ; E, posterior division ;

ate representation of the F, metanotum; a, b, c, d, e, chief wing-

chief nervures in the teo- nervures ; @, mediastinal ; }, radial; c, ulnar ;

A d, dividens ? ; e, plicata ?, .

men of a female P. cruri-

folium. It is interesting to compare this with the diagrams we

give of the tegmina of a Blattid (Fig. 121) and of an Acridiid

270 ORTHOPTERA CHAP.

(Fig. 167); the tegmen of the Phylliwm is very different, the radial
vein and all the parts behind it being placed quite close to the
posterior edge of the structure. A similar. view is taken by
both Redtenbacher and Brauer. The latter says,’ “In Phyllium
(the walking-leaf) almost the whole of the front wing is formed
by the praecostal and subcostal fields; all the other fields with
their nervures, including even the costa, are compressed towards
the hind margin into a slender stripe. In the hind wing the
costa is, however, marginal.” Unfortunately no examination
appears to have been made of the male tegmen, so that we
do not know whether that of the female differs from it morpho-
logically as strongly as it does anatomically. It is, however,
clear that the tegmina of the female Phylliwm not only violate
a rule that is almost universal in the Insecta, but also depart
widely from the same parts of its mate,and are totally different—
and, for a Phasmid, in an almost if not quite unique fashion—
from the other pair of alar organs of its own body.

Q Qa

Fig. 157.—Egg of Phyllium scythe. (After Murray.) A, The whole egg, natural size ;
A’, magnified ; B, the capsule broken, showing the true egg inside, natural size ;
B’, magnified. :

We have already alluded to the resemblance to seeds displayed
by the eggs of Phasmidae. The eggs of Phyllivm have been

1 SB. Ak. Wien, xci. 1885, p. 361. The nomenclature applied to the nervures
by these authors is not the same’as that of Brunner ; according to their view the
wing of Phyllium, female, differs more from the wing ‘of Llatia than it does accord-
ing to a comparison made with the nomenclature we adopt.

XI ‘LEAF-INSECTS 271,

studied by several entomologists, and their resemblance to seeds
excites general astonishment. Murray describes the egg-capsule
of Phyllium scythe, and says: “It looks uncommonly like some
seeds; if the edges of the seed of Mirabilis jalapa were rubbed
off, the seed might be mistaken for the egg. The ribs are all
placed at equal distances, except two, which are wider apart, and
the space between them flatter, so that on the egg falling it rolls
over till it comes to this flatter side, and there lies... . At the
top there is a little conical lid, fitting very tightly to the mouth.
. . . On removing the lid we see a beautiful porcelain chamber

Fia. 158.—Portion of a longitudinal section of the egg capsule of Phyllium crurifolium :
a, external; 0b, middle; c, inner zones; d, elongate alveoli, x 100, (After
-Henneguy.)

of a pale French-white colour, bearing a close resemblance to the
texture of a hen’s egg, but it is not calcareous, and has more the
appearance of enamel.” The eggs of P. crurifolium have been
examined by Joly and Henneguy; their account confirms that
of Murray. Henneguy adds that a prominent lozenge on the
egg represents the surface by which the achene of an umbelliferous
plant is united to the column, and that the micropyles are placed
on this lozenge. The minute structure of the capsule has also
been examined by several entomologists; and Henneguy,’ who
has described and figured some of the details of the capsule of
P. crurifolium, says, “ Almost every botanist, on examining for

1 Bull. Soc. Philomathique.(8), ii. p. 18.

272 : ORTHOPTERA CHAP.

the first time a section of this capsule, would declare that he is
looking at a vegetable preparation.” |

We may remark that, although there is difference of opinion |
on the point, the evidence extant goes to show that the egg-
capsules are formed in the egg-tubes, only one egg being pro-
duced at a time in a tube,' the others in it remaining quite
rudimentary.

About 600 species of the family are known; there are only
four or five kinds found in Europe, and they are all confined to
the south, only one of them extending as far north as Central
France. The males of these European Bacilli are extremely rare
in comparison with the females, which are common Insects.
Phasmidae are of almost universal distribution in the warm parts
of the world, and even the species whose individuals are of large
size seem to be able to continue their existence in comparatively
small islands. Australia is perhaps the region where they are
most largely developed at present. Macleay says of Podacanthus
wilkinsont that it is rare in any part of Australia to find in the
summer season a gum-tree without a few of these Insects grazing
on it; and occasionally this Insect has been so abundant there
that the trees for miles around have been denuded of their foliage
by it, and the dead and dying Insects have been found lying
beneath the trees almost in heaps. There are several Phasmidae
in New Zealand, all wingless forms, and different from those
found in Australia. In Brazil a species of the genus Prisopus
has the peculiar habit of seeking shelter under the stones sub-
merged in the mountain streams; to enable it to do this it is
remarkably constructed, the under side of the body being hollowed,
and various parts set with a dense fringe of hairs; the Insect is
supposed to expel the air from the body in order to adhere to the
upper surface of a stone, where it sits with its fore legs extended
in front of its head, which is directed against the current. At-
tention has been called to a still more remarkable form said to
be allied to the Prisopi, by Wood-Mason,? who calls the Insect
Cotylosoma dipneusticum. This Insect is apparently known only
by a single example of the female sex; it is 3 or 4 inches in
length, has rudimentary organs of flight, and along the lower
margins of the metathorax there are said to be on each side five

1 Laboulbene, Bull. Soc. ent. France, 1857, p. cxxxvi., and Henneguy as above.
2 Ann. Nat. Hist. (5) i. 1878, p. 101.

- PHASMIDAE | eae

conspicuous fringed plates of the nature of tracheal gills; these
coexist with open stigmata for aerial respiration, as in the imago
of Pteronarcys. The writer has examined this curious Insect,
and thinks it very doubtful whether. the plates are branchiae at
all. The locality for this Insect is the island of Taviuni, not
Borneo, as stated by Wood-Mason. These and one or two <Acri-

% \
axe

()
Le
LR

we
ak

SL
7

AT

PES

Fic. 159.—Calvisia atrosignaia, female. Tenasserim., (After Brunner.)

_ diidae are the only Insects of the Order Orthoptera at present
believed to possess aquatic habits.
Although the number of species of Phasmidae is small in
comparison with what we find in many of the large families of
Insecta, yet there is probably no other family that equals it in
multiplicity of form and diversity of external appearance.

VOL. V z

274 ; ORTHOPTERA . _ CHAP.

Karabidion (Fig. 160), a genus found in some of the islands of
the southern hemisphere, has the hind legs enormously thickened
in the male. Some Phasmids, e.g. Orwines zeuais, have the hind
wings marked and coloured after the manner of butterflies or
moths. Lamponius laciniatus has an elaborately irregular out-
line, looking like a mass of moss, and some species of Bacteria
are so very slender that the linear body is scarcely equal in size

Fic. 160.—Lurycantha (Karabidion) Fic. 161.—Anisomorpha parda-

australis, male. Lord Howe’s lina, Chili, (After West-
Island. (After Westwood. ) wood. )

to one of the legs it bears. Among the most interesting forms
are the Insects for which the genera Agathemera and Aniso-
morpha (Fig. 161) have been established; they are remarkably
broad and short, have the mesothorax but little elongated, with
the tegmina attached to it in the form of two short, thick,
leathery lobes; while the wings are seen as marks on the meta-
notum looking like a mere sculpture of the surface ; these Insects

u

—

< PHASMIDAE 275

have quite the appearance of larval forms, and it is worthy of
note that the elongation of the mesothorax, which is one of the

Fie. 162.—Palophus centaurus. Old Calabar. Half natural size. (After Westwood.’)
most marked features of the Phasmidae, is in these forms only

very slight. ;

* The antennae in the specimen represented were no doubt mutilated, though
Westwood did not say so.

276 ORTHOPTERA CHAP.

Some Insects said to belong to the genera Phasma and
Bacteria have been found in amber. A single Insect-fossil found
in the Tertiary strata in North America has recently been referred

Fria. 163.—Titanophasma fayoli, Carboniferous formation at Commentry. x 4.
7 (From Zittel. )

by Scudder to the family, and even to a genus still existing in
the New World—Agathemera; the fragment is, however, so
aw defective, and the charac-
ac, Re fear a! teristic points of the
PI bi / ne Phasmidae are so little
SNS, wena) evident in it, that not
ag 4 Seas much reliance can be

s Hit as SEO, ee 8 :
3% Sota SY placed on the determina-
| SE tion. No Phasmid has
7 been unearthed from
Mesozoic strata, so that,
with the exception of the
fragment just mentioned,

: nothing that evidently
- belongs to the Phasmidae
Fic. 164.—Titanophasma fayoli (restoration). has been discovered older
x0: than the remains pre-

served in amber. In the Carboniferous layers of the Palaeozoic
epoch there are found remains of gigantic Insects that may
possibly be connected with our living Phasmidae. These fossils
have been treated by Brongniart and Scudder as forming a
distinct family called Protophasmidae. The first of these authors
says* that our Phasmidae were represented in the Carboniferous

1 CR. Ac. Paris, xeviii. 1884, p. 832.

x1 | PHASMIDAE 3 277

epoch by analogous types differing in the nature of the organs
of flight: these ancient Insects were of larger size than their
descendants, being 25 to 50 centimetres long, and as much as
70 in spread of wing. To this group are referred, on somewhat
too inferential grounds, the fossil wings found in the Carbon-
iferous layers, and called by Goldenberg Dictyonewra.

We reproduce from Zittel’s handbook a figure (Fig. 163) of
one of these gigantic Insects, and add an attempt at a restora-
tion of the same after the fashion of Scudder (Fig. 164). From
these figures it will be seen that the relation to our existing
Phasmidae must at best have been very remote It will be
noted that the larger of the two figures is on a } scale.

The classification of Phasmidae was left in a very involved
state by Stal, but has recently been brought into a more satis-
factory condition by Brunner von Wattenwyl. We give a trans-
lation of his table of the tribal characters :—

1. Tibiae beneath carinate to the apex, without an apical area.

2. Antennae much longer than the front femora, many jointed, the
joints being above 30 in number and only distinct at the base and
towards the apex.?

3. Median [true first abdominal] segment much shorter than the
metanotum.® The species all apterous,

4. The anal segment of the males roof-like, more or less
bilobate. The female has a supra-anal lamina. The
species inhabit the Old World, Tribe 1. LoNcHODIDES

(Fig. 148, Lonchodes nematodes.)

4°. The anal segment of the males arched, straight behind.
No supra-anal lamina in the female. The species are
American. Tribe 2. BACUNCULIDES.

3°. Median segment as long as, or longer than the metanotum.
Species with the male or both sexes winged.

4. Females apterous or rarely possessed of short wings.*
Males winged. Femora dentate beneath, or lobed, or at
least armed with one tooth. Species occur both in
America and in the Old World. ‘Tribe 3. BAcTERIIDEs.

(Fiz. 162, Pulophus centaurus. )

1 In his recent Jnsectes fossiles des temps primaires, pp. 373 and 396, M.
Brongniart has himself removed this Insect to Protodonates. We shall again men-
tion it when discussing that group.

* Bactridiwm, though placed in this tribe, has only short antennae, of 20 joints.

3 Bostra and Clonistria, belonging to Bacunculides, have the median segment
almost as long as the metanotum.

4 The American genera Pterinoxylus, Haplopus, and Candaules, as well as the
African Palophus, possess winged females.

278 PHASMIDAE CHAP. XI

4’, Each sex winged. Femora smooth beneath. The
species belong to the Old World. Tribe 4. NEcro-
SCIDES. (Fig. 159, Calvisia atrosignata.)

2’. Antennae (at any rate in the females) shorter than the front femora,
the joints distinct, not more than 28 in number. The species
belong to the Old World. |

3. Median segment shorter than the metanotum. Apterous
species. Cerci plump. Tribe 5, Cuirumniprs. (Fig. 160,
Eurycantha australis.)

3’. Median segment longer than the metanotum. Species usually
winged. Cerci (except in some genera of the group Platy-
eraninae) flattened, elongate. Tribe 6. ACROPHYLLIDES.

(Fig. 153, Cyphocrania aestwans. )
1’. Tibiae furnished beneath with a triangular apical area.

2, Antennae many jointed, longer than the front femora.

3. Median segment shorter than the metanotum. Apterous

species.!

4. Either head, thorax, or legs spiny or lobed. Tribe 7.
CLADOMORPHIDES. (Fig. 149, Heteropteryx grayi.)

4’. Head, thorax and legs unarmed. Tribe 8. Awntso-
MORPHIDES. (Fig. 161, Anisomorpha pardalina.)

3’, Median segment longer than the metanotum.

4, Claws unarmed. Tegmina lobe-like, either perfectly
developed or entirely absent. The winged species are
all American, the apterous are both African and
Australian. Tribe 9. PHASMIDES.

4’, Claws toothed on the inner side. 'Tegmina spine-like.
Wings well developed. The species are Asiatic. Tribe
10. AscHIpasMiIDES. (Fig. 150, Aschipusma catadromus.)

2’. Antennae shorter than the anterior femora,?. formed of not more
than 20 joints. Old World species.

3. Body slender. Apterous. Tribe 11. BacrLuipEs.

3’. Body very broad, lamina-like. Either wings or tegmina
present. Tribe 12, PHytimpes. (Fig. 155, Phylliwm scythe,
male; Fig. 154, zdem., female. )

1 The African and Australian genera Orobia and Paraorobia, although they have
a short median segment, are placed in the tribe Phasmides of this division.

* This character is evidently erroneous as regards the males of the genus
Phyllium.—D. 8.

ee ee | ee a
=

ee

CHAPTER XII

ORTHOPTERA CONTINUED—ACRIDIIDAE

Fam. VI. Acridiidae—Locusts and Grasshoppers.

Orthoptera with the hind legs differing from the others by being —
more elongate and having their femora broader near the
base. Antennae short, with less than 30 joints. No
exserted ovipositor in female. Tarsi short, with three
distinct joints. The auditory organ placed on the side of
the upper part of the first abdominal segment.

Fic. 165.—Tryxalis nasuta, female. Natural size. Europe.

WE commence the consideration of the saltatorial Orthoptera
with the family Acridiidae. It includes the grasshoppers of our
native fields as well as the destructive migratory locusts of
foreign countries, and is the most numerous in species and indi-
viduals of any of the Orthopterous families. Our native grass-

- hoppers, though of small size, give a very good idea of the

Acridiidae. Active little Insects, with large head, conspicuous

~

\

280 ORTHOPTERA CHAP,

eyes, laterally somewhat compressed body, long hind legs with
femur directed upwards and backwards, the knee-joint forming
an acute angle, the organs of flight pressed to the sides of the
body, our common grasshoppers represent the Acridiidae quite as
truly as do the gigantic exotic forms, some of which measure
9 or 10 inches across the expanded wings. ,
The large head is immersed behind in the thorax ; the front

is deflexed, or even inflexed, so as to be placed in a plane at an
acute angle with that of the vertex (Fig. 165); the compound
eyes are placed at the sides of the head and rather widely
separated ; in front there are three small ocelli. Two of these
are placed one on each side close to
the eye between the eye and the base
of the antenna; the third ocellus
being in the middle just in front of
the insertion of the antennae, be-
tween the edges of the margined
space that usually runs down the
middle of the front. The positions
of these ocelli and the shape of the
front and upper parts of the head
are of importance in the classification
of the family; the ocelli vary much
Fic. 166.—Front of head of Porthetis in their development, being-:in some

ape See species beautifully clear and promi-
nent (Fig. 166), while in others they are small, not easily detected,
apparently functionally imperfect. The antennae are never very
long, are sometimes compressed and pendent from the front of the
head. The parts of the mouth are very large. The prothorax is
much arched; it is often carinate or crested along the middle of
the notum ; this part is frequently prolonged backwards, forming a
sort of hood over the base of the wings; the surface may be
rugged or warty, forming in some species inexplicable structures ;
the legs are widely separated, all of them being placed at the
sides of the body; the edge of the pronotum is distinct and
situate close to the base of the leg; the prosternum frequently
bears a large projection extending directly downwards . between
the front legs. The mesothorax is short, its chief sternal piece
is ‘very broad, the middle legs being very widely separated. The
metathorax is larger; its sternal plate usually exhibits behind a

bs yee ge a ae > ee

i =

_ovipositor—ain the male, the modi-

| li ACRIDIIDAE wine 281

sort of embrasure filled up by a portion of the first ventral plate.
The hind body is elongate, and shows distinctly eight dorsal
segments, behind which are the
pieces forming—in the female, the
fossorial organs which replace an

fied parts connected with the ter-
minal segment. The alar organs
(Fig. 167) exhibit, according to
Brunner, the same areas as we
have described in Blattidae. Ac-
cording, however, to Redtenbacher *
the tegmina of the Acridiidae and
other saltatorial Orthoptera differ
from those of the cursorial group
(with the exception of the Phas- Fig. 167.—Alar organs of <Acridiidae

; : (Bryodema. tuberculata). A, Left
midae) in that they possess a tegmen; B, left wing: ar.med, area
praecostal field, due to the fact

mediastina ; a7.sc, area scapularis ;
: : : ar.disc, area discoidalis ; ar.an, anal
that the vein which in the Cur-
soria 1s costal, z7.c. forms the front
margin, in the Saltatoria lies, on
the contrary, in the field of the
wing. If this view be correct the
mediastinal area of Brunner is not

area; v.m, vena mediastina; v.7,
vena radialis; v.7.a, vena radialis
anterior ; v.7.m, vena radialis media ;
v.7.p, vena radialis posterior; v.7,
vena intercalata ; v.w.a, vena ulnaris
anterior; v.u.p, vena ulnaris pos-
terior ; v.d, vena dividens ; v.pl, vena
plicata. (After Brunner.)

homologous in the two divisions. The tegmina are long and
comparatively narrow; they are of firm parchment-like texture,
with several longitudinal veins, which divide beyond the middle,
so as to become more numerous as they reach the extremity of
the wing; there is much reticulation, dividing the surface into
numerous small cells. The hind wings are much more ample,
and of more delicate texture; the longitudinal veins fork but
little, the numerous cross veinlets are fine. In repose the hind
wings fold together in a fan-like manner, and are entirely con-
cealed by the upper wings. The front and middle legs are
similar and small, the coxae are quite small, and do not com-
pletely fill the articular cavities, which are partly covered by
membrane ; all the tarsi are three-jointed. The basal joint, when
looked at beneath, is seen to bear three successively placed pads,
so that from beneath the tarsi look as if they were five-jointed

1 Ann. Hofmus. Wien, i. 1886, p. 175.

282 ORTHOPTEPA CHAP.

(Fig. 185, C). The hind legs are occasionally very long; their
femora, thicker towards the base, are generally peculiarly sculp-
tured, bearing longitudinal ridges or grooves, which are more
or less spinose, and are also
very frequently marked with
short parallel lines meeting a -
central longitudinal line at
similar angles, so as to give
rise to a well-marked pattern ;
where the legs are broader
the pattern is more complex
(Fig. 168). The long tibiae
bear two rows of spines on
their upper or posterior edge ;
this part of the hind leg can
be completely bent in under
the femur. The stigmata consist of one prothoracic, one meta-
thoracic, and eight abdominal pairs.

In reference to the ocelli, which are shown in Fig. 166, we
may remark that the Acridiidae is one of the large groups of
Insects in which the coexistence of compound and single eyes is
most constant, though in some of the wingless forms the ocelli
are very imperfect. We know at present of nothing in the
habits of Acridiidae to render two kinds of eyes specially neces-
sary. We shall subsequently see that a similar condition in
regard to the function of hearing is believed to exist in this
family. :

Acridiidae are remarkable amongst the Orthoptera for the
possession of air sacs or vesicular dilatations in the interior of the
Insect in connexion with the tracheae (Fig. 176). Such vesicles
are found in many of the higher winged Insects, but not in larval
forms, or in those that are destitute of powers of flight.’ They,
no doubt, assist the Insect in its movements in the air. The body
of a large grasshopper or locust is naturally of considerable
weight, and it is more than probable that true flight can only be
accomplished when these vesicles are dilated and filled with air.
The exact mode in which the sacs are dilated is not known;
possibly it may be accomplished by the elasticity of the structure
of the vesicles coming into action when the other contents of the

1 Newport, 77. Linn. Soc. xx. 1851, p. 419.

Fic. 168.—Hind leg of Porthetis sp.
Transvaal.

= ao ACRIDIIDAE 283

body are not completely developed, or are temporarily diminished.
_ Although air vessels are absent in the neighbouring groups of
Orthoptera, Dufour says they are present even in apterous forms
of Acridiidae, but he gives no particulars." Packard has given
an account? of the arrangement of these remarkable sacs in the
Rocky Mountain Locust. He finds that there are two sets: a
thoracic group, consisting of a pair of very large size, with which
are connected some smaller sacs placed in the head; and an
abdominal set, which forms a very remarkable series. The
figures we give (Fig. 176, A, B) show that these sacs are of such
large size that if fully distended they must interfere with the
development of the ovaries, and that they must be themselves
greatly diminished, if not obliterated, by the distension of the
alimentary canal. We may look on them
as only coming into full play when the
normal distension of the canal is prevented,
and there is only small development of the
reproductive organs. Under such circum-
stances the locust becomes a sort of balloon,
and migrates. In addition to the air sacs
there are many dilatable tracheae, placed
chiefly in parts of the body where there is
not space for the large air sacs. These are,
for the sake of clearness, omitted from our
figure. .

The ganglia constituting the brain are
simpler in Acridiidae than they are in the
higher Insects, such as bees and wasps, and
have been specially studied by Packard °
and Viallanes.* The other ganglia of the Fre. 169.—Ovaries of Oedi-
nervous cord are eight in number, three poda caerulescens: a,

: : calyx ; 6, its gut-like
thoracic and five abdominal. appendage; ¢, sebific

The salivary glands are small. The lan Vehee Dufour)
_alimentary canal is- capacious but not

coiled. It has no gizzard, but the crop has a peculiar structure,
apparently as a substitute’ There are diverticula connected
with the true stomach. The Malpighian tubes are elongate

1 Mem. Ac. Sci. Etrang. vii. 1834, p. 274.
2 First Ann. Rep. U.S. Ent. Comm. 1878, p. 271.
3 Rep. U.S. Ent. Comm. ii. 1880, p. 223. 4 Ann. Set. Nat. (7) iv. Zool. 1887.

284 ACRIDIIDAE CHAP. —

and extremely numerous. The pair of testes is united in a
single envelope. The form and arrangement of the ovaries
is remarkable (Fig. 169); the egg-tubes are united by the con-
vergence of their terminal threads into a single mass; outside of
each ovary there extends a large calyx, into which the tubes
open; each calyx is prolonged at its extremity, and forms a long,
convoluted tube.

Acridiidae possess structures for the production of sound, together
with others that are, no doubt, for hearing. The chirping of grass-
hoppers is accomplished by rubbing together the outer face of the

upper wing and the inner face of the hind

SSS 3 femur. This latter part bears a series of
( SS “ small bead-like prominences placed on

4 the upper of the two lower ridges that
Fic. 170.—Inner face of femur ‘ ‘
of Stenobothrus, male, TUN along the side that is nearest to the
sera rnie Miata, bedy (ig, 10 Riera a a
magnified three times.) has projecting veins, one of which is
slightly more prominent, and has a sharp
edge ; by scraping this edge over the beads of the femur the wing
is thrown into a state of vibration and a musical sound is produced.
The apparatus for producing sound was for long supposed to be
confined to the male sex of grasshoppers; it was indeed known
that females made the move- :
ments appropriate for producing
music, but as they appeared to
be destitute of instruments, and
as no sound was known to
follow from their efforts, it was
concluded that these were
merely imitative. Graber has,
however, discovered ! that rudi-
mentary musical organs do A ide
. . ; ‘ Fic. 171.-—A, Some of the knobs projecting
exist in the females of Bhat Si from the surface of the femur of Stenobo-
Te BL Ted tee tn famule Highly maga. (After Graber)
comparison with those of the male (Fig. 171, A) they are
minute, but it would appear that they are really phonetic,
though we can hear no sounds resulting from their use.
Graber considers that the musical pegs of <Acridiidae are

1 Verh. zool.-bot. Ges. Wien, xxi. 1871, p. 1097.

XII EARS | 285

modified hairs, and he states that in certain females the stages
intermediate between hair and peg can be found. There is
apparently much variety in the structure of these instruments in
different species, and even in individuals of the same species.
In Stenobothrus lineatus, instead of pegs, the instrument consists
of raised folds.

In some of the aberrant forms of Acridiidae—certain Eremo-
biudes and Pneumorides—the males are provided with sound-
producing instruments different to those we have described, both
as regards situation and structure.

If the dorsal aspect of the first segment of the hind body of
an Acridian Insect be carefully exainined there may be seen in
the majority of species an organ which has
somewhat the appearance of an ear (Fig. 172),
and which there is: great reason for believing to
be really an organ of that nature. It is situate
a little over the articulation of the hind leg,

very close to the ¥

spot where . the *™ Page isa
B sound 18, as above tylus nigrofasci-
described, produced. nae aie.
There are three (After Brunner.)
forms of these Acri-
dian ears as described by Brunner: *
(1) a membrane surrounded by a.
rim; (2) the membrane somewhat
depressed, a portion of the segment
projecting a little over it; (3) the
depression very strongly marked,
* and the sides projecting over it so
much that all that is seen externally
is a sort of broad slit with a cavity
beneath it. This last is the con-
rete Atacostithuw roseus': A, dition in which the ear exists in
Insect with wings expanded; B, the genera MMecostethus (Fig. 173)
con balay : and prothorax. ond Stenobothrus, which are among
our few native grasshoppers. On
minute examination this ear proves to consist of a tympanum

supplied internally with nerve and ganglion in addition to
1 Verh. zool.-bot. Ges. Wien, xxiv. 1874, p. 286.

é.

cs CQ /;
SaeaeceT NS as
See

7 Saar = a nts Be le MH Ea hy RE ae RF om Nm

286 ORTHOPTERA CHAP. —

muscles, and tracheal apparatus of a complex nature; it is no
doubt delicately sensitive to some forms of vibration. Unlike
the stridulating organ, these ears exist in both sexes; they are
found in a great majority of the species of Acridiidae. The
forms in which the ears are absent are usually at the same time
wingless and destitute of organs of stridulation ; but, on the other
hand, there are species—some of them wingless—that are, so far
as is known, incapable of stridulation and yet possess these ears.
It is, indeed, a matter of great difficulty to decide as to the
exact function of these ear-like acoustic organs, which, we may
remind the reader, are peculiar to the’saltatorial Orthoptera, and
we must refer for a full discussion of the subject to Graber’s
masterly works,’ contenting ourselves with a brief outline, which
we may commence by saying that the Orthoptera with ears are
beheved to be sensitive to sounds by means other than these
organs. This suggests that the latter exist for some purpose

of perception of special sound. But if so what can this be? _

Only the males possess, so far as we know, effective sound-
producing organs, but both sexes have the special ears; more-
over, these structures are present in numerous species where
we do not know of the existence of phonetic organs in either
sex. Thus it appears at present impossible to accept these
organs as being certainly special structures’ for the perception
of the music of the species. It is generally thought that the
females are charmed by the music of. the males, and that these
are stimulated to rivalry by the production of the sounds; and
Dufour? has suggested that this process reacts on the physio-
logical processes of the individual. There has not been a sufficient
amount of observation to justify us in accepting these views, and
they do not in any way dispose of the difficulty arising from the

existence of the acoustic organs in species that do not, so far as -

we know, produce special sounds. It is possible that the solution
of the difficulty may be found in the fact that these apparently
dumb species do really produce some sound, though we are quite
ignorant as to their doing so. It is well known that sounds
inaudible to some human ears are perfectly distinct to others.
Tyndall, in his work on Sound, has illustrated this by a fact that
is of special interest from.our present point of view. “ Crossing

1 Denk. Ak. Wien, xxxvi. 1875; Arch. mikr. Anat. xx. and xxi., 1882.
* Mem. Ac. Sci. Etrang. vii. 1834, p. 306.

> >a.

XII ACRIDIIDAE 287

the Wengern Alp with a friend,” he says, “ the grass on each side
of the path swarmed with Insects which to me rent the air with
their shrill chirruping. My friend heard nothing of this, the
Insect world lying beyond his limit of audition.” If human
ears are so different in their capacities for perceiving vibrations, it
of course becomes more probable that auditory organs so differently
constituted as are those of Insects from our own may hear sounds
when the best human ear can detect nothing audible. On the
whole, therefore, it would appear most probable that the Orthoptera
provided with acoustic organs, and which we consider dumb, are
not really so, but produce sounds we cannot hear, and do so in
some manner unknown to us. If this be the case it is probable
that these ears are special organs for hearing particular sounds.

Scudder, who has given considerable attention to the subject
of Orthopteran music, says that in N. America “the uniformity
with which each species of Stenobothrus plays its own song is
quite remarkable. One kind, Stenobothrus curtipennis, produces
about six notes per second, and continues them from one and a
half to two and a half seconds; another, S. melanopleurus, makes
from nine to twelve notes in about three seconds. In both
cases the notes follow each other uniformly, and are’ slower in the
shade than in the sun.”

Some of the species of Acridiidae, it should be noticed, produce
a noise during their flights through the air, due to the friction

of the wings; whether this has a definite importance, or whether

it may be entirely incidental, has scarcely yet been considered.
Information of a satisfactory kind as to the pogt-embryonic
development of the Acridiidae is but scanty. We have repre-
sented in Fig. 84, A, the condition in which a migratory locust,
Schistocerca peregrina, leaves the egg, and we will here complete

the account of its growth; following Brongniart,’ whose statement

is confirmed by Lestage and other naturalists. Immediately
on leaving the egg the young locust casts its skin, and is then ©
of a clear green colour, but it rapidly becomes brown, and in
twelve hours is black. At this early age the gregarious in-
stinct, possessed by this and some other species of Acridiidae,
becomes evident. In six days the individual undergoes a second
moult, after which it is black, spotted and banded with white, and
with a rose-coloured streak on each side of the hind body. The

1 Bull. Soc. Philomath. (8) v. 1893, p. 5.

288 ORTHOPTERA ‘CHAP.

third ecdysis occurs in six or eight days after the second; the
rose colour becomes more distinct, and the head is of a brown tint
instead of black. After eight days the fourth ecdysis occurs ;
the creature is then about 35 millimétres long; its colour has
much changed, the position of the markings is the same, but the
rose colour is replaced by citron yellow, the line of the spiracles
is marked with white, and at this time the creature has the “ first
rudiments of wings,” and is very voracious. In ten days another
ecdysis takes place, the yellow colour is more vivid, the prothorax
is definitely speckled with white, and the hind body is increasing

Fia. 174.—Development of wings in Caloptenus spretus: the upper row gives a lateral
view of the thoracic segments, and the lower row a dorsal view of these segments ;
1, second instar ; 2, third instar; 3, fourth instar; 4, fifth instar. (After Riley.)
zt, tegmen ; w, wing.

’

much in size. In fifteen or twenty days the sixth moult occurs,
and the Insect appears in its perfect form; the large tegmina
now present are marked with black in the manner so well known,
and the surface generally is variegated with bluish and rosy marks.
Although this is the colour in Algeria, yet apparently it is not
so farther south; the Insects that arrive thence in the French
colony are on some occasions of a different colour, viz. reddish or

yellowish, those of this latter tint being, it is believed, older

specimens of the reddish kind. M. Brongniart points out that
some Phasmidae—of the Phylliwm group—undergo an analogous
series of colour-changes in the course of the individual develop-
ment, though other species do not.

oy =. ae
f =

Mae =

ACRIDIIDAE 289

Riley and Packard have given an account * of some parts of the
post-embryonic development of the Rocky Mountain Locust, which

enables us to form a satisfactory conception of the stages of de-

velopment of the wings. Fig. 175, A, represents the first instar,
the young locust, just emerged from the egg and colourless. Fig.
174 shows some of the subsequent stages of development of the
wings, the upper line of figures giving a profile view of the
thoracic segments, and.
the lower line showing
their dorsal aspects; 1
shows the condition of
the parts in the second
instar, the chief differ-
ence from the first instar
being the development
of colour; in the third
instar there is an evident
slight development of
the future alar organs,
exhibited chiefly in the
outgrowth and lobing g&&
of the free posterior —
angles of the meso- and
metanota, as shown in
Fig. 174, 2. After the
third moult there is a
great difference; the in- .
star then disclosed —
the fourth—has under-
gone a considerable

change in the position Fie. 175.—Caloptenus spretus. North America. A,

Newly hatched, much magnified ; B, adult, natural
of the meso- and meta- ize. "(After Riley.)

thoraces, which are

thrust forward under the pronotum ; this has become more enlarged
and hood-like (Fig. 174, 3); at the same time the wing-rudiments
have become free and detached, the metathoracic pair being the
larger, and overlapping the other pair. The fifth instar (Fig. 174,
4) differs but little from the fourth, except in the larger size of the
pronotum and wing-rudiments. The sixth—shown in Fig. 175, B

1 First Ann. Rep. U.S. Ent. Comm. 1878, p. 279.
VOL. V U

290 ORTHOPTERA CHAP.

—is the perfect Insect, with the alar organs free and large, the
prothorax much changed in form, the colour different. From the
above it will be seen that the chief changes occurred at the third ~
and fifth ecdyses, after each of which a considerable difference in the
form of the Insect was revealed. In the first three instars the
sexes can scarcely be distinguished, in the fourth they are quite
distinct, and in the fifth coupling is possible, though usually it
does not occur till the final stage is attained.

The discovery that Orthoptera change their colours in the
course of their development, and even after they have become
adult, is important, not only from a physiological point of view,
but because it throws some light on the questions as to the
number of species and the geographical distribution of the
migratory locusts, as to which there has existed a great confusion.

The Acridiidae are considered to be exclusively vegetable
feeders, each individual consuming a very large quantity of food.
The mode in which the female deposits her eggs has been
described by Riley,’ and is now widely known, his figures having ©
been frequently reproduced. The female has no elongate ovi-
positor, but possesses instead some hard gonapophyses suitable for
digging purposes ; with these she excavates a hole in the ground,
and then deposits the eggs, together with a quantity of fluid, in
the hole. She prefers hard and compact soil to that which is
loose, and when the operation is completed but little trace is left
of it. The fluid deposited with the eggs hardens and forms a
protection to them, corresponding to the more definite capsules of —
the cursorial Orthoptera.

The details of the process of oviposition and of the escape of
the young from their imprisonment are of much interest. Accord-
ing to Kiinekel d’Herculais? the young Stauronotus maroccanus
escapes from the capsule by putting into action an ampulla
formed by the membrane between the head and the thorax; this
ampulla is supposed to be dilated by fluid from the body cavity,
and is maintained in the swollen condition by the Insect accumu-
lating air in the crop beneath it. In order to dislodge the lid of
the capsule, six or seven of the young ones inside combine their
efforts to push it off by means of their ampullae. The ampulla

1 Rep. Ins. Missouri, ix. 1877, p. 86.
> Bull. Soc. ent. France (6), x. 1890, p. xxxvii., and OR. Ac. Paris, cx. 1890,
p. 657.

7

i as ie ae

XII LOCUSTS 2gI

subsequently serves as a sort of reservoir, by the aid of which the

_ Insect can diminish other parts of the body, and after emergence

from the capsule, penetrate cracks in the earth so as to reach the
surface. Immediately after doing this the young Stauronotus
moults, the skin it casts being called by Kiinckel an amnios.
The cervical ampulla reappears at subsequent moults, and enables
the Insect to burst its skin and emerge from it.

The process is apparently different in Caloptenus spretus,
which, according to Riley, ruptures the egg-shell and works its
way out by the action of the spines at the apex of the tibiae.
This latter Insect when it emerges moults a pellicle, which Riley
considers to be part of the embryonic membranes. |

Riley states that a female of Caloptenus spretus makes several
egg-masses. Its period of ovipositing extends over about 62
days, the number of egg-masses being four and the total number
of eggs deposited about 100. The French naturalists have
recently observed a similar fact in Algeria, and have ascertained
that one of the migratory locusts—Schistocerca peregrina—may
make a deposit of eggs at more than one of the places it may
alight on during its migration.

It has been ascertained that the eggs of Acridiidae are very
nutritious and afford sustenance to a number of Insects, some of
which indeed appear to find in them their sole means of subsist-
ence. Beetles of the family Cantharidae frequent the localities
where the eggs are laid and deposit their eggs in the egg-masses
of the Orthoptera, which may thus be entirely devoured. Two-
winged flies of the family Bombyliidae also avail themselves of
these eggs for food, and a mite is said to be very destructive to
them in North America. Besides being thus destroyed in
enormous quantities by Insects, they.are eaten by various birds
and by some mammals,

Most of the Insects called locusts in popular language are
members of the family Acridiidae, of which there are in different
parts of the world very many species, probably 2000 being
already known. To only a few of these can the term Locust be
correctly applied. A locust is a species of grasshopper that
occasionally increases greatly in number, and that moves about. im
Swarms to seek fresh food. There are many Orthoptera that
occasionally greatly increase in numbers, and that then extend
their usual area more or less; and some <Acridiidae multiply

292 ORTHOPTERA CHAP.

locally to a great extent—very often for one or two seasons only,
—and are then called locusts. The true migratory locusts are
species that have gregarious habits strongly developed, and
that move over considerable distances in swarms. Of these there
are but few species, although we hear of their swarms in many
parts of the world. |

The migratory locusts do much more damage than the endemic
species. In countries that are liable to their visitations they
have a great influence on the prosperity of the inhabitants, for
they appear suddenly on a spot in huge swarms, which, in the

space of a few hours, clear off all the vegetable food that can be

eaten, leaving no green thing for beast or man. It is difficult
for those who have not witnessed a serious invasion to realise the
magnitude of the event. Large swarms consist of an almost
incalculable number of individuals. A writer in Nature’ states
that a flight of locusts that passed over the Red Sea in November

1889 was 2000 square miles in extent, and he estimated its —

weight at 42,850 millions of tons, each locust weighing +), of an
ounce. A second similar, perhaps even larger, flight was seen

passing in the same direction the next day. That such an
estimate may be no exaggeration is rendered probable by other

testimony. From official accounts of locusts in Cyprus we find that
in 1881,? up to the end of October, 1,600,000,000 egg-cases had
been that season collected and destroyed, each case containing a

considerable number of eggs. By the end of the season the weight _

of the eggs collected and made away with amounted to over 1300
tons, and, notwithstanding this, no less than 5,076,000,000 egg-
cases were, it is believed, deposited in the island in 1883.

When we realise the enormous number of individuals of which
a large swarm of locusts may consist we can see that famine is
only a too probable sequence, and that pestilence may follow—as
it often has done—from the decomposition of the bodies of the
dead Insects. This latter result is said to have occurred on some
occasions from locusts flying in a mass into the sea, and their
dead bodies being afterwards washed ashore.

Locust swarms do not visit the districts that are subject to
their invasions every year, but, as a rule, only after intervals of
a considerable number of years. It has been satisfactorily

1 Carruthers in Nature, xli. 1889, p. 153.
2 Blue-book, C, 4960, 1887 ; and P. ent. Soc. London, 1881, p. xxxviii.

1
;

5
‘
,
5

xIt LOCUSTS 293

ascertained that in both Algeria and North America large swarms
occur usually only at considerable intervals. In North America
Riley thought’ the average period was about eleven years. In

Algeria the first invasion that occurred after the occupation of

the country by the French was in 1845, the second in 1864,
the third in 1866, since which 1874 and 1891 have been
years of invasion. These breaks seem at first strange, for it
would be supposed that as locusts have great powers of increase,
when once they were established in any spot in large numbers,
there would be a constant production of superfluous individuals
which would have to migrate as regularly as is the case with
swarms of bees. The irregularity seems to depend on three facts:

viz. that the increase of locusts is kept in check by parasitic

Insects; that the eggs may remain more than one year in the
ground and yet hatch out when a favourable season occurs; and
that the migratory instinct is only effective when great numbers
of superfluous individuals are produced.

It is not known that the parasites have any power of re-
maining in abeyance as the locust eggs may do; and the bird
destroyers of the locusts may greatly diminish in numbers during
a year when the Insects are not numerous; so that a dispro-
portion of numbers between the locusts and their destroyers may
arise, and for a time the locusts may increase rapidly, while the
parasites are much inferior to them in numbers. If there should
come a year when very few of the locusts hatch, then the next
year there will be very few parasites, and if there should then be
a large hatching of locusts from eggs that have remained in
abeyance, the parasites will not be present in sufficient quantity

to keep the destructive Insects in check; consequently the next

year the increase in number of the locusts may be so great as to
give rise to a swarm.

It is well established that locusts of the migratory species
exist in countries without giving rise to swarms, or causing any
serious injuries; thus Pachytylus cinerascens—perhaps the most

important of the migratory locusts—is always present in various

localities in Belgium, and does not give rise to swarms. When
migration of locusts does occur it is attended by remarkable
manifestations of instinct. Although several generations may
elapse without a migration, it is believed that the locusts when

1 Rep. Entomologist, 1885, p. 229.

294 ORTHOPTERA ~ CHAP.

they migrate do so in the direction taken by predecessors.
- Their movements are to a large ex-
tent dependent on the wind, and it
is said that they make trial flights
to ascertain its direction. When on
the wing probably very little mus-
cular effort is necessary. Their
bodies contain elastic air sacs in
communication with the tracheae,
and at the time of flight it may be
presumed that the body is compara-
tively empty, food being wanting,
and the internal organs of repro-
duction, which occupy a large space
when in activity, yet undeveloped,
hence the sacs have full room for
expansion, as explained on p. 285.
A Thus the Insects exert but little
der Pam crn ; lige sae a effort in their aerial movements, and
of the eta (Modified from are, 1t is believed, chiefly borne by
Deckers iso the wind. Should this become un-
of posterior parts of body ; a,en- favourable it is said that they alight
largements of tracheae in head; and wait. for a change.

b, pair of large sacs in thorax ; 5s ;
c, sacs on the tracheal trunks of The most obscure point in the
Satu TA manele natural history of the migratory |
locusts appears to be their disappearance from a spot they
have invaded. A swarm will alight on a locality, deposit there
a number of eggs, and then move on. But after a lapse of a
season or two there will be few or none of the species present
in the spot invaded. This appears to be partly due to the young
locusts dying for want of food after hatching; but in other cases
they again migrate after growth to the land of their ancestors. The
latter fact is most remarkable, but it has been ascertained by the
U.S. Entomological Commission that these return swarms do occur.
In South Africa it would appear that the movements of
the migratory locusts are frequently made before the Insects have
acquired their wings. Mrs. Barber, in an account of “ Locusts and
Locust-Birds in South Africa,” * has illustrated many points in the

1 Tr. S. Afr. Phil. Soc. i, 1880, p. 193. The species is thought to be Pachytylus
sulcicollis Stal.

“yee Ay --

ae

XII MIGRATION OF LOCUSTS 295

Natural History of these Insects. The South African species mani-
fests the gregarious and migratory disposition when the individuals
are quite young, so that they travel in flocks on foot, and are called
by the Dutch “ Voetgangers.” After hatching, the various families
of young amalgamate, so that enormous numbers come together.
Having denuded the neighbourhood of all its food-supplies, they
move off in search of freshcrops and pastures new. They take advan-
tage of roads, and sometimes a good many miles will be traversed in
a day; they proceed by means of short leaps,rapidly repeated. When
the “ Voetgangers” are thus returning northwards towards the
lands in the interior from which their progenitors departed, no
obstacles can stay their course. Forests or rivers may intervene,
diverting them for a while from their line of march, but they
succeed ultimately in continuing their journey to the interior.
The manner in which these wingless locusts occasionally cross
broad rivers is interesting, as it has some bearing on the
difficult question of the possibility of winged locusts crossing seas
of considerable width. Mrs. Barber refers to an instance that
took place on the Vaal River in the spring of the year 1871,
shortly after the discovery of the Diamond-fields. The country
was at that time swarming with young locusts; every blade of
grass was cleared off by them. One day a vast swarm of the
“ Voetgangers”” made their appearance on the banks of the Vaal
River; they appeared to be in search of a spot for crossing,
which they. could not find, the river being somewhat swollen.
For several days the locusts travelled up the stream; in the
course of doing this they paused for some time at an abrupt
bend in the river where a number of rocks were cropping out,
as if in doubt whether to attempt a passage at this place. They,
however, passed on, as if with the hope of finding a better ford ;
in this apparently they were disappointed, for three days after-
wards they returned to the same bend of the river, and there
plunged in vast multitudes into the stream, where, assisted by a
favourable current and the sedges and water-plants which grew
upon the projecting rocks, they managed to effect a crossing,
though great numbers were drowned and carried away by the
flooded river. Mrs. Barber adds that “ Voetgangers” have been
known to attempt the passage of the Orange River when it was
several hundred yards in breadth, pouring their vast swarms into
the flooded stream regardless of the consequences, until they

296 ORTHOPTERA | CHAP.

became heaped upon each other in large bodies. As the living
mass in the water accumulated, some portions of it were swept
away by the strong current from the bank to which they were
clinging, and as the living locusts tightly grasped each other and
held together, they became floating islands, the individuals con-
tinually hopping and creeping over each other as they drifted
away. Whether any of the locust-islands succeeded in reaching |
the opposite bank is unknown; probably some of them were
drifted on land again. They are by no means rapid swimmers ;
they do not perish easily in the water when in masses, their
habit of continually changing places and hopping and creeping
round and round upon each other being very advantageous as a
means of preservation. It is a common practice for the young
locusts to form a bridge over a moderately broad stream by
plunging indiscriminately into it and holding on to each other,
grappling like drowning men at sticks or straws, or, in fact,
anything that comes within their reach, and that will assist in
floating them; meanwhile those from behind are eagerly pushing
forward over the bodies of those that are already in the stream
and hurrying on to the front, until at length by this process
they reach the opposite bank of the river; thus a floating mass
of living locusts is stretched across. the stream, forming a bridge
over which the whole swarm passes. In this manner few,
comparatively speaking, are drowned, because the same in- —
dividuals do not remain in the water during the whole of the
time occupied by the swarm in crossing, the Insects continually
changing places with each other; those that are beneath are
endeavouring to reach the surface by climbing over others, whilst
those above them are, in their turn, being forced below. Locusts
are exceedingly tenacious of life, remaining under water for a
considerable time without injury. An apparently drowned locust
will revive beneath the warm rays of the sun, if by chance it
reaches the bank or is cast on shore. Mrs. Barber relates an
interesting case where the instinct of the “ Voetgangers” was at
fault, they plunging into a river from a steep sandy bank, only
to find another similar sandy precipice on the other side. On this
they could gain no footing, and all perished in the stream, where
they putrefied, and caused the death of the fish, which floated
likewise on the surface; so powerful were the effluvia produced
that no one was able to approach the river.

x1 | MIGRATORY LOCUSTS 297 .

Locusts are able to travel considerable distances, though how
far is quite uncertain. Accounts vary as to their moving by
night. It has, however, been recently proved that they do
travel at night, but it is not ascertained how long they can
remain in the air without descending. The ocean is undoubtedly
a source of destruction to many swarms; nevertheless, they
traverse seas of considerable width. They have been known
to reach the Balearic Islands, and Scudder gives’ a well-authen-
ticated case of the occurrence of a swarm at sea. On the
2nd of November 1865 a ship on the voyage from Bordeaux
to Boston, when 1200 miles from the nearest land, was in-
vaded by a swarm of locusts, the air and the sails of the ship
being filled with them for two days. The species proved to
be Acridium (Schistocerca) peregrinum. This is an extra-
ordinary case, for locusts do not fly with rapidity, being, indeed,
as we have remarked, chiefly carried by the wind. — Possibly
some species may occasionally rest on the water at night, pro-
ceeding somewhat after the fashion of the “ Voetgangers” when
passing over rivers as described by Mrs. Barber. In Sir Hans
Sloane’s history of Jamaica an account of an occurrence of this
kind is given on the authority of Colonel Needham, who states
that in 1649 locusts devastated the island of Tenerife, that they
were seen to come from Africa when the wind was blowing thence,
that they flew as far as they could, then alighted on the water,
one on the other, till they made a heap as big as the greatest
ship, and that the next day, being refreshed by the sun, they took
flight again and landed in clouds at Tenerife. De Saussure says”
that the great oceans are, as a rule, impassable barriers, and that
not a species of the tribe Oedipodides has passed from the Old
World to the New. It is, however, possible that Acridium pere-
grinum, of the tribe Acridiides, may have originally been an inhabi-
tant of America, and have passed from thence to the Old World.

The species of Acridiidae that have been ascertained to be
migratory are not numerous.” The most abundant and widely
distributed of them is Pachytylus cinerascens (Fig. 177), which
has invaded a large part of the Eastern hemisphere, extending
from the Atlantic Ocean to China. It exists in numerous spots

1 CR. Soc. ent. Belgique, xxi. 1878, p. 5.
2 Addit. ad Prodromum Oedipodiorum, 1888, p. 12.
3 See Redtenbacher, Uber Wanderheuschrecken, in Jahresber. Realschule Budweis, 1893.

298 ORTHOPTERA CHAP.

in the Oriental region and the Asiatic Archipelago, and even in
New Zealand. It is the commoner of the locusts of Europe. Its
congener, P. migratorius, is much less widely distributed, its
migrations being, according to
de Saussure, limited to Turke-
stan and Eastern Europe. A
third species, P. migratori-
oides, inhabits Eastern Africa,
and a variety of it is the
“Yolala” or locust of Mada-
gascar. Mr. Distant has in-
Fic. 177.—European migratory locust, formed the writer that this
Pachytylus cinerascens 9. migratory locust is found in

South Africa. P. (Oedaleus)

marmoratus has almost as wide a distribution in the Eastern
hemisphere as P. cinerascens, except that it is more exclusively
tropical; it is thus excluded from New Zealand. P. (Oedaleus)
nigrofasciatus has a more northern distribution than its congener,
but has extended to Africa and the Asiatic Archipelago. This
Insect is so variable that the distinctions of its races from other
species of the same genus are not yet clear. All the above-
mentioned locusts belong to the tribe Oedipodides. Acridium pere-
grinum, now more frequently called Schistocerca peregrina, belongs
to the tribe Acridiides. It is a large locust (Fig. 84), and has
a wide distribution. It is the chief species in North Africa, and is
probably the locust of the plagues of Egypt mentioned in the
book of Exodus. It is also, according to Cotes,’ the chief locust
of North-West India. In this latter country Pachytylus ciner-
ascens and some other species also occur. With the exception of
S. peregrina, the species of the genus Schistocerca are confined to
the New World. In North America locusts are more usually
called grasshoppers. Several species of the genus Caloptenus are
injurious in that country, but the chief migratory species is C.
spretus (Fig. 175). This genus belongs to Acridiides. A large
locust, Schistocerca americana, is also migratory to a small extent
in the United States. In South America other species of Schis-
tocerca are migratory ; it is not known how many there may be, and
it is possible that one or more may prove to be the S. peregrina
of the Old World. A Chilian species, according to Mr. E. C. Reed,

1 J. Bombay N. H. Soc. viii. 1893, p. 120. 2 P. ent. Soc. London, 1893, p. xxi.

nb 6x

¢ XI ACRIDIIDAE

299

exhibits distinctions of colour similar to those that have been

observed in S. peregrina in Algeria.

In Britain weare now exempt from the ravages of locusts, though
swarms are said to have visited England in 1693 and 1748.

Individuals of the migratory species are, how-
ever, still occasionally met with in England
and the south of Scotland. P. cinerascens has
been recorded from Kerry in Ireland, but

_ erroneously, the Insect found being JMecos-

tethus grossus (Fig. 173). According to Miss
Ormerod,’ large locusts are imported to this
country in fodder in considerable numbers,
but are usually dead; living individuals are,
however, sometimes found among the others.
In 1869 living specimens of Schistocerca
peregrina were found in various parts of the
country, having, in all probability, arrived
here by crossing the German Ocean. Pachy-
tylus cinerascens has also, it is believed,
occurred here, the specimens that have been
recorded at different times under the name of
P. migratorius being more probably the former
species.

Although the .majority of the very large
number of species included in Acridiidae are
recognised with ease from their family like-
ness as belonging to the group, yet there are
others that present an unusual aspect. This
is specially the case with the members of the
small tribes Tettigides, Proscopides, and
Pneumorides, and with some of the apterous
forms of the Oedipodides. The tribe Pros-
copides (Fig. 178, Cephalocoema lineata,
female) includes some of the most curious of
the Acridiidae. Breitenbach gives” a brief
account of the habits of certain species which
he met with near Porto Alegre in South
America. On a stony hill there was some

|
()
Yj

be

Fic. 178..— Cephalocoema
lineata, female. x2.
S. America, (After
Brunner.)

grass which, by several months’ exposure to the sun’s rays, had
1 Rep. injurious Insects, xvii. 1898, p. 47. 2 Ent. Nachricht. viii. 1882, p. 160.

i

300 ORTHOPTERA CHAP,

become withered and brown. Apparently no live thing was to
seen on this hillock except the ubiquitous ants, but after a while
he noticed some “ lightning-like ” movements, which he found were
due to specimens of Proscopia. The Insects exactly resemble the
withered vegetation amongst which they sit, and when alarmed
seek safety with a lengthy and most rapid leap. When attention
was thus directed to them he found the Insects were really
abundant, and was often able to secure fifty specimens on a single
afternoon. These Insects bear a great general resemblance to the
Phasmides, but there is no evidence at present to show that the
two kinds of Insects live in company, as is the case with so many
of the Insects that resemble one another in appearance. Although
the linear form and the elongation of the body are common to the
stick-Insects and the Proscopides, yet this structure is due to the
growth of different parts in the two families. In the Phasmidae
the prothorax is small, the mesothorax elongate, while in the
Proscopides the reverse is the case. The elongation of the head
_ 1s very curious in these Insects; the mouth is not thus brought
any nearer to the front, but is placed on the under side of the
head, quite close to the thorax. The tribe Tryxalides contains
Insects (Fig. 165) that approach the Proscopides in the form of
the head and other characters. In most cases the sexes of the
Proscopides differ from one another so strongly that it is difficult
to recognise them as being of the same species. Usually both
sexes are entirely apterous, but the Chilian genus Astroma
exhibits a remarkable exception and an almost unique condition
of the alar organs, the mesonotum being in each sex entirely
destitute of such appendages, while the female has on the meta-
notum rudiments of wings which are absent in the male.

The tribe Tettigides is a very extensive group of small
Acridiidae, in which the
pronotum extends back-
wards as a hood and
covers the body, the
tegmina and wings

Fic. 179.—Tettix bipunctatus. Britain. A, The Insect being more or less modi-
magnified ; B, part of the middle of the body; a 1t7
prolongation of pronotum ; 8, tegmen ; ¢, wing. fied. In , aces British

species (Fig. 179) this

condition does not greatly modify the appearance of the Insect,
but in many exotic species (Fig. 180) the hood assumes remark-

Saat ie Is I FS
ee =

IK FE EAESESTD

5D aaapaeee—

x C= oe a ao

XII ACRIDITIDAE 301

able developments, so that the Insects have no longer the appear-
ance of Orthoptera. It would be impossible, without the aid of
many figures, to give an idea of the.
variety of forms assumed by this
prothoracic expansion. It is a repe-
tition of what occurs in the Order
Hemiptera, where the prothoracic
hoods of the Membracides exhibit a
similar, though even more extra-
ordinary, series of monstrous forms.
So great is the general similarity
of the two groups that when the
genus Aerophyllum (Fig. 180, A)
was for the first time described, it
was treated by the describer as
being a bug instead of a grass-
hopper. This genus includes several pyg, 180,—Tettigides: A, Xerophyllum
species from Africa. The curious — simile Fairm.; B, Cladonotus hum-
Cladonotus (Fig. 180, B) is a native Bie aia Naso lial
of Ceylon, where it is said to live in sandy meadows, after the
fashion of our indigenous species of Zettiz (Fig. 179). Very
little is known as to the habits of these curious Tettigides, but
it has been ascertained that some of the genus Scelimena are
amphibious, and do not hesitate to enter the water and swim
about there; indeed it is said that they prefer plants growing
under water as food.
This habit has been
observed both in Ceylon
and the Himalayas. The
species are said to have
the hind legs provided
with dilated foliaceous
appendages useful for
swimming.

The tribe Mastacides
includes thirty or forty

Fic. 181.—A, Mastax (Erianthus) guttatus, male. Species of Acridiidae
Sumatra. (After Westwood.) B, profile; C, front with short antennae

of head. and vertical head (Fig.

181, Mastax guttatus); they are apparently all rare and little

302 ORTHOPTERA CHAP.

known, but are widely distributed in the tropics of the Old and
New Worlds. Nothing whatever seems to be known of their
habits or of their development.

The tribe Pneumorides includes a still smaller number of species
of very aberrant and remarkable grasshoppers, of large size, with
short antennae, and with the pronotum prolonged and hood-like ;
they are peculiar to South Africa. Although amongst the most
remarkable of Insects, we are
not able to give any infor-
mation as to their habits.
It would appear from the form
of their legs that they have
but little power of hopping.
The species of which we figure
' the female (Fig. 182) is very
remarkable from the difference
in colour of the sexes. The
female is so extravagantly col-
oured that she has been said
to look as if “got up” for a
fancy-dress ball. She is of a
gay green, with pearly white
marks, each of which is sur-
rounded by an edging of ma-
genta; the white marks are
very numerous, especially on
the parts of the body not

shown in our figure; the face
Fig. 182.—Pneumora scutellaris, female,

Soath Ativn. has magenta patches and a
large number of tiny pearly-
white tubercles, each of which, when placed on a green part, is
surrounded by a little ring of mauve colour. Though the female
is certainly one of the most remarkably coloured of Insects, her
consort is of a modest, almost unadorned green colour, and is con-
siderably different in form. He is, however, provided with a
musical apparatus, which it is possible may be a means of pleas-
ing his gorgeous but dumb spouse. It consists of a series of
ridges placed on each side of the inflated abdomen, which, as we
have previously (p. 200) remarked, has every appearance of being

inflated with the result of improving its resonance.

iH ey

;
; Fr
2

XII ACRIDIIDAE 303

The Pyrgomorphides * is a small tribe of about 120 described
species, two of which are found in the south of Europe (Fig. 183,
Pyrgomorpha grylloides). The tribe |
includes a number of large and curious
Insects, among them the species of
Phymateus and Petasia, with peculiar
excrescences on the pronotum and
vivid colours on some parts of the iif,
body or its appendages, which are
apparently common Insects in South
Africa.

The tribe Tryxalides includes a
great many species of grasshoppers.

In them the front of the head joins vaca the fey &
the upper part at an acute angle

(Figs. 165 and 173). This tribe and the <Acridiides are the
most numerous in species of the family. To the latter belong
most of the migratory locusts of the New World (Fig. 175,
Caloptenus spretus). A Spanish species of this tribe, Hupre-
pocnemis plorans, though provided with well-developed wings,
possesses the remarkable habit of seeking shelter by jumping:
into the water and attaching itself below the surface to the
stems of plants.

The tribe’ Pamphagides” includes some 200 species, found
chiefly in Africa and the arid regions near the Mediterranean
Sea, They are mostly apterous forms, and this circumstance has,

Y
4
=
s
SN
Y

| i f
|
f
)
nS
al

SS

Fic. 184.—Xiphocera (Hoplolopha) asina. S. Africa. (After de Saussure.)

according to de Saussure, exercised a marked influence on the
geographical distribution of the species. Although the tribe
consists chiefly of apterous forms, several species possess well-

1 Monograph by Bolivar, Ann. Soc. Esp. xiii. 1884, p, 1, ete.
2 Monograph, de Saussure, Spicilegia entomologica Genavensia, pt. 2, Geneva, 1887.

304 ORTHOPTERA _ CHAP.

developed wings; sometimes this is the case of the male but
not of the female. Some of the species are highly modified for
a desert life, and exhibit a great variation in the colour of the
individuals in conformity with the tint of the soil they inhabit.
Xiphocera asina (Fig. 184) is thought by Péringuey to be the
prey of the extraordinary South African tiger-beetles of the
genus Manticora.

We have already mentioned the tribe Oedipodides ' as including
most of the species of migratory locusts of the Old World. Some
striking cases of variation in colour occur amongst the winged
Oedipodides. In certain species the hind wings may be either
blue or rosaceous in colour; it is thought that the latter is the
tint natural in the species, and that it is due to the mixture of
a red pigment with the pale blue colour of the wing; hence the
blue-coloured wings are analogous to cases of albinism. But the
most remarkable fact is that this colour difference is correlative
with locality. Brunner von Wattenwyl says? that the blue
variety of Oe. variabilis occurs only in a few localities in Europe—
he mentions Vienna and Sarepta,—and that where it occurs not
a single red example can be met with. Similar phenomena occur
in other species in both Europe and North America, and L. Bruner
has suggested® that the phenomena in the latter country are
correlative with climatic conditions.

The group Eremobiens, a subdivision of Oedipodides, includes
some of the most interesting forms of Acridiidae. Its members.
have several modes of stridulation. Cueulligera flexuosa and
other of the winged forms, according to Pantel,* produce sounds
by the friction of the middle tibia against the wing, both of these
parts being specially modified for the purpose in the male sex.
The most peculiar members of the Eremobiens are some very
large Insects, modified to an extraordinary extent for a sedentary
life in deserts and arid places. Trimen says’ that a South
African species, Z’rachypetra bufo, which lives amongst stones, is
so coloured that he had much difficulty in detecting it, and that
he noticed in certain spots, often only a few square yards in
extent, where the stones lying on the ground were darker, lighter,

1 Monograph, de Saussure, Mem. Soc. Phys. Genéve, xxviii. 1884, No. 9; and
xxx. 1888, No. 1.

2 Prod. Eur. Orthopt. 1882, p. 160. 3 Science, xxi. p, 183.

4 An. Soc. Espan. xv. 1886, p. 273. 5 Nature, iv. 1871, p. 333.

XII ACRIDIIDAE 305

or more mottled than usual, that the individuals of the grass-
hopper were of a similar colour to the stones. The Insect
referred to by Trimen is, we believe, the Batrachotettia whiti of de

Fic. 185.—Methone anderssoni, female. S. Africa. a, Front of head ; 6, posterior leg ;
c, d, front and hind feet. (c¢c and d magnified, the others natural size.)

Saussure. In this species the alar organs are completely absent,

and the pronotum forms a sort of hood that protects the base of

the hind body. Some of the desert Eremobiens vary so much

that the differences found among individuals of the same species
VOL. V x

306 ORTHOPTERA CHAP.

are said by Brunner and de Saussure to be so great as to affect
even the generic characters, and give rise to the idea of an
“uncompleted species-formation.” |
Methone anderssoni, an inhabitant of the Karoo Desert of South
Africa, is one of the largest of the Acridiidae. A female of this
species is represented of the natural size in Fig. 185. This
Insect is remarkable on account of the complex organs for pro-
ducing sound, and for the great modification of the posterior legs —
(Fig. 185, 6), which do not possess locomotive functions, but serve ;
as a portion of the sound-
producing apparatus, and as
organs for protecting the sides
m, of the body. This Insect is
\“\ said to be very efficient in
making a noise. The sexes
differ considerably in their
sound - producing organs, a
portion of which are present
in the female as well as in
the male (Fig. 186). Con-—
nected with the first abdominal
segment, but extending back-
wards on the second, there is
Fro, 186 Porton of middie ot te nian q peculiar swelling bearing
b, an inferior fold; c, rattling-plate; d, two or three strongly raised
seat ara o he adjonng spt; chitinous folds (Fig. 186, 0).
is really, like d, a portion of the second When the leg is rotated these
sonia segment, not of the third @8 folds are struck hy some peg-
} like projections situate on the
inner face of the base of the femur, and a considerable noise is
thus produced. The pegs cannot be seen in our figure. This
apparatus is equally well developed in female and male. On the.
second abdominal segment, immediately behind the creaking folds
we have described, there is a prominent area, densely and finely
striated (Fig. 186, d): this is rubbed by some fine asperities on
the inner part of the femur near its base. Sound is produced by
this friction on the striated surface, the sculpture of which is
abruptly contrasted with that of the contiguous parts: these struc-
tures seem to be somewhat better developed in the male than they
are in the female, and to be phonetic, at any rate in the former sex.

XII ACRIDIIDAE 307

The male has the rudimentary tegmina (Fig. 186, /) much longer
than they are in the female (Fig. 185), and their prolonged part
is deeply grooved, so as to give rise to strong ridges, over which
plays the edge of the denticulate and serrate femur. There is
nothing to correspond to this in the female, and friction over the
surface of this part of the male produces a different and louder
sound. There can be little doubt that this is a phonetic structure
-peculiar to the male. It approximates in situation to the sound-
producing apparatus of the males of the Stenobothri and other
Acridiidae. Methone anderssoni. has large tympanal organs: the
small tegmina cover them up completely. In the female the tips
of the tegmina seem to be adapted for forming covering-flaps
for the tympana. In both sexes there is a sac (Fig. 186, d)
adjoining the structures we have mentioned, but which is not
directly phonetic, though it may be an adjunct of the apparatus.

There is no other Orthopteron in which the phonetic organs
are so complex as they are in the male of Methone anderssoni,
and it would appear probable that this Insect possesses the
power of producing two, if not more, distinct sounds, one in
common with the female, and peculiar to this and one or two
other species; the other somewhat similar to that of other Acri-
diids, and more specially developed in the male, if not absolutely
confined to it.

This Insect is of a very sedentary disposition, and when
disturbed apparently seeks safety rather by the noise it can make
than by flight. Its powers of locomotion indeed are very feeble.
The alar organs are quite rudimentary, and of no assistance what-
- ever for movement. The hind legs seem to be almost equally
useless for this purpose; they are broader than they are in other
Acridiidae, and have different functions. When Methone moves

it does so by means of the anterior four legs, on which it walks
- propped up as if on stilts. When at rest the hind legs are pressed
close to the body, and the tibiae are inflexed and not seen, the
creature in this position greatly resembling a clod of earth. We
know nothing of the life history of this Insect, except that the
young resemble the adult in appearance, and are provided with
the sound-producing apparatus, or some portion thereof.

The geographical distribution of the Eremobiens corresponds
with that of the Pamphagides, with two important differences,
viz. that in the Old World the former group occupies a somewhat

308 ORTHOPTERA CHAP.

more restricted area, and that it is represented in the New World
by two peculiar North American genera, Haldmanella and Brachy-
stola. B. magna is an Insect nearly equal in size to Methone
anderssoni. Its peculiar form and movements have procured for it
in Texas and Colorado the popular names of “ buffalo hopper ~
and “lubber grasshopper.” This Insect has not—lke Methone—
the colours of the desert sands; it is of a green tint, with com-
paratively smooth body, and during the day rests concealed
under tufts of grass. It has apparently no sound organs, though
de Saussure thinks there are structures present that are vestiges
or rudiments thereof. |

The family Acridiidae includes a large part of the species that
make up our meagre list of British Orthoptera. Indeed, the
only native Orthoptera at the present time sufliciently common
to attract general attention are, in addition to the earwig, the
species of the genera Stenobothrus and Gomphocerus, whose
musical instruments we have described previously. We have
eight species of these Insects. They are the little grasshoppers,
so common in our fields and gardens, the hunting of which is
a source of much amusement to children. The Insect goes off
with a sudden and long hop just as it is going to be seized, and
this is appreciated by. the child as very clever. The hunt, as a
rule, does not result in much damage to the grasshoppers, the
ingenious escape being the greater part of the pleasure. These
Stenobothri are remarkable for their variation in colour, and it .
is thought by some that they frequent spots where they find
themselves a match with their surroundings. There is, how-
ever, little or no information of importance on this point extant.
Mecostethus grossus (Fig. 173), though larger, is very like the
common field grasshoppers, but appears to have become rare
since the fens were drained. The two curious little grasshoppers
of the genus Zettiz (Fig. 179) are not uncommon. In addition
to these Acridiidae, three species of migratory locusts are occa-
sionally met with in Britain, viz. Pachytylus cinerascens (Fig.
177), P. migratorius, and Schistocerca peregrina (Fig. 84); this
latter we have already alluded to as being probably the locust
mentioned in the book of Exodus.

Acridiidae have never been found in amber, owing possibly to
their large size and strength. There are but few fossil forms known,
and these do not extend farther back in time than the Mesozoic

ia

XII ACRIDIIDAE 309

epoch. Several forms, including three peculiar genera, have
been found in the Tertiary strata at Florissant. The remains
from the Mesozoic layers are apparently very fragmentary and
obscure.

Brongniart has instituted a family of Insects under the name
Palaeacrididae’ for some fossil Insects from the Carboniferous
strata at Commentry. He considers that these Insects were
abundant in the epoch of the Carboniferous strata.

The very large number of genera and species of Acridiidae
have been recently arranged in nine tribes by Brunner von
Wattenwy! :— .

1. Feet without a claw-pad.? [Pronotum covering all the body.] Tegmina
lobe-like. Tribe 1. Terricipes. (Figs. 179, 180, Tettiz, Xerophyllum,
Cladonotus. ) |

1’. Feet with a claw-pad.

2. Antennae shorter than the anterior femora.
3. Head short, as if compressed from in front.

4. Body bladder-like, inflated. [Pronotum covering half the
abdomen.] South African species. Tribe 2. PNEUMORIDES.

(Fig. 182, Pnewmora scutellaris.)

4’, Body ordinary. Tribe 3. Masractpres. (Fig. 181, Mastax

guttatus.)
3’. Head very elongate. [Body apterous or sub-apterous.] Tribe
4, ProscoplipEs. (Fig. 178, Cephalocoema lineata.)
2’. Antennae longer than the anterior femora.
3. Prosternum unarmed.

4, The plane of the vertex of the head meeting the plane of
the front of the head as an angle. The former produced or
declivous. The face looking down, Tribe 5. TRYXALIDES.
(Fig. 165, Tryxalis nasuta ; Fig. 173, Mecostethus grossus.)

4’. Planes of the vertex and front of the head connected in
a rounded manner. Face looking forwards. Tribe 6.
OEDIPODIDES. (Fig. 177, Pachytylus; Fig. 185, Methone.)

3’. Prosternum with an elevated lamina in front, either irregularly
swollen or mucronate. ;

4, Foveoles of the vertex superior, contiguous, forming the
apex of the vertex. Face looking much downwards.
Tribe 7. PyrGomorpHipes. (Fig. 183, Pyrgomorpha
grylloides.)

4’. Foveoles of the vertex, either superior (but not forming the
apex of the vertex), or lateral, or inferior, or quite obsolete.

1 Bull. Soc. Rowen, 1885, and Jnsectes fossiles, etc. 1894, p. 439.

2 A few species of Proscopiides and Oedipodides, though placed in the next
division, are destitute of any claw-pad.

8 This applies specially to the males.—D. S.

310 ACHIDERGG

5. Foveoiss superior, open ah P cerias T
swollen, rarely mucronate. ‘Tribe 8. Pamp
(Fig. 184, Xtphocera asina,)

ce ’, Foveoles Istana or inferior, closed behind or
; entirely obsolete. Prosternum distinetly mucror

- tubereulate. Tribe 9. Acrip J
peregrinum ; ; Hig 176, Jalo

er

* CHAPTER Xill

ORTHOPTERA CONTINUED—LOCUSTIDAE, GREEN
GRASSHOPPERS, KATYDIDS

Fam. VII. Locustidae—-Green Grasshoppers.

Orthoptera, with very long delicate antennae composed of many more
than thirty joints ; hind legs longer than the others, thicker
at the base. Tarsi with four joints. Front tibiae usually
provided with tympanal organs placed below the knee; stridu-
lating apparatus of males, when present, situate on the basal
part of the tegmina. Females usually with an elongate ex-
serted ovipositor, formed by the apposition of six pieces.
Wingless forms numerous.

Fic. 187.—Cyrtophyllus crepitans, male. West Indies.

AN unfortunate confusion has long existed as to the term
Locustidae, and has resulted in the application of the name to a
group of Insects that contains none of the locusts of ordinary
language. Some entomologists therefore use the term Phasgonu-
ridea for this family, but the great majority prefer the term
Locustidae. |

The Locustidae are, as a rule, more fragile Insects than the

312 ORTHOPTERA - CHAP.

Acridiid, from which they can be readily distinguished by the
characters we have mentioned in our definition. According to
Dufour, there are no air vesicles connected with the tracheal
system in this family; possibly to this it may be due that none
of the family undertake the long flights and migratory wanderings
that have made some of the Acridiidae so notorious. Very little
is known as to the life histories of the members of this extensive _
family of Orthoptera. Graber, however, has given some particulars
as to the development of Platycleis grisea, and of one or two other |

Fig. 188.— Development of wings in Platycleis grisea: A, B, C, D, E, consecutive
stages; p, prothorax; m, mesothorax; mt, metathorax; ¢, tégmen; w, wing ;
ab’, position of first abdominal segment. In C, D, and E, m points to the part by
which the m, shown in A and B, is concealed ; in D and E only the positions of m#
are indicated. (After Graber.)

species. He recognises five instars, but his first is probably
really the second, as he did not observe the Insect in its youngest
condition. Although his figures are very poor, we reproduce
them, as they give some idea of the mode of growth of the wings,
and of the correlative changes in the thoracic segments. It
will be seen that in the first three of these instars the alar organs
appear merely as prolongations of the sides of the posterior two
thoracic rings, and that in D a great change has occurred in the
position of these segments, so that the alar organs are free
processes, the two posterior thoracic rings being insignificant in
size in comparison with the now greatly developed prothorax.
In E the tegmen is shown fully developed, the positions of some

é, oy T

_ present in a fairly well-developed state

xi | LOCUSTIDAE sa

of the rings covered by it being indicated by the letters m, mt,
ab’. These changes are very similar to those we have described
in Acridiidae, the chief difference being the greater development
of the dependent wing-pads previous to the fourth instar.

The ocelli in Locustidae are much more imperfect than they
are in Acridiidae, and are frequently rudimentary or nearly totally
absent, or there may be but one in- ©
stead of three. They are, however,

in some species, and this is the case
with the one whose face we portray
in Fig. 189, where the anterior of the
three ocelli is quite conspicuous, the
other two being placed one on each
side of the curious frontal cone near
its base. The peculiar head ornament
shown in this figure exists in both
sexes, and something similar occurs in
a large number of Conocephalides. We
have not the slightest idea of its im-
port. Individuals of one or more
species of this curious South American
genus are occasionally met with alive
in gardens near London. They are, no
doubt, imported as eggs, for they are
sometimes met with in the juvenile. :
state, but in what way they are intro- Fie. 189.— Front of head of
duced is not known. Copiophora cornuta, female.
Demerara.
The ovipositor frequently attains a
great length in these Insects, so as to exceed that of the body. It is
used in different ways, some of the family depositing their eggs in
the earth, perhaps in vegetable matter under the surface ; but other
species place the ova in twigs or stems of plants, arranging them
in a very neat and compact manner in two series, as depicted by
Riley * in the case of Microcentrum retinerve (Fig. 190). These
eggs are laid in the autumn, and in the following spring become
more swollen before hatching. The Insect undergoes a moult
during the process of emerging from the egg. By the time the
emergence is completed the Microcentrum has expanded so much

1 Ann. Rep. Insects Missouri, vi. 1874, p. 155.

314 ORTHOPTERA CHAP.

in size that it is a matter of astonishment how it can ever have
been packed in the egg; the young commence jumping and
eating leaves in a few minutes. Including
the ecdysis made on leaving the egg, they
cast their skins five times. The post-embryonie
development occupies a period of about ten
weeks. The larvae eat their cast skins. "When
the final moult occurs the tegmina and wings
are at first quite soft and colourless, but
within an hour they assume their green colour.
These Insects, as remarked by Riley, make in-
teresting pets. The people of the Amazon valley
are in the habit of keeping a species in cages,
and our British Locusta viridissima does very
well in confinement. One of the most curious
habits of these Locustidae is a constant lick-
ing of the front paws. Riley says that JL
retinerve bestows as much attention on its
long graceful antennz as many a maiden does
: upon her abundant tresses, the antenne being

Fic. 190. — Eggs of ‘
Katydid (Microcen- drawn between the jaws and smoothed by the
trum retinerve): A, yalpi. This American naturalist also tells us

the two series at . .

deposition ; B, side that he reared three successive broods in con-
nant rite tile) finement, and that the Insects gradually
deteriorated, so that the eggs of the third

generation failed to hatch.

The ovipositor, which is one of the most characteristic features
of the Locustidae, is not present in the newly-hatched Locustid
(Fig. 191, A), the organ being then represented only by two
papillae placed on the penultimate segment. The structure and
development of the ovipositor in Locusta viridissima have been
described by Dewitz.' Fig. 191, A, shows the young Insect taken —
from the egg just as it is about toemerge. The abdomen consists
of ten segments, the terminal one bearing at its extremity two
processes, the cerci, a’. These persist throughout the life of the
Insect, and take no part in the formation of the ovipositor. The
tenth segment subsequently divides into two (a, a’, Fig. 191, C),
giving rise to the appearance of eleven abdominal segments,
and of the ovipositor springing from the antepenultimate. Near

1 Zeitschr. wiss. Zool. xxv. 1875, pp. 174-200, pl. xii.

sy = =

= = S

==>

ee

?

xl | LOCUSTA OVIPOSITOR 315

to one another, on the middle of the ventral aspect of the true

ninth abdominal segment, are
seen the two papillae (b’), which

at first are the only visible indi-

cations of the future ovipositor.

- If, however, the integument be

taken off and carefully examined,
it will be found that there exist
on the eighth abdominal plate
two spots, where there is a slight
thickening and prominence of
the integument (Fig. 191, B, ec).
From these two spots the two
lower rods of the ovipositor are
produced; these two, together
with the two growths from the
ninth segment, form the four ex-
ternal rods of the ovipositor.

,

Fia. 191.—Development of ovipositor of

Locusta viridissima : a, terminal seg-
ment ; a’, cerci ; a, secondary division
of terminal segment ; 8, penultimate
(ninth) segment ; 0’, primary papillae
of this segment ; 6”, secondary divi-
sions thereof; c, eighth segment ;-c’,
its papillae. (After Dewitz.) A,
embryo ready for emergence; B,
portion of integument of the ventral
plates of eighth and ninth segments ;
C, the appendages in a condition
somewhat more advanced than they
are in A.

Inside these there exist in the

completed structure two other rods (Fig. 192, B, b"). These are
produced by a growth from the inner parts of the two papillae
of the ninth segment. The relations of the six rods in their
early condition are shown in Fig. 191, C, where the two primary
papillae 0’ of the ninth segment are seen with their secondary

Fic. 192. —Structure of
ovipositor of Locusta
viridissima ; A, ar-
rangement of parts at
base, c’ being separated
and turned outwards ;
B, transverse section.
The parts of the ap-
pendage bear the same
lettering as in Fig. 191.
(After Dewitz. )

offshoots 6”; c’ being the papillae of the eighth segment. The
subsequent relations of the pieces are shown in Fig. 192; A
exhibiting the base of the organ with the lower rods turned
on one side to show the others, the shaded parts indicating

316 LOCUSTIDAE CHAP,

muscular attachments ; B is a transverse section of the organ. In
these figures the different parts of the appendages bear the same
lettering as they do in Fig. 191. It will be seen that in the com-
pleted structures the parts c’ have become very intimately con-
nected with the parts b’ and b”, which belong to another segment.
The Locustidae resemble the Acridiidae in the possession of
specialised ears and sound-producing organs; neither of these is,
however, situate in the same part of the body as in Acridiidae.
The ears of Locustidae are
placed on the front legs, below
the knee; a tympanum (Fig.
193, A), or a crack giving en-
trance to a cavity in which the
tympanum is placed (Fig. 193,
B), being seen on each side of
each of the anterior pair of
limbs. In this family, as in
the Acridiidae, three kinds of
ear are recognised according to
the condition of the tympanum,
_ which is either exposed (Fig.
Fic, 193.—Ears of Locustidae: A, portion
of front leg of Odontura serricauda, 193, A) or closed by an Over-
adult ; p, prominence of integument; 7, orowth of the integument (Fig.
rim of ear; 7, tympanum ; 4, thickened ; wes
area thereof; Fu, remains of groove in 193, B), or in a condition to a
which the structure was developed. B, certain extent different from
portion of front leg of Zhamnotrizon , ‘
apterus; i, inner margin; a, slit - like either of these. The existence of
enna entre of ers i ovevaPDINE ears placed on the legs is a euri-
ous fact, but it is beyond doubt
in the Locustidae, and there is good reason for believing that analo-
gous organs exist in this situation in other Insects that have special
means of sound-production, such as the ants and the Termites.
The structure of these organs in the Locustidae has been
investigated by Graber,’ and their acoustic functions placed
beyond doubt, though to what special kind of sounds they may
be sensitive is not ascertained, this point being surrounded by
even greater difficulties than those we have discussed in the case
of the Acridiidae. In the Locustidae there is a special structure
of a remarkable nature in connexion with the ears. In Acridiidae

1 Arch. f. mikr. Anat. xx. 1882, and xxi. See also von Adelung, Zeitschr. wiss.
Zool. liv. 1892, p. 316.

XIII EARS 7 337

a stigma is placed close to the ear, and supplies the internal
structures of the organ with air. There are no stigmata on the
legs of Insects, consequently admission of air to the acoustic
apparatus in Locustidae is effected by means of a gaping orifice
at the back of the prothorax, just over the base of the front leg
(Fig. 101); this communicates with its fellow of the other side,
and from them there extend processes along the femora into the
tibiae, where they undergo dilatation, so as to form vesicular
cavities, one of which is in proximity to each drum of the ear.
These leg-tracheae are not con-
nected with the ordinary tracheal
system; the prothoracic stigma
exists in close proximity to the
acoustic orifice we have described,
but is much smaller than it. It
is not yet clear why the acoustic
apparatus should require a supply
of air apart from that which could
be afforded by the ordinary tracheal
system. ‘This special arrangement
—to which there is hardly a
parallel in Insect anatomy—has
still to be accounted for; we do 5

not know whether the necessity ; J

for it may be connected with the T9104-Diasramof arangement of prt

respiratory system or the acoustic _ thetibiaofaLocustid. A, J,V, H, outer,
inner, anterior, posterior aspects of leg ;

organ. a,d,thin part of integument forming an-
The chief features of the acous- war rig: tee b, c, thicker portion

: of same ; 7, g, posterior tympanum ;
tic apparatus of the legs of Locus- ~ @, f and‘d, h, g, thick portions of

tidae will be gathered from the integument ; 7, %, internal protuber-
© ances of same ; /, m, n, 0, Walls of the

accompanying diagrammatic trans- _ anterior tracheal vesicle, v7; p, q 8, 7,

verse section through the tibia. In walls of the posterior tracheal vesicle,
5 y hTr ; 0”, projection of tympanal orifice

this figure the deep black parts of prothorax ; ¢r-n, tracheal inerve-

ae Oe : end organ, crista acustica ; st, rod ;
indicate the outer wall of the de, curtain-membrane ; hn, e, supra-

tibia and its prolongations, the tympanal, nerve-end organ ; in, gang-
hit aeAisata:-t t lion cells; st’, rods; ¢, point of in-
white spaces indicate 16 parts tegumental fixation of nerve endings.

filled with air, while the dotted (After Graber.)
portions are occupied by blood or some of the body organs;' the

1 The small space above Jm left free from dots is,we presume, due to an omission on the
part of Graber’s artist, but we have not thought it right to interfere with his diagram.

318 : LOCUSTIDAE | CHAP.

circular space o” is not part of the actual structure, but repre-_—
sents the area of the external acoustic orifice of the protaena
it is not, however, so large as it should be.

Although the tibial ears of Locustidae are very perfect organs,
there is great difficulty in deciding on the exact nature of their
functions. They would appear to be admirably adapted to
determine the precise locality from which a sound proceeds,
especially in those cases—and they are the highest forms—in
which the tympanum is. placed in a cavity the external orifice
of which is a slit (Fig. 193, B); for the legs. can be moved in
the freest manner in every direction, so as to bring the drum
into the most direct line of the vibrations. But as to what
kinds of vibrations may be perceived, and the manner in which
they may be transmitted to the nerves, there is but little
evidence. On reference to the diagram it will be noticed that
the tympanum, the tympanal vesicles, and the nervous apparatus
are not in close connexion, so that even the mode by which the
impulses are transmitted is obscure.

The musical organs of the Locustidae are different from those
of the Acridiidae, and are invariably situate on the basal part of
the tegmina. They are found, in the great majority of cases, only
in the male; in the tribes Ephippigerides and Callimenides they
exist in each sex. One of the wings bears a file on its inner sur-
face, while the other—on the right side of the body—is provided
with a sharp edge placed on a prominent part of its inner margin.
By slightly tilting the tegmina and vibrating them rapidly, the edge
passes under the file, and a musical sound is produced. These
structures are limited to the small anal area of the wing, and when
the tegmina are very greatly reduced in size, it is this part that
still remains. There is much variety in the details. of the structure.
The nervures of this part of the tegmina are different in the
male from what they are in the female, and, moreover, the two
wing-covers of the male differ from one another. It is apparently
the vibrations of the right tegmen that produce the sound, and
this part usually bears a space of a glassy nature, which probably
improves the character of the sound produced. Our chief British
songster of this group, Locusta viridissima, is only provided with
phonetic organs (Fig. 195) of a somewhat imperfect character,
but in the genus Mecopoda there is great perfection of the
structures. The anal areas of the two tegmina are in this case

XIII MUSIC 319

very different; that of the left one, which bears the file, being
similar in texture to the rest of the wing-cover, while the corre-
sponding part of the other tegmen is
rigid and transparent, and greatly
distorted, so as to create a cavity
which, no doubt, improves the sound ;
the scraper too is very perfectly
formed. The difference between this
form of musical organ and that of
L. viridissima is curious, inasmuch
as in the better instrument the im-
portant modifications are confined to
one tegmen, while in the other form
both tegmina are largely changed.
The difference appears to be that in
Locusta the left tegmen, as well as
the right one, acts as a sounding-
board, while in Mecopoda it does not pte ts
do so, but when the wings are closed "™%,,)90-—immer face of, ase ot
? 5 tegmina of Locusta viridissima :
quite covers and conceals the musical — A, the two wing-covers separ-

; ated ; B, in natural position with
istrument. mesonotum connecting them,

The Locustidae, notwithstanding showing file and edge scraping
‘ it; a, the stridulating file; 3,
the fact that their alar organs are the rudimentary file on other
generally more ample than those of the ‘sen.
Acridiidae, seem to be, as a rule, of more sedentary habits, and more
nocturnal in their activity. The musical powers of the different
species are very varied. Locusta viridissima produces.a shrill and
monotonous but not disagreeable, sound, and is capable of sustain-
ing it for a quarter of an hour without any intermission, except
a break for the sake of starting again immediately with greater
force, like a performer on a flute. It occasionally chirps in the
day, but the act is then very brief. Bates informs us that one
of these singing grasshoppers, called Tanana by the natives
of the Amazon valley, is much admired for its singing, and
is kept in little cages. The Amazonian naturalist thought the
music of this species superior to that of any other Orthopterous
Insect he had heard. The name of this grasshopper is Z7’h/iboscelus
camellifolius. It is very similar in appearance to Cyrtophyllus
crepitans, the Insect we have represented in Fig. 187.
The most notorious of the musical Locustids are the Katydids

320 ORTHOPTERA CHAP.

of North America. There are several species of them—they belong,
indeed, to more than one genus,—but it seems that sounds some-
what resembling the words Katy-did are perceptible in most of
their performances. These sounds are frequently repeated with
slight variations—Katy-did, O-she-did, Katy-did-she-did. Riley
describes the music of the Katydid we represent in Fig. 196 as
follows:' “The first notes from this Katydid are heard about
the middle of July, and the species is in full song by the first
of August. The wing-covers are partially opened by a sudden
jerk, and the notes produced by the gradual closing of the same.
The song consists of a series of from twenty-five to thirty rasp-
ings, as of a stiff quill drawn across a coarse file. There are
about five of these raspings or trills per second, all alike, and
with equal intervals, except the last two or three, which, with

Fic. 196.—Katydid, Microcentrum retinerve. N. America. (After Riley.)

the closing of the wing-covers, run into each other. The whole
strongly recalls the slow turning of a child’s wooden rattle, ending
by a sudden jerk of the same; and this prolonged rattling, which
is peculiar to the male, is invariably and instantly answered by
a single sharp ‘chirp’ or ‘tschick’ from one or more females,
who produce the sound by a sudden upward jerk of the
wings.”

Pertinacity is one of the most curious features of the perform-
ance of musical Locustids. One would say they desire to distinguish
themselves as much as possible. Harris says that Cyrtophyllus
concavus mounts on the uppermost twigs of trees and there per-
forms its Katy-did-she-did in rivalry with others. He says even
the female in this species gives forth a feeble noise. Scudder
says that some of the Katydids sing both by day and night, but
their day song differs from that of the night. “On a summer’s
day it is curious to observe these little creatures suddenly chang-

1 Ann, Rep. Insects Missowri, vi. 1874, p. 159.

ere ea ee >. ,.

>
=

XIII LOCUSTIDAE 321

ing from the day to the night song at the mere passing of a
cloud, and returning to the old note when the sky is clear. By
imitating the two songs in the daytime the grasshoppers can be
made to respond to either at will; at night they have but one
note.”

Although but little is known as to the habits of Locustidae,
it is ascertained that they are less exclusively herbivorous in
their food habits than the Acridiidae are; many seem to prefer
a mixed diet. Locusta viridissima will eat various leaves and
fruits, besides. small quantities of flesh. It has been recorded
that a specimen in confinement mastered a humble-bee, extracted
with its mandibles the honey-bag, and ate this dainty, leaving
the other parts of the bee untouched. Many of the Locustidae
are believed to be entirely carnivorous. Brunner considers a
minority to be exclusively phytophagous. The species very
rarely increase to large numbers; this, however, occurs some-
times with Orphania denticauda and Sarbitistes yersini in
Europe, and Anabrus purpurascens in North America. We
have already mentioned that the eggs of some species are
deposited in parts of plants, and of others in the earth. The

British Meconema variwm deposits its eggs in the galls of Cynips

in the autumn; these eggs do not hatch till the following
spring. Xiphidiwm ensiferum has somewhat similar habits in
North America, the gall selected for the reception of the eggs
being the scales formed by a species of Cecidomyia on the leaves
of willows. It has been ascertained that the development of
the embryo in the last-named species is commenced in the
autumn, but is suspended during the winter, being only com-
pleted in the following spring, eight or nine months afterwards.
We owe to Wheeler! a memoir on the embryology of this Insect.

Some of the species have the peculiar habit of dwelling in
caves. This is especially the case with the members of the tribe
Stenopelmatides (Fig. 197), which frequently possess enormously
long antennae and legs, and are destitute of alar organs and
ears. The species with this habit, though found in the most
widely separated parts of the world, have a great general
resemblance, so that one would almost suppose the specimens
found in the caves of Austria, in the Mammoth cave of Ken-
tucky, and in the rock-cavities of New Zealand to be one

1 Wheeler, J. Morphol. viii. 1893.
VOL, V Y

322 ORTHOPTERA CHAP,

species, although they are now referred by entomologists to
different genera.

\ AVY
| LC®

“aN je! LP
| Qe

J
g ~~
~

Fig. 197.—Dolichopoda palpata, male. Dalmatia, (After Brunner. )

The Locustidae display in the greatest possible perfection
that resemblance of the tegmina to leaves which we mentioned
when speaking of the general ‘characters of the Orthoptera. The
wing-covers are very leaf-like in colour and appearance in many
Locustidae, but it is in the tribe Pseudophyllides and in the South
American genus Pterochroza (Fig. 198) that the phenomenon is
most remarkable. The tegmina in the species of this genus
look exactly like leaves in certain stages of ripeness or decay.
In the tegmina of some of the species not only are the colours
of faded leaves exactly reproduced, but spots are present like
; those on leaves due to
cryptogamic growths.
Perhaps the most
remarkable feature
of these resemblances
is the one pointed
out by Brunner
von Wattenwyl,
viz. that the tracks

and spots formed on

Fic. 198.—Leaf-like tegmen of Pterochroza ocellata: a wit
a, a, marks like those made by Insects on leaves, > leaves by the Bais. of

Insects in their tissues
are also represented in the leaf-like wing-covers of the Pterochroza ;
transparent spots (a, a, Fig. 198) being present, just as they are
in many leaves that have been attacked by Insects. Brunner was
so much impressed by these facts that he came to the conclusion ©
that they cannot be accounted for on the grounds of mere utility,

1 Verh. zool.-bot. Ges, Wien, xxxiii, 1883, p. 248.

XIII HYPERTELY 323

—

and proposed the term Hypertely to express the idea that in
these cases the bounds of the useful are transcended. We
will mention here another peculiar case

of resemblance described by Brunner as

occurring in a Locustid. Two specimens 2 |

of a little Phaneropterid were brought

from the Soudan by the Antinori ex- a
_pedition, and have been described by

Brunner under the name of Myrmeco- |
phana fallax. The Insect is said to

bear an extraordinary resemblance to

an ant. The most peculiar feature in f

5 , an

the resemblance is shown in Fig. 199,

A, B. The most characteristic point in

the external form of an ant is the stalked

abdomen, this structure being at the

same time quite foreign to the Orthoptera.

In the other parts of the body and in Ong fee oat

_ the colour generally, the Myrmecophana “see Fallin. sti ine
resembles an ant, but the abdomen of

the Orthopteron is not stalked; it has, however, the appearance
of being so, in consequence of certain parts being of a white
colour, as shown in our figure. If abstraction be made of the
white parts, the form of the stalked abdomen of the ant is nicely
reproduced. The specimens brought from the Soudan were wing-
less and destitute of ovipositor, and may be immature, but Brunner
suggests that they may prove to be really mature, the ovipositor,
tegmina, and wings being permanently absent. The existence
of a long ovipositor would certainly detract greatly from the ant-
_like appearance of the Orthopteron.

It is certain that the plant-like appearance of some of the
Locustidae renders them inconspicuous to the human eye in the
situations they frequent. It is a matter of common observation
that though the noise of their chirpings may be heard to such an
extent as to make it certain that many individuals must be in the
immediate neighbourhood, yet at the same time it may be most
difficult to detect even a single individual. M. Boutan noticed
this phenomenon in the case of Hphippigera rugosicollis, and
tells us that the human eye can, with a little practice, acquire
the art of detecting these concealed creatures. This consists

324 ORTHOPTERA CHAP.

apparently in making use, not of a general inspection, but of a
scrutiny of the outlines of the leaves and twigs of a tree. By
this means, when the eye is accustomed to the task, the Insects
can be detected with comparative ease; much in the same way,
M. Boutan says, as a figure, placed
in an engraving in such a way as to-
elude the eye, is appreciated with ease
after the eye has once perceived it.
Some of the Locustidae are pro-
vided with means of defence of a posi-
tive nature. The Algerian Hugaster
guyont ejects two jets of a caustic
orange-coloured fluid from two pores
situate on the sides of the meso-
sternum, and covered by the anterior
coxae. This species is carnivorous as
well as herbivorous, and produces a.
sound more like humming than stridu-
lation.t |
We have previously pointed out
that some of the Acridiidae resemble
the stick-Insects rather than the
members of their own group; and
similar cases occur amongst the Locus- —
tidae. Such a resemblance has, how-
ever, only been found in a few species
of the tribe Prochilides. We figure
one of these, Phasmodes ranatriformis,
a native of South-West Australia.
The very elongate. linear form and the
total absence of alar organs give this
Fic. 200.— Phasmodes ranatri- Insect a considerable resemblance to
avadlaans os Australia, (After the stick-Insects or apterous Phas-
midae. Prochilus australis is allied
to this curious Locustid, but the alar organs are present in both
sexes, and the Insect bears a great resemblance to the winged
Phasmidae. This is due not only to the general form and colour,
but also to the fact that the tegmina are very narrow, which -

1 Bonnet and Finot, Rev. Sci. Nat. (3) iv. p. 845. The word we have translated
as humming is *‘ bruissement.”

ea

XIII LOCUSTIDAE 325

causes them to look like the coloured slip on the anterior parts
of the wings of some of the Phasmidae (cf. p. 266). Another
case of a Locustid with elongate, slender form is found. in the
extraordinary Peringueyella jocosa of South Africa, a member of
the tribe Sagides. It has minute organs of flight, and repro-
duces, to a considerable extent, the form and appearance of
Proscopides or of some Tryxalides.'

\

Fic. 201.—Schizodactylus monstrosus, male. Natural size. East India.

We follow Brunner in placing among the Locustidae the large
Insect we represent in Fig. 201. It is remarkable on account of its
tegmina and wings; these have their extremities much prolonged

_and curled; moreover, the flat interior area and the abruptly de-

1 De Saussure, Ann. Soc. ent. France, 1888, p. 151, pl. v. fig. 1.

326 ORTHOPTERA CHAP.

flexed exterior area make them look more like the wings of
Gryllidae. This species has no ocelli, and is said to be destitute
of ears. The inflated condition of the anterior and middle tibiae
suggest that it possesses auditory structures, though there appears
to be no external opening for them. This Insect is found in India,
where it is said to be common on the banks of sandy rivers, |
living there in burrows of the depth of three feet. Very little
is known, however, as to this curious Insect. It has recently
been reported’ as being injurious to tobacco and other crops on
high ground in Durbungha by cutting off their roots. The local
name for the Insect is bherwa. We should think it somewhat
doubtful whether this refers really to S. monstrosus.

Tia. 202.— Anostostoma australasiae, male, Australia.

In number of species the Locustidae are perhaps scarcely
inferior to the Acridiidae, and in variety of form they surpass
this latter family. Many of the most gigantic forms are apterous,
and these very often have a repellant aspect. The genus Anosto-
stoma is remarkable for its large head. Allied to it is Deinaerida
heteracantha, the “ Weta-punga” of the New Zealand natives, an
Insect formerly abundant in the forests north of Auckland, but
of late years become extremely rare. The head and body of
this Insect may measure more than 24 inches in length, and
when the antennae and legs are stretched out the total length
may be 14 or 15 inches. Although bulky and absolutely wing-
less, yet, as Buller informs us,’ it climbs with agility, and is
sometimes found on the topmost branches of lofty trees. When
disturbed it produces a clicking, accompanied by a slow movement

1 Indian Mus. Notes, ii. 1893, p. 172. 2 Zoologist, 1867, p. 489.

XUI LOCUSTIDAE | 327

of its hind legs. A second species, D. thoracica, lives in decayed
wood, and a third, D. megacephala, is remarkable from the very
large size of the head and mandibles in the male sex. The fact
that a clicking noise is produced by the Weta-punga is of some
interest, for the genus Deinacrida is among. the Locustidae that
possess ears, but are said to be destitute of sound-producing organs.

Amongst the most remarkable of the Locustidae are the two
species of which Brongniart has recently formed the genus
Humegalodon and the tribe Eumegalodonidae, which is not included
in Brunner’s table of the tribes of Locustidae. The ovipositor

a

CPT ee a UPN re oie ea
1, “Ah Gia Way

Fic. 203.—Lumegalodon blanchardi, female. Borneo. x. (After Brongniart.)
is large and sabre-shaped; the male is unknown. The genus
Megalodon is placed by Brunner in the tribe Conocephalides ; it
also consists of extremely remarkable Insects.

The Locustidae appear to be of slow growth, and the autumns
of Britain are usually not warm enough for them. Hence we
have but nine British species, and of this number only three or
four are known to occur north of the Thames. The only one
that attracts attention is Locusta viridissima, which in some
districts of the south of England occurs in considerable numbers,
and attests its presence by its peculiar music. It is called the
green grasshopper.

328 ORTHOPTERA CHAP.

The geological record is rather obscure in the matter of
Locustidae. Scudder considers that a fair number of Tertiary
forms are known, and says that they represent several of the
existing tribes and genera. One or two have been found in
Mesozoic rocks.

TABLE OF THE TRIBES OF LOCUSTIDAE

1. Tarsi more or less depressed.
2. Front tibiae furnished with auditory cavities.

3. Antennae less distant from the summit of the occiput than from
the labrum ; inserted between the eyes.! i
4. First two joints of the tarsi laterally smooth. (Posterior tibiae

furnished on each side with an apical spine.) Tribe -1.
PHANEROPTERIDES. (Fig. 196, Muécrocentrum; Fig. 199,
Myrmecophana. Fig. 101, Poecilimon affinis.)
4’, First two joints of the tarsi laterally, longitudinally sulcate.
5. Foramina of the anterior tibiae normally open. (Fig.
193, A.)
6. Posterior tibiae furnished on each side with apical spines,
7. Prosternum unarmed. ‘Tribe 2. MECONEMIDES.
7’. Prosternum bispinose or bituberculate. Tribe 3.
MECOPODIDES. |
6’. Posterior tibiae with no apical spines. (Head prognath-
ous.) Tribe 4. Procuinipes. (Fig. 200, Phasmodes.)
5’. Foramina of the anterior tibiae forming a chink, or pro-
tected by a scale. (Fig. 193, B.)
6. Anterior tibiae with no apical spines.
7. Margins of the scrobes? of the antennae prominent.
Tribe 5. PsEUDOPHYLLIDES. (Fig. 187, Cyrtophyllus
crepitans ; Fig. 198, Pterochroza ocellata.)
7’. Margins of the scrobes of the antennae not prominent,
8. Posterior tibiae furnished above on each side with
apical spines, or with a single spine on the side.
9. Posterior tibiae either furnished with apical
spines on each side, or only on the inner side.
Tribe 6. CONOCEPHALIDES. (Fig. 189, Copio-
phora cornuta.)
9’. Posterior tibiae furnished above with an
apical spine placed only on the outer side.
Tribe 7. TYMPANOPHORIDES.
8’. Posterior tibiae without apical spines. Tribe 8.
SAGIDES.
6’. Anterior tibiae furnished with an apical spine on the
inner side.?

1 This diagnosis is an attempt to express in something apprvaching an exact
manner the distinction of the flattened from the arched or convex head.

2 Scrobes are the depressions in which the antennae are inserted.

3 There are unfortunately a few exceptions in the case of this character.

XIII LOCUSTIDAE 329

7, The first joint of the posterior tarsi destitute of a free
sole-lobe. Tribe 9. LocusTIDEs.
7’. The first joint of the posterior tarsi furnished with a
| free sole-lobe. Tribe 10. DecriciDEs.

_ 3’, Antennae more distant from the summit of the occiput than from
the labrum, inserted either beneath the eyes or on their inferior
border. Tegmina and wings greatly abbreviate, scale-like ; when
tegmina are present they are furnished in each sex with a
tympanum.

4. Third joint of the posterior tarsi shorter than the second. Both.
anterior and posterior tibiae furnished on each side with a
spine. Tribe 11.. CALLIMENIDEs.

4’. Third joint of posterior tarsi longer than the second joint.
Anterior tibiae with no apical spine on the inner side, and
posterior tibiae with no apical spine on the outer side.

5. Antennae inserted at the edge of the eyes. Pronotum
unarmed. Tegmina present in each sex. Anterior tibiae
furnished on the outer side with an apical spine. Posterior
tibiae furnished beneath with four apical spines. Tribe
12. EPHIPPIGERIDES.

5’. Antennae inserted distinctly below the eyes. Pronotum
spinous. Elytrain the females wanting. Anterior tibiae
without apical spine on either side. Posterior tibiae
beneath with two apical spines or with none. Tribe 13.

. HeErTRopIDEs.

2’. Anterior tibiae without auditory cavities. Tegmina with no tym-
panum. Tribe 14. Gryzuacripes. (Fig. 201, Schizodactylus
monstrosus. )

1’. Tarsi distinctly compressed (most of the species apterous.) Tribe 15.

STENOPELMATIDES. (Fig. 202, Anostostoma australasiae; Fig. 197,

Dolichopoda palpata.) |

PINT a BP 8 n

CHAPTER XIV
ORTHOPTERA CONTINUED—GRYLLIDAE, CRICKETS

Fam. VIII. Gryllidae—Crickets. |

Antennae very slender, generally long and setaceous; hind legs
long, saltatorial. Tegmina with the outer portion deflexed
on to the side of the body, and with the inner part lying flat
on the body. Tarsi usually three-jointed (rarely two- or four-
jointed). Female with a long ovipositor (except in Gryllotal-
pides). Apterous forms numerous. | |

THE Gryllidae are closely connected with the Locustidae, the
musical and auditory organs
being in both similarly situate,
and the female in both possess-

. ing, in most of the tribes, an

\ elongate exserted ovipositor.

| The two families differ in the

| number of joints of the tarsi,
in the form of the tegmina,
and in the fact that in Gryl-
lidae the portion of the wing
modified for musical purposes
consists of a larger portion
of the organ — according to
de Saussure, the discoidal as

. well as the anal area.

Fia. 204. —House-cricket, Gryllus (Acheta) ~The family would be a
domesticus, male. ;

very natural one if we were

to exclude from it the mole-crickets which have fossorial front

legs and no ovipositor, and the Tridactylides, which. also are

—

tO ees

CHAP. XIV f CRICKETS 331

destitute of ovipositor, and have short antennae, consisting of
about ten joints.
The head is generally very large; ocelli are present, though

usually imperfect; the extremity of the body bears a pair of

remarkably long cerci. The hind tibiae are usually armed with
very strong spines; the first joint of the hind tarsus is elongate,
and terminates in two spines, between which the small second

_ joint is often almost completely concealed; the feet are not pro-

vided beneath with pads, but only bear remote setae.

The alar organs are difficult of comprehension, and different:

opinions prevail as to their morphology. The tegmina are
extremely different to the hind wings, and never attain large
dimensions, neither do they exhibit any leaf-like or ornamental
Structures. In the genus Pteroplistus they are formed some-
what like the elytra of Coleoptera, and close over the-pack of
the Insect in a fashion very
like that found in beetles.
According to Brunner the
larger part of the tegmen
—which, as we have said,
reposes fiat on the back
of the Insect — represents
merely the anal area, and
all the other parts must be

sought a the smaller, , de- Fic. 205.—Tegmina (sinistral) of the house-cricket.
flexed portion of the wing- A, male, inner aspect; B, female, outer
Des ’ atts aspect: a, inner margin; 0, outer margin ;
Cover. Ve saussure s Opinion, c, nervure bearing stridulating file.
to a’ somewhat different .
effect, we have already mentioned. The tegmina of the male
are extremely different from those of the female, so that it is a
matter of much difficulty to decide what nervures correspond.’
The wing-covers of the male differ from those of the Locustidae,
inasmuch as the pair are of similar formation, each bearing a
stridulating file on its lower aspect. This file projects somewhat
inwards, so that its position is marked on the outer aspect of the

wing-cover by a depression. Usually the right tegmen overlaps |

the other, an arrangement contrary to that which prevails in
other Orthoptera. The wings are ample and delicate; they
possess numerous nervures that are not much forked and have a

1 See Pungur, Termes. Fiizetek, 1877, p. 223.

332 ORTHOPTERA CHAP.

simple, somewhat fan-like arrangement; the little transverse
nervules exhibit only slight variety. These wings are frequently
rolled up at the apex, and project beyond éhe body like an
additional pair of cerci (Fig. 204). The abdomen is chiefly
remarkable for the large development of the pleura, the stigmata
being consequently very conspicuous. The cerci are not jointed,
though they are flexible and, often, very long; they bear a
variety of sense-organs (Fig. 67). The saltatorial powers of the
crickets are frequently considerable.

_ Graber has observed the post-embryonic development of the
field-cricket, Gryllus campestris, though unfortunately not from
the very commencement, so that we do not know whether there
are five, six, or seven ecdyses; the number is probably either six
or seven. ‘The manner in which the alar organs are developed is
similar to that we have described and figured in the Locustidae.
In the earlier instars there is a slight prolongation of each side
of the meso- and meta-notum, but about the middle of the
development a considerable change occurs—the rudimentary
organs then become free appendages and assume a different
position.

The Gryllidae possess a pair of tympana on each front leg,
but these organs contrast with those of the Locustidae in that
the pair on each leg usually differ from one another, the one on
the outer or posterior aspect being larger than that on the inner
or front face of the leg.

The ears of the Gryllidae have not been so well investigated
as those of the Locustidae, but are apparently of a much. less
perfect nature. No orifice for the admission of air other than
that of the prothoracic stigma has been detected, except in
Gryllotalpa. On the other hand, it is said’ that in addition to
the tibial organs another pair of tympana exists, and is seated
on the second abdominal segment in a position analogous to that
occupied by the ear on the first segment of Acridiidae.

The musical powers of the crickets are remarkable, and are
familiar to all in Europe, as the performance of the house-cricket
gives a fair idea of them. Some of the Insects of the family are
able to make a very piercing noise, the note of brachytrypes
megacephalus having been heard, it is said, at a distance of a
mile from where it was being produced. The mode of produc-

1 Brunner, Verh. zool.-bot. Ges. Wien, xxiv. 1874, p. 288.

;

XIV MOLE-CRICKET 333

tion is the same as in the Locustidae, rapid vibration of the
tegmina causing the edge of one of them to act on the file of the
other. |

The mole-cricket, Gryllotalpa vulgaris—the Werre of the
Germans, Courtiliére of the French — dis placed with a few
allies in a special group, Gryllotalpides, characterised by the
lated front legs, which are admirably adapted for working
underground. Like the mole, this Insect has a subterranean
existence. It travels in burrows of its own formation, and it also
forms beneath the surface a habitation for its eggs and family.
Its habits have been alluded to by Gilbert White,’ who tells us
that “a gardener at a house where I was on a visit, happening
to be mowing, on the 6th of May, by the side of a canal, his
Sseythe struck too deep, pared off a large piece of turf, and laid
open to view a curious scene of domestic economy: there were
many caverns and winding passages leading to a kind of chamber,
neatly smoothed and rounded, and about the size of a moderate
snuff-box. Within this secret nursery were deposited near a
hundred eggs of a dirty yellow colour, and enveloped in a tough
skin, but too lately excluded to contain any rudiments of young,
being full of a viscous substance. The eggs lay but shallow, and
within the influence of the sun,
just under a little heap of fresh
moved mould like that which is
raised by ants.” ;

The front legs are remark-
able structures (Fig. 206), being
beautifully adapted for burrow-
ing; the tibiae and tarsi are
arranged so as to act as shears
when it may be necessary to
sever a root. The shear - like
action of the tarsus and tibia is
very remarkable; the first and
second joints of the former are
furnished -with hard processes,
which, when the tarsus is moved, pass over the edges of the
tibial teeth in such a way as to be more effective than a
pair of shears. In consequence of its habit of cutting roots,

Fig. 206.—Front leg of the mole-cricket.
A, outer ; B, inner aspect : @, ear-slit.

1 Natural History of Selborne, Letter xe.

334 GRYLLIDAE CHAP,

the mole-cricket causes some damage where it is abundant. It_
is now a rare Insect in England, and is almost confined to the
southern counties, but in the gardens of Central and Southern
Europe it is very abundant. Its French name cowrtiliére is
supposed to be a corruption of the Latin ewrtilla. Its fondness
for the neighbourhood of water is well known. De Saussure
says that in” order to secure specimens it 1s only necessary to
throw water on the paths between the flower-beds of gardens
and to cover the wetted places with pieces of board; in the
morning some of these Insects are almost sure to be found under
the boards disporting themselves in the mud. The Gryllotalpae
swim admirably by aid of their broad front legs.

Ears exist in the mole-cricket, and are situate on the front
leg below the knee, as in other Gryllidae, although it seems strange.
that a leg so profoundly modified for digging and excavating
as is that of the mole-cricket should be provided with an ear.
In Gryllotalpa the ear is concealed and protected by being
placed in a deep slit or fold of the surface, and this depression
is all that can be seen by examination of the exterior (Fig. 206, ¢).
In the allied genus Scapteriseus the tympanal membrane is, how-
ever, destitute of special protection, being completely exposed on
the surface of the leg.

Although the tegmina or upper wings in Gryllotalpa are of
small size, yet the true wings are much more ample; they are
of delicate texture and traversed by many nearly straight radii,
so that they close up in the most complete manner, and form
the two long delicate, flexible processes that in the state of repose
may be seen projecting not only beyond the tegmina, but actually
surpassing the extremity of the body hanging down behind it,
and looking like a second pair of cerci.

The mole-cricket is believed to be chiefly carnivorous in its
diet, though, like many other Orthoptera, it can accommodate
its appetite to parts of the vegetable as well as of the animal
kingdom. The Insect is capable of emitting a sound consisting
of a dull jarring note,somewhat like that of the goat-sucker.
For this purpose the tegmina of the males are provided with an
apparatus of the nature we have already described, but which is
very much smaller and less elaborate than it is in the true
crickets. |

The alimentary canal and digestive system of Gryllotalpa

mee

H |
:

XIV. MOLE-CRICKET 335

present peculiarities worthy of notice. Salivary glands and
reservoirs are present; the oesophagus is elongate, and has on
one side a peculiar large pouch (Fig. 207, ¢); beyond this is the
gizzard, which is embraced by two lobes of the stomach. This
latter organ is, beyond the lobes, continued backwards as a
neck, which subsequently becomes larger and rugose-plicate. On
the neck of the stomach there is a pair of branching organs,
which Dufour considered to
be peculiar to the mole-
cricket, and compared to a
spleen or pancreas. The single
tube into which the Mal-
pighian tubules open is seated
near the commencement of
the small intestine. These
tubules are very fine, and are
about one hundred in num-
ber. The arrangement by
which the Malpighian tub-
ules open into a common duct
instead of into the intestine
itself appears to be charac-
teristic of the Gryllidae, but
is said to occur also in
Ephippigera, a genus of
Locustidae. According to
Leydig! and Schindler the
Malpighian tubules are of
two kinds, differing in colour,
and, according to Leydig, in
contents and histological Fic. 207.—Alimentary canal and appendages of
; the mole-cricket: a, head; 0, salivary
structure. Near the posterior glands and receptacle ; c, lateral pouch ; d,
extremity of the rectum stomsto-gastric nerves ; ¢, ea lobes of
stomach ; f, peculiar organ; g, neck of
there is a lobulated gland stomach ; h, plicate portion of same; 7%, rec-
having a reservoir connected = "i be traps sg . pieces! decal ;
with it; this is the chief
source of the foetid secretion the mole-cricket emits when seized.
The nervous chain consists of three thoracic and four abdominal
ganglia; these latter do not extend to the extremity of the body ;

1 Miiller’s Arch. 1859, p. 159.

yy

336 ORTHOPTERA "CHAP.

the three anterior of the four ganglia are but small, the terminal
one being much larger.

The number of eggs deposited by a female mole-cricket is
large, varying, it is said,from 200 to 400. The mother watches
over them carefully, and when they are hatched, which occurs in
a. period of from three to four weeks after their deposition, she
supplies the young with food till their first moult; after this
occurs they disperse, and begin to form burrows for themselves.

It has been said that the young are devoured by their parents,
and some writers have gone so far as to say that 90 per cent of
the progeny are thus disposed of M. Decaux, who has paid
considerable attention to the economy of the mole-cricket,’ acquits
the mother of such an offence, but admits that the male commits
it. The number of eggs in one nest is said.to be about 300.

The embryonic development of the mole-cricket has been
studied by Dohrn? and Korotneff? and is considered by the
former to be of great interest. The
tracheae connected with each stigma
remain isolated, while, according to
Korotneff, the development of the
alimentary canal is not completed
when the young mole-cricket is
hatched. Perhaps it may be this con-
dition of the digestive organs that
necessitates the unusual care the
mother bestows on her young.

The genus Cylindrodes (Fig. 208,
C. kochi) comprises some curious and
rare Insects of elongate, slender form.
They are natives of Australia, where
i the first species known of the genus

Fic. 208. — Cylindrodes kocht. was found in Melville Island by Major

Australia. A, outline of the
Insect with five of the legs and Campbell, from whom we learn that

the extremity of the body muti- these Insects burrow in the stems of
lated ; B, middle leg. (After ‘

de Saussure.) plants, and are so destructive that he

was unable to keep a single plant in

his greenhouse on account of the ravages of Cylindrodes

campbell. The form of these Insects is beautifully adapted to

1 Bull. Soe. ent. France, 1893, p. ceexli.
2 Zeitschr. wiss. Zool. xxiii. 1876, p. 122. 3 Ibid, xli. 1885, p. 570.

.

XIV TRIDACTYLIDES 337

their habits, the body being contracted in the middle in such a
way as to permit the middle and hind legs to be packed against
it, so that the cylindrical form is not interfered with by these
appendages while the excavating anterior legs are at work in
front of the Insect. The abdomen has nine segments; the
terminal one, said to be remarkably long and destitute of cerci,
is not shown in our figure.

The genus 7ridactylus is considered by de Saussure to form,
with its ally Rhipipteryx, a division of Gryllotalpinae, but ney
are treated, perhaps more
correctly, by Brunner as a
separate tribe. TZ. varie-
gatus (Fig. 209) is a small
Insect, abundant in sandy
places on the banks of
rivers in Southern Europe,
—extending on the Rhone
as far north as Geneva,—
and is remarkable for its
great power of leaping, and
for the rapidity with which
it can burrow in the sand.
This anomalous Insect has
only ten joints to the an- /f
tennae. Its alar organs
are imperfect, and not like

Fic, 209.—Tridactylus variegatus, France.

those of other Gryllidae in either form or neuration. The hind

legs are of peculiar structure, the tibiae terminating in two pro-
cesses between which is situate a rudimentary tarsus. Near the
extremity of the tibia there are some plates, forming two series,
that can be adpressed to the tibia, or extended as shown in our
ficure. The body is terminated by four rather short, very
mobile processes; the upper pair of these are each two-jointed,
and are thought by de Saussure and Haase’ to be cerci; the

inferior pair, being articulated processes of the anal segment,

their presence in addition to cerci is remarkable. It is difficult
to distinguish the sexes of this Insect.

The exotic genus Rhipipteryx is allied to Tridactylus. It is
widely distributed in South America, but the little Insects that

1 Morph. Jahrb. xv. 1889, p. 400.
VOL. V Z

338 ORTHOPTERA CHAP,

compose it are rare in collections, their saltatorial powers no
doubt making it difficult to catch them; little is known as to
their habits. In the undescribed Ama-
zonian species we figure (Fig. 210), the
wings, instead of being mere rudiments,
as in 7'ridactylus, are elongate and project
beyond the body; they are of a_blue-
black colour, and arranged so as to look
as if they were the abdomen of the Insect ;
they, moreover, have a transverse pallid
mark, giving rise to an appearance of
division. It is difficult to form any
surmise as to the nature of so curious a
~ modification of the wings.
Fig. 210.—Rhipipteryz sp., The Tridactylides have no tympana on
AIBN OEE the legs, and their affinity with the Gryl-
lidae is very doubtful. Dufour thought 7. variegatus to be more
allied to the Acridiidae. He based this opinion chiefly on some
points of the internal anatomy, but pointed out that Zridactylus
differs from the Acridiidae in having no air-sacs in the
body.

Not many of the Gryllidae are so peculiar as the forms we
have mentioned. The family consists in larger part of Insects
more or less similar to the common cricket, though exhibiting
a great variety of external form. The common cricket of our
houses, Gryllus (Acheta) domesticus (Fig. 204), has a very wide
distribution in the Old World, and is also found in North America.
It is believed to have had its natural distribution extended by
commerce, though really nothing is known as to its original
habitat. The shrill chirping of this little Insect is frequently
heard at night in houses, even in the most densely inhabited
parts of great cities. Neither the female nor the young are
musical, yet the chirping may be heard at all seasons of the year,
as young and adults coexist independent of season. The pre-
dilection of Gryllus domesticus for the habitations of man is very
curious. The Insect is occasionally found out of doors in the
neighbourhood of dwelling-houses in hot weather, but it does not
appear that this species leads anywhere a truly wild life. It is
fond of heat; though it rarely multiplies in dwelling-houses to
any great extent, it is sometimes found in profusion in bake-

a. de

Locustidae (Fig. 189) and Mantidae

a _ GRYLLIDAE 339

houses. Usually the wings in the cricket are elongate, and pro-
ject backwards from under the tegmina like an additional pair
Of cerci; a variety, however, occurs in which these tails are
absent, owing to abbreviation of the wings.

There is no beauty in the appearance of any of the Gryllidae,
though many of them are very bizarre in shape. Very few of
them venture to leave the surface of the earth to climb on
plants. The species of Oecanthus, however, do so, and may be

found sitting in flowers. They have a more Locustoid appearance

than other Gryllidae. One of the most curious forms of the
family is Platyblemmus, a genus of
several species found in the Mediter-
ranean region, the male of which has
the head prolonged into a curious pro-
cess (Fig. 211); this varies greatly in
development in the males of the same
species. It would seem that this organ
is of a similar nature to the extra-
ordinary structures we have figured in ¢

A

(Fig. 136), though it appears impossible

. Fia. 211.—Platyblemmus lusi-
to treat the cephalic appendages of Platy- sities wenlee We Gent or
blemmus as ornamental objects; their head; B, profile of Insect
‘ ; : with most of the appendages
import is at present quite obscure. valiovad.

A curious form of variation occurs :

in this family, and is called micropterism by de Saussure; we
have already mentioned its occurrence in the house-cricket.. The

hind wings, which are usually ample, and frequently have their

extremities rolled up and protruding like cerci, are sometimes
much smaller in size, and not visible till the tegmina are ex-
panded. De Saussure at one time supposed these micropterous
individuals to be distinct species; it is now, however, known
that intermediate examples can be found by examining a great
mnany specimens. Some species are always micropterous.

In Britain we have only four representatives of the Gryllidae,
viz. the mole-cricket, the house-cricket, and two field-crickets,
one of which, Nemobius sylvestris, is considerably smaller than
the house-cricket, while the other, Gryllus campestris, the true
field-cricket, is a larger Insect. Its habits have been described
in an interesting manner in Gilbert White's 88th letter.

340 GRYLLIDAE CHAP. XIV

This Insect, like so many others, is apparently becoming rare in °
this country. |

A single fossil from the Lias has been described as belonging to
the Gryllidae, but in the Tertiary strata a variety of members of the
family have been discovered both in Europe and North America. |

The classification of Gryllidae is due to de Saussure, and is
said by Brunner to be very natural. In the following synopsis of
the tribes of crickets we give de Saussure’s arrangement, except that
we follow Brunner in treating Tridactylides as a distinct tribe:—

1. Antennae ten-jointed ; posterior tarsi aborted. Tribe 1. TRIDACTYLIDEs.
(Fig. 209, Tridactylus variegatus ; Fig. 210, Rhipipterysx sp.)

1’. Antennae many jointed ; posterior tarsi normal.
2. Tarsi compressed, the second joint minute.

3. Anterior legs fossorial ; anterior tibiae at the apex with two to
four divisions. Pronotum elongate, ovate, rounded behind.
Female without ovipositor, Tribe 2. GRyLLoTALPIDES. (Fig.
206, front legs of Gryllotalpa; Fig. 208, Cylindrodes kochi.)

3’. Anterior legs formed for walking. Ovipositor of the female
visible (either elongate or rudimentary).

4, Posterior tibiae biseriately serrate. Tribe 3. MyrmeEco-
PHILIDES.

4’. Posterior tibiae biseriately spinose. Ovipositor straight.

5, Antennae short, thickish, almost thread-like. Facial
scutellum exserted between antennae. Posterior tibiae
dilated. Gen. Myrmecophila,?

5’. Antennae elongate, setaceous. Facial scutellum trans-
verse, visible below the antennae. ‘Tibiae slender,

6. Posterior tibiae armed with two strong spines, not
serrate between the spines. -Tribe 4. GRYLLIDES.
(Fig. 204, Gryllus domesticus; Fig. 211, Platy-
blemmus lusitanicus.)

6’. Posterior tibiae slender, armed with slender spines,
and serrate between them. Tribe. 5. OxcAN-
THIDES.

2°, Second joint of the tarsi depressed, heart-shaped.

3. Posterior tibiae not serrate, but biseriately spinose.

4, The spines on each side three and mobile; apical spurs
on the inner side only two in number. Ovipositor short,
curved. Tribe 6, TRIGONIDIIDES.

4’. The spines numerous, fixed. Ovipositor elongate, straight.
Gen. Stenogryllus,

3’. Posterior tibiae serrate and spinose on each side, the apical spurs,
as usual, three on each side. Ovipositor straight or curved.
Tribe 7, ENEOPTERIDES.

* Mem. Soc. phys. Genéve, xxv. 1877, and Biol. Centr. Amer. Orthoptera, 1894, p. 198.
* The genus Myrmecophila, being exceptional in several respects, is treated separately.

CHAPTER XV

NEUROPTERA——MALLOPHAGA——EMBIIDAE

Order III. Neuroptera.

Imago with biting mouth ; with two pairs of wings, the anterior
as well as the posterior membranous, usually with extensive
neuration, consisting of elongate nervures and either of

~ short cross-nervules forming numerous cells or of a com-
plez minute mesh-work. (One division, Mallophaga, con-
sists entirely of wingless forms ; in TLermitidae some of the
individuals of each generation become winged, but others
do not: except in these cases adult wingless forms are few.)
The metamorphosis differs in the several divisions.

ee Y

AS Ms
s sa> >! eee! cans
FEIN an N
ee: are
es, E95 d
LITE 5
Kg

Fic. 212.—Osmylus chrysops, New Forest.

THE Neuroptera form a heterogeneous, though comparatively
small, Order of Insects, including termites, stone-flies, dragon-
flies, may-flies, caddis-flies, lace-wings, scorpion-flies, ant-lions, etc.
Bird-lice are also included in Neuroptera, though they have no

_ trace of wings. |
We treat the Order as composed of eleven distinct families,

342 NEUROPTERA CHAP.

and, as a matter of convenience, arrange them in _ five
divisions :—

1. Mallophaga.—Permanently wingless Insects, living on the bodies of birds *
or mammals, (Development very imperfectly known.) Fam. 1,
Mallophaga, |

2. Pseudoneuroptera.—Insects with wings in adult life (in some cases wings _
are never acquired). The wings are developed in a visible manner
outside the body. There is no definite pupa. Live entirely on land.
Fam. 2. Embiidae ; 3. Termitidae; 4. Psocidae.

. Neuroptera amphibiotica—Wings developed as in division 2. Three ocelli
usually exist. Life aquatic in the early stages. Fam, 5. Perlidae;
6. Odonata ; 7, Ephemeridae.

4. Neuroptera planipennia.—Wings developed internally ; not visible in early
stages, but becoming suddenly evident when the pupal form is
assumed. Mandibles present in the adult Insect. Life in early
stages aquatic or terrestrial. Fam. 8. Sialidae; 9. Panorpidae; 10,
Hemerobiidae.

. Trichoptera.—Development as in division 4. Mandibles absent in the adult
Insect. Life aquatic in the early stages. Fam. 11. Phryganeidae.

ww

on

The families we have enumerated in the preceding scheme are
now generally adopted by entomologists. Great difference of
opinion exists, however, as to the groups of greater value than
the family, and for a long time past various schemes have been
in vogue. Though it is necessary to allude to the more important
of these systems, we can do so only in the briefest manner.

Some of the families of Neuroptera are similar in many points
of structure and development to Insects of other Orders; thus
Termitidae are somewhat allied to Blattidae, Perlidae to Phas-
midae in Orthoptera, while the Phryganeidae or Trichoptera make a
considerable approach to Lepidoptera. Some naturalists—among
whom we may mention Burmeister and Grassi—unite our Aptera,
Orthoptera, and most of our Neuroptera into a single Order
called Orthoptera. Others treat our Neuroptera as consisting
of eight or nine distinct Orders ; these, together with the names
proposed for them, we have already alluded to in our chapter
on classification, pp. 171-177.

Erichson, impressed by the variety existing in Neuroptera,
separated some of the groups into a sub-Order called Pseudo-
neuroptera; this sub-Order comprised our Termitidae, Psocidae,
Eplemeridae, and Libellulidae. This division is still adopted in
several treatises; the Pseudoneuroptera are indeed by some
naturalists retained as an Order distinct from both Orthoptera

XV FOSSIL NEUROPTERA 343

and Neuroptera. Gerstaecker subsequently made use of a system
somewhat different from that of Erichson, uniting the Perlidae,
Ephemeridae, and Odonata into a group called Orthoptera
amphibiotica, from which the Termitidae and Psocidae were
excluded. The divisions we have here adopted’ differ but little
from those of Gerstaecker, though we have arranged them in a
very different manner. It is probable that not one-tenth part of
the Neuroptera existing in the world have yet been examined by
entomologists, and of those that are extant in collections, the
life-histories and development are very imperfectly known. We
have, therefore, not considered it wise to adopt a system that
would involve great changes of nomenclature, while there can
be little hope of its permanency.

Fossils.—When considering the subject of fossil Insects we
briefly alluded to the discussions that have occurred as to whether
the fossils of the palaeozoic period should be referred to existing
Orders. Since the pages we allude to were printed, M. Brong-
niart’s very important work! on the Insects of that epoch has
appeared. He considers that these ancient fossils may be classi-
fied with the existing Orders of Insects, though they cannot be
placed in existing families; and he assigns the palaeozoic fossil
Insects at present known, to the Orders Neuroptera and Orthop-
tera, and to the homopterous division of Hemiptera. The greater
part of the species he looks on as Neuroptera, and places in
six families— Megasecopterides, Protephemerides, Platypterides,
Stenodictyopterides, Protodonates, and Protoperlides. Of these
he considers the ancient Protephemerides, Protodonates, and
Protoperlides as the precursors, which, we presume, we may inter-
pret as the actual ancestors, of our existing Ephemeridue, Odonata,
and Perlidae.

Some of the fossils restored and described by the French ento-
mologist are of great interest. We shall notice the Prote-
phemerides, Protodonates, and Protoperlides in connexion with
the families to which they are specially allied, and shall now
only allude to the quite extinct families of Neuroptera, the
Megasecopterides, Platypterides, and Stenodictyopterides.

It is a peculiarity of these ancient Insects that they were
much larger creatures than the corresponding forms that now
exist. This may be due, to some extent, to the fact that tiny,

1 Insectes fossiles des temps primatires, 1893, vol. i. and atlas.

344 NEUROPTERA CHAP. |

fragile forms have not been preserved in the rocks, or have not
attracted the attention. of collectors ; but as some of the palaeozoic
Insects were absolutely the largest known—surpassing consider-
ably in size any Insects at present existing—it is probable that,
even if small forms existed at the remote epoch we are alluding
to, the average size of the individual was greater than it is at
present. The Megasecopterides of the carboniferous epoch were
Insects of large size, with long, narrow wings, a small prothorax,
and large meso- and meta-thorax, these two segments being equal
in size; the abdomen was elongate and moderately voluminous,
and was terminated by a pair of very elongate, slender filaments
like those of the may-flies. The family includes several genera
and species found at Commentry. One of these forms, Cory-
daloides scudderi, is of great interest, as it is believed by Brong-
niart that the imago possessed tracheal gills situated on the
sides of the abdomen, analogous-with those ‘that exist at present
in the immature condition of certain Ephemeridae. They are of
interest in connexion with the gills found at the present time in
the imagos of Pteronarcys (see p. 401). Although these fossils
are of such enormous antiquity, the tracheae can, M. Brongniart
says, be still perceived in these processes.

The Platypterides include also a considerable number of
Insects of large size, with four large equal wings, frequently
spotted or variegate. Some of
these Insects were provided
with expansions or lobes on
the sides of the prothorax
(Fig. 215); these are looked
on as analogous to the ex-
pansions of meso- and meta-
thorax, which are supposed by
some writers to have been
Fic, 213.—Lithomantis carbonaria. Car- the rudiments from which

boniferous strata of Commentry, France. wings were developed. These

Anes epneniaes prothoracic wing -rudiments, if
such they be, are said to have a system of nervures similar to
what we find in true wings. The genus Lithomantis includes a
Scotch fossil, and has already been mentioned by us on p. 259.

The third family of extinct carboniferous Neuroptera is the
Stenodictyopterides, in which Brongniart places the Dictyoneura of

> tee

“Nat

—-

ime Nh Re Peo: J nent time,

XV MALLOPHAGA 345

*

Goldenberg, the North American Haplophlebiwm, and several genera

from Commentry. Some of them were very large Insects, with
robust bodies, and possessed wing-like expansions on the prothorax,
and lateral gill-like appendages on the sides of the abdomen.

It is worthy of note that though so large a number of car-
boniferous Neuroptera have now been discovered, no larvae or
immature forms have been found.

We now pass to the consideration of the divisions of Neurop-
tera still living. }

Fam. I. Mallophaga—Bird-Lice or Biting Lice.

Small Insects, wingless, with large head; thorax usually cf two,
rarely of one or three segments ;
prothorax always distinct ; hind
body consisting of eight to ten
segments, in addition to the pos-
terior two thoracic segments which
usually are but little or not at
all separated from it. The meta-
morphosis is very slight. The
creatures live on the skins of birds ,
or mammals, finding nourishment
in the epidermal products.

The whole of the Insects of this
family live a parasitic, or rather epizoic,
life. They all creep about those parts
that are near to the skin, the feathers
of birds or the hair of mammals ; Fic. 214.—Trinoton luridum.
they rarely come quite to the surface, Lives on the common duck
so)-that they are not detected on a 4 Various species of Anas.
(After Giebel.)

superficial examination. It is curious

that under these circumstances they should exhibit so great a

variety of form and of anatomical characters as they do.

They are very depressed, that is, flat, Insects, with a large
head, which exhibits a great variety of shape; frequently it is
provided in front of the antennae with some peculiar tubercles
called trabeculae, which in some cases are mobile. The antennae
are never large, frequently very small; they consist of from three
to five joints, and are sometimes concealed in a cavity on the

346 _ MALLOPHAGA CHAP.

under side of the head. The eyes are very rudimentary, and
consist of only a small number of isolated facets placed behind
the antennae; sometimes
they are completely absent.
The mouth parts are situ-
ated entirely on the under-
surface of the head and in
a cavity. The upper lip
is frequently of remarkable
form, as if it were a scrap-
ing instrument (o/, Fig.
Fic. 215.—Under-surface of head of Lipeurus 215). The mandibles are
heterographus. (After Grosse.) ol, Labrum ; sharply toothed and appar-
md, mandible ; mx, maxilla; ul, labium. i ;
| ently act as cutting instru-
ments. The maxillae have been described in the principal
work on the family’ as possessing in some cases well-developed
palpi. According to Grosse? this is erroneous; the maxillae, he
says, are always destitute of palpi, and are of peculiar form, being
each merely a lobe of somewhat conical shape, furnished on one
aspect with hooks or setae. The under lip is peculiar, and-
apparently of very different form in the two chief groups of
Mallophaga. | The ©
large mentum bears,
in Liotheides (Fig.
216, B), on each side
a four-jointed palpus,
the pair of palps
being .very widely
separated; the ligula
is broad and undi-

vided; on each side

We . Fic. 216.—Under lip of Nirmus, A; and of Tetroph-
there ne paraglossa thalmus chilensis, B. (After Grosse.) m, Mentum ;
bearing an oval pro- g, ligula ; pl, palp ; pg, paraglossa ; hy, lingua.

cess, and above this

is a projection of the hypopharynx. In Philopterides (Fig. 216,
A) the palpi are absent, and the parts of the lower lip are—
with the exception of the paraglossae—but little differentiated.
The lingua (hypo-pharynx) in Mallophaga is largely developed,

1 Giebel and Nitzsch, Jnsecta epizoica, folio, 1874.
2 Zeitschr. wiss. Zool. xiii. 1885, p. 537.

weXV | MALLOPHAGA 347

and bears near the front a chitinous sclerite corresponding with
another placed in the epipharynx.

The prothorax in Mallophaga is a distinct division of the
body even when the meso- and meta-thorax appear to be part of
the abdomen. The mesothorax is frequently very small; it and
the metathorax are sometimes intimately connected. In other
cases (Laemobothrium) the metathorax appears to differ from the
following abdominal segment only by having the third pair of
legs attached to it. In Zvrinoton (Fig. 214) the three thoracic
segments are well developed and distinct. The abdominal
segments visible, vary in number from eight to ten; there is
sometimes a difference according to sex, the male having one
segment taken into the interior in connexion with the repro-
ductive organs. The legs have short, broad coxae and small
tarsi of one or two joints; very rarely three joints are present ;
there are either one or two claws; the legs with one claw being
adapted for clinging to or clutching
hairs. The front pair of legs is used
not for locomotion so much as for
grasping the food and bringing it
within the range of the mouth. No

trace of wings has been detected in Sf Yry a

any species. & Res ~
The nervous system has been Ned ;

examined by Giebel in Lipeurus \

bacillus; there is a supra- and an
infra-oesophageal ganglion, and three
thoracic, but no abdominal ganglia.
' The supra-oesophageal is remarkably
small, in fact not larger than the
infra - oesophageal; it consists evi-
dently of two conjoined halves. The
alimentary canal has a slender, elon- ye, 217,.—Ganglia of nervous sys-
gate oesophagus, dilated behind into a ite, eee enn i aad
crop; this is frequently received be-
tween two cornua formed by the anterior part of the stomach,
_ which, except for these, is simply tubular in form, though some-
what narrower at the posterior extremity. In some forms—
Philopterides—the crop is of a very peculiar nature (Fig. 218),
forming an abrupt paunch separated from the stomach by the

‘

348 MALLOPHAGA CHAP,

There are only four Mal-
pighian tubes; in some species the basal
half of each tube is much dilated. The
two divisions of the intestine are short
and are separated by the intervention of a
glandular girdle. Salivary glands exist;
Giebel figures what we may consider to
be an enormous salivary reservoir as exist-
ing in Menopon leucostomum..

The testes and ovaries are of a simple
nature. The former consist of two or
three capsules, each having a_ terminal
thread; the vasa deferentia are tortuous
and of variable length; they lead into
the anterior part of the ejaculatory duct,
where also opens the elongate duct pro-
ceeding from the bicapsular vesicula semi-

posterior portion of the oesophagus...

Fic. 218.—Alimentary canal

of Docophorus fuscicollis.
(After Giebel.) a, Oeso-
phagus ; 6, paunch; a’,
posterior division of oeso-
phagus ; ¢, chylific ven-
tricle or stomach ; d,'Mal-
pighian tubes; e, small
intestine ; jf, glandular
girdle ; g, rectum.

nalis; these structures have been figured
by Grosse’ as well as by Giebel. The
ovaries consist of three to five short egg-
tubes on each side; the two oviducts
combine to form a short common duct
with which there is connected a recepta-

culum seminis.

The eggs of some Mallophaga have been figured by Melnikow ;?
they possess at one extremity a cover with a multiple micropyle-
apparatus, and at the opposite pole are provided with seta-like
appendages. They are very like the eggs of the true lice, and are
said in.some cases to be suspended by threads to the hairs or
feathers after the fashion of the eggs of Pediculi.

Little is known as to the development; the young are ex-
tremely like the adult, and are thought to moult frequently ; ths
duration of life is quite unknown.

It has been stated by some writers that the mouth is truly of
the sucking kind, and that the Mallophaga feed on the blood of
their Liseha: This is, however, erroneous; they eat the delicate
portions of the feathers of birds, and of mammals perhaps the
young hair. Their fertility is but small, and it is believed that

1 Zeitschr. wiss. Zool. xiii. 1885, pl. xviii. f. 15.
2 Arch. f. Naturg. xxxv. i. 1869, p. 154, pls. x. xi.

Le

EE

xv. MALLOPHAGA 349

ina state of nature they are very rarely an annoyance to their

hosts. The majority of the known species live on birds; the
forms that frequent mammals -are less varied and have been less
studied ; most of them have only one claw to the feet (Fig. 220),
while the greater portion of the avicolous species have two
claws.

Fic. 219.—Lipeurus ternatus, male ; Fia. 220.—Trichodectes latus, male ;

inhabits Sarcorhamphus papa. inhabits the dog, Canis famili-
(After Giebel.) aris.

Most of the forms have the anterior legs small, and they are
usually drawn towards the mouth, owing, it is believed, to their
being used after the manner of hands to bring the food to the
mouth; hence in some of our figures (219, 220) the body looks
as if it had only four legs.

Very diverse statements have been made as to whether allied
forms of Mallophaga are found only on allied birds. It would

appear that this is the case only to a limited extent, as certain

species are found on quite a variety of birds; moreover, some
birds harbour several species of bird-lice, even five genera having
been found, it is said, on one species of bird. Docophorus
icterodes has been recorded as occurring on many kinds of ducks
and geese; the swan, however, harbours a distinct species, Doco-
phorus cygni, and this is said to have also been found on the
bean-goose.

At least five species, belonging to three distinct genera, have
been found on the common fowl. The parasite most frequently
met with on this valuable creature is Menopon pallidum (Fig.

350 MALLOPHAGA cua.

221), which is said to have been figured by Redi two hun-
dred years ago under the name of Pulex
capt. This species multiplies to a con-
siderable extent; it is of very active
habits, and passes readily from one bird
to another, so that it is found on other
species besides the domestic fowl. It is
even said that horses kept near hen-
roosts have been seriously troubled by
Menopon pallidum, but it is suggested
by Osborn that these attacks, may per-
Be haps have been really due to itch-mites.
inhabits the common fowl, Lhere is, however, no doubt that this
sa domesticus, (After snecies may infest poultry, especially if
Re sickly, to an enormous extent. The dust-
baths in which poultry are so fond of indulging are considered
to be of great use in keeping down the numbers of this Insect.

A table of the birds and mammals on which Mallophaga
have been found, together with the names of the latter, has been
given by Giebel.t The classification of the group, so far as the
principal divisions are concerned, by no means accords with the
kind of animals that serve as hosts, for the only two genera
peculiar to quadrupeds (Z'richodectes, Fig. 220; and Gyropus)
belong to the two chief divisions of Mallophaga. The genus
Menopim includes numerous species found on birds, and three or
four others peculiar to mammals.

Two very natural divisions, Philopterides and Liotheides, were
adopted by Giebel and Nitzsch, but unfortunately the chief
character they made use of for diagnosing the two groups—the
presence or absence of maxillary palpi—was illusory. Apparently
the labial palps will serve the purpose of distinguishing the
two divisions, they being present in the Liotheides and absent in
the Philopterides. A table of the characters of the avicolous
genera of these two groups is given by Grosse.”

The Liotheides are more active Insects, and leave their host
after its death to seek another.. But the Philopterides do not
do so, and die in about three days after the death of their host.
Possibly Mallophaga may be transferred from one bird to another

1 Op. cit. pp. vii.-xiv. For classification, ete., see also Piaget, Les Pédicudlines.
Leyden, 1880. * Zeitschr. wiss. Zool. xiii. 1885, p. 532.

xv EMBIIDAE 351

by means of the parasitic two-winged flies that infest birds.
The writer has recorded! a case in which a specimen of one of
these bird-flies captured on the wing was found to have some
Mallophaga attached to it.

We should perhaps point out that these Mallophaga, though
called bird-lice, have nothing to do with the true lice which are
so frequently found with them, and that live by sucking the
blood of their hosts. It would in fact be better to drop the
name of bird-lice altogether, and call the Mallophaga biting lice.
Trichodectes latus, according to this method, would be known as
the biting louse of the dog, the true or sucking louse of which
animal is Haematopinus piliferus, and belongs to the anoplurous
division of Hemiptera.

Fam. II, Embiidae.

Hlongate feeble Insects ; with small prothoraz, elongate meso- and
meta - thorax, which
may either bear wings
or be without them.
In the former case
these organs are not
caducous, are deli-
cately membranous,
and all of one consist-
ence, with three or
four indefinite longi-
tudinal nervures and

-veinle Fic. 222.—Oligotoma michaeli. (After
a few cross-veinlets. ds)

hy, | y
MEL Di a
AS ae Up
rt
. i }
. m» A
fj
we 17S
i
4 di

The development 1s
incompletely known. The individuals do not form organised

societies.

The Embiidae are one of the smallest families of Insects ;
not more than twenty species are known from all parts of the
world, and it is probable that only a few hundred actually exist.
They are small and feeble Insects of unattractive appearance,
and shrivel so much after death as to render it difficult to
ascertain their characters. They require a warm climate. Hence

1 P, ent. Soc. London, 1890, p. xxx.

352 NEUROPTERA CHAP.

it is not a matter for surprise that little should be known about
them.

The simple antennae are formed of numerous joints, probably
varying in number from about fifteen to twenty-four. The mouth
is mandibulate. Chatin states’ that the pieces homologous with
those of a maxilla can be detected in the
mandible of Hmbia. The labium is divided.
The legs are inserted at the sides of the
body, the coxae are widely separated (Fig.
223), the hind pair being, however, more
approximate than the others. The abdo-
men is simple and cylindrical, consisting of
ten segments, the last of which bears a pair
of biarticulate cerci. In the male sex there
is a slight asymmetry of these cerci and
of the terminal segment. The thorax is
remarkable on account of the equal develop-
ment of the meso- and meta-thorax and
their elongation in comparison to the pro-
thorax. When they bear wings there is no
modification or combination of the segments
Fic, 223.—Under-surface for the purposes of flight, the condition of
of Embia sp. Andalusia. : ; ee

these parts being, even then, that of wing-
less Insects; so that the Embiidae that have wings may be
described as apterous-
like Insects provided
with two pairs of in-
efficient wings. ° The
wings are inserted on
a small space at the
front part of each of
the segments to which
they are attached.
The legs have three-
jointed tarsi, and are

destitute of a terminal wing ; B, outline of the wing, showing nervures.
appendage between (After Wood-Mason.) 1, Costal; 2, subcostal; 3,

radial ; 4, discoidal ; 5, anal nervure.
the claws. Ai Sian"

The wings in Embiidae are very peculiar; they are extremely
1 Bull. Soc. Philom. (7) ix. p. 33.

Fig. 224.—Anterior wing of Oligotoma saundersii: A, the

ee
f * + 4

=!

ted Wess

wes?

XV EMBIIDAE 353

flimsy, and the nervures are ill-developed; stripes of a darker
brownish colour alternate with pallid spaces. We figure the an-
terior wing of Oligotoma saundersit, after Wood-Mason ; but should

remark that the neuration is really less definite than is shown

in these figures; the lower one represents Wood-Mason’s inter-
pretation of the nervures. He considers! that the brown bands
“mark the original courses of veins which have long since dis-
appeared.” A similar view is taken by Redtenbacher,? but at
present it rests on no positive evidence. |

One of the most curious features of the external structure
is the complex condition of the thoracic sternal sclerites. These
are shown in Fig. 223, representing the under-surface of an
Embia of uncertain species recently brought by Mr. Bateson
from Andalusia.

According to Grassi* there are ten pairs of stigmata, two
thoracic and eight abdominal; these are connected by longi-
tudinal and transverse tracheae into a single system. The
ganglia of the ventral chain are, one suboesophageal, three thor-
acic, and seven abdominal; these are segmentally placed, except
that there is no ganglion in the fifth abdominal segment. There
is a stomato-gastric system but no “sympathetic.” Salivary
glands are present. The stomodaeal portions of the alimentary
canal are remarkably capacious; the stomach is elongate and
slender, without diverticula; the Malpighian tubes are elongate
and slender; they vary in number with the age of the individual,
attaining that of twenty in the adult. The ovaries are arranged
somewhat after the fashion of those of Japya#, there being in
each five short egg-tubes, opening at equal intervals into a
straight duct. The testes are remarkably large; each one con-
sists of five masses of lobules, and has a large vesicula seminalis,
into the posterior part of which there open the ducts of two
accessory glands. The large joint of the front tarsus includes
glands whose secretion escapes by orifices at the tips of certain
setae interspersed between the short spines that are placed on

the sole.

Species of this genus occur in the Mediterranean region, but
their characters have not yet been examined. Our information

1 P. Zool. Soc. London, 1883, p. 628.

2 Ann. Hofmus. Wien, i. 1886, p. 171.

3 Atti Acc. Gioenia, vii. 1893.

VOL, V 2A

354 NEUROPTERA CHAP,

as to these is chiefly to be found in Grassi’s work. The two
species studied by him were wingless. They live under stones,
where they spin webs by means of the front feet, whose first
joint is, as we have said, enlarged and contains glands; the-
Insect uses the webs as a means of support in progression, acting
on them by means of papillae and a comb-like structure placed
on the four posterior feet.

Grassi informs us that these Insects are not uncommon under
stones in Catania; they require moisture as well as warmth, but
not too much; sometimes there is only one individual found
under a stone, at others eight or ten. In the winter and spring
their galleries are found on the surface of the earth, but in
the hot months of summer they secure the requisite amount
of moisture by sinking their galleries to the depth of ten or
fifteen centimetres. Their food consists chiefly of vegetable
matter. They may be reared with ease in glass vessels. Other
species of the family attain wings; the details of the process are
not well known. Oligotoma michaeli (Fig. 222) was discovered
in a hothouse in London among some orchid roots brought from
India, and was found in more than one stage of development ;
the young greatly resemble the adult, except in the absence of
wings. A nymph-form is described by M‘Lachlan’ as possess-
ing wings of intermediate length, and Hagen has suggested that
this supposed nymph is really an adult female with short wings.
If this latter view be correct, nothing is known as to the mode
of development of wings in the family. It is still uncertain
whether female Embiidae ever possess wings. Wood-Mason and
Grassi have shown that there are wingless females in some species,
and we know that there are winged males in others, but what the
usual relation of the sexes may be in this respect is quite uncer-
tain. These Insects have been detected in various parts of the
world. In the Sandwich Islands Oligotoma insularis was dis-
covered by the Rey. T: Blackburn in the wood and thatch form-
ing the roofs of natives’ houses. A species has been found in
Prussian amber, and Grassi thinks that Hmbia_ solieri—one of
the Mediterranean species—is not to be distinguished with cer-
tainty from the Insect found in amber.

Embiidae still remains one of the most enigmatic of the
families of Insects. Although Grassi’s recent observations are

1 J. Linn. Soe, Zool. xiii. 1878, pl. xxi. f. 2.

XV ! EMBIIDAE 355

of great value from an anatomical point of view, they rather add
to, than diminish, the difficulties we encounter in endeavouring

to understand the lives of these obscure creatures. That

Embiidae form webs has long been known, and it was thought
by some that the webs, like those of spiders, might be of assist-
ance in procuring food. We may, however, infer from Grassi’s
observations that this is not the case, but that the silken tunnels
or galleries—as he calls them—serve chiefly as a means of
locomotion and protection, the feet of the Insects being highly
modified in conformity with this mode of life. Grassi seems
to be of opinion that the galleries are also useful in preserving
a proper degree of humidity round the Insects. We have
already alluded to the mystery that surrounds the mode of
growth of their wings. Nearly all that is known as to the
Embiidae is_contained in Grassi’s paper, or is referred to in
Hagen’s monograph of the family.

Considerable difference of opinion has prevailed as to the
allies of thes? obscure Insects. It would seem that they
are most nearly allied to Termitidae and Psocidae. Grassi,
however, considers these affinities only remote, and suggests that
Embiidae should form a separate Order, to be placed in a super-
Order Orthoptera, which would include our Aptera, the two
families mentioned above, Mallophaga, Embiidae, and the ordi-
nary Orthoptera. Brauer places the family in his Orthoptera
genuina.

1 Canadian Entomologist, xvii. 1885, throughout.

CHAPTER XVI

NEUROPTERA CONTINUED—TERMITIDAE, TERMITES OR WHITE ANTS

Fam. III. Termitidae—White Ants, Termites.

Each species is social, and consists of winged and wingless indi-
viduals. The four wings are, in repose, laid flat on the
back, so that the upper one only is seen except just at the
bases ; they are membranous and very elongate, so that they

_

Fic, 225.—Termes (Hodotermes) mossambicus. Winged adult. (After Hagen.)

extend far beyond the apex of the abdomen; the hind pair
‘as remarkably similar in size, form, and consistence to the
JSront pair.: near the base of each wing there is a suture,
or line of weakness, along which the wings can be broken off,
the stumps in that case remaining as short horny flaps re-
posing on the back. Ligula channelled but not divided into
two parts. The wingless individuals are very numerous, and
have the head and thirteen body segments distinct ; the body

CHAP. xXVl TERMITIDAE 357

is terminated by a pair of short cerci. The metamorphosis
is slight and gradual, and in some individuals is dispensed
with.

THE term White Ants has been so long in use for the Termitidae
that it appears almost hopeless to replace it in popular use by
another word. It has, however, always given rise to a great
deal of confusion by leading people to suppose that white ants
differ chiefly from ordinary ants by their colour. This is a most
erroneous idea. There are scarcely any two divisions of Insects
more different than the white ants and the ordinary ants. The
two groups have little in common except that both have a social
life, and that a very interesting analogy exists between the forms
of the workers and soldiers of these two dissimilar Orders of
Insects, giving rise to numerous analogies of habits. The word
Termites—pronounced as two syllables—is a less objectionable
name for these Insects than white ants.

The integument in Termites is delicate, and the chitinous
plates are never very hard; frequently they are so slightly
developed that the creature appears to consist of a single mem- .
branous sac with creases in it, the head alone being very distinct.
The head is exserted, frequently of large
size, sometimes as large as all the rest
of the body together. Termites may
be quite blind, or possess facetted and
simple eyes, the latter when present
being two in number and always accom-
panied by facetted eyes. The antennae »,, 926.— Termes bellicosus.
are simple, consisting of from nine to Labium, A, maxilla, B, of

° fs : ; winged adult ; lower face of
thirty-one joints, which differ but gach. (After Hagen.)
little from one another; the number in
each individual increases as the development progresses. The
parts of the mouth are large, the ligula consists of one piece
(Fig. 226, A), but often has the appearance of being formed by
two united pieces; on its extremity are seated two pairs of
lobes,

The head is articulated to the thorax by means of two very
large cervical sclerites on each side, placed at right angles to one
another, and visible on the under-surface. The prothorax is

well developed and distinct from the parts behind it. The pro-

358 NEUROPTERA CHAP.

notum, of variable form and size, is very distinct in the perfect
Insects ; with it are connected the largely developed pleura. The
episternum is very peculiar, consisting of an’ elongate chitinous
slip on each side hanging downwards, the two not quite meeting
in the middle; they thus form the margin of the very large
anterior orifice, and are in contiguity with the cervical sclerites ;
behind them are the very large epimera. The prosternum
appears to be usually entirely membranous; in some cases the
sclerite in it is small and delicate, and apparently differs accord-
ing to the species. The meso- and meta-thorax are sub-equal
in size; the mesosternum forms a peculiar, large, adpressed fold.
The metasternum is membranous, but is terminated behind by
a sclerite apparently of variable form. The hind body is volumi-
nous, simple in form, consisting of ten segments and bearing at
the extremity two short distant cerci of a variable number of
joints. The terminal ventral sclerites differ greatly in form
according to the species and sometimes according to the sex;
there are sometimes, if not always, present near the extremity
two peculiar minute biarticulate styles, called appendices anales.
The coxae are all large, free, and exserted; at the base of each
is a transverse trochantin. The femora are articulated with
the trochanters, not with the coxae; both femora and tibiae
are slender, the tarsi small, four-jointed; the terminal joint
elongate. ;
It is now well established that Termites have a means of
communication by sounds. The individuals have a peculiar way
of jerking themselves, as has
been frequently noticed by ob-
servers of the Insects; these con-
vulsive movements may possibly
Fic. 227.—Front tibia and tarsus of be connected a ahh thie produpiion
Calotermes rugosus larva, showing of sound, which may perhaps be
Millen} organ, x 90. (After F. evoked by contact between the
back of the head and the pro-

notum ; the exact mode by which the sounds are produced is not,
however, known. The existence of an auditory organ in the
front tibia has been demonstrated by Fritz Miiller, and we
reproduce (Fig. 227) one of his figures. The structure seems to

1 Jena. Zeitschr. Naturw. ix. 1875, pl. xii. See also Stokes in Science, xxii.
1893, p. 273.

XVI TERMITIDAE 359

be in plan and position similar to the ear of Locustidae,
though much less perfect.

The wings of Termitidae.are not like those of any other
Insects; their neuration is very simple, but nevertheless the
wings of the different
forms exhibit great differ-
ences in the extent to
which they are made up
of the various fields. This ,
is shown in Fig. 228, 2%
where the homologous * >
nervures are numbered
according to-the systems
of both Hagen and Red-
tenbacher. The area, VII,

that forms the larger part

; ; »o_. FIG. 228.—Wings of Termites: A, Termes lucifugus ;
of the Beeee Ul C, ore B, Hodotermes brunneicornis; C, Culotermes
spondstothesmall portion — nodulosus. (After Redtenbacher: B and C

: diagrammatic.) III, V, VII, homologous areas
at the base of the mane and nervures according to Redtenbacher. 1,

m4 B; The most re- Costal ; 2, subcostal ; 3, median; 4, submedian
markable feature of the nervures according to Hagen,

Wing is, however, its division into two parts by a suture or line
- of weakness near the base, as shown in Fig, 225. The wings
are used only for a single flight, and are then shed by detach-
ment at this suture; the small basal portion of each of the four
wings is horny and remains attached to the Insect, serving as
a protection to the dorsal surface of the thorax.

The nature of the suture that enables the Termites to cast
their wings with such ease after swarming is not yet understood.
There are no true transverse veinlets or nervules in Termites.
Redtenbacher suggests’ that the transverse division of the wing
at its base, as shown in Fig. 225, along which the separation of
the wing occurs at its falling off, may have arisen from a coales-
cence of the subcostal vein with the eighth concave vein of such
a wing as that of Blattidae. The same authority also informs us
that the only point of resemblance between the wings of Termi-
tidae and those of Psocidae is that both have an unusually small
number of concave veins.

The information that exists as to the internal anatomy of

1 Ann. Hofmus. Wien, i. 1886, p. 183.

360 NEUROPTERA , CHAP.

Termites is imperfect, and refers, moreover, to different species ;
it would appear that considerable diversity exists in many
respects, but on this point it would be premature to generalise.
What we know as to the respiratory system is chiefly due to
F. Miiller." The number of spiracles is ten; Hagen says three
thoracic and seven abdominal, Miiller- two thoracic and eight
abdominal. In fertile queens there usually exist only six
abdominal stigmata. There is good: reason for supposing that
the respiratory system undergoes much change correlative with
the development of the individual; it has been suggested that
the supply of tracheae to the sexual organs is deficient where
there is arrest of development of the latter. | .
The alimentary canal is only of moderate length. . Salivaky
glands exist, as also do salivary reservoirs; these latte are large,
in some species remarkably so. The
oesophagus is slender, but abruptly
enlarged behind to form a large crop;
a proventriculus is apparently either
present or absent; the chylific ventricle,
or stomach, is slender and simple. The
Malpighian tubules are very long; their
number is probably from four to eight
in the adult, and in the earlier stages
less. Behind the tubes the alimentary
canal forms a large paunch, and after
this there is a small intestine and
rectum. The paunch is a_ peculiar
structure, and probably of great import-
ance in the economy of Termites.
‘These creatures emit minute quanti-
Fic. 229.—Head and Savane ties of a secretion that is corrosive, and
canal of Termes lueifugus can act on metal and even glass; its
(nymph). a, head ; 4, salivary
glands ; ¢, salivary receptacles; Nature and source are not understood.
d, crop; @ stomach ; Jf, intes- Hagen describes peculiar structures in
tinal paunch; g, small, h, ; ac mika 4
large intestine ; 7, Malpighian the rectum to which he is inclined ®
» tubes ; &, extremity of body. to ascribe the origin of this substance,
(After Dufour.) he ;
but this is very uncertain,
The brain is small; the infra-oesophageal ganglion is placed

ty

1 Jena. Zeitschr, Naturw. ix. 1875, p. 257.
2 Bidie, in Nature, xxvi. 1882, p. 549, * Linnaea Entomologica, xii. 1858, p. 305.

XVI ; TERMITIDAE 361

‘immediately under the supra-oesophageal ; there are three thoracic
and six abdominal ganglia. The nervous system apparently
differs but little in the various forms, or in the different stages
of life, except that in the fertile females the abdominal ganglia
become so much enlarged that they even exceed the brain in size.
The testes are unusually simple; each consists of eight capsules
opening into the vas deferens; the two vasa converge and are
continued as a short ejaculatory duct; at the point of convergence
there is a pair of curled vesiculae seminales,

The ovarian system is also simple; there is a variable number
of elongate egg-tubes, each of which opens separately into the
‘oviduct ; the two ducts unite to form a short uterus, on which
there is placed first a spermatheca, and near the extremity a
convolute tubular sebific gland. The number of egg-tubes is
subject to extraordinary variation, according to the species, and
according to the age of the fertilised individual.

Social Life.— Termites live in communities that consist
sometimes of enormous numbers of individuals, The adult forms
found in a community are (1) workers; (2) soldiers; (3) winged
males and females; (4) some of these winged forms that have
lost their wings. Some species have no worker caste. The
individuals of the third category are only present for a
few days and then leave the nest in swarms. In addition
to the adult individuals there are also present various
forms of young. The individuals that have lost their wings
are usually limited to a single pair, king. and queen;
there may be more than one king and queen, but this is not
usual. The king and queen may be recognised by the stumps
of their cast wings, which exist in the form of small triangular
pieces folded on the back of the thorax (Fig. 235). The con-
tinuance of the community is effected entirely by the royal pair ;
they are the centres of activity of the community, which is thrown
into disorder when anything happens to them. Usually the pair
are physically incapable of leaving the nest, especially the queen,
and frequently-they are enclosed in a cell which they cannot leave.
In consequence of the disorganisation that arises in the com-
munity in the absence of a royal pair, Termites keep certain
individuals in such a state of advancement that they can rapidly
be developed into royalties should occasion require it. These
reserve individuals are called complementary by Grassi; when

362 NEUROPTERA CHAP.

they become royalties they are usually immature as regards
the condition of the anterior parts of the body, and are then
called by Grassi and others neoteinic, as is more fully explained
on p. 380. .

Swarms.— As a result of the Termite economy large
numbers of superfluous individuals are frequently produced ;
these, in the winged state, leave the community, forming swarms
which are sometimes of enormous extent, and are eagerly preyed
on by a variety of animals including even man. Hagen has
given particulars? of a swarm of 7. flavipes in Massachusetts,
where the Insects formed a dark cloud; they were accompanied
by no less than fifteen species of birds, some of which so gorged™
themselves that they could not close their beaks.

There is but little metamorphosis in Termitidae. Young
Termites are very soft; they have a thin skin, a dispropor-
tionately large head, and are of a peculiar white colour as if
filled with milk. This condition of milkiness they retain, not-
withstanding the changes of form that may occur during their
growth, until they are adult. The wings first appear in the
form of prolongations of the meso- and meta-nota, which increase
in size, the increment probably taking place at the moults. The
number of joints of the antennae increases during the develop-
ment; it is effected by growth of the third joint and subsequent
division thereof; hence the joints immediately beyond the
second are younger than the others, and are usually shorter and
altogether more imperfect. The life-histories of Termites have
been by no means completely followed ; a fact we can well under-
stand when we recollect that these creatures live in communities
concealed from observation, and that an isolated individual cannot
thrive; besides this the growth is, for Insects, unusually slow.

Natural History.—The progress of knowledge as to Ter-
mites has shown that profound differences exist in the economy
of different species,.so that no fair general idea of their lives can
be gathered from one species. We will therefore briefly sketch
the economy, so far as it has been ascertained, in three species,
viz. Calotermes flavicollis, Termes lucifugus, and T. bellicosus.

Calotermes flavicollis inhabits the neighbourhood of the
Mediterranean Sea; it is a representative of a large series of
species in which the peculiarities of Termite life are exhibited

1 P. Boston Soc. xx. 1878, p. 118.

i
:

a TERMITIDAE 363

in a comparatively simple manner. There is no special caste of
workers, consequently such work as is done is carried on by the
other members of the community, viz. soldiers, and the young
and adolescent. The habits of this species have recently been
studied in detail in Sicily by Grassi and Sandias! The Insects
dwell in the branches and stems of decaying or even dead trees,
where they nourish themselves on those parts of the wood in
which the process of decay is not far advanced; they live in the
interior of the stems, so that frequently no sign-of them can be
seen outside, even though they may
be heard at-work by applying the
ear to a branch. They form .no
special habitation, the interior of
the branch being sufficient protec-
tion, but. they excavate or increase
the natural cavities to. suit their
purposes. It is said that they
line the galleries with proctodaeal
cement; this is doubtful, but they
form barricades and _ partitions
where necessary, by cementing
together the proctodaeal products py, 939,—gome individuals of Calo-
with matter from the salivary _— termes flavicollis: A, nymph with
glands or regurgitated from the aie rial vino Mi
anterior parts of the alimentary dividual. (After Grassi.)

canal. The numbers of a com- :

munity only increase slowly and remain always small; rarely do
they reach 1000, and usually remain very much below this. The
king and queen move about, and their family increases but slowly.
After fifteen months of their union they may be surrounded by
fifteen or twenty young; in another twelye months the number
may have increased to fifty, and by the time it has reached some
five hundred or upwards the increase ceases. This is due to the
fact that the fertility of the queen is at first progressive, but
ceases to be so. A queen three or four years old produces at
the time of maximum production four to six eggs a day. When
the community is small—during its first two years—the winged
individuals that depart from it are about eight or ten annually,
but the numbers of the swarm augment with the increase of the

1 4tti Acc. Gioen. vi. and vii. 1893 and 1894.

364 ) NEUROPTERA CHAP,

population. The growth of the individuals is slow; it appears —
that more than a year elapses between the hatching of the egg
and the development of the winged Insect. The soldier may
complete its development in less than a year; the duration of its
life is not known; that of the kings and queens must be four or
five years, probably more. After the winged Insects leave the
colony they associate themselves in pairs, each of which should,
if all goes well, start a new colony.

The economy of Termes lucifugus, the only European Termite
besides Calotermes flavicollis, has been studied by several
observers, the most important of whom are Lespés’ and Grassi
and Sandias. This species is much more advanced in social life
than Calotermes is, and possesses both workers and soldiers —
(Fig. 231, 2, 3); the individuals are much smaller than those of —
Calotermes. Burrows are made in wood of various kinds, furni-
ture being sometimes attacked. Besides making excavations
this species builds galleries, so that it can move from one object
to another without being exposed; it being a rule—subject to
certain exceptions—that Termites will not expose themselves
in, the outer air. This is probably due not only to the
necessity for protection against enemies, but also to the fact
that they cannot bear a dry atmosphere; if exposed to a drying
air they speedily succumb. Occasionally specimens may be seen
at large; Grassi considers these to be merely explorers. Owing
to the extent of the colonies it is difficult to estimate with
accuracy the number of individuals composing a community, but
it 1s doubtless a great many thousands. Grassi finds the economy
of this species in Sicily to be different from anything that has
been recorded as occurring in other species; there is never a true
royal pair. He says that during a period of six years he has
examined thousands of nests without ever finding such a pair.
In place thereof there are a considerable number of complementary
queens—that is, females that have not gone through the full
development to perfect Insects, but have been arrested in various
stages of development. In Fig. 231, Nos. 4 and 5 show two of
these abnormal royalties; No. 4 is comparatively juvenile in
form, while No. 5 is an individual that has been substituted in
an orphaned nest, and is nearer to the natural condition of perfect
development. We have no information as to whether any develop-

1 Ann. Set. Nat. Zool. (4) v. 1856, p. 227. .

XVI TERMITIDAE 3 365

ment goes on in these individuals after the state of royalty is
assumed, or whether the differences between these neoteinic queens
are due to the state of development they may happen to be in
when adopted as royalties. Kings are not usually present in
these Sicilian nests; twice only has Grassi found a king, but

Fig. 231.—Some of the forms of Termes lucifugus. 1, Young larva; 2, adult worker ;
3, soldier ; 4, young complementary queen; 5, older substitution queen ; 6, per-
fect winged Insect. (After Grassi.)

he thinks that had he been able to search in the months of
August’ and September he would then have found kings. It
would appear therefore that the complementary kings die, or are
killed after they have fertilised the females. Parthenogenesis
is not thought to occur, as Grassi has found the spermathecae of
the complementary queens to contain spermatozoa.

366 NEUROPTERA CHAP. XVI~

The period of development apparently occupies from eighteen
to twenty-three months. At intervals swarms of a great number
of winged individuals leave the nest, and are usually promptly
eaten up by various animals. After swarming, the wings are
thrown off, and sometimes two specimens or three may be seen
running off together; this has been supposed to be preliminary
to pairing, but Grassi says this is not the case, but that the
object is to obtain their favourite food, as we shall mention
subsequently. | :

Although these are the usual habits of Zermes lucifugus at
present in Sicily, it must not be concluded that they are invari-
able; we have in fact evidence to the contrary. Grassi has
himself been able to procure in confinement a colony—or rather
the commencement of one—accompanied by a true royal pair;
while Perris has recorded’ that in the Landes he frequently -
found a royal pair of TZ. lucifugus under chips; they were
accompanied in nearly every case by a few eggs. And Professor ~
Perez has recently placed a winged pair of this species in a box
with some wood, with the result that after some months a young
colony has been founded. It appears probable therefore that
this species at times establishes new colonies by means of royal
pairs derived from winged individuals, but after their establish-
ment maintains such colonies as long as possible by means of
complementary queens. It is far from improbable that distinc-
tions as to the use of true and complementary royalties may be
to some extent due to climatic conditions. In some localities
T. lucifugus has multiplied to such an extent as to be very
injurious, while in others where it is found it has never been
known to do so.

The Termitidae of Africa are the most remarkable that have
yet been discovered, and it is probably on that continent that the
results of the Termitid economy have reached their climax. Our
knowledge of the Termites of tropical Africa is chiefly due to
Smeathman, who has described the habits of several species,
among them 7’ bellicosus. It is more than a century since
Smeathman travelled in Africa and read an account of the
Termites to the Royal Society. His,information was the first
of any importance. about Termitidae that was given to the
world; it is, as may be well understood, deficient in many

1 Ann. Soc. ent. France (5), vi. 1876, p. 201. 7 Phil. Trans. xxi. 1781, pp. 139-192.

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368 NEUROPTERA "CaP.

details, but is nevertheless of great value. Though his state-
ments have been doubted they are truthful, and have been
confirmed by Savage. 7. bellicosus forms buildings compar-
able to human dwellings; some of them being twenty feet in
height and of great solidity. In some parts of West Africa
these nests were, in Smeathman’s time, so numerous that they
had the appearance of villages. Each nest was the centre of

a community of countless numbers of individuals; subter-

ranean passages extended from them in various directions. The
variety of forms in one of these communities has not been well
ascertained, but it would seem that the division of labour is
carried to a great extent. The soldiers are fifteen times the size
of the workers. The community is dependent on one royal
couple. It is the opinion of the natives that if that couple perish
so also does the community; and if this be correct we may
conclude that this species has not a perfect system of replacing
royal couples. The queen attains an almost incredible size
and fertility. Smeathman noticed the great and gradual growth
of the abdomen, and says it enlarges “to such an enormous size
that an old queen will have it increased so as to be fifteen
hundred or two thousand times the bulk of the rest of her body,
and twenty or thirty thousand times the bulk of a labourer, as
I have found by carefully weighing and computing the different
states.” He also describes the rate at which the eggs are pro-
duced, saying that there is a constant peristaltic movement” of
the abdomen, “so that one part or other alternately is rising
and sinking* in. perpetual succession, and the matrix seems never
at rest, but is always protruding eges to the amount (as I
have frequently counted in old queens) of sixty in a minute, or
eighty thousand and upward in one day of twenty-four hours.”

_ This observer, after giving an account of the great swarms of
perfect winged Insects that are produced by this species, and after
describing the avidity with which they are devoured by the
Hymenopterous ants and other creatures, adds: “ I have discoursed
with several gentlemen upon the taste of the white ants; and on
comparing notes we have always agreed that they are most

1. Ann. Nat. Hist. (2) v. 1850, p. 92.

2’Dr. G. D. Haviland informs the writer that he thinks it probable this so-called
peristaltic movement is merely the result of alarm ; he has not, however, had any
apportunity of observing 7’. belZicosus.

.

XVI. TERMITIDAE 369

delicious and delicate eating. One gentleman compared them to
sugared marrow, another to sugared cream and a paste of sweet
almonds.”

From the preceding brief sketch of some Termitidas we may
gather the chief points of importance in which they differ from
other Insects, viz. (1) the existence in the community of in-
dividuals—workers and soldiers—which do not resemble their
parents; (2) the limitation of the reproductive power to a single
pair, or to a small number of individuals in each community, and
the prolongation of the terminal period of life. There are other
social Insects besides Termitidae: indeed, the majority of social
Insects—ants, bees, and wasps—belong to the Order Hymen-
optera, and it is interesting to note that analogous phenomena
occur inthem, but nevertheless with such great differences that
the social life of Termites must. be considered as totally distinct
from that of the true ants and other social Hymenoptera.

Development.—Social Insects are very different to others not
only in the fact of their living in society, but in respect of
peculiarities in the mode of reproduction, and in the variety of
habits displayed by members of a community. The greatest
confusion has arisen in reference to Termitidae in consequence
of the phenomena of their lives having been assumed to be
similar to those of Hymenoptera; but the two cases are very
different, Hymenoptera passing the early parts of their lives as
helpless maggots, and then undergoing a sudden metamorphosis to
a totally changed condition of structure, intelligence, and instinct.

The development of what we may look on as the normal form
of Termitidae—that is, the winged Insects male and female—is
on the whole similar to that we have sketched in Orthoptera ; the
development in earwigs being perhaps the most similar. The
individuals of Termitidae are, however, in the majority of cases
if not in all, born without eyes; the wing-rudiments develop
from the thoracic terga as shorter or longer lobes according to

_ the degree of maturity ; ; as in the earwigs the number of joints

in the antennae increases as development advances. All the young

are, when hatched, alike, the differences of caste appearing in the

course of the subsequent development; the most important of

these differences are those that result in the production of two

special classes—only met with in social Insects—viz. worker

and soldier. Of these the workers are individuals whose develop-
VOL, V 28

370 NEUROPTERA CHAP.

ment is arrested, the sexual organs not going on to their full
development, while other organs, such as the eyes, also remain
undeveloped ; the alimentary canal and its adjuncts occupy nearly
the whole of the abdominal cavity. The adult worker greatly
resembles—except in size—the young. Grassi considers that the
worker is not a case of simple arrest of Sa Mages but - that
some deviation accompanies the arrest.

The soldier also suffers an arrest of development in certain
respects similar to the worker; but the soldier differs'in the im-
portant fact that the arrest of the development of certain parts
is correlative with an extraordinary development of the head,
which ultimately differs greatly from those of either the ‘worker
or of the sexual males and females,

Soldier.—All the parts of the head of the oldie undergo a
greater or less change of form; even
the pieces at its base, which connect

it by means of the cervical sclerites
with the prothorax, are altered. The
parts that undergo the greatest modi-
fication are the mandibles (Fig. 233,
B); these become much enlarged in size
and so much changed in form that in
a great many species no resemblance.
to the original shape of these organs
can be traced. It is a curious fact that.
the specific characters are betterexpressed
in these superinduced modifications than

E they are in any other part of the
organisation (except, perhaps, the wings).
The soldiers are not alike in any two
‘species of Termitidae so far as “we
D

know, and it séems impossible to ascribe
the differences that exist between. the
Fic. 238.—The pairs of mandi- soldiers of different species of Termitidae
bles of different adult indi- to special adaption for the work they
id: " - t . Me
Suigepore, *. OF peti, have to perform. Such a suggestion 1s
B, bas “seat oF. dee justifiable only in the case of the: Nasuti
Ne NINE AINE’ (Fig. 23.4, 1), where the front of the head
is prolonged into a point: a duct opens at the extremity of

this point, from which is exuded a fluid that serves as a cement for

‘SOLDIERS. 37a

- constructing the nest, and is perhaps also used to disable enemies.
_ Hence the prolongation and form of the head of these Nasuti may
be fairly described as adaptation to useful ends. As regards the —
_ great variety exhibited by other soldiers—and their variety is
- much greater than it is in the Nasuti—it seems at present im-
_ possible to treat it as being cases of special adaptations for useful
_ purposes. On the’ whole it would be more correct to say

CU

\

Fic. 234.—Soldiers of different species of Termites. (After Hagen.) 1, Termes armiger ;
2, T. dirus; 3, Calotermes flavicollis; 4, T. bellicosus; 5, T. occidentis; 6, T.
cingulatus (2) ; 7, Hodotermes quadricollis (?); 8, T. debilis(?), Brazil.

j that the soldiers are very dissimilar in spite of their having to
_ perform similar work, than to state that they are dissimilar in
conformity with the different tasks they carry on.

The Termite soldier is a phenomenon to which it is difficult
_ to find a parallel among Insects. The soldier in the true ants
is usually not definitely distinguished from the worker, but it is
possible that in the leaf-cutting ants, the so-called soldier may
_ prove to be more similar in its nature to the Termite soldier,
_ The soldiers of any one species of Termite are apparently ex-

:

372: NEUROPTERA CHAP,

tremely similar to one another, and there are no intermediates
between them and the other forms, except in the stages of
differentiation, But we must recollect that but little is yet
known of the full history of any Termite community, and it is
possible that soldiers which in the stage of differentiation promise
to be unsatisfactory may be killed and eaten,—indeed there is some
evidence to this effect. . There is too in certain cases some difference
—larger or smaller size being the most important—between the
soldiers of one species, which may possibly be due to the different -
stage of development at which their differentiation commenced.
It would at present appear that, notwithstanding the remark-
able difference in structure of the soldiers and workers of the
white ants, there is not a corresponding difference of instinct.
It is true that soldiers do more of certain things than workers
do, and less of others, but this appears to be due solely to their
possession of such very different structures; and we are repeatedly
informed by Grassi that all the individuals in a community take
part, so far as they are able, in any work that is going on, and
we find also in the works of other writers accounts of soldiers
performing acts that one would not have expected from them.
The soldiers are not such effective combatants as the workers are.
Dudley and Beaumont indeed describe the soldiers as merely look-
ing on while the workers fight So that we are entitled to con-
clude that the actions of the soldiers, in so far as they differ from
those of the rest of the community, do so because of the different —
organisation and structures of these individuals. We shall, when
speaking of food, point out that the condition of the soldier in
relation to food and hunger is probably different from that of
the other forms.’ 3 ; Of
Various Forms of a Community.—tThe soldiers and workers
are not the only anomalous forms found in Termitid communi-
ties; indeed on examining a large nest a variety of forms may
be found that is almost bewildering. Tables have been drawn
up by Grassi and others showing that as many as fifteen kinds
may be found, and most of them may under certain circumstances
coexist. Such tables do not represent the results of actual
examination in any one case, and they by no means ade-
quately represent the number that, according to the most recent
observations of Grassi, may be present; but we give one taken

1 Tr, N. York Ac, viii. 1889, pp. 85-114; and ix. 1890, pp. 157-180.

i
F

les)

Q

XvI¥ TERMITIDAE 373

from Grassi, as it conveys some idea of the numerous forms that
exist in certain communities. .In this table the arrangement,
according to A, B, C, D, E, represents successive stages of the
Beretopment + — :

Forms of Reeves. fosfuguss (After Grassi.) Zool. Anz. xii. 1889, p. 360.

1. Young, undifferentiated larvae.
| | |
g | |
2. Larvae that will 3. Larvae that will 4, Reserves for royal specimens:
not mature the sexual mature the sexual (only present when 14, 15, and 11
organs, - organs. are wanting, or when 14and ld are

present in insufficient numbers).
. |.

| |
5. Larvae of 6. Pie il of - 9, Nymphs of the - 10. Nymphs of - LT. Reserves for
soldiers, workers. first form. the second form, royal pairs (only
| present when 14,
15, and 4 are want-
ing, or when the
two latter are
present in insuffi-

7. Soldiers. '8. Workers. cient numbers).
Wie 12. Winged 13. Reserve
Insects. royal pairs ?
14: poral 16. Substi tution
couple. . " royal pairs.

On inspecting this table it will be perceived that the variety of
forms is due to three circumstances—(1) the existence of castes
that are not present in ordinary Insects; (2) the coexistence of
young, of adolescents, and of adults; and (3) the habit the Termites
have of tampering with forms in their intermediate stages, the
result of which may be the substitution of neoteinic individuals in
place of winged forms.

This latter procedure is far from being eamen lace understood,
but to it are probably due the various abnormal forms, suchas
soldiers with rudiments of wings, that have from timé to time
been discovered in Termite. communities, and have given rise to
-much perplexity.

- ~ In connexion with this subject we may call attention to the
necessity, when examining Termite nests, of taking cognisance
of the fact that more than one species may be present. Bates
found different Termites living together in the Amazons Valley,
and Mr. Haviland has found as many as five species of Termitidae
and three of true ants in a single mound in South Africa. In
this latter case observation showed’ that, though in -such close
proximity, there was but little further intimacy between the
‘species. There are, however, true inquiline, or guest, Termites,

374 NEUROPTERA CHAP.

of the genus Hutermes, found in various parts of the world living
in the nests of other Termitidae.

Origin of the Forms.—The interest attaching to the various
forms that exist in Termites, more particularly to the worker and
soldier, is evident when we recollect that these never, so far as
we know,. produce young. In the social Hymenoptera it has
been ascertained that the so-called neuters (which in these
Insects are always females) can, and occasionally~do, produce
young, but in the case of the Termites it has never been sug-
gested that the sexual organs of the workers and soldiers, whether
male or female, ever become fruitful; moreover, the phenomena
of the production of young by the white ants are of such a nature
as to render it in the highest degree improbable that either —
workers or soldiers ever take any direct part in it. Now the
soldier is extremely different from the sexual individuals that
produce the young, and seeing that: its peculiarities are not, in

the ordinary sense of the word, hereditary, it must be of great

interest to ascertain how they arise. .

Before stating the little information we possess on this sub-
ject, it is necessary to reiterate what we have already said to the
effect that the soldiers and workers are no% special to either sex,
and that all the young are born alike. It would be very natural
to interpret the phenomena by supposing the workers to be
- females arrested in their development—as is the case in social
Hymenoptera—and by supposing the soldiers to be males with —
arrested and diverted development.

The observations already made show that this is not the case.
It has been thoroughly well ascertained by Lespés and Fritz Miiller
that in various species of Calotermes the soldiers are both males
and females. Lespés and Grassi have shown that the workers of
Termes lucifugus are of male and female sex, and that this is
also true of the soldiers. Although the view of the duality of
the sexes of these forms was received at first with incredulity, it
appears to be beyond doubt correct. Grassi adds that in all the
individuals of the workers and soldiers of Z’ermes lucifugus the
sexual organs, either male or female, are present, and that they
are in the same stage of development whatever the age of the
individual. This statement of Grassi’s is of importance because
it seems to render improbable the view that the difference of form
of the soldier and worker arises from the arrest of the develop-

XVI TERMITIDAE 375

y

ment of their sexual organs at different periods. The fact that
sex has nothing whatever to do with the determination of the
form of workers and soldiers may be considered to be well
established. |
The statement that the young are all born alike is much
more difficult to substantiate. Bates said that the various forms
could be detected in the new-born. His statement was made,
however, merely from inspection of the nests of species about
which nothing was previously known, and as it is then very
difficult to decide that a specimen is newly hatched, it is probable
that all he meant was that the distinction of workers, soldiers,
and sexual forms existed in very small individuals—a statement
that is no doubt correct. Other observers agree that the young
are in appearance all alike when hatched, and Grassi reiterates his
statement to this effect. Hence it would appear that the differ-
ence of form we are discussing arises from some treatment subse-
quent to hatching. It may be suggested, notwithstanding the
fact that the young are apparently alike when hatched, that they
are not really so, but that there are recondite differences which are
in the course of development rendered conspicuous. This con-
clusion cannot at present be said with certainty to be out of the
question, but it is rendered highly improbable by the fact
ascertained by Grassi that a specimen that is already far advanced
on the road to being an ordinary winged individual can be diverted
from its evident destination and made into a soldier, the wings
that were partially developed in such a case being afterwards
more or less completely absorbed. This, as well as other facts
observed by Grassi, render it probable that the young are truly,
as well as apparently, born in a state undifferentiated except as
regards sex. Fig. 230 (p. 363) is designed to illustrate Grassi’s
view as to this modification; the individual A is already far
advanced in the direction of the winged form C, but can never-
theless be diverted by the Termites to form the adult soldier B.
According to the facts we have stated, neither heredity nor
‘sex nor arrest of development are the causes of the distinctions
between worker and soldier, though some arrest of development is
common to both; we are therefore obliged to attribute the dis-
tinction between them to other influences. Grassi has no
hesitation in attributing the anatomical distinctions that arise
between the soldiers, workers, and winged forms to alimentation.

376 NEUROPTERA CHAP.

‘Food, or the mode of feeding, or both combined, are, according
to the Italian naturalist, the source of all the distinctions,
except those- of sex, that we see in the forms of any one ispecies
of Termite. —

-Feeding.—Such knowledge as we possess of the food-habits
of Termitidae is chiefly due to Grassi; it is of the very greatest
importance, as giving a clue-to much that was previously obscure
in the Natural History of these extraordinary creatures.

In the abodes of the Termites, notwithstanding the enormous
numbers of individuals, cleanliness prevails; the mode by which
it is attained appears to be that of eating all refuse matter.
Hence the alimentary canal in Termitidae contains material of
various conditions of nutritiveness. These Insects eat their cast
skins and the dead bodies of individuals of the community ; even
the material that has passed through the alimentary canal is
eaten again, until, as we may presume, it has no further nutritive
power.. The matter is then used for the construction of their
habitations or galleries, or is carried to some unfrequented part
of the nest, or is voided by the workers outside of the nests;
the pellets of frass, 7.e alimentary rejectamenta, formed by —
the workers frequently betraying their presence in buildings
when none of the Insects themselves are to be seen. The
aliments of Calotermes flavicollis are stated by Grassi and
Sandias to be as follows: (1) wood; (2) material passed
from the posterior part of the alimentary canal or regurgi-
tated from the anterior part; (3) the matter shed during
the moults; (4) the bodies of other individuals; (5) the
secretion of their own salivary glands or that of their fellows;
(6) water. Of these the favourite food is the matter passed .
from the posterior part of the alimentary canal. We will speak of
this as proctodaeal food. When a Calotermes wishes food it strokes
the posterior part of another individual with the antennae and
palpi, and the creature thus solicited yields, if it can, some
proctodaeal food, which is then devoured. Yielding the proctodaeal
food is apparently a reflex action, as it can be induced by friction
and slight pressure of the abdomen with a small brush. The
material yielded by the anterior part of the alimentary canal may
be called stomodaeal product. It makes its appearance in the
mouth in the form of a microseopie globule that goes on in-
creasing in size till about one millimetre in diameter, when it is

TS aye es

XVI TERMITIDAE | 377

either used for building or as food for another individual. The
mode of eating the eédysial products has also been described by
Grassi and Sandias. When an individual is sick or disabled it
is frequently eaten alive. It would appear thatthe soldiers are

great agents in this latter event, and it should be noticed that

owing to their great heads and mandibles they can obtain food by
other means only with difficulty. Since they are scarcely able to
gnaw wood, or to obtain the proctodaeal and stomodaeal foods,
their condition may be considered to be that of permanent
hunger, only to be allayed by carnivorous proceedings. When
thrown into a condition of excitement the soldiers sometimes
exhibit a sort of Calotermiticidal. mania, destroying with a few
strokes five or six of their fellows. It is, however, only proper to
say that these strokes are made at random, the creature having
no eyes. The carnivorous propensities of Calotermes are ap-
parently limited to cannibalism, as they slaughter other white
ants (Termes lucifugus) but never eat them.
~The salivary food is white and of alkaline nature; when
excreted it makes its appearance on the upper lip. It is used
either by other individuals or by the specimen that- produced
it; in the latter case it is transferred to the lower lip and
swallowed by several visible efforts of deglutition. The aliments
we have mentioned are made use of to a greater or less extent by
all the individuals except the very young; these are nourished
only by saliva: they commence taking proctodaeal and stomo-
daeal food before they can eat triturated wood.
Royal Pairs.—The restriction of the reproductive powers of
a community to a single pair (or. to a very restricted number. of
individuals) occurs in all the: forms of social Insects, and in
all of them it is concomitant with a prolongation of the repro-
ductive‘ period far exceeding what is natural in Insects. We are
not in a position at present to say to what extent the lives of the
fertile females of Termitidae are prolonged, there being great: diffi-
culties in the way of observing these Insects for long periods owing
to their mode of life ; living, as they do, concealed from view, light
and disturbance appear to be prejudicial to them. We have every
reason to believe, however, that the prolongation extends as a
rule over several years, and that it is much greater than that of
the other individuals of the community, although the lives of
even these latter are longer than is usual in Insects; but this

378 NEUROPTERA CHAP.

point is not yet satisfactorily ascertained. As regards the males
there is reason to think that considerable variety as to longevity
prevails. But the belief is that the royal males of Termitidae also
form an exception to other Insects in the prolongation of the
terminal periods of their lives. In Hymenoptera, male in-
dividuals are profusely produced, but their lives are short, and
their sole duty is the continuation of the species by a single
| act. We have seen that
Grassi is of opinion that
a similar condition of
affairs exists at present
with Termes lucifugus in
Sicily, but with this ex-
ception it has always been
considered that the life
of the king Termite is,
roughly speaking, con-
temporaneous with that
of the queen; it is said
that in certain species the
king increases in bulk,
though not to an extent
that can be at all com-
pared with the queen.
It must be admitted.
that the duration of life
of the king has not been

Fic. 235.—Royal pair of Termes malayanus from sufficiently established, for
Singapore, taken out of royal cell. A, A, King, the coexistence of a king

intra and dora views BB. quem, donald with g queen in the
royal cell is not incon-
sistent with the life of the king being short, and with his replace-
ment by another. Much that is imaginary exists in the litera-
ture respecting Termites, and it is possible that the life of the
king may prove to be not so prolonged as has been assumed.
Returning to the subject of the limitation of the reproduction
of the community to a single pair, we may remark that a priori
one would suppose such a limitation to be excessively unfavour-
able to the continuation of the species; and as it nevertheless is
the fact that this feature is almost, if not quite, without exception

XVI TERMITIDAE 379

in Insect societies, we may conclude that it is for some reason
absolutely essential to Insect social life. It is true that there
are in Termitidae certain partial exceptions, and these are so
interesting that we may briefly note them. When a royal cell is
opened it usually contains but a single female and male, and
when a community in which royal cells are not used is inspected
it is usually found that here also there are present only a single
fertile female and a single king. Occasionally, however, it
‘happens that numerous females are present, and it has been
‘noticed that in such cases they are not fully matured females, but
are imperfect, the condition of the wings and the form of the
anterior parts of the body being that of adolescent, not adult
Insects. It will be recollected that the activity of a community
of Termites centres round the great fertility of the female ;
without her the whole community is, as Grassi graphically puts
it, orphaned; and the observations of the Italian naturalist
make it clear that these imperfect royalties are substitution
queens, derived from specimens that have not undergone the
natural development, but have been brought into use to meet the
calamity of orphanage of the community, The Termites appar-
ently have the power of either checking or stimulating the reproduc-
tive organs apart from other organs of the body, and they appear to
keep a certain number of individuals in such a condition that in case
of anything going wrong with the queen, the reserves may be brought
as soon as possible into a state of reproductive activity. The in-
dividuals that are in such a condition that they can become pseudo-
royalties are called complementary or reserve royalties, and when
actually brought into use they become substitution royalties. It
is not at present quite clear why the substitution royalties should be
in such excess of numbers as we have stated they were in the case
we have figured (Fig. 236), but it may be due to the fact that when
the power of the community is at a certain capacity for supporting
young a single substitution royalty would not supply the requisite
producing power, and consequently the community adopts a
greater number of the substitution forms. Termites are utterly
regardless of the individual lives of the members of the community,
and when the reproductive powers of the company of substitution
royalties become too great, then their number is reduced by the
effective method of killing and eating them.

According to Grassi’s observations, the communities of Termes

380 ‘daz NEUROPTERA CHAR.

lucifugus are now kept up in Sicily almost entirely by substitution
royalties ; the inference being
that the age of each com-
munity has gone beyond the
capacity for life of any single
royal queen.
The substitution- royal-
ties’ are, as we have said,
| ~ ealled neoteinic (véos, youth-
ful, reivw, to belong to), be-
cause, though they carry on
the functions of adult Insects,
they retain the juvenile con-
dition in certain respects,
and ultimately die without
having completed the normal
development. © The. pheno-
menon.is not quite peculiar
to Insects, but oecurs in

- Fig. 236.—Pair of neoteinic royalties, taken some other animals having

from the royal chamber of Termes mirabilis r Z
at Singapore by Mr. G. D. Haviland, The @ Well = marked’ ometqmios

queen was one of thirteen, all in a nearly phosis, notably in the Mexi-

similar state. A, king; B, C, queen. ean Axolotl:1

A point of great importance in connexion with the neoteinic
royalties is that they are not obtained from the instar im-
mediately preceding the adult state, but are made from Insects
in an earlier stage of development. The condition immediately
preceding the adult state is that of a nymph with long wing-
pads; ‘such specimens are not made into neoteinic royalties, but
nymphs of an earlier stage, or even larvae, are preferred. It. is
apparently by an interference with one of these earlier stages of
development that the “nymphs of the second form,” which have ~
for long been an enigma to zoologists, are produced.

Post-metamorphic Growth.—The increase of the fertility of
the royal female is accompanied by remarkable phenomena of
growth. Post-metamorphic growth is a phenomenon almost
unknown in Insect life, except in these Termitidae; distension
not infrequently occurs toa certain extent in other Insects, and

Veale

> Ct

1 Camerano,. Bull. Soc. ent. Ital. xvii. 1885, p- 89; and Kollmann, Verh. Ges.
Basel, vii. 1883, p. 391.

XVI | TERMITIDAE 381

is usually due to the growth of eggs inside the body, or to the
repletion of other parts. But in Termitidae there exists post-
metamorphic growth of an extensive and complex nature; this
growth does not affect the sclerites (i.e. the hard chitinous parts
of the exo-skeleton), which remain of the size they were when the
post-metamorphic growth commenced, and are consequently mere
islands in the distended abdomen (Fig. 236, B,C). | The growth
is chiefly due to a great increase in number and size of the egg-
tubes, but there is believed to be a correlative increase of various
other parts of the abdominal as distinguished from the anterior
regions of the body. A sketch of the distinctions existing
between a female of a species at the time of completion
of the metamorphosis and at the period of maximum fertility
does not appear to have been yet made,

New Communities.—The progress of knowledge in respect of
Termitidae is bringing to light a quite unexpected diversity of
_ habits and constitution. Hence it is premature to generalise on
important matters, but we may refer to certain points that
haye been ascertained in connexion with the formation of new
communities. The duration of particular communities and the
modes in which new ones are founded are still very obscure.
It was formerly considered that swarming took place in
order to increase the number of communities, and likewise for
promoting crossing between the individuals of different com-
munities. Grassi, however, finds as the result of his prolonged
observations.on Termes lucifugus that the swarms have no further
result than that the individuals composing them are eaten up.
And Fritz Miiller states* that in the case of the great majority
of forms known to him the founding of a colony by means
of a pair from a swarm would be just about as practicable
as to establish a new colony of human beings by placing a
couple of newly-born babes on an uninhabited island. It was
also thought that pairs, after swarming, re-entered the nests
and became royal couples. It does not, however, appear that
any one is able to produce evidence of such an occurrence. The
account given by Smeathman of the election of a royal couple
of Termes bellicosus is imperfect, as, indeed, has already been
pointed out by Hagen. It suggests, however, that a winged
pair after leaving the nest do again enter it to become king

1 Jena. Zeitschr. Naturw. vii. 1873, p. 458.

Ki de NEUROPTERA CHAP.

and queen. The huge edifices of this species described by
Smeathman are clearly the result of many years of labour, and at
present substitution royalties are not known to occur in them,
so that it is not improbable Smeathman may prove to be correct
even on this point, and that in the case of some species mature
individuals may re-enter the nest after swarming and may become
royal couples. _On the whole, however, it appears probable that
communities of long standing are kept up by the substitution
royalty system, and that new communities when established are
usually founded by a pair from a swarm, which at first are not
in that completely helpless condition to which they come when
they afterwards reach the state of so-called royalty. Grassi’s
‘observations as to the sources of food remove in fact one of the
difficulties that existed previously in regard to the founding of
new colonies, for we now know that a couple may possibly bear
with them a sufficient supply of proctodaeal and. stomodaeal
aliment to last them till workers are hatched to feed them, and
till soldiers are developed and the community gradually assumes
a complex condition. Professor Perez has recently obtained * the
early stages of a community from a winged pair after they had
been placed in captivity, unattended by workers. Miiller’s
observation, previously quoted, is no doubt correct in relation
to the complete helplessness of royal pairs after they have
been such for some time; but that helplessness is itself only
gradually acquired by the royal pair, who at first are. able to
shift for themselves, and produce a few workers without any
assistance,

Anomalous Forms.—Miiller has described a Calotermes under
the name of C. rugosus, which is interesting on account of the
peculiar form of the young larva, and of the changes by which
it subsequently becomes similar in form to other species of the
genus. We represent the development of this larva in Fig.
237. We may call attention to the fact that this figure illus-
trates the large size of the paunch, which is so extraordinary
in some of the states of the Termitidae. i

It will be recollected that the genus Calotermes is destitute
of workers. There is another genus, Anoplotermes, in which the
reverse condition prevails, and the soldier is absent; this is the
only case. yet known in which such a state of affairs exists.

1 CR. Ac. Paris, cxix. 1894, p. 804..

rT an an

XVI? TERMITIDAE ! 383

The species is called A. pacificus by Fritz Miller; it differs from
other Termitidae in possessing a proventriculus destitute of tritu-
rating ridges. The nests of this species are utilised by a little
Eutermes (E. inguilinus Miiller) for its own advantage; whether
by first ‘destroying the Anoplotermes or whether by merely taking
possession of the nests abandoned by their owners is not known.
It is a most remarkable fact |
that the Hutermes resembles
the <Anoplotermes so ex-
tremely that the two can.
scarcely be distinguished,
though anatomically they are
quite different. The resem-
blance is indeed so great that
it deceived Von Jhering into ©
supposing that the two genera
were alternate generations of a
single species, one generation
possessing soldiers, the other
being without them. Subse- :
quently, by anatomical inves- pas
tigation, he recognised’ the c 6
error into which he had fallen F!¢- 237.—Changes in external form of the
young larva of Calotermes rugosus. A,
—an error that, under such Newly hatched with nine joints in an-
peculiar circumstances, was enmst) 8B, older, larva, vith ten
quite pardonable. joints, x 8; D, larva with twelve joints ;
Hagen has suggested 2 that the position of the parts of, the aliment-

4 : ary canal are shown—v, crop; m,
Hodotermes japonicus never pro- stomach ; 6, paunch; e, intestine; 7,

duces winged forms. Itis, how- dorsal vessel, x 3,°. (After Fritz Miiller.)
ever, now known that this supposed Termite is really an earwig.
Marching and’ Harvesting Termites.—Smeathman alluded
to a remarkable Zermes seen by him in Africa, giving it the
name of 7. viarum. Nothing further is known of this Insect,
which, according to Smeathman’s account, may possibly be: the
most remarkable-of the family. 7. viarwm is said to be larger
than 7. bellicosus, and was discovered issuing in large numbers
from a hole in the ground and marching in columns consisting
of workers directed by soldiers of enormous size, some of whom

1 Congr. internat. Zool. ii. 1892, pt. i. p. 249,
' 2 P. Boston Soe. xi. 1868, p. 399:

384 NEUROPTERA 3 CHAP.

climbed up plants and gave audible signals to the army, which
immediately responded with a hissing noise and by increasing
their pace with the utmost hurry; they continued marching by
the spot where Smeathman observed them for upwards of an
hour. He was not able to find their nests, and no specimens have
been preserved ; both soldiers and workers possessed eyes. March-
ing in this way by daylight is contrary to the nature of ordinary
Termites, and some doubt has existed as to the correctness of
Smeathman’s observation, which has in fact remained for upwards
of a century. without confirmation.

Mr. G. D. Haviland has, however, this year - discovered: in
Natal a Termite which shows that there are species in Africa
of the kind described by Smeathman, the workers and soldiers
being possessed of facetted eyes. Mr, Haviland states that the
workers of this species issue from holes in the ground during the
heat of the day and

cut grass both dead
and green. They
‘ carry it, in lengths
of about two inches,
to the mouths of
the holes, often
leaving it there and
going at once to
fetch more. Under
acacia bushes they
carry acacia leaflets

; as well as grass. In
Fic. 238.—Eyed, grass-cutting Termite, Hodotermes havilandi, :
A, soldier; B, worker. South Africa, In life the head the middle of the
is carried horizontally, so the piece of grass sticks up like day more grass ac-

o Hepple, | cumulates at the
entrance to the holes than can be taken in, but as the heat of
the day diminishes the workers cease to forage and take in the
accumulation. When the grass is all in they sometimes close
- the mouth of the hole with moistened pellets of earth brought
in their mouths. The soldiers remain in the holes; when dis-
turbed they jerk themselves like soldiers of other species to
frighten away the intruder; when they bite, their grip is very
tenacious. The holes are about 4 of an inch in diameter, and
there are usually several of them a few yards apart; around each

XVI > | TERMITIDAE 385

of them is a patch over which the grass has been cut quite
short. Mr. Haviland followed these holes by digging for a
distance of 20 feet and to a depth of 54 feet; they remain
uniform in size except that near the aie there may
be one or two chambers in which the grass is temporarily
stored, but these do not hold more than would be collected
in an hour or two. As the burrow descends it is occa-
sionally joined by another, and at the point of junction there
is usually a considerable widening. Sometimes they run straight
for 6 or 7 feet, sometimes they curve abruptly, sometimes they are
nearly horizontal, but near the mouth may be almost vertical in
direction. These Termites are very local, but the specimens are
numerous when found. Mr. Haviland dug for these Insects at
two places on the Tugela river, one of them being at Colenso. It
is much to be regretted that he was unable to reach the nest.
We figure a soldier selected from specimens sent by Mr. Haviland
to the Cambridge University Museum. This Insect is apparently
much smaller than Smeathman’s 7. viarwm. Other species of
Termitidae have been described * as forming underground tunnels
in Africa, but none of the a have ‘yet been satisfactorily
identified.

It was stated by Smeathman that some species of Termites
had chambers in their habitations in which grew a kind of fungus
used by the Insects for food; Mr. Haviland is able to confirm
Smeathman in this particular; he having found fungus-chambers
in the nests of more than one species both in Binpation and
South Africa (Fig. 240). |

Habitations.—In nothing do Termites differ more than in
the habitations they form.. Sometimes, as we have mentioned in
the case of Calotermes, there is no real structure formed; only a
few barriers being erected in burrows or natural hollows in wood.
In: other cases very extensive structures are formed, so that the
work of the Termites becomes a conspicuous feature in the land-
scape. This is of course only the case in regions that are not
much interfered with by man; the great dwellings spoken of
by Smeathman and others soon disappear from the neighbourhood
of settlements, but in parts of Africa and in Australia large
dwellings are still formed by these creatures. In the latter part
of the world there exists a very remarkable one, formed by an

She tt pane. Dae - 1. Kolbe, Ent.-Nachr. xiii. 1887, p. 70. ,
VOL. V 2 C

386 NEUROPTERA CHAP,

undetermined species called by the officers and crew of her
Majesty’s ship Penguin the “compass ant.” The outline of one
of the structures formed by this Termite we represent in Fig. 239.
Mr. J. J. Walker, to whom we are indebted for the sketch from
which this figure is taken, has also favoured us with the following
extract from his diary, of date 4th August 1890: “The most in-
teresting feature in the scenery (about forty miles inland from Port
Darwin) was the constant succession of huge mounds raised by
the Termites, of which I had seen some comparatively small
examples in my rambles near Port Darwin; but these exceeded
in dimensions all I had ever seen. The most frequent as well as
the largest kind was usually of a reddish or ferruginous colour
outside, and generally almost cylindrical in shape with obtusely-
pointed top, but nearly always more or less weather-worn, with
great irregular buttresses and deep ruts down the sides; many of
them look like ruined towers in miniature. Their usual height
was from 8 to 10 feet, but many were much higher, and some
attained an (estimated) elevation of at least 20 feet: Another
kind, seen only in one or two places along the line, was of a much ~
more singular character; they averaged only 4 to 5 feet high,
were built of a dark-gray mud,
and in shape were like thin flat
wedges set upright (see Fig. 239),
reminding one of tombstones in
a churchyard. But the most ©
remarkable feature about these
mounds was that they had all
the same orientation, viz. with
the long faces of the wedge
; “iat B _— pointing nearly north and south.
Fi, 280. Termitariay of compass or ney Why this is so I am quite at a
face extending south and north ; B, cross- less to imagine, and I much re-
Serres eret that I had no opportunity
of closely examining these most singular structures. A third
kind of mound, usually not exceeding 2 feet in height, was of a
simple, acute, conical figure, and generally of a gray colour some-
what paler than the last, f.
The material used for the construction of the dwellings is
either earth, wood, or the excrement of the Termites. The huge
edifices mentioned by Smeathman are composed of earth cemented

ee a ae ae

= ae

XVI TERMITIDAE 387

together so as to look like stone or brick, and the buildings appear
to be almost as strong as if they were eeey ésnstrneted with
these materials. In many cases
the substance used is comminuted
wood that has passed one or
more times through the alimen-
tary canal of the Insects, and
may therefore be called excrement.
Whether the stone-lke material
is made from earth that has
passed through the alimentary :
canal or from grains gathered Mf a eee of Termitarium of
ermes angustatus, 8. Africa, showing
for the purpose has not been fungus chambers and orifices of com-
well ascertained. In any case = ™™™catiom |
the material is cemented together by means of the secretions of
glands. Dudley and Beaumont have described the process of
construction, in a species observed by them, saying that earth
is brought*and placed in position by the mandibles, and cemented
by liquid from the abdomen! Von Jhering says” that some
species form the exterior walls of their dwellings of stene-like
material, but make use of woody matter for the construction
of the interior. Smeathman has described the nest. of Temes
bellicosus. The whole of the very strong external wall consists
of clay-like material, cemented by the secretions of the Termites
to a very firm consistence. The royal cell is built of the same
material as the framework of the nest; whilst the nurseries
in which the young are chiefly found are built of woody
material, and are always covered with a kind of mould—the
mycelium of a fungus—and plentifully sprinkled with small
white bodies, which, under the microscope, are found to be filled
with a number of oblong, spore-like cells. 3
These nurseries rest on the clay-like framework of the nest,
but are not attached thereto; they in no way support it, or one
another, indeed they have the appearance of being constantly
added to on their upper margins and constantly eaten away on
their under parts. Fig. 240 represents the appearance of the
upper: boundary of a nursery taken from a nest of Zermes angus-
tatus. The small white bodies, mentioned above, have dis-
appeared: the mycelium of the fungus, though not shown in the

1 Trans. N. York Ac. viii. 1889, p. 91. 2 Congr. internat. Zool. ii, 1892, p. 249,

388 NEUROPTERA CHAP. _

figure, is still visible on the specimen from which it was drawn,
and.gives rise to a whitish, glaucous appearance.
In various parts of the world nests formed on trees by Termites
are to be seen; these tree nests are, it would appear, in some cases
only parts of a community, and are connected with the main body —
by galleries. In other cases nests are formed in various positions of ©
advantage; Messrs. Hubbard and Hagen have given us an account *
of some of these—probably the work of Hutermes ripperti—as seen
in Jamaica, They describe the nests as spherical or conical masses,
looking externally as if composed of loamy earth; they are placed
on trees, fences, or walls; they vary in size from that of a man’s
fist to that of a hogshead; they appear to be composed of finely
comminuted. wood fastened together by saliva. .These nests are
formed on the same principle as those of the wasps that make
nests hanging to trees and bushes, as they consist of an external
protecting envelope covering a comb-like mass in the interior.
At the bottom of the nest there is a covered gallery leading to
the earth, where the main nest appears to be situate; galleries
also are constructed so as to lead to the tops of trees and other
places, in such a manner that the Termite can still keep up its
peculiarity of working and travelling in tunnels and yet roam
over a large area; the activity of these Termites continues day
and night. _In each nest there is a queen, who lays eggs that
are removed by the worker Termites to. the bottom of the nest.
The young are fed on a prepared food, consisting apparently of —
comminuted vegetable matter, of which considerable masses are
laid in store. Some of the nests are rich in containing many
pounds’ weight of this material, while others are apparently quite

destitute of it. There is a soldier form and at least two kinds of -

workers. -. Some species of true ant frequently shares the nest of
these white ants, but on what terms the two kinds of Insects lve
together is not stated. |

Termite Ravages.—In countries whose climate is favourable
to their constitutions certain kinds of Termites become of great
importance to our own species. Owing to their taste for woody
matter and to their habit of working in concealment, it 1s no
‘uncommon thing for it to be discovered that Termites have
obtained access to a building and have practically destroyed the
wooden materials used in its construction ;. all the interior of the

- 4+. P, Boston. Soc. xix, 1878, p. 267.;.and xx. 1881, p. 121.

>

XVI TERMITIDAE 389

wood being eaten away and only a thin outer shell left intact.
A Termite, 7. tenuis, was introduced—in what manner is not
certainly known'—to the Island of St. Helena, and committed
such extensive ravages there that Jamestown, the capital, was
practically destroyed and new buildings had to be erected. Other
such cases are on record. Destructive species can sometimes be
destroyed by placing in the nests a portion of arsenicated food.
This is eaten by some individuals, who perish in consequence ;
and their dead bodies being consumed by their comrades, the colony
becomes checked if not exterminated.

The number of described species of Termitidae does not much
exceed 100, but this is certainly only a. small portion of those
existing, the total of which may probably reach 1000 species.

Termitidae are classed by some naturalists with the Orthoptera,
and they have a great deal in common with some of the cursorial
division of that Order, more particularly Forficulidae and Blattidae;
but they differ from Orthoptera in the nature and form of the
wings. They are also classed by some, with a few other forms, as
a separate Order of Pseudo-Neuroptera called Corrodentia, but this
is not a very satisfactory course, as the Termitidae do not agree
closely with the forms associated with them, while the aggregate
so formed is far from being very distinct from other forms of
Neuroptera. On tho whole the best plan appears to be to treat the
Termitidae as forming a distinct family of the Order Neuroptera,
or to make it a distinct Order, as proposed by Grassi. Packard
now associates Termites in an Order with the biting-lice, and
calls it Platyptera.

Fossil Termites.—Termitidae were very abundant in Rasthacry
times, and the genera appear to have been then much the same as
at present. In.Mesozoic strata the remains of true Termitidae
apparently exist in the Lias in Europe, but farther back than
this the family has not been satisfactorily traced. It was formerly
supposed that Termitidae existed in the Carboniferous strata, but
this appears to be very doubtful; and the fossil remains of that
epoch, which were presumed to be those of Termites, are now
referred by Scudder and others to the Neuropteroid division of the
Order Palaeodictyoptera, an Order which is formed entirely of
Palaeozoic fossil remains.

1 According to Melliss, it is thought that the Insect may have been carried to
the island in a captured slave-ship. Melliss, S#. Helena, 1875, p. 171.

CHAPTER XVII

NEUROPTERA CONTINUED—PSOCIDAE (BOOK-LICE AND DEATH-
WATCHES )—THE FIRST FAMILY OF AMPHIBIOUS NEUROPTERA
(PERLIDAE, STONE-FLIES).

Fam. IV. Psocidae—Book-Lice, Death-Watches.

Minute Insects with slender, thread-like, or hair-like antennae ;
four delicate membranous wings, the front pair of which are

the larger; their neuration is not
abundant and is irregular, so that
the cells are also irregularly ar-
ranged ; the transverse nervules are
only one or two in number Pro-
| thorax very small, in the winged
ia) eet tae Veikaiin forms quite concealed between the
England. (After M‘Lachlan.) head and the large mesothorax ; this
latter closely connected with, or fused

with, the metathorax. Species quite wingless, or with wings
unfitted for flight, exist ; in them the prothorax is not so ex-
tremely small, while the mesothoraxz is smaller than in the
winged forms. Tarsi of two or three segments. Metamorphosis
slight, marked chiefly by the development of wings and ocelli.

THE Psocidae are without exception small and soft-bodied Insects,
and are only known to those who are not entomologists by the
wingless forms that run about in uninhabited or quiet apart-
ments, and are called dust-lice or book-lice. They are perhaps
more similar to Termitidae than to any other Insects, but
the two families differ much in the structure of their wings, and
are totally dissimilar in the nature of their lives.

1 In some exotic species there is a dense network on a part of the anterior wing.

CHAP. XVII ° PSOCIDAE . 391

The antennae consist of eleven to twenty-five joints, or even
more, about thirteen being the
usual number; the basal two are
thicker than the others, and are
hy destitute of setae or pubescence
3 such as the others possess. The
-. maxillae and labium are remark-
able. The former possesses a
peculiar hard pick or elongate
rod; this is considered by many
naturalists to be the inner loke, Fic. 242.—Transverse horizontal section
but Burgess thinks it more prob- peteees: Le a ae
ably an independent organ,' as it =P, stipes; m.m, muscles ; m.s, socket

APSE Te ‘ of mandible,
has no articulation of any kind
with the outer lobe. The latter is remarkably thick and fleshy ;

‘ the palpus is 5-jointed. Other
| ~ authorities consider the pick to
be certainly the inner lobe; if’
it be not, the latter is quite
wanting. Hagen agrees with
Burgess in stating that the
pick slides in the outer lobe as
in a sheath, The labium has
a large mentum and a ligula
divided anteriorly into two lobes;
at each outer angle in front
there is a globular projection,
which is doubtless the labial
palpus; reposing on the labium
there is a. large free lingua.
The labrum is large, attached
to a distinct clypeus, behind
Fic. 243.—A, Front of head of Psocushetero- which there is a remarkable

morphus ; cl, post clypeus ; g, epicran- , .

ium: B, transverse horizontal section post-clypeus, which is usually

of post-clypeus of Psocus: cl, post- prominent as if inflated; to its

clypeus ; ¢.m, clypeal muscles; g, epi- ~

cranium ;¢, tendons ;/.m,labial musclein Inner face are attached several

section ; 0e, oesophagus ; 0e.b, oesopha- _

geal bone. (After Burgess and Bertkau. ) muscles which Baro shes te to be
inserted on a plate placed below

the anterior part of the oesophagus, and called by Burgess the
1 P. Boston Soc. xix. 1878, p. 292.

392 NEUROPTERA CHAP,

oesophageal bone; under or within the lingua there is a pair
of lingual glands, Judging from Grosse’s. study of the mouth
of Mallophaga, we may conclude that the oésophageal bone will
prove to be a sclerite of the hypopharynx. , The eyes of the
winged forms are frequently remarkably convex, and there are
also three ocelli, triangularly placed on the vertex. The head
is free and very mobile. The coxae are rather small, exserted,
contiguous; the sterna small. _ The abdomen has usually, ten
segments, though sometimes only nine can be detected. -

The thorax in Psocidae usually: looks as if it consisted of
only two segments. This is due to’ two opposite conditions: (1)
that in the winged forms the prothorax is reduced to a plate
concealed in he. fissure between the head. and the mesothorax
bearing the first pair of wings; (2) that in the wingless forms
(Fig. 24.7 ), though the Srotheite is distinct, the meso- and meta-
thorax are fused into one segment.

The internal anatomy is only very incompletely known.
Nitzsch * has, however, described the alimentary canal and the
reproductive organs of Clothilla pulsatoria. The former is |

Fic. 244.—Reproduc-
tive organs of Clo-
thilla pulsatoria.
A, Male; a, vesi-
culae seminales ; 0,
testes ; ¢, vasa de-
ferentia; d, ejacu-
latory duct. B,
Female ; a, 0, egg-
tubes ; ¢, oviduct ;
d, uterus, contain-
ing egg; @, acces-
sory gland (the en-
veloping sac in sec-
tion) ; f, its duct.
(After Nitzsch.)

remarkably sunple: no proventriculus or crop was found; the
stomach is very elongate, and consists of a sac-like anteriae
portion and an elongate, tubular posterior part. There are four
Malpighian tubes. The posterior part of the canal is remark-
ably short, the small intestine being scarcely as long as the
rectum. The ovaries (Fig. 244, B) consist of five egg-tubes on
each side; connected with the oviduct there is a peculiar acces-
sory gland consisting of a sac containing other small sacs each

? Germar, Mag. Entomol. iv. 1821, p. 276, pl. ii.

XVII | -PSOCIDAE 393

with an elongate efferent duct; the number of the secondary
sacs varies from one to four according to the individual. The
testis (Fig. 244, A, b) is a simple capsule; connected with the
base of the ejaculatory duct there is a pair of elongate accessory
glands or vesiculae seminales,

The life-history has never been satisfactorily sketched. The
young greatly resemble the old, but have no ocelli or wings, and
sometimes the tarsi are of two joints, while in the adult they
have three. The antennae have also in these cases a less number
of joints in the young stage. The food is animal or vegetable
refuse substances; many live on fungoid matter of various kinds,
mouldy chaff being, it is said, a favourite pabulum; the mould
on palings is a source of food to many; others live on the -rust-
fungi of leaves, and many frequent the bark of trees. They are
able to spin webs, probably by the aid of the lingual glands;
the eggs are deposited, in some cases, on leaves and covered. with
a web. Hagen says that a peculiar organ, possibly a gland—he
ealls it a Sead? —exists at the base of the tarsal claws. In’ our
climate most. of the species pass the winter in the egg-state.
There may be two generations in a year, perhaps more.

The nomenclature of the wing-veins of Psocidae has given
rise to much discussion.” The
system shown in the accom-
panying figure is probably the
most convenient ; the subcos-
tal vein (2) is always obscure,
and sometimes can only be
detected by very minute @X- Fic. 245.—Anterior wing of Elipsocus brevi-
amination. Some interesting vu (Afte: Reuter) 1, Costa vein
information as to the minute branches of cubitus; 5, sector of the radius ;
structure and mode of forma- — °™ 10*S thereof.
tion of the wings and their nervures has been given by Hagen.°

In the young the wings first appear as buds, or outgrowths
of the sides of the meso- and meta-thorax ; afterwards eek pro-
thorax decreases, while the other two thoracic segments and
the wing-rudiments attached to them increase. The wings
from their very origin appear to be different from. those of the
Orthoptera, and the changes that take place in the thoracic

_ Psyche, iii. 1881, p..196. 2 Kolbe, Stettin. ent. Zeit. xli. 1880, p. 179.
3 Op. cit. p. 209, ete.

394 : NEUROPTERA CHAP.

segments in the course of the development, differ from those
that occur in Orthopiera. |

There are several peculiarities connected with the wings.
Frequently they exist,
though of no-~ use for
flight ; some Psocidae that
have __ perfectly - forme
wings are so reluctant to

dP. ty use them that, M‘Lachlan
ill “= says, they will allow them-
Fie. 246.—Micropterous form of Mesopsocus unt- selves to be crushed with-
punctatus. a, a, Wings. (After Bertkau.)
out seeking to escape by
flight. At certain periods, however, some Peocidae float. on
the wing in considerable numbers, especially in a moist still
atmosphere, and then drift about like the winged Aphididae,
which are frequently found with them. There is evidence
that individuals,’or generations, of some of the winged species
occur with only rudimentary wings; although this has been
denied by Kolbe, there can be no doubt about it. The form
figured above (Fig. 246) was described by Bertkau’ as a dis-
tinct genus, but was afterwards recognised by him? to be a
short-winged form of Mesopsocus unipunctatus. It is probable
that the adult female of this species has the wings always
micropterous, while the male has these organs of the full size.
In other species the condition of the rudimentary wings seems to
be quite constant. The facts concerning the wings of Psocidae
are so peculiar that Kolbe came to the conclusion that the
organs exist not because they are of use for flight, so much as
because it is the nature of an Insect to develop wings.”

Some of the species of Psocidae have never any trace of wings.
These apterous forms are mostly included in the division
Atropinae, and are usually very minute; it has been again and
again erroneously stated that they are the young state of winged
forms. Hagen kept a large colony of Atropos divinatoria for
some years in confinement, so that he saw numerous generations
as well as many specimens. He found the apterous condition
quite constant. |

1 Arch. f. Naturg. xlix. i. 1883, p. 99.
2 Verh. Ver. Rheinland, xxxix. 1882, Corr. -bl. p. 128.
3 Berlin ent. Zeit. xxviii. 1884, p. 36.

XVII , PSOCIDAE 395

The association of ocelli with wings is nearly constant in
Psocidae. The genus Clothilla—allied to -Atropos—possesses
very rudimentary wings but no ocelli. Hagen, however, found *
that in a certain locality no less than 12 per cent of the indi-
viduals of this species were provided with ocelliima most extra-
ordinary variation.

In some of these apterous forms there is found on each side
of the prothorax a tubercular prominence which, according to
Hagen, can be considered only as the rudiment of a wing that
never develops. Though no existing Insect is known to possess
rudimentary wings on the prothorax, we have previously men-
tioned (p. 344) that in the Carboniferous epoch appendages of
the nature alluded to were not very rare.

A genus of living forms—AHyperetes—in which the three
thoracic segments are well developed, but in which there are no
alar appendages or rudiments, is considered by Hagen to be more
primitive than the Psocidae found in amber to which we shall
subsequently allude.

The number of described species of Psocidae does not reach
two hundred; we have, however, thirty species or more in
Britain.” Nietner observed about the same number in the
immediate vicinity of his house in Ceylon. The isolated and
remote Hawaiian group of islands is remarkably rich in Psocidae.
Two thousand is a moderate estimate of the number of existing
species. The largest forms yet discovered belong to the Brazilian
genus Thyrsophorus; they attain, however, a breadth of only
about one inch with the wings fully expanded. The Cuban
genus Hmbidopsocus is said to be of great interest from its
approximation to Embidae. It is at present very inadequately
known. .

One (or more) very minute Insects of this family—Clothilla
pulsatoria according to Hagen, Atropos*® divinatoria according to
some other authors—is widely known under the name of the
death-watch, owing to its being believed to make a peculiar

1 Stettin. ent. Zeit. xliv. 1883, pp. 299, 305.

2 For the British species, see M‘Lachlan, Ent. Month. Mag. iii. 1867, p. 177.

3 The genera Atropos and Clothilla were named after the two fates Atropos and
Clotho. Westwood attempted some years ago to complete the trio by establishing a
genus Lachesilla. This proved a failure, the genus being a misconception. As the
name Lachesis is in use in various branches of zoology, the desired circle of Psocid
fates is likely to remain always incomplete.

396 NEUROPTERA | CHAP,

ticking noise, supposed to be prophetic of the decease of some
individual—a human being we fancy,
not a death-watch. It is difficult
to believe that so minute and soft an
Insect can produce a sound audible to
human ears, and many entomologists are
of opinion that the sound in question
is really produced by a beetle—of the
genus Anobiwum—which lives in wood,
and that as the beetle may be concealed
in a hole, while the Clothilla is seen
running about, the sound is naturally,
: though erroneously, attributed to the
Fic. 247.—A, Atropos divina- latter. But the rapping of the Ano-
ate f Mee biwm is well known, is produced while
the Insect is at large, and is said to be
a different noise from that of the Psocid; evidence too has been
given as to the production of the sound in a .workbox when the
Psocid was certainly present, and the most careful search failed
to reveal any beetle.

The Rev. W. Derham, who two hundred years ago was Rector
of Upminster, in Essex, and was well known as a distinguished
writer and philosopher, gave an account of the ticking of death-
watches to the Royal Society.’ This gentleman was a most
accurate and minute observer; he was well acquainted’ with the
ticking of the greater death-watch — Anobiwm — which he
describes very accurately, as well as the acts accompanying it,
the details he mentions being exactly such as occur at the present
time. He not only heard the ticking of the Psocid or lesser
death-watch, but repeatedly witnessed it. He says: “I am now
so used to, and skilful in the matter as to be able to see, and
show them, beating almost when I please, by having a paper
with some of them in it conveniently placed and imitating their
pulsation, which they will readily answer.” He also states that
he could only hear them beating when it was done on paper, and
that this death-watch will tick for some hours together without
intermission, with intervals between the beats, so that it much
resembles the ticking of a watch. The act of ticking was accom-

1 Phil. Trans. xxii. 1701, pp. 832-834 ; and xxiv. 1704, pp. 1586-1594, Plate 291,
Figs. 4, 5 (pp. 1565 to 1604 occur twice in this sacs

I i el

Lill
i

XVII PSOCIDAE 397

panied by rapping the front of the head on the paper, but Mr.

Derham could not be sure that the sound
was produced in that manner, because each
stroke was also accompanied by a peculiar
shudder, or recoil. After a prolonged tick-
ing he observed that another individual of
the other sex made its appearance. The
species figured by Mr. Derham more.
resembles a Hyperetes than it does either
of our two known book-lice, Atropos and yg. 948 The lesser death-

Clothilla. watch of Upminster.
: ‘ After Derham. mag-
Numerous species of Psocidae are pre- pee B, sea eh :

served in amber; Hagen’ has made a )

careful study, based on a considerable number of specimens,
of about thirteen such species. They belong to no less than
nine genera and five sub-families. Sphaeropsocus is the most
remarkable; this Insect. has a well-developed prothorax, as
is the case in the wingless
Psocids, and a pair of large
Wings or tegmitia meeting
by a straight suture along
+ the back, as is usual in
~"\ beetles, though quite un-
3 known in existing Psocidae.
Another species, Amphiento-
mum paradoxum, has the
body and appendages covered
with scales like a butterfly
or moth; other species, found

Fic. 249.—Sphaeropsocus kunowii. From jy oyum-copal or still liv-
amber. x30. (After Hagen.) 8 P

ing, have scales on various
parts of the body, but not to so great an extent as this amber
species. The genus Amphientomum is still represented in Ceylon

and elsewhere by living forms; Packard has figured some of the
‘scales ;? they appear to be extremely similar to those of Lepi-
‘doptera or Thysanura. The facts connected with this fauna of
‘amber Psocidae would seem to show that the family was formerly
more extensive and important than it is at present; we should
therefore expect to find numerous fossil forms in strata of date

1 Stettin. ent. Zeit.-xliii. 1882, p. 265: - ? P. Boston Soc. xiii. 1871, p. 407.

398 NEUROPTERA CHAP.

anterior to that of the amber; but this is not the case, all that:
is known as to fossil Psocidae being that Scudder has recently
ascribed traces of an Insect found in the Tertiary rocks of Utah
to this family as a distinct genus. ©

Fam. V. Perlidae.

Insects of moderate or large size, furnished with four membranous
wings ; these are usually complealy reticulate ; the hind pair
are much the larger, and have a large anal area of more
simple venation, which becomes plicate when folded. The
coxae are small, the legs widely separated. The larvae are
aquatic in habits ; the metamorphosis is slight.

SS SS
Ro So

SA

Fig. 250.—Pteronarcys frigida, mele. (After Gerstaecker.)

The Perlidae form a small family of Insects unattractive in their
general appearance. The life-history of each individual consists
of two abruptly contrasted portions; the earlier stage being
entirely aquatic, the later aerial. Hence the Perlidae come into
the amphibious division of Neuroptera. The definition we have
given above would, except as regards the texture of the front
wings and the aquatic habits of the larvae, apply to many
Insects of the Order Orthoptera. The Phryganeidae, another

XVII PERLIDAE 399

family of Neuroptera, have aquatic larvae and wings somewhat
similar in form to those of the Perlidae, but the members of the two
families cannot be confounded, as the Phryganeidae have hairy
front wings and large and contiguous coxae.

The antennae of the Perlidae are long, very flexible, and com-
‘posed of a very large number of joints. The parts of the mouth
vary a good deal. The mandibles and maxillae are usually rather
small, and all the parts of the mouth are of feeble consistence or
even membranous; the maxillary palpi are, however, well developed
and exserted from the mouth, five-jointed. The labium is short
and but little conspicuous. The mandibles in some forms are
almost membranous, but in other genera they are firmer and are
toothed. The labium is composed of a very large mentum, beyond
which is a large piece, usually undivided, bearing the four terminal
lobes; the three-jointed palpus ‘is seated on the side of the large
middle sclerite, which is no doubt of composite nature. Con-
siderable variety as to the lower lip prevails. The head is broad
and flat; there is an indistinctly-indicated clypeus, three—
more rarely two—ocelli, and on each side an eye neither very
large nor perfect. The prothorax is free, and has a flat,
margined notum. The meso- and the meta-thorax are large,
equal segments. The pro-, meso-, and meta-sternum are large
pieces; between the first and second, and between the second
and third there is an intervening membrane. The metasternum
is much prolonged backwards, and has on each side a_ peculiar
slit; similar orifices exist on the other sterna (Fig. 254, 0).
Newport, who has examined them in Pteronarcys, says that they
are blind invaginations of the integument; he calls them the
sternal or furcal orifices." According to this naturalist these very
_ peculiar openings pass into the body “as strong bone-like tubes,
diverging from the axis to the periphery of the body in the
immediate vicinity of some of the principal tracheae, but that
they do not in any way communicate with them, as they terminate _
abruptly as caecal structures.’ He thinks them analogous with
the endo-skeleton of other Insects; a view which cannot be con-
sidered sufficiently established. Laboulbéne states? that when
Perla parisina is seized and placed on its back, it does not move,
but emits a liquid at the base of the articulation of the legs.

WTr, Linn. Soc. xx. 1851, p. 433.
2 Bull, Soc. ent. France (4), viii. 1868, p. xxxvii.

400 |

NEUROPTERA CHAP.

This suggests that it may come from these sternal orifices. The

abdomen consists of ten dorsal plates, the
first being short, and of nine ventral;
the dorsal plates are much more ample
transversely than the ventral. Frequently
the hind body is terminated by two long;
many-jointed cerci, looking like antennae.
The coxae are small, not prominent, and
are directed outwards. The legs are

Slender, the tibiae often grooved. The

tarsi are three-joiited, terminating in two
claws and a more or less distinct pad.
In the genus Jsopteryx an auditory organ
has been described as existing in the legs,
in a position similar to that of the analo-

gous structures
Fig. 251.—Perla maxima. in ‘Termitidae
ha Say and Blattidae.

The.wings when closed repose flat on the:

back, and fold and overlap so that only
one is seen (Fig. 251); in this state

the costal portion of each front wing is ~

turned downwards, so as. to protect to
some extent, the sides. of the body.

The early stages are known, but have
not been described minutely, and there
appears to be very little information as
to the youngest life. All the species
are, when immature, aquatic in their
habits; the larvae greatly resemble the
perfect: Insects in form, though differing
in not possessing wings and in the
ocelli being merely opaque spaces.
They have rather large compound eyes ;

the future wings are represented by

lobe - like prolongations — varying in
length according to age—of the meso-
and-meta-notum., .In the Nemourae the
cerci are absent in the imago though

é
Zz
_ 4, .
j
Z Fe!
A:
0
*
f R
Vs, *
# \\
fy
nd »

Fig. 252. — Perla SP. nymph,
showing tracheal gills, Py: ré-
nées orientales. -

present in the young. The larvae of Perlidae are carnivorous

XVII PERLIDAE 401

and are able to swim well, the legs being provided with abundant
swimming hairs; they, however, as a rule, prefer to walk at the
bottom of the pool. or on rocks or boulders in the water they
live in. |

One of the most peculiar features of the Perlidae is their
respiratory system. Unfortunately the greatest differences of
opinion have prevailed on various matters in connexion with this
subject, and there are several points about which it is not possible
at present to express a decided opinion.

The larvae have no stigmata; it appears to be generally
agreed that there is ii them no means
of admitting air to the tracheal system
by means of orifices. Some breathe
entirely through the integument, the pro-
cess being aided by the accumulation of
tracheae at the spots where the breath-
ing orifices should be, and where the
integument is more delicate. Others,
however, possess gills in the form of pro-
truded bunches of filaments, connected
with tracheae in the manner shown in
Fig. 253. These filamentous branchiae 5,, 953 mvacheal gill and
occur in numerous species of the family, portion of a trachea of Ptero-
and are situate on various parts of the — ™7¥% (After Newport.)
body, but many species are destitute of them in genera, other mem-
bers of which possess the filaments. In some Nemourae instead
of bunches of filaments there are tubular projections on the pro-
thoracic segment; and in Dictyopteryx signata similar structures
oceur even in the cephalic region, Hagen stating * that there exists
a pair on the submentum and another on the membrane between
the head and the thorax. In the imago state, stigmata are present
in the normal fashion, there being two thoracic and six abdominal
pairs. In several species the filaments persist in the imago, so that
in these cases we meet with the curious condition of the coexistence
of branchiae with a well-developed and functionally active system
of spiracles ; this is the more curious because the creatures usually
have then nothing to do with the water, it having been ascer-

tained that in these cases the species live out of the water as other

terrestrial and aerial Insects do. These instances of persistence

; a 1 Zool. Anz. iii. 1880, p. 304.
VOL. V 2D

402 . NEUROPTERA CHAP,

of branchiae during the aerial life have been the source of some
perplexity ; the condition was shown to exist
in Pteronarcys by Newport, and has since
been demonstrated in various other forms.
Newport believed that the imago of Ptero-
narcys breathes by means of the gills,
although it lives out of the water and
possesses spiracles; and he informs us that
Mr. Barnston observed the Insect when on
the wing “constantly dipping on the surface
of the water.” Hence Newport concluded
that Pteronarcys in the winged state is “an
amphibious animal.” That a winged Insect
should live in the air and yet breathe by
means of gills would be truly extraordinary,
and there can be little doubt that Newport’s
CWI idea was erroneous. Hagen’ was able to

Fie, 54D ide of examine living imagos of the species in ques-
regalis,imago. (After tion. He found that they avoided the

Newport) ot water, and though he placed some indi-

gills; 0, sternal : :

orifices. viduals therein, yet they did not use the

gills. He also informs us that the branchiae
have, during life, a shrivelled appearance, indicating that they
are not functionally active, but are merely useless organs carried
over to the imago from the previous instar, in which they were
truly the means of obtaining air. Hagen also ascertained that
the spiracles of the imago are in a normal state, being adapted
for breathing, even as far back as the seventh abdominal
segment.

Great difference of opinion has prevailed as to the relations
of the branchiae to the stigmata, it having been contended that
the falling off of some of the branchiae left the stigmatic orifices.
The facts appear to be only consistent with the conclusion that
the two are totally independent organs. This subject has been
investigated by Palmén,’ who finds that in Perlidae—contrary
to what occurs in may-flies—the species are either entirely
destitute of gills, or these organs are persistent throughout
life. It is not to be inferred from this that the gills in. the

1 Stettin. ent. Zeit. xxxviii. 1877, p. 487.
2 Morphologie des Tracheensystems, Helsingfors, 1877, p. 21.

/

i hicsintnd
_—

XVII PERLIDAE

403

the exceptional Pteronarcys :
moult the gills usually become very
much contracted and concealed by the
new integument; in some cases they
merely appear as slight prominences
in the neighbourhood of the stigmata.
Pictet, Dufour, Newport, and Imhof?
have studied the internal anatomy. The
alimentary canal is remarkable for the
enormous oesophagus; there is no dis-
tinction between this and the crop. A
proventriculus is quite absent, and there
are no chitinous folds in the position it
usually occupies. The true stomach is
small, and only commences in the fourth
abdominal segment. It has a prolonged
lobe on each side in front, and in
addition to this eight sacs; thus there
are formed ten diverticula, fastened to
the posterior part of the oesophagus by
ligaments. The terminal portion of the
stomach is small, and apparently only
distinguished from the short intestine
by the point of insertion of the Mal-
pighian tubes; these vary in number
from about twenty to sixty. There are
two pairs of large salivary glands. In
Pteronarcys the caecal diverticula of the
stomach are wanting. In some Perlidae

the terminal parts of the gut are more

New-

complex than in Perla maxima ;

‘port figures both an ilium and colon
very strongly differentiated, and states
that these parts differ much in Perla and Pteronarcys.

perennibranchiate Perlidae are as conspicuous as they ave in
for it appears that at the final

fae ii
i)
(WD)

Fig. 255.—Alimentary canal and

“outline of body of Perla
maxima. (After Imhof.) 7,
Upper lip ; mh, buccal cavity ;
ap, common termination of
salivary ducts ; 0, oeso-
phagus ; s, salivary glands ;
ag, duct of salivary gland ;
6, anterior diverticula of
stomach ; dg, their ligaments
of attachment ; mp, Malpi-
ghian tubes; 7, rectum; af,
anal orifice.

Accord-

ing to him the stomach is embraced by a network of tracheae,
and Imhof tells us that he found the stomach to contain only air.

The brain is small, but, according to Imhof, consists of four .
amalgamated divisions; the infra-oesophageal ganglion is small,

1 Beitr. Anat. Perla maxima.

— Inaug.-Diss. Aarau, 1881.

404 NEUROPTERA CHAP. .

and placed very near the brain. There are three thoracic and
six abdominal ganglia on the
ventral chain. The nerves
to the wings are connected
with the longitudinal com-
missures of the ventral: chain
by peculiar, obliquely-placed,
short commissures. The repro-
ductive glands are peculiar,
inasmuch as in each sex
the pair of principal glands
is connected together in the
middle. The testes thus form
an arch consisting of a large
number of sub-spherical or
pear-shaped follicles; the
vasa deferentia are short in
Perla maxima, and there are
Fie, 250,—ahe yar of nite ovaries of Perl no vesiculae seminales; the
ceptaculum seminis concealing the orifice of ejaculatory duct is divided
the duct and an accessory gland. irita thee parts by coratrie
tions. In Pteronarcys and in Perla bicaudata, according to
Newport and. Dufour, the vasa deferentia are very long and
tortuous, and thers are elongate vesiculae
seminales. The arrangement of the ex-
tremely numerous egg-tubes is analogous to
that of the follicles of the testes, so that, as
Dufour says, there is but a single ovary ;
connected with the short, unpaired portion of
the oviduct, there is a large receptaculum
seminis, and near the terminal orifice of
the duct there is in P. maxima an eight- |
lobed accessory gland. Fic. 257.—Ege of Perla
The eggs are produced by Perlidae in ‘™awima. (After Imhof.)
c, chorion; d, oolemn ;
enormous numbers: they are rather small, gs, glass-like covering of .
but peculiar in form, and possess at one pag Feige 2
extremity a micropyle apparatus, covered canals penetrating
by a glassy substance through which Imhof = “°™"
could find no orifice. On the other hand, the chorion on another
part of the egg is perforated by several canals.

PEL
WIG I 47

BAK OMY |
Mid Vi i
4 Wy Y
3 wie ge
w yy y ‘wy
NAL BV fA
Y IU ee J

“xv PERLIDAE AOS

The Perlidae being of aquatic habits in their early stages,
and, notwithstanding their ample wings, very poor adepts in the
art of flying, are rarely found at any considerable distance from
their native element. They are specially fond of running water,
and delight in the neighbourhood of waterfalls, or other spots
where the current is broken by obstacles so that a foaming water
results. It is probable that the larvae which breathe by means
of gills find an advantage in living in strongly-aerated water.
Mountain streams and torrents are therefore specially affected by
them; but Pictet informs us that they do not like the waters
descending from glaciers. The food of the larvae is believed to
be chiefly young may-flies, or other small, soft creatures, and it
may possibly be owing to the absence of these that the Perlidae
do not affect the glacier streams. Although Perlidae are remark-
able for their capacity for enduring cold, it is possible that they
may require warmth of the water at some period of their
development, and this the glacier-streams cannot offer to them.
They are among the earliest Insects to appear in the spring in
Europe. Mr. Barnston says that on the Albany river in Canada
the nymph of Capnia vernalis comes up frequently in the cracks
of the ice and casts its skin there; “it frequently comes up
when the thermometer stands at freezing.” Of Nemoura glacialis,
which inhabits similar localities, he says that “it appears in the
spring (end of March or beginning of April) when the ice
becomes honeycombed, and even before then, at the same time
as Capnia vernalis. It pairs in the crevices of decaying ice.
The male has long antennae, and his wings are generally rumpled
as if glued together.” Newport entertained the idea that those
Perlidae that live at low temperatures are of lower organisation
than the other forms of the family.

It is a remarkable fact that several Perlidae frequently
have—like Nemoura glacialis—the wings of the male much
reduced in size; this being the contrary of the rule that
usually prevails among Insects to the effect that, when there is a
difference in the powers of flight, or even in the size of the wings,
it is the male that is superior. Mr. J. J. Lister met with a very
interesting Perlid at Loch Tanna in Arran at the beginning of
April 1892. In this Insect, which is, according to Mr.
M‘Lachlan, a form of Jsogenus nubecula, the wings of the female
(Fig. 258, B) are reduced to a size much less than those of ordinary

406 NEUROPTERA CHAP.

Perlidae, while those of the male (Fig. 258, A) are mere useless
rudiments, Morton has pointed out that in Scotland more
than one species of Zaeniopteryx occasionally produces. micro- _
pterous males, and he associates this phenomenon with the early
time of their appearance
“almost in winter.” In
Nemoura trifasciata this
reduction of the wings
takes another but equally
curious form; the hind
wings of the male being
long enough to cover the
body, while the anterior
pair are reduced to mere
rudiments.

The phenomena of mi-
Fic. 258.—Tsogenus nubecula, Loch Tanna. A, cropterism in Perlidae are

Male ; A’, wings of male more magnified; B, well worthy of more de-

wings of female. , : : .

tailed investigation. Mr.
Morton informs the writer that the male of Perla maxima (Fig.
251) in North Britain has the wings so short that they cannot
be of any use as organs of flight. In Central Europe the wings are
ample, as shown in our figure. In Perla cephalotes the male is
short-winged in both Britain and Central Europe; of the male of |
Dictyopteryx microcephala only the micropterous form is known to —
exist. In Jsogenus nubecula (Fig. 258) it appears that the
wings of the female are always more ample than those of the
male of the same locality, and that local micropterism affects
the. two sexes unequally. Within the Arctic circle this Insect
is usually of the Scotch form, though the male there occasionally
has more ample wings.

It has been observed that in some Perlidae the eggs, after
they have been extruded, are carried about by the female; for
what reason is not at all known. They are said to be enclosed
in a membranous capsule at the apex of the abdomen. The
number of eggs deposited is sometimes very large, amounting to
five or six thousand, and they are often of very minute size.

About twenty-four species of Perlidae occur in Britain.” The

1 Entom. Month. Mag. xxix. 1893, p. 249.
*No satisfactory systematic work of a general character on British Perlidae

XVII | PERLIDAE ' 407

species from all parts of the world existing in collections probably
scarcely exceed two hundred. The insignificance of this number
is no doubt chiefly due to the fact that these unattractive Insects
are rarely captured by collectors, and are so fragile that unless
good care is taken of them, specimens soon go to destruction
after being dried. Perlidae are known to occur in most parts
of the world, so that the number of species really existing may
reach two or three thousand. They are known to anglers as
stone-flies and creepers and are a favourite bait for trout.

The family in its character comes near to the Orthoptera,
especially to the more simple forms of Phasmidae, but the two
groups differ in the texture of the
front wings and in the structure
of the mouth-parts, as well as in
the different proportions of the
mesothorax and metathorax. Ac-
cording to Pictet,in the Australian
genus Lusthenia the trophi (Fig.
259) approach nearer to those of
the Orthoptera, so that it appears
possible that a more intimate con-
nexion will be found to exist as more Fic. 259.—A, Maxilla, B, labium
forms are discovered. Of the groups of usthenia spectabilis. (After
we include in Neuroptera, Perlidae Pte)
are in structure most allied to Sialidae, but the development in
the two groups exhibits very important distinctions. Brauer
treats the Perlidae as forming a distinct Order called Plecop-
tera, a name applied to the family by Burmeister many years
ago. |

Several species of Perlidae, considered to belong to existing
genera, have been found in amber. A _ fossil from the Eocene
deposits in the Isle of Wight and another from the Miocene of
Continental Europe are referred to the family. Brauer has
recently described’ some fossils from the Jurassic formation in
East Siberia as forming three genera, now extinct, of Perlidae.

Brongniart informs us” that several fossils have been found

exists. References to the scattered descriptions and notes will be found in the
Catalogue of British Neuroptera published by Entom. Soc. London, 1870.

1 Mem. Ac. Pétersb. (7) xxxvi. No. 15, 1889.

2 Insectes fossiles, etc., p. 407, 1893.

ee ST a nee > res a ee 1

408). Whit, NEUROPTERA ssid gs he

in the Carboniferous strata of Commentry that intr us
asserting that allies of Perlidae then existed. He considers: i
Carboniferous Insects to have belonged to a separate famil
Protoperlides. The fragments are, however, so small the
must await further information before forming a definite opini
as to these Protoperlides. < 3 eae a

CHAPTER XVIII

AMPHIBIOUS NEUROPTERA CONTINUED—ODONATA, DRAGON-FLIES

Fam. VI. Odonata—Dragon-flies.
(LIBELLULIDAE OF SOME AUTHORS) )

Elongate Insects with very mobile head and large eyes, with small
and inconspicuous antennae ending in a bristle; with four
elongate wings sub-equal in size and similar in texture, of
papyraceous consistency and having many veinlets, so that
there exists a large number of small cells. All the legs placed
more anteriorly than the wings. The earlier- stages of the
life are aquatic ; there is great change in the appearance of
the individual at the final ecdysis, but there is no pupal
enstar.

THE dragon-flies form a very natural and distinct group of
Insects. All the species are recognised with ease as belonging
to the family. They are invariably provided with wings in the
perfect state, and many of them are amongst the most active of
Insects. Their anatomy is, in several respects, very remarkable.

The head is large and is concave behind; it is attached to
the thorax in such a way that it rotates on two cervical sclerites
that project forwards, and in some cases almost meet in a point
in front; hence it possesses extreme mobility, the power of
rotation being very great.

The eyes are always large; in some cases they are even enor-
mous, and occupy the larger part of the area of the head: the
upper facets of the eye are in many cases larger than the
lower, and in a few forms the line of division is sharply marked
transversely. There are three ocelli, which, when the size of
the compound eyes is not too great, are placed in the usual

410 ; NEUROPTERA CHAP.

manner as a triangle on the vertex; but in the forms where
the compound eyes are very large the portion of the head
between is, as it were, puffed out so as to form a projection just
in front of where the eyes meet, and one ocellus is then placed
on each side of this projection, an antenna being inserted quite
close to it; the third ocellus is placed in front of the projection

Kae 7
0 Os SND fe oY
ap

a vl
a =
a)

Soy est Oke on,
SBE

=4|\— ase - —S

}
|
al : =

ad |

—_—
—— =

taal \ cael

Fic. 260.—Anaz formosus, Britain. (After Migneaux.) (The legs are not in a
natural position. )

we have mentioned, by which it is often much concealed; this
anterior ocellus is in some cases of unusually large size, and oval
or transverse in form.

The parts of the mouth are very peculiar, especially the
lower lip: we will briefly allude to its characters in the highly
modified forms, premising that in the smaller and less active
species it is less remarkable. The Libellulidae are carnivorous,
their prey being living Insects which are captured by the dragon-
fly on the wing; it is believed that the mouth is largely instru-
mental in the capture, though the flight of these Insects is so
excessively rapid that it is difficult, if not impossible, to verify

XVIII DRAGON-FLIES 411

the action of the mouthpieces by actual observation. For the
purpose of securing the prey a mouth that can change its
capacity to a considerable extent and with rapidity is a desider-
atum, and these qualities are present in thee mouths of those
Libellulidae that capture their prey while hawking. The upper lip
is very mobile, is pendent, and closes the mouth above, while the
lower lip entirely closes the under part by means of two mobile
plates; these in some forms (Libellula) meet together in the
mesial line, while in others a third plate separates them in the
middle (Fig. 261, B,/). These plates are, according to Gerstaecker’s
view, portions of the much changed labial palpi, the part that
separates them in Aeschna being the inner lobes of the labial max-
illae; in Libellula, where the dilated and valve-like joints of the

Fic. 261.—A, Maxilla
of Libellula quad-
rvimaculata ; B, la-
bium of Aeschna
grandis. Dp, Pp’,
Palpus; a, ter-
minal spine of
palpus ; ¢, cardo ;
t,stipes ; s,squama ;
le, outer lobe of
maxilla, partly
covered by, Ji,
inner lobe; 1m,
mentum ; 7, inter-
vening lobe. (After
Gerstaecker. )

palpi meet in the middle line, the labial lobes remain small and are —
overlapped by the dilated portions of the palpi. The maxillae
proper (Fig. 261, A) are less peculiar, their chief character being
that the inner and outer lobes are not separated, and that the palpus
is of only one joint. Some entomologists take, however, another
view of this structure, looking on the palp-like outer part (p of
our figure) as the true outer lobe of the maxillae, the palpus
proper being in that case considered to be entirely absent. The
mandibles are very powerful, and armed with largely developed
teeth. In the interior of the mouth there is a large, free, semi-
membranous lingua, the posterior part of its delicate inferior
lamina being connected with the mentum; the upper lamina of
the lingua is stronger and is pilose. The antennae of the dragon-
flies are always small, and consist of two stouter joints at the

1 Festschrift Ges. naturf. Freunde Berlin, 1873.

412 . NEUROPTERA CHAP.

base, and a terminal part which is very slender and pointed, and
formed of four or five joints.

The prothorax is always small; the pronotum is distinct,
though in some forms it is quite concealed in the concavity of
the back of the head; the sternum is small; the anatomy of the
pleura and basal pieces of the legs is obscure.

The meso- and meta-thorax are very intimately combined, —
and their relations are such that the former is placed much
above the latter. This.
peculiarity is carried to its
greatest extent in some of
the Agrioninae (Fig. 262,
A), where not only are
the wings placed at a
considerable distance be-
hind the three pairs of ©
legs, but also the front
pair of wings is’ placed
almost directly above the
hind pair. In the Anisop-
terides these peculiarities
are much less marked
(Fig. 262, B), nevertheless
even in them the three
pairs of legs are placed
quite in front of the wings.
This peculiar structure of
the wing-bearing segments

Fic. 262.—A, Agrion pulchellum, natural size ; B, 1s accompanied by an
Aeschna cyanea, profile ; C, same from front to unusual development of |

show position of legs. 4 natural size.

the pleura, which, indeed,
actually form the larger part, if not nearly the whole, of the
front region of the dorsal aspect of these two segments. We
shall not enter into more minute particulars as to the struc-
ture of the thorax, for difference of opimion prevails as to the
interpretation of the parts.’ The abdomen is remarkable for
its elongation ; it is never broad, and in some genera—AMecisto-
gaster, e.g.—it attains a length and slenderness which are not

1 Reference may be made to Calvert’s recent paper introductory to the study of
Odonata, in Jr. Amer. ent. Soc. xx. 1893, pp. 159-161.

XVIII DRAGON-FLIES 413

reached by any other Insects. It consists of ten segments and
a pair of terminal calliper-like or flap-like processes of very
various sizes and forms. |

The wings of the dragon-flies are usually transparent and
provided with a multitude of small meshes. The hind wings
are about as large as the front pair, or even a little larger; the
main nervures have a sub-parallel course, and are placed in
greater part on the anterior region of each wing. The relations

of the more constant nervures and the cells of which they are

parts form a complex subject, and are amongst the most im-
portant of the characters used in classifying these Insects. The
wings are always elongate in comparison to their’ breadth and
have no folds; they are held partially extended, or are placed

so as to project backwards, or backwards and outwards. They

exhibit another peculiarity, inasmuch as the front or costal
margin is slightly uneven before or near the middle, giving
rise to an appearance such as might result from the breaking
and subsequent mending of the marginal rib at the spot in
question, which is called the nodus. In some forms a peculiar
character exists in the shape of a small opaque space called the
membranule, lying close to the body of the Insect in the anal
area of the wing, as shown in Fig. 260.

The legs are slender and are chiefly remarkable for the
beautiful series of hair-like spines with which they are armed,
and which in some forms (eg. Platyenemis, Fig. 264) are of
considerable length. We believe that the legs are of great
importance in capturing the prey, they being held somewhat
in the position shown in Fig. 262, C. The tarsi are three-
jointed. In the male of Libellago caligata the legs exhibit a
remarkable condition, the tibiae being dilated, and on the upper
side of a vivid red colour, while below they are white. This
coloration and form are each unusual in the family. The male
of Platycnemis pennipes, a British species (Fig. 264), shows a
similar dilatation of the tibiae, but to a less extent and without
any great difference in the colour of the two faces of the dilata-—
tion. This dilatation reaches its maximum in Psiloenemis
dilatipes M‘Lach. ‘The position of the legs in relation to
the other parts of the body is peculiar to the dragon-flies; the
legs seem to be unfit for walking, the Insects never using them
for that purpose.

A414 NEUROPTERA CHAP,

Several peculiarities in the internal anatomy deserve notice.
The alimentary canal in Libellula is about as long as the body,
the oesophagus and chylific stomach being elongate, while the
intestine is short and divided into only two parts; there is no
definite proventriculus. The Malpighian tubules are shorter
than usual; they are about forty in number. The male has no

vesiculae seminales; the vasa deferentia are elongate, and the ©

ejaculatory duct is very short, being in fact merely a common
sinus formed by the terminations of the vasa deferentia. The
opening of this duct is situated on the penultimate ventral plate ;
the organs of intromission are, however, placed much anterior
to this, on the under side of the second segment. The mode in
which the fertilising fluid is transferred from the ninth to the

second segment is not well understood, but it is known that’

the abdomen is flexed by the Insect so as to bring the ninth

ventral plate into contact with the second. The three thoracic —

ganglia of the nervous chain are all contiguons, though not
completely amalgamated; the abdominal ganglia are seven in
number, and are all separated, the terminal one being larger than

the others. Dufour, after repeated dissections, was unable to find —

any salivary glands, but Olga Poletajewa' states that they exist.

The Odonata must. be ranked among the most highly-
organised Insects so far as external structure and powers of
locomotion are concerned; the peculiar modifications of the
thoracic segments and the relative positions of the wings and
legs mark a great departure from the normal type of Insect
structure. Their prey consists of living Insects, which they cap-
ture on the wing by their own superior powers of flight. They
destroy a great many Insects, their appetite for food being, as in
the cases of the Mantidae and of the tiger-beetles, apparently
almost insatiable. They are admirably constructed for the pur-
poses of their predatory lives; they fly with great swiftness and
change the direction of their flight with admirable facility.
They are, however, dependent on sunshine, and conceal them-
selves in dull and cloudy weather. The larger Insects of the
family belong to the division Anisopterides (Fig. 260, Anaxz
formosus), and some of these may, in our own country, usually be
seen, in the bright sunshine of the summer and autumn, engaged
in hawking in their favourite haunts. Places where other Insects

"1 Horae Soc. ent. Ross. xvi. 1881, p. 3.

“toy

XVII DRAGON-FLIES AI5

abound are naturally those most frequented; the glades of woods,
country lanes and hedge-sides, the borders of streams and the

margins of sheets of water are the places they most affect. They
inspire the rustics with some feeling of fear, and hence have
‘received the name of “ horse-stingers,’ and in North America are

called “devil's darning-needles.”. The aversion to dragon-flies
may perhaps be due to their appearance, which is certainly, in
the case of some of our species of Aeschna, Cordulegaster, and

Gomphus, very remarkable, consisting of a dark ground-colour

with bars and spots of vivid green or yellow, giving, it must be
admitted, a peculiar, even savage appearance to the Insects.
Whatever the reason may be, they are, it is certain, held in much
fear, and it is difficult to induce a country lad to touch one even
when it is captured and held by another person. The idea of
dragon-flies being dangerous to anything but their Insect victims
is, however, entirely erroneous; they may be captured and
handled without their inflicting any injury. It is probable that
the life of the imago may endure for several weeks if not months.
It is known that Sympyena fusca—a common European though
not British dragon-fly—hibernates in the imago state.

In the case of the large dragon-flies we have mentioned, each

‘ individual appears to have a domain, as it were, of its own.

Westwood tells us that he has seen what he believed to be the
same individual hawking daily for several weeks together over a
small pond. The writer observed a specimen of Cordulegaster
annulatus to frequent a particular bush, to which it returned
—frequently to the same leaf—after an excursion in search
of food. The way in which these Insects actually seize their
prey has not yet been made clear; it is certain that they
capture flying Insects, and it seems most probable, as we
have already said, that this is done by means of the legs.
These, as we have said, are inserted so as to be very near
to the mouth; they are directed forwards, and are held bent
at right angles so as to form a sort of net, and are armed
with a beautiful system of fine spines; it is probable that
if the dragon-fly pursue an Insect on the wing and strike it
with the trap, formed by its six.legs (Fig. 262, C), then these

immediately come together under the mouth, so that the victim,

directly it is captured by the leg-trap of its pursuer, finds
itself in the jaws of its destroyer. It is perhaps impossible to

416 NEUROPTERA CHAP,

verify this by actual observation, as the act of capture and trans-

fer is so very brief and is performed in the midst of a rapid

dash of flight, but it seems more probable that the prey is first
struck by the legs than that the mouth is the primary instrument
of capture. The excessive mobility of the head permits the victim
to be instantly secured by the mouth, and the captured fly is

turned about by this and the front pair of legs, and is nipped

rapidly so that the wings and drier parts fall off; the more
juicy parts of the prey are speedily squeezed into a little ball,
which is then swallowed, or perhaps we should rather say that
the mouth closes on it, and submits it to further pressure for the
extraction of the juices. We
have already noted that many of
these large and active dragon-
flies, particularly in the Libellu-
linae and Aeschninae, have their
eyes distinctly divided into two
parts, the facets in the lower
part of the eye being different

Exner considers * that the upper

movement, the lower for the
perception of the form of rest-
ing objects. Plateau thinks”
that the dragon-flies perceive

only movement, not form.

Fig. 263.—Inner view of a portion of . .
the left side of body of Libellula de- The splendid acts of flight

» press, showing a part of the mechanism of the Anisopterid Odonata are

of flight, viz. some of the chitinous . :
ridges at base of the upper wing, and accomplished by the aid of. a

some of the insertions of the tendons complex arrangement of chitin-
of muscles. A, line of section through :
base of upper wing, the wing being ous pleces at the bases of the

supposed to be directed backwards ; C, wings (Fig. 263). In Insects
upper portion of mechanism of the , :
lower wing ; 5, lever extending between with considerable powers of
the pieces connected with the two wings. 4; : Shae
(After von Lendenfeld, ) 8 flight the hind wings are usually
subordinate in functional im-
portance to the anterior, to which they are attached by a series

of hooks, or some other simple mechanism, on the wings.

1 Physiol. facett. Aug. 1891, p. 115.
2 Bull. Ac. Belgique (8), xvi. 1888, No. 11, p. 31.

from those of the upper part.

division is for the perception of -

XVIII DRAGON-FLIES 417

In the Odonata the two wings of each pair are quite free, but
they are perhaps brought. into correlative action by means of a
lever of unusual length existing amongst the chitinous pieces in
the body wall at the base of the wings (Fig. 263, >). The wing
muscles are large; according to von Lendenfeld* there are three

elevator, five depressor, and one adductor muscles to each wing:

he describes the wing movements as the results of the correlative
action of numerous muscles and ligaments, and of a great num-
ber of chitinous pieces connected in a jointed manner.

Amans?” has suggested that the mechanism of flight of the
dragon-fly would form a suitable model for a flying-machine, to
be propelled by electricity.

7 ED =
SS SNe
ee iw
SELES | \ SSS
CEES | 3 SS

Fic. 264.—Platycnemis pennipes, $, Britain.

The Zygopterides—the second of the two divisions of the’
Odonata—are Insects different in many respects from the large
and robust Anisopterides. The division comprises the delicate
Insects called “demoiselles,’ damsel-flies, by the French (Fig.
262, A,and Fig. 264). Great power of flight is not possessed by
these more fragile Insects; they flit about in the most gentle
and airy manner from stem to stem of the aquatic plants and
grasses that flourish in the localities they love. To this group
belong the fairy-like Insects of the genus Calepteryx, in which
various parts of the body and wings are suffused with exquisite

1 SB. Ak. Wien, \xxxiii. 1881, pp. 289-376, pls. i.-vii.
2 Rev. Sct, Nat. Montpellier (3), ii. p. 470.
VOL. V ) : ae Re

418 NEUROPTERA , CHAP.

metallic tints, while sometimes the two sexes of one species have
differently coloured wings. The smallest and most delicate
dragon-flies that are known are found in the tropics; some of
the genera allied to Agrion consist of Insects of extraordinary
fragility and delicacy.

Although the mature Odonata are so pre-eminently endowed
for an aerial and active life, yet in the earlier stages of their
existence they are very different; they are then, without excep-
tion, of aquatic habits; though carnivorous also in this period
of their existence, they are sluggish in movement, lurking in
concealment and capturing their prey by means of a peculiar
conformation of the mouth, that we shall subsequently describe.
Their life-histories are only very imperfectly known.

The éggs are deposited either in the water or in the stem of
some aquatic plant, the female Insect occasionally undergoing
submersion in order to accomplish the act. The young on
hatching are destitute of any traces of wings (Fig. 265), and the
structure of the thoracic segments is totally different from what
it is in the adult, the rectal respiratory system (Fig. 265, x), to
which we shall subsequently allude, being, however, already present.
The wings are said to make their first’ appearance only at the third
or fourth moult. At this time the pleura of the second and third
thoracic segments have grown ina peculiar manner so as to form
a lateral plate (Fig. 266, B, shows this plate at a later stage), and
the wing-pads appear as small projections from the membranes at
the upper margins of these pleural plates (Fig. 266, A, B). The
plates increase in size during the subsequent stadia, and meet
over the bases of the wing-pads, which also become much longer
than they were at first. The number of moults that occur during
growth has not been observed in the case of any species, but they
are believed to be numerous, There is no pupa, nor is there any
well-marked quiescent stage preceding the assumption of the
winged form at the last ecdysis, although at the latter part of its
life the nymph appears to be more inactive than usual. When full
grown, the nymph is more like the future perfect Insect than it was
at first, and presents the appearance shown in Figs. 266 and 270.
At this stage it crawls out of the water and clings to some sup-
port such as the stem or leaf of an aquatic plant; a few minutes
after doing so the skin of the back of the thoracic region splits,
and the imago emerges from the nymphal skin. The nymphs

a

XVIIr DRAGON-FLIES 419

never have the body so elongate as the perfect Insect, the differ-
ence in this respect being frequently great, and the nymphs of »
the subfamily Libellulinae being very broad (Fig. 266, nymph of
Ictinus sp.); consequently the creature on emergence from the
nymph-skin is very much shorter than it will soon become.

Fic. 265.—Larva of Diplax justhatched. n, Fie. 266.—Ictinus sp., nymph, Hima-

a ganglion of the ventral chain ; d, dorsal laya. <A, Dorsal, B, lateral view.
vessel ; x, tracheal network round rectum. (After Cabot.)

(After Packard, P. Boston Soc. xi, 1868,

p. 865.)

Extension begins to take place almost immediately ; it has been
thought by some that this is accomplished by swallowing air ;

‘this is, however, uncertain. At first the wings have only the

length of the wing-pads of the nymph, and their apical’ portion
is an unformed mass. The colour of the perfect Insect is not
present when the emergence takes place. The wing grows
quickly until the full length is attained. In the genus Aygrion

420 NEUROPTERA CHAP.

the expansion of the wings is accompanied by frequent eleva-
tions and depressions of the body, and
occupies an hour or so; the elongation
of the abdomen is not so soon completed,
and its brilliant colours do not appeas
for several hours.

The mouth of thenymph bears a remark-
able structure called the mask (Fig. 268).
It is apparently formed by a backward
growth of the basesof thelabium and lingua,
a hinge being formed between the two at
the most posterior point of their growth.
The prolonged portions of these parts
Fic. 267.—Young nymph of are free: usually the mask is folded under -

Aeschna sp. (Cambridge) the head, but it can be unfolded and —

about fourth moult.

thrust forward, remaining then attached
to the head by means of the more anterior
parts of the lingua and by the mavxillae,
the whole of the elongate apparatus be-
ing, when used, extended from this anterior
part of its attachment. The front parts
of the labium form a prehensile appa-
ratus armed with sharp teeth, so that the
structures make altogether a very effectual
trap, that can be extended in order to
secure the prey.

The fact that the Mate passes
suddenly, in the middle of its existence,
from an aquatic to an aerial life, makes
the condition of its respiratory organs a
subject for inquiry of more than usual
interest. Réaumur was of opinion that
the nymph was, in spite of its aquatic
existence, provided with an extensive
system of stigmata or orifices for breath-

Fic. 268.— Under side of
head of Calepteryx virgo,
nymph, with mask un-
folded. a, Lingua; 8,
line from which the mask

ing air; this was, however, denied by
Dufour, and his opinion seemed to be
supported by the fact that other means
of obtaining air were discovered to exist
in these nymphs.

swings ; c, line of doub-
ling up; a, lower lip pro-
per; e, articulated lateral
processes thereof.

The inquiries connected with the respiration

stomach. The dorsal pair of the

-”

- XVIII. DRAGON-FLIES 421

of Odonata are still very incomplete, but some interesting points
have been ascertained, the most important of which is perhaps
the existence in some forms of a
respiratory system in connexion
with the posterior part of the ali-
mentary canal (Fig. 269). In the
nymphs of Anisopterides the system
consists of four main _ tracheal
trunks, traversing the length of
the body, and by their ramifica-
tions and inosculations forming an
extensive apparatus. Connected
with the four main trunks we
have described, there is a shorter
pair confined to the abdomen,
where it supplies a large number
of branches to the walls of the

main tubes give numerous sub-

sidiary branches to the outside of Fra. 269.—Portion of tracheal system

the rectum, and the ventral pair of nymph of Aeschna cyanea.

Sovniah ll b Th R, R, R, R, rectum ; A, anus; ¢d,

urns &. Smaler vache er. © dorsal ; ¢v, ventral, tracheal tubes ;

walls of the gut are penetrated by ro epiguies tubes. (After Ous-
° . * alet.

the branches, which inside the )

rectum form numerous loops; these, covered by a membrane,

project into the interior in the form of multitudinous papillae

(schninae). In the Libellulinae the papillae are replaced by

more flattened processes or lamellae. The structures attain a
remarkable development, there pene in Aeschna cyanea upwards
of 24,000 papillae.

These rectal gills obtain air from water admitted into the
rectum for the purpose; the extremity of the body being armed
with projections. of variable form, that can be separated to
allow ingress and egress of the fluid, or brought into close
apposition so as to close the orifice. The water so taken in
can, by some species, be ejected with force, and is used occa-
sionally as a means of locomotion. These rectal branchiae can
absorb free air, as well as air dissolved in water. If the fluid
in which the creatures are placed has been previously boiled,
so as to expel the air from it, the nymphs then thrust the

422 ' NEUROPTERA CHAP.

ey

extremity of the body out of the water and so obtain a supply
of air.

Oustalet and Palmén state that at the last ecdysis the
lamellae, or the papillae, do not: disappear, but remain quite
empty, and are consequently functionless, while on the tracheal
trunks there are developed air vesicles to fit the creature for its
aerial career. Hagen says that in “Lpitheca the whole structure
of the gills is shed at the final moult.

The subject of the rectal branchiae of Zibellula has been dis-

cussed and illustrated by

Chun,’ who states that Ley-

dig has made known that in
y Phryganea grandis a structure
' is found connecting the rectal

branchiae of Zibellula with the
rectal glands of some other

Insects. We have not been

able to find a confirmation of

this in the writings of Leydig
or elsewhere. he
In the nymphs of the —

Zygopterides the highly-de-

veloped rectal branchiae found

in the Aeschninae.and Libel-
lulinae do not exist, and the

respiration seems to be of a

complex character. In one

division of the Zygopterides

— Calepteryginae — rectal

Fic. 270.—Calepteryx viryo, mature nymph, gills of an imperfect character
roca are said by Hagen and others —
to exist.2. The nymphs of the Zygopterides are provided with three
- mobile processes at the extremity of the body (Fig. 270); these serve
the purposes of locomotion. They are believed to possess also a
respiratory function, but this must be of an accessory nature, for
the nymphs live after the removal of the processes, and indeed
reproduce them; the skin of these processes is harder than is
usual+in Insect gills. In the nymph of Luphaea—a genus of
Calepteryginae found in tropical Asia—there are also external

1 Abh. Senckenb. Ges, x. 1875, p. 18, pl. iii. 2 Zool. Anz. iii. 1880, p. 160.

XVIIL DRAGON-FLIES ‘aes

abdominal gills, and in this case respiration may, according to
Hagen,’ take place in four different manners: (1) by ten pairs of
stigmata ; (2) by lateral branchiae well furnished with tracheae ;
(3) by caudal branchiae; (4). by rectal branchiae. It is further
said that in this Insect the lateral branchiae persist in the imago.

Although the means of respiration of the nymphs have been
fairly well ascertained, yet the mode in which the nymph is
prepared for the sudden change from the aquatic to aerial life
is still obscure, the condition of the stigmata not being
thoroughly elucidated. It appears probable, however, that the
young nymph has no stigmata; that these organs appear in the
course of its development, being at first quite impervious, but
becoming—at any rate in the case of the larger and more im- .
portant pair—open previous to the final ecdysis. We have
mentioned the contradictory opinions of Réaumur and Dufour,
and will now add the views of some modern investigators.
Oustalet says? that there are two pairs of spiracles in the
nymphs; the first pair is quite visible to the naked eye, and is
situate between pro- and meso-notum; it is in the nymph closed
by a membrane. The other pair of spiracles is placed above the
posterior pair of legs, is small and completely closed. He does
not state what stage of growth was attained by the nymphs he.
examined. Palmén was of opinion that not only thoracic but
abdominal spiracles exist in the nymph,’ and that they are com-
pletely closed so that no air enters them; he says that the
spiracles have tracheae connected with them, that at each moult
the part closing the spiracles is shed with some of the tracheal
exuviae attached to it. The breathing orifices are therefore for a
short time at each ecdysis open, being subsequently again closed
by some exudation or secretion. This view of Palmén’s has been
thought improbable by Hagen and Dewitz, who operated by
- placing nymphs in alcohol or warm water and observing the
escape of bubbles from the spots where the supposed breathing
orifices are situate. Both these observers found much difference
in the results obtained in the cases of young and of old nymphs.
Hagen concludes that the first pair of thoracic spiracles are
functionally active, and that abdominal stigmata exist though

1 OR. Soc. ent. Belgique, xxiii. 1880, p. lxvii.
2 Ann. Sci. Nat. (5) xi. Zool. 1869, p. 377.
3 Zur Morphologie des Tracheensystems, Helsingfors, 1877, p. 38.

424 NEUROPTERA CHAP.

functionless;. he appears to be of opinion that when the first
thoracic stigma is closed this is the result of the abutting against
it of a closed trachea. Dewitz found’ that in the adult nymph
of Aeschna the thoracic stigma is well developed, while the other
stigmata—to what number and in what position is not stated—
are very small. In a half-grown Aeschnid nymph he found the
thoracic stigma to be present in an undeveloped form. On placing
a full-grown nymph in alcohol, gas escaped from the stigma in
question, but in immature nymphs no escape of gas occurred
although they were subjected to a severe test. A specimen that,
when submitted to the above-mentioned immersion, emitted gas,
subsequently moulted, and thereafter air escaped from the
spiracle previously impervious. The observations of Hagen and
Dewitz are perhaps not so adverse to the views of Palmén as has
been supposed, so that it would not be a matter for surprise if
Palmén’s views on this point should be shown to be quite correct.

The number of species of Odonata or Libellulidae that have
been described is somewhat less than two thousand, but constant
additions are made to the number, and when the smaller and more
fragile forms from the tropics are collected and worked out it will
probably be found that the number of existing species is somewhere
between five and ten thousand. They are distributed all over
the world, but are most numerous in species in the warmer regions,
and their predominance in any one locality is very much regulated
by the existence of waters suitable for the early stages of their
lives. )

A good work on the British Odonata is still a desideratum.
In Britain about forty-six species are believed to be native. They
are said to be of late years less numerous than they used to be.
Notwithstanding their great powers of flight, dragon-flies are
destroyed by birds of various kinds; several hawks are said to be
very fond of them, and Merops persicus to line its nest with their —
wings. The number of Insects killed by dragon-flies in places
where they are abundant must be enormous; the nymphs, too,

1 Zool. Anz. xiii. 1890, p. 500.

2 The following works convey the best information : Evans’s British Libellulinae or
Dragonflies, illustrated in a series of lithographic drawings, 1845. Hagen, “A
Synopsis of the British Dragon-flies,” in Hntomologists’ Annual, 1857. M‘Lachlan,
Catalogue of the British Neuroptera, published by the Entomological Society of London
in 1870; and ‘‘The British Dragon-flies annotated,” Lntom. Month. Mag. xx. 1884,
pp. 251-256.

XVIII DRAGON-FLIES 425

are very destructive in the waters they inhabit, so that dragon-
flies have no doubt been no mean factor in maintaining that
important and delicate balance of life which it is so difficult
for us to appreciate. The nymphs are no doubt cannibals,
and this may perhaps be an advantage to the species, as the eggs
are sometimes deposited in large numbers in a limited body of
water, where all must perish if the nymphs did not, after exhaust-
ing other food, attack one another. Martin, speaking of the
Odonata of the Département de l’Indre in France, says:* “The
_ eggs, larvae, and nymphs are the prey of several fishes, snakes,
newts, Coleoptera, aquatic Hemiptera, and of some diving birds.
Sometimes the destruction is on a considerable scale, and one
may notice the dragon-flies of some piece of water to diminish
gradually in numbers, while the animals that prey on them
increase, so that a species may for a time entirely disappear in
_a particular spot, owing to the attacks of some enemy that has
been specially prosperous, and also eager in their pursuit. De
Selys found that from a pond filled with carp, roach, perch,
and eels, several of the dragon-fly denizens disappeared directly the
bream was introduced.” On the other hand, there can be little
doubt that the nymphs are sometimes injurious to fish; 1t has
been recorded that in a piscicultural establishment in Hungary
50,000 young fishes were put into a pond in spring; in the
following autumn only fifty-four fish could be found, but there
were present an enormous quantity of dragon-fly nymphs.

Odonata are among the few kinds of Insects that are known
to form swarms and migrate. Swarms of this kind have been
frequently observed in Europe and. in North America; they
usually consist of species of the genus Lzbellula, but species of
various other genera also swarm, and sometimes a swarm may
consist of more than one species. JL. guadrimaculata is the species
that perhaps most frequently forms these swarms in Europe ;
a large migration of this species is said to occur every year in
the Charente inférieure from north to south It>is needless to
say that the instincts and stimuli connected with these migrations
are not understood. .

The nymphs are capable, under certain circumstances, of
accommodating themselves to very peculiar conditions of life.
The Sandwich Islands are extremely poor in stagnant waters, and

1 Rev. d@ Entomol. v. 1886, p. 232. * Riveau, Fewille Nat. xii. 1882, p. 123.

426 NEUROPTERA CHAP.

yet there exist in this remote archipelago several highly
peculiar species of Agrioninae. Mr. R. C. L. Perkins has
recently discovered that the nymphs of some
of these are capable of maintaining their
existence and completing their development
in the small collections of water that accumu-
late in the leaves of some lilies growing on
dry land. These nymphs (Fig. 271) have a
shorter mask than occurs, we believe, in
any other Odonata, and one would suppose
that they must frequently wait long for a
meal, as they must be dependent on stray
Insects becoming immersed in these tiny
reservoirs. The cannibal habits of the

te dha. Speen Odonata probably stand these lily-dwellers
short mask, living in in good stead; Mr. Perkins found that there

“ced ag ae were sometimes two or three nymphs of

different sizes together, and we may suspect
that it sometimes goes hard with the smaller fry. The extension
in the length of the body of one of these lily-frequenting Agrions
when it leaves the water for its aerial existence is truly extra-
ordinary.

The Odonata have no close relations with any other group of
Insects. They were associated by Latreille with the Ephemeridae,
in a family called Subulicornia. The members of the two groups
have, in fact, a certain resemblance in some of the features of
their lives, especially in the sudden change, without intermediate .
condition, from aquatic to aerial life; but in all important points
of structure, and in their dispositions, dragon-flies and may-flies
are totally dissimilar, and there is no intermediate group to
connect them. We have already said that the Odonata consist:
of two very distinct divisions—Anisopterides and Zygopterides.
The former group comprises the subfamilies Gomphinae, Cordu-
legasterinae, Aeschninae, Corduliinae, and Libellulinae,—Insects
having the hinder wings slightly larger than the anterior pair ;
while the Zygopterides consist of only two subfamilies—Calep- .
teryginae and Agrioninae; they have the wings of the two pairs
equal in size, or the hinder a little the smaller. The two groups
Gomphinae and Calepteryginae are each, in several respects, of
lower development than the others, and authorities are divided

a

XVIII DRAGON-FLIES 427

in opinion as to which of the two should be considered the more
primitive. It is therefore of much interest to find that there
exists an Insect that shares the characters of the two primitive
subfamilies in a striking manner. This Insect, Palaeophlebia
superstes (Fig. 272), has recently been discovered in Japan, and

‘is perhaps the most interesting dragon-fly yet obtained. De

Selys Longchamps refers it to the subfamily Calepteryginae, on
account of the nature of its wings; were the Insect, however,
deprived of these organs, no one would think of referring Palaeo-
phlebia to the group in question, for it has the form, colour, and
appearance of a Gomphine Odonate. Moreover, the two sexes

Fie. 272. — Palaeo-
phiebia superstes.
A, The Insect with
wings of one side
and with two legs
removed ; B, front
view of head of
female ; C,of male.
(After De Selys.)

ius
nui

differ in an important character—the form of the head and eyes.
In this respect the female resembles a Gomphine of inferior
development; while the male, by the shape and large size of
the ocular organs, may be considered to combine the characters
of Gomphinae and Calepteryginae. The Insect is very remark-
able in colour, the large eyes being red in the dead examples.
We do not, however, know what may be their colour during life,
as only one pair of the species is known, and there is no record
as to the life-history and habits. De Selys considers the nearest
ally of this Insect to be Heterophlebia dislocata, a fossil dragon-
fly found in the Lower Lias of England.

Numerous fossil dragon-flies are known; the group is well
represented in the Tertiary strata, and specimens have been
found in amber. In strata. of the Secondary age these Insects

weg iye ue NEUROPTERA CHAP. XVIII _

have been found as far back as the Lower Lias; their remains
are said to exist in considerable variety in the strata of that
epoch, and some of them to testify to the existence at that period
of dragon-flies as highly specialised as those now living. Accord-
ing to Hagen’ Platephemera antiqua and Gerephemera simplex,
two Devonian fossils, may be considered as dragon-flies; the
_ evidence as to this appears inadequate, and Brongniart refers the ~
latter Insect to the family Platypterides, and considers Plate-
phemera to be more allied to the may-flies.

One of the most remarkable of the numerous discoveries lately
made in fossil entomology is the finding of remains of huge Insects,
evidently allied to dragon-flies, in the Carboniferous strata at Com-
mentry. Brongniart calls these Insects Protodonates,’? and looks on
them as the precursors of our Odonata. Meganeura monyi was
the largest of these Insects, and measured over two feet across the
expanded wings. If M. Brongniart be correct in his restoration
of this giant of the Insect world, it much resembled our existing
dragon-flies, but had a simple structure of the thoracic segments,
and a simpler system of wing-nervures. On p. 276 we figured ©
Titanophasma fayoli, considered by Scudder and Brongniart as
allied to the family Phasmidae, and we pointed out that this
supposed alliance must at best have been very remote. This view
is now taken by M. Brongniart himself,? he having removed the
Insect from the Protophasmides to locate it in the Protodonates
near Meganeura. There appears to be some doubt whether the
wings supposed to belong to this specimen were really such, or
belonged rather to some other species.

1 Bull. Mus. Harvard, viii. 1880-81, p. 276.
* Insectes fossiles, p. 394. % Insectes fossiles, p..396.

CHAPTER XIX

AMPHIBIOUS NEUROPTERA CONTINUED——EPHEMERIDAE, MAY-FLIES

Fam. VII. Ephemeridae—May-flies.

Delicate Insects with atrophied mouth and small, short antennae ;
with four membranous wings
having much minute cross-
veining ; the hinder pair very
much smaller than the other
parr, sometimes entirely absent:
the body terminated by three
or two very elongate slender
tails. The earlier stages are
passed through in water, and
the individual then differs
greatly in appearance from
the winged Insect ; the passage
between the two forms is sud-
den; the creature in vts first
winged state is a subimago,
which by shedding a delicate
skin reveals the final form of
the individual.

THE may-flies are well known—in
literature—as the types of a_ brief
and ineffective life. This supposed
brevity relates solely to their existence in the winged form. In
the earlier stages the may-fly is so unlike its subsequent self
that it is not recognised as a may-fly by the uninitiated. The
total life of the individual is really quite as long as that of most

Fic. 273.—Ephemera danica, male,
Britain.

430 NEUROPTERA . CHa

other Insects. The earlier stages and life-histories of these
Insects are of great importance. The perfect Insects are so
delicate and fragile that they shrivel much in drying, and are
very difficult to preserve in a condition suitable for study.

The mouth of the imago is atrophied, the trophi scarcely
existing as separate parts. Packard says that in Palingenia
bilineata he could discover no certain traces of any of the mouth-
parts, but in Leptophlebia cupida he found, as he thought, the
rudiments of the maxillae and labium, though not of the mandibles.
The antennae are always short, and consist of one or two thick
basal joints sueceeded by a delicate needle-like segment, which,
though comparatively long, is
not divided. The ocular organs
are remarkable for their large
size and complex development ;
they are always larger in the
male than they are in the
female. The compound eyes of
the former sex are in certain

we species, e.g. Cloéon (Fig. 274),

Fia. 274.—Front of head of Cloéon, male. a, quite divided, so that each eye

Pillared eye ; 0, sessile eye ; ¢, ocellus. ‘

becomes a pair of organs of a

different character; one part forms a pillar facetted at its summit,

while the other part remains as a true eye placed on the side of

the head; in front of these compound eyes there are three ocelli.

Thus the Insect comes to have three different kinds of eyes,
together seven in number.

The prothorax is small, the pronotum being, however, quite
distinct. The mesothorax is very large; its notum forms by far
the larger part of the upper surface of the thoracic region, the
metathorax being small and different in structure, resembling
in appearance a part of the abdomen, so that the hind wings
look as if they were attached to a first abdominal segment. The
mesosternum is also disproportionately large in comparison with
the homologous piece preceding it, and with that following it.
The pleural ‘pieces are large, but their structure and disposition are
only very imperfectly understood. The coxae are small and are
widely separated, the anterior being, however, more elongate and
approximate than the others. The other parts of the legs are
slender ; the number of joints in the tarsi varies from five to one.

XIX . MAY-FLIES 431

The legs throughout the family exhibit a considerable variety of
structure, and the front pair in the males of some species are remark-
ably long. The abdomen is usually slender, and consists of ten
segments ; the terminal one bears three, or two, very long flexible
appendages. The first dorsal plate of the abdomen is either
wanting or is concealed to a considerable extent by the meta-
notum. The wings
are peculiar; the an-
terlor pair vary a
great deal in their
width, but are never
very long in propor-
tion to the width;
the hind pair are
always dlispropor-
tionately small, and
sometimes are quite
wanting. The vena-
tion consists of a few, or of a moderate number, of delicate longi-
tudinal veins that do not pursue a tortuous course, but frequently

Fig. 275.—Wings of Ephemera danica. (After Eaton.)

are gracefully curved, and form a system of approximately similar

curves, most of the veins being of considerable length ; close to the
anterior margin of the wing there are two or three sub-parallel
veins. Frequently there are very numerous fine, short cross-
veinlets, but these vary greatly and may be entirely wanting.
The earlier stages of the life of Ephemeridae are, it is believed,
in the case of all the species, aquatic. May-flies, indeed, during
the period of their post-embryonic development are more modified
for an aquatic life than any other Insects, and are provided with
a complex apparatus of tracheal gills. The eggs are committed
to the waters without any care or foresight on the part of the
parent flies, thus the embryonic development is also aquatic ;
little, however, is known of-it. According to Joly* the process
in Palingenia virgo is slow. The larva on emerging from the

egg has no respiratory system, neither could Joly detect any

circulation or any nervous system. The creature on emergence
is very like Campodea in form, possessing long antennae and tails
—caudal setae. Owing to the organisation being inferior, the
creature in its earlier stages is called a larvule; in its later stages

1 Mem. Ac. Sci. Toulouse (7), iii. 1871, p. 379.

432 NEUROPTERA CHAP.

it is usually spoken of as a nymph, but the term larva is also
frequently applied to it. Soon the gills begin to appear in the
form of small tubular caeca placed in the posterior and upper
angles of the abdominal rings; in fifteen days the gills begin to
assume their characteristic form, are penetrated by tracheae, and

e

\
¥

SOSS esa
~eee o
oF

GT 4 MAE

é ka

Fia.276.—Nymph of Cloéon dipterum.' Wing-sheath Fic. 277.—Larvule of Oloéon

of left side, gills of right side, removed ; g, dimidiatum. (After Lub-
tracheal gills. (After Vayssiére.) bock.)

the circulation can be seen. The amount of growth accomplished
after hatching between March and September is but small.

The metamorphosis of Cloéon has been described by Sir John
Lubbock; he informs us that the young creature undergoes a
constant and progressive development, going through a series of
more than twenty moults, each accompanied by a slight change
of form or structure. His observations were made on captured

' In reference to a doubt as to the name of this nymph cf. Eaton, 77. Linn.
Soc. Zool, (2) ili, p. 20.

ia.’
13

tN ga SD

XIX MAY-FLIES 433

specimens, so that it is not certain that what he calls' the first
stage is really such. He found no tracheae in the earliest stages ;
the small first rudiments of the gills became visible in the third
stage, when there were no tracheae; the fourth instar possessed |
tracheae, and they could be seen in the gills. The wing rudi-
ments could first be detected in the ninth and tenth stages. The
changes of skin during the winter months are separated by
longer intervals than those occurring at other periods of the year.
The nymphs differ greatly in the structure and arrangement
of their tracheal gills, and display much variety in their general
form and habits; some of them are very
curious creatures. Pictet? divides them
in accordance with their habits into four
groups: (1) Fossorial larvae: these live
in the banks of streams and excavate
burrows for ‘shelter; they are of cylin-
drical form, possess robust legs, abundant
gills at the sides of the body, and
frequently processes projecting forwards
from the head: examples, Lphemera (Fig.
278) and Palingenia. (2) Flat larvae:
these live attached to rocks, but run with
rapidity when disturbed ; they prefer rapid
streams, have the breathing organs at-
tached to the sides. of the body and not
reposing on the back; they are exclu-
sively carnivorous, while the fossorial
forms are believed to obtain their nutri-
ment by eating mud: example, Baétis.
(3) Swimming larvae: elongate delicate
creatures, with feeble legs, and with strongly |
ciliated caudal setae: example, Cloéon (Fig.
276). (4) Climbing larvae: these live in
slowly-moving waters, especially such as
have much slimy mud in suspension, and yy, 278,—Adult nymph of
they have a habit of covering them- welts vulgata. (After
2 : , aton.) Britain.
selves with this mud sometimes to such
an extent as to become concealed by it: example, Potamanthus.

1 Tr. Linn. Soc. xxiv. 1863, p. 62, and xxv. 1866, p. 477.
-2 Hist. Nat, Newropt. Ephémérines, 1843, p. 24.

bo
os

VOL. V

434 me NEUROPTERA CHAP.

~The anatomy of the nymphs has been treated by Vayssiére,"
who arranges them in five groups in
accordance with the conditions of the
tracheal gills: (1) The gills are of large
size, are exposed and furnished at the
sides with respiratory fringes: ex-
ample, Ephemera (Fig. 278). (2) The
branchiae are blade-like, not fringed,
and are exposed at the sides of the
body: example, Cloéon (Fig. 276). (3)
The respiratory tubes are placed on
the under surface of plates whose —
upper surface is not respiratory: ex-
ae eal, ample, Oligoneuria garumnica (Fig.
xt 279). (4) The anterior gill is modi-
a: fied to form a plate that covers the
others: example, Tricorythus (Fig.
282,B). (5) The gills are concealed in
a respiratory chamber : example, Proso-
pistoma (Fig. 280). The last of these
Fin. Ste /aeieveneh. Gt Oligoneuria nymphs is more completely adapted
garumnica, France. gz and g,, for an aquatic life than any other
tee dorsal tracheal gills. Tnsect: at present known; it was for
yssiere. )

long supposed to be a Crustacean, but

it has now been shown to be the early stage of a may-fly,
the sub-imago having been reared from the nymph. The
carapace by which the larger part of the body is covered is
formed by the union of the pro- and meso-thorax with the sheaths
of the anterior wings, which have an unusually extensive develop-
ment; under the carapace there is a respiratory chamber, the
floor and sides of which are formed by the posterior wing-
sheaths, and by a large plate composed of the united nota of the
metathorax and the first six abdominal segments. In this
chamber there are placed five pairs of tracheal gills; entrance of
water to the.chamber is effected by two laterally-placed orifices,
and exit by a single dorsal aperture. These nymphs use the
body as a sucker, and so adhere strongly to stones under water.
When detached they swim rapidly by means of their caudal
setae; the form of these latter organs is different from that

1 Ann. Sci. Nat. Zool. (6) xiii. 1882, pp. 1-137, pls. 2-11.

XIX MAY-FLIES 435

of other Ephemerid nymphs. This point and other details
of the anatomy of this creature have been
described -in detail by Vayssiére.’ These
nymphs have a very highly developed tracheal
system; they live in rapid watercourses
attached to stones at a depth of three to six
inches or more under the. water. Species of
Prosopistoma oceur in Europe, Madagascar,
and West Africa.
. According to Eaton, in the nymphs of
some Ephemeridae the rectum serves, to a
certain extent, as a respiratory agent ; he con-
siders that water is admitted to it and ex-
pelled after the manner we have described in a, yh i
Odonata, P: £21. , Fia. 280. — Prosopi-
The internal anatomy of the nymphs cf stoma punetifrons,
Ephemeridae shows some points of extreme Y™Ph. France.

; (After Vayssiére.) 0,
interest. The long Orifice of exit from

+ :
Ll eben Y caudal setae are — T@spitatory chamber.
respiratory organs of a kind that
a ae is almost if not quite without
parallel in the other divisions of
+ SN i Insecta. The dorsal vessel for the

circulation of the blood is elongate,
aa Hy rst and its chambers are arranged one
Fic. 281.—A, Last three abdominal to each segment of the body. It
segments and bases of the three drives the blood forwards in the usual
caudal processes of Cloéon dip- .
ferum: +, dorsal vessel : kl, ostia MANNer, but the posterior chamber
thereof ; %, special terminal cham- possesses three blood-vessels, one of
ber of the dorsal vessel with its , . :
entrance « ; b, blood-vessel of the Which is prolonged into each caudal
. . av agioats prone H B, Ai pe seta. This terminal chamber is so
= S1X olnt O e€ leit caudal pro- °
: ews are below ; b, a Cortina of arranged as to drive the blood back-
the blood-vessel ; 0, orifice in the wards into the vessels of the setae;
latter. (After Zimmermann.) ‘

: on the under surface of the vessels
there are oval orifices by which the blood escapes into the
cavity of the seta so as to be submitted to the action
of the surrounding medium for some of the purposes of

respiration. This structure has been described by Zimmer-

1 Ann. Sci. Nat. Zool. (7) ix. 1890, pp. 19-87, pls. 2-5.
2 Ann. Nat. Hist. (3) xviii. 1866, p. 145.

' Fic. 282.—A, Nymph of Ephemerella ignita

436 NEUROPTERA CHAP.

mann,’ who agrees with Creutzberg ’ that the organ by which the
blood is propelled into the setae is a terminal chamber of the
dorsal vessel ; Verlooren,* who first observed this accessory system
of circulation, thought the contractile chamber was quite separate
from the heart. The nature of the connexion between this
terminal chamber that drives the blood backwards and the
other chambers that propel the fluid forwards appears still to
want elucidation.

The nymphs of the Ephemeridae being creatures adapted for
existence in water, the details
of their transformation into
creatures having an entirely
aerial existence cannot but. be
of much interest. In the
nymphs the tracheal system is
well developed, but differs from
that of air-breathing Insects
in the total absence of any
spiracles. Palmén has inves-
tigated this subject,* and finds
that the main longitudinal
tracheal trunks of the body of
the nymph are not connected
with the skin of the body by
tracheae, but are attached
thereto by ten pairs of slender
strings extending between the

with gills of left side removed; g, gills: Chitinous integument and the

B, nymph of Tricorythus sp. with gill tracheal trunks. When the

ae aie Mey gill covers skin is shed these strings—or

- rather a chitinous axis in each
one—are drawn out of the body, and bring with them the chitinous.

A A 4 B

Sa:

linings of the tracheae. Thus notwithstanding the absence of spir-

acles, the body wall is at each moult pierced by openings that
extend to the tracheae. After the ordinary moults these orifices close
immediately, but at the change to the winged state they remain open
and form the spiracles. At the same time the tracheal gills are com-

1 Zeitschr. wiss. Zool. xxxiv. 1880, p. 404.
2 Ann. Nat. Hist. (5) xv. 1885, p. 494. 3 Mem. Cour. Ac. Belg. 4to, xix. 1847, p. 1.
4 Zur Morphologie des Tracheensystems, Helsingfors, 1877, pp. 1-20.

XIX MAY-FLIES 437

pletely shed, and the creature is thus transformed from a water-
breather to an Insect breathing air as usual. In addition to this
change there are others of great importance, such as the develop-
ment of the great eyes and the complete atrophy of the mouth-
parts. The precise manner of these changes is not known; they
occur, however, within the nymph skin. The sudden emergence
of the winged Insect from the nymph is one of the most
remarkable facts in the life-history of the may-fly; it has been
observed by Sir John Lubbock,’ who describes it as almost in-
stantaneous. The nymph floats on the water, the skin of the back
opens, and the winged Insect flies out, upwards and away ;
“from the moment when the skin first cracks not ten seconds are
over before the Insect has flown away.” The creature that thus
escapes has not, however, quite completed its transformation. It
is still enveloped in a skin that compresses and embarrasses it ;
this it therefore rapidly gets rid of, and thus becomes the
imago, or final instar of the life-cycle. The instar in which the
creature exists winged and active, though covered with a skin, is
called the sub-imago. The parts of the body in the sub-imago are
as a whole smaller than they are in the imago, and the colour is
more dingy; the appendages—wings, legs, and caudal setae—are
generally considerably shorter than they are in the imago, but
attain their full length during the process of extraction. The
creatures being, according to Riley, very impatient and eager to
take to the wing, the completion of the shedding of the skin of
the sub-i “imago is sometimes performed while the Insect is flying
in the air.

The food of young Rah auenie is apparently of a varied and
mixed nature. Eaton says”
that though sometimes the
stronger larvae devour the
weaker, yet the diet is even
in these cases partly. vege- Ss
table. The alimentary canal
frequently contains much
mud ; VESEY: small organisms, Fig. 283.—Lingua of Heptagenia longicauda,
such as diatoms and con- x16. m, Central; /, lateral pieces. (After

: Vayssiére.)
fervae, are thought to form
a large part of the bill of fare of Ephemerid nymphs. Although

1 Tr. Linn. Soc, xxv. 1866, p. 483. 2 Ann. Nat. Hist. (3) xviii. 1866, p. 145.

438 | NEUROPTERA CHAP.

the mouth is atrophied in the imago, yet it is highly
- developed in the nymphs. This is especially notable in the
case of the lingua or hypopharynx (Fig. 283); indeed Vayssiére *
seems to incline to the opinion that this part of the mouth may
be looked on in these Insects as a pair of appendages of a head-
segment (see p. 96 ante), like the labium or maxillae. |

The life-history has not been fully ascertained in the case of
any species of may-fly ; it is known, however, that the develop-
ment of the nymph sometimes occupies a considerable period, and
it is thought that in the case of some species this extends to
as much as three years. It is rare to find the post-embryonie
development of an Insect occupying so long a period, so that we
are justified in saying that brief as may be the life of the may-
fly itself, the period of preparation for it is longer than usual.
Réaumur says, speaking of the winged fly, that its life is so short
that some species never see the sun. Their emergence from the
nymph-skin taking place at sunset, the duties of the generation
have been, so far as these individuals are concerned, completed before
the morning, and they die before sunrise. He thinks, indeed,.
that individuals living thus long are to be looked on as Methuselahs
among their fellows, most of whom, he says, live only an hour or
half an hour. It is by no means clear to which species these
remarks of Réaumur refer; they are doubtless correct in certain
cases, but in others the life of the adult is not so very short, and
in some species may, in all probability, extend over three or four —
days; indeed, if the weather undergo an unfavourable change so
as to keep them motionless, the life of the flies may be prolonged
for a fortnight.

The life of the imago of the may-fly is as remarkable as it is
brief; in order to comprehend it we must refer to certain peculi-
arities of the anatomy with which the vital phenomena are con-
nected. The more important of these are the large eyes of the
males, the structure of the alimentary canal, and that of the
reproductive organs. We have already remarked that the parts
of the mouth in the imago are atrophied, yet the canal itself not
only exists but is even of greater capacity than usual; it appears
to have much the same general arrangement of parts as it had in
the nymph. Its coats are, however, of great tenuity, and according

1 Ann. Sci. Nat. Zool. (6) xiii. 1882, p. 118.
2 Réaumur, A/em. vi. 1742, p. 457.

XIX MAY-FLIES 439

to Palmén? the divisions of the canal are separated by changes

in the direction of certain portions anterior to, and of others

posterior to, its central and greater part—the stomach—in such
a manner that the portions with diverted positions act as valves.
The stomach, in fact, forms in the interior of the body a delicate

capacious sac; when movement tends to increase the capacity of

the body cavity then air enters into the stomachic sac by the
mouth orifice, but when muscular contractions result in pressure
on the sac they close the orifices of its extremities by the valve-
like structures we have mentioned above; the result is, that as
complex movements of the body are made the stomach becomes
more and more distended by air. It was known even to the old
naturalists that the dancing may-fly is a sort of balloon, but they
were not acquainted with the exact mode of inflation. Palmén
says that in addition to the valve-like arrangements we have
described, the entry to the canal is controlled by a circular muscle,

with which are connected radiating muscles attached to the walls

of the head. Palmén’s views are adopted, and to a certain extent
confirmed, by Fritze,? who has examined the.alimentary canal of
the may-fly, and considers that though the normal parts of the
canal exist, the function is changed in the imago, in which the
canal serves as a sort of balloon, and aids the function of the
reproductive organs. The change in the canal takes place in an
anticipatory manner during the nymph and sub-imago stages.
The sexual organs of Ephemeridae are remarkable for their
simplicity ; they are destitute of the accessory glands and diver-
ticula that, in some form or other, are present in most other
Insects. Still more remarkable is the fact that the ducts by
which they communicate with the exterior continue as a pair to the
extremity of the body, and do not, as in other Insects, unite into
a common duct. Thus in the female there is neither bursa copu-
latrix, receptaculum seminis, nor uterine portion of oviduct, and
there is no trace of an ovipositor; the terminations of the ducts
are placed at the hind margin of the seventh ventral plate, just
in front of which they are connected by a fold of the integu-
ment. The ovary consists of a very large number of small egg-
tubes seated on one side of a sac, which forms their calyx, and
one of whose extremities is continued backwards as one of the

1 Uber paarige Ausfiihrsginge, etc., Helsingfors, 1884, p. 53.
2 Ber. Ges. Freiburg, iv. p. 5; ef. J. R. Mier. Soc. 1889, p. 206.

440 NEUROPTERA CHAP.

pair of oviducts. The male has neither vesiculae seminales, acces-
sory glands, nor ductus ejaculatorius. The testes are elongate
sacs, whose extremities are prolonged backwards forming the vasa
deferentia; these open separately at the extremity of the body, —
each on a separate intromittent projection of more or less complex
character, the two organs being, however, connected by means of —
the ninth ventral plate, of which they are, according to Palmén,
appendages. We should remark that this authority considers
Heptagenia to form, to some extent, an exception as regards the
structures of the female; while Polymitarcys is in the male sex
strongly aberrant, as the two vasa deferentia, instead of being
approximately straight, are bent inwards at right angles near
their extremities so as to meet, and form in the middle a common
cavity, which then again becomes double to pass into the pair of —
intromittent organs.

According to the views of Exner and others, the compound
eyes of Insects are chiefly organs for the perception of movement ;
if this view be correct, movements such as those made during
the dances of may-flies may, by the number of the separate eyes, by
their curved surfaces and innumerable facets, be multiplied and
correlated in a manner of which our own sense of sight allows
us to form no conception. We can see on a summer's evening how
beautifully and gracefully a crowd of may-flies dance, and we may
well believe that to the marvellous ocular organs of the flies them-
selves (Fig. 274) these movements form a veritable ballet. We
have pointed out that by this dancing the peculiarly formed aliment-
ary canal becomes distended, and may now add that Palmén and
Fritze believe that the unique structure of the reproductive organs
is also correlated with the other anatomical peculiarities, the con-
tents of the sexual glands being driven along the simple and
direct ducts by the expansion of the balloon-like stomach. During
these dances the momentary conjugation of the sexes occurs,
and immediately thereafter the female, according to Eaton,
resorts to the waters appropriate for the deposition of her eggs.
As regards this, Eaton says:* “Some short-lived species discharge
the contents of their ovaries completely en masse, and the pair
of fusiform or subcylindrical egg-clusters laid upon the water
rapidly disintegrate, so as to let the eggs sink broadcast upon
the river-bed. The less perishable species extrude their eggs

1 Tr. Linn, Soc. 2nd ser. Zool. iii. 1883, p. 11.

SSE

XIX MAY-FLIES 441

eradually, part at a time, and deposit them in one or other of
the following manners: either the mother alights upon the
water at intervals to wash off the eggs that have issued from
the mouths of the oviducts during her flight, or else she creeps
down into the water to lay her eggs upon the under-side of

stones, disposing them in rounded patches, in a single layer

evenly spread, and in mutual contiguity.” The eggs are very
numerous, and it is thought may sometimes remain in the
water as much as six or seven months before they hatch.

The number of individuals produced by some kinds of may-
flies is remarkable. Swarms consisting of millions of individuals
are occasionally witnessed. D’Albertis observed Palingenia
papuana in countless myriads on the Fly River in New Guinea:
“For miles the surface of the river, from side to side, was white
with them as they hung over it on gauzy wings; at certain
moments, obeying some mysterious signal, they would rise in
the air, and then sink down anew like a fall of snow.” He
further states that the two sexes were in very disproportionate
numbers, and estimates that there was but a single female to
every five or six thousand males.

Ephemeridae in the perfect state are a favourite food of
fishes, and it is said that on some waters it is useless for the
fly-fisher to try any other lure when these flies are swarming.
Most of the “duns” and “spinners” of the aigler are
Ephemeridae ; so are several of the “ drakes,” our large ZL. danica
and #. vulgata being known as the green drake and the gray drake.
Ronalds says’ that the term “dun” refers to the pseud-imago
condition, “spinner” to the perfect Insect. . danica and E£.
vulgata are perhaps not distinguished by fishers;. Eaton says
that the former is abundant in rapid, cool streams, while JZ.
vulgata prefers warmer and more tranquil rivers.

These sensitive creatures are unable to resist the attractions
of artificial lights. Réaumur noticed this fact many years ago,
and since the introduction of the electric light, notes may
frequently be seen in journals recording that myriads of these
Insects have been lured by it to destruction. Their dances may
frequently be observed to take place in peculiar states of light
and shade, in twilight, or where the sinking sun has its light
rendered broken by bushes or trees; possibly the broken lights

1 Fly-Fisher’s Entomology, 4th ed. 1849, p. 49.

442 NEUROPTERA CHAP,

are enhanced in effect by the ocular structures of the Insects. |

It has recently been ascertained that a species of Zeleganodes
is itself luminous. Mr. Lewis,' who observed this Insect in
Ceylon, states that in life the whole of the abdomen was lumin-
ous, not brightly so, but sufficient to serve as a guide for captur-

ing the Insect on a dark night. It has also been recorded that

the male of Caenis dimidiata gives a faint blue light at night.
Nearly 300 species of Ephemeridae are known, but this
may be only a fragment of what
‘ foi actually exist, very little being
known of may-flies of other
parts of the world than Europe
and North America. One of the
more curious forms of the family
is Oniscigaster wakefieldi; the
body of the imago is unusually
rotund and furnished with lateral
processes. In Britain we have
about forty species of may-fly.
The family is treated as a distinct
Order by Brauer and Packard, and
is called Plectoptera by the latter.
That Insects so fragile, so
highly organised, with a host of
powerful enemies, but themselves
destitute of means of attack or

Fig, 284.—Oniscigaster wakefieldi. New defence, should contrive to exist
. Zealand. (After M‘Lachlan.)

nah
pe\\
Tr
oN
wf
Gina i
Ns
pun,

afi

appears still more unlikely that such delicate Insects as
Ephemeridae should leave implanted in the rocks their traces
in such a manner that they can be recognised; nevertheless,
such is the case,—indeed, the may-fly palaeontological record is
both rich and remarkable. Several forms are preserved in
amber. In the Tertiary bed of the old lake at Florissant, Scudder
has been able to distinguish the remains of no less than six
species; while in the Jurassic layers of ‘the Secondary epoch, in
more than one locality, the remains of several other species
have been detected and described. Still more remarkable is the
fact that in the Devonian and Carboniferous layers of the

1 P. ent. Soc. London, 1882, p. xiii.

at all is remarkable; and it >

*
2 a « - >
ee ~ =

> fe

Mies

5 EE er ee

XIX _ MAY-FLIES 443

Palaeozoic period, remains are found that appear to be akin to
our existing Ephemeridae. Palingenia feistmantelic from the
Carboniferous of Bohemia is actually referred to a still existing
genus; it is said to have been of gigantic size for a may-fly.

The families Megasecopterides, Platypterides, and Stenodicty-
opterides of the Carboniferous epoch (see p. 343) are all more or
less closely allied to the Ephemeridae, and in addition to these
Brongniart has established the family Protephemerides for some
Insects that he considers to have been the precursors in the
Carboniferous epoch of our existing
may-flies. These ancient Insects
differed in having the wings of
another form from those of exist-
ing Ephemeridae, and in having
the hind wings equal in size to
the front pair. Besides this, these
Insects had, as shown in Fig. 285,
prothoracic dorsal appendages ;
some had also projections from the
abdominal segments, considered by
Brongniart to be of the nature-of
gills. Some doubt must exist as to
this point, for we find in the imago
of one of our existing Ephemeridae,
Oniscigaster wakefieldi, Fig. 284,
abdominal processes that are not
gills.

It ‘is remarkable that may-
flies, which now form a com-
paratively unimportant part of
the Insect tribe, should in far
distant times have been represented Fic. 285.—Homaloneura bonnieri ; Car-
by so great a variety of allied forms. — boniferous of Commentry, (After
Our fragile, short-lived may-flies wien
appear to be, as Scudder says, the lingering fragments of an
expiring group.

CHAPTER XX

NEUROPTERA PLANIPENNIA——SIALIDAE, ALDER-FLIES, SNAKE-FLIES—_
PANORPIDAE, SCORPION-FLIES — HEMEROBIIDAE, ANT-LIONS,
LACEWINGS, ETC.

Fam. VIII. Sialidae—Alder-flies and Snake-flies.

Four wings of moderate size, meeting in repose over the back at
an angle; the hinder of the two pairs slightly the smaller ;
the anal area small or nearly absent, not plicate. Nervures
moderately numerous, transverse veinlets moderately numerous,
forming irregularly disposed cells. The metamorphosis is
great; there is a quiescent pupa. Thelarvahas the mandibles
JSormed for biting, armed with strong teeth. | |

THE Sialidae, though but a small family of only some six or
eight genera, comprise
a considerable variety of — -
forms and two sub- —
families — Sialides and
Raphidiides. The former
eroup has larvae with
aquatic habits possessed
of branchiae but no
spiracles.

Sialis lutaria is one
of the commoner British
Insects frequenting the
a vegetation about the
tn banks of tranquilstreams;
Pi 286 Mh ey, int din, Bei. ig well known 8

anglers, being used by

them for a bait. According to Ronalds it is called the alder or

é

nae ee ee ey ee

= 5

=e

CHAP. XX» SIALIDAE 445

orl-fly, and in Wales the humpback. It is very unattractive in
appearance, being of a _ blackish colour, with wings of a
yellow-brown tinge, and makes but a poor show when flying.
The female deposits patches of elongate eggs, placed on end and
packed together in a very clever manner (Fig. 287). These patches
of eggs, of a stone-gray colour, are common objects on rushes
or stems of grass near water, and it is stated that there may
be no less than 2000 or 3000 eggs in one of them. Our
figure gives some idea of the mode in which the eggs are arranged,

Fic. 287.—Portion of a row of eggs of Fig. 288.—Sialis lutaria,
Sialis lutaria. (After Evans.) larva.

and the curious narrow process that exists at the end of each.
The eggs are said to be sometimes placed at a considerable distance
from water, so that when the tiny larvae are hatched they
must begin their lives by finding the way to a suitable pool or
stream. The larvae (Fig. 288) are objects of very great interest
owing to each of segments 1 to 7 of the hind body- being furnished
on each side with a jointed filament, while the last segment ends
in a still longer, but unjointed process. These filaments are
branchiae by means of which the Insect obtains air, being, as we
have said, destitute of spiracles. It is an active creature and
waves its filaments in a very graceful manner; this process no
doubt aids the branchiae in their respiratory work. These larvae
are well able to exist out of water if they have a sufficiently
damp environment. They live on animal matter, but their life-
history has not been followed in much detail and it is not known

446 NEUROPTERA - CHAP.

how many moults they make. The young larva has the head.

disproportionately large and the branchial filaments longer.
When the growth is completed the larva returns to land, seeks a
suitable situation in the soil, and after an interval changes to a
pupa, in which the characters of the perfect Insect are plainly

visible. Subsequently, without becoming again active, it changes

to the perfect Insect, and enjoys, for a few days only, an aerial life.
The anatomy of the larva has been treated by Dufour.’ The
supra-oesophageal ganglion is remarkably small; nothing is. said
as to the existence of an infra-oesophageal ganglion; there are
three thoracic and eight abdominal

5 te ganglia; the first pair of these latter

: Te ff y. axe nearer together than the others, and
a A f= this is also the case with the last three.

PE The alimentary canal in the adult is

a provided with a large paunch attached

to the crop by a narrow neck, but

chiae has also been described by the
indefatigable French entomotomist. A
tracheal tube sends a branch into one
of. the appendages (Fig. 289);
branch gives off numerous smaller
tracheae, which at their extremities
break up into branchlets close to the
integument. The tracheal tube that
receives each main branchial trachea,
sends off from near the point of entry
Fic. 289.—Structure of tracheal gill Of the latter another trachea, that
: “56% the ae ae distributes its branchlets on the ali-
trunk with which it is con- mentary canal. The margins of each
by altvnetaey Oeeaee given off» ypendage are set with swimming hairs,
so that the branchiae act as organs of
locomotion as well as of respiration, and by their activity in the
former capacity increase the efficiency of their primary function.
The genus Sialis occurs in a few species only, throughout the

1 Ann. Sci. Nat. series 8, ix. Zool. 1848, p. 91, pl. 1.

? Newport, Zr. Linn. Soc. xx. 1851, pl. 21, fig. 13. Loew, however, who also
describes and figures the anatomy of s. lutaria, states that there is no paunch,
Linnaea entomologica, iii, 1848, p. 354.

Dufour could find no trace of this in °
the larva. The structure of the bran-—

pr, Oa

Reet, : | | SIALIDAE 447

whole of the Palaearctic and Nearctic regions, and reappears in
Chili, though absent in all the intervening area: Several other
. genera of Insects exhibit the same peculiarity of distribution.

The genera Corydalis and Chauliodes form a group distinct
from Stalis, and are totally differ- |

ent in appearance, being gigantic ——— ; i ie
Insects, sometimes with the man-
fi

dibles of the male enormously
elongated (Fig. 290). The species
of Corydalis are called in North
America Hellgrammites; Riley
has described and figured the
metamorphosis of C. cornutus, the
life-history being very similar to
that of our little Sialis. A mass
consisting of two or three thousand
eggs is formed by the female, and
the young larva has long fila-
ments at the sides of the body
like Sialis. These in the later
larval life are comparatively shorter,
but the Insect is then provided
with another set of gills in the Fre, 290.—Corydalis crassicornis, male,
form of spongy masses on the ith grater portions of te wing
under-side of the body. Riley, .
however, considers that these organs serve the purpose of attach-
ment rather than ‘of respiration. The
larvae are known to the Mississippi
fishermen as crawlers, and are greatly
esteemed as bait.

The Raphidiides. or snake-flies form
the second tribe of Sialidae. There are
only two genera, Raphidia and Inocellia,
| peculiar to the Palaearctic and Nearctic
Fig. 291.—Raphidia notata, fe- regions. The perfect Insects are chiefly

male. Britain, (After Curtis.) :
: remarkable for the elongation of the
prothorax and back of the head to form a long neck, and for
the existence in the female of an elongate exserted ovipositor.

1 M‘Lachlan, Ent. Month. Mag. vii. 1870, p, 145.
2 Rep. Ins. Missouri, ix. 1877, p. 125.

448 NEUROPTERA CHAP.

The species are rather numerous, and have been recently
monographed by Albarda.’ The three or four British species
of the genus are all rare Insects, and occur only in wooded
regions,

The Raphidiides, like the Sialides, have a carnivorous larva,
which, however, is terrestrial in habits, feeding, it would appear,

chiefly on Insects that harbour in old timber. The snake-fly

larvae (Fig. 292) are very ingenious in their manner of escaping,
which is done by an extremely rapid wriggling backwards. They
are capable of undergoing very prolonged
fasts, and then alter in form a good deal,
becoming shorter and more shrivelled;
Fig. 292 is taken from a specimen that
had been fasting for several weeks. They
are excessively voracious, and hunt after
the fashion of beasts of prey; their habits
have been described by Stein,? who states
that he kept a larva from August to the
end of May of the following year without
food ; it then died in a shrivelled-up state.
The larva of the snake-fly changes to a
pupa that is remarkably intermediate in
form between the perfect Insect and the
larva; the eyes, legs, wing-pads, and ovi-
positor being but little different from those
of the imago, while the general form is
Bro, 292.—Raphidia notaity that of the larva, and the peculiar elonga-
arva. New Forest. 2 “ .

tion of the neck of the imago is absent.
This pupa differs from that of Sialis in the important particular
that before undergoing its final ecdysis it regains its activity and
is able to run about.

The internal anatomy of Raphidia has been treated by Loew,*
and is of a very remarkable, character ; we can here only mention
that the salivary glands consist of a pair of extremely elongate
tubes, that there is a very definite paunch attached as an ap-
pendage to one side of the crop, and that the most peculiar
character consists of the fact that, according to Loew, four of the
six Malpighian tubes have not a free extremity, being attached

-
a

aM TN
giill|
|

Mb
Nit
as
i

= <a

Cite
ar.
p0>
Ar
Te
oO
+

Ls

Kua be

Aad eC

1 Tijdschr. Ent. vol. xxxiy. 1891. 2 Arch. f. Naturg. iv. i. 1838, p. 315.
> Linnaea entomologica, iii. p. 1848, 346, pl. i.

=

Y

XX SIALIDAE AND SCORPION-FLIES 449

at each end so as to form elongate loops; the mesenteron is very

complex in character.
A considerable number of fossil re-

mains from both Tertiary and Mesozoic .

strata are referred to Sialidae; and a
laryal form from the red_ sandstone
of Connecticut has been considered by
Seudder to be a Sialid, and named
Mormolucoides articulatus, but the cor-
rectness of this determination is - very
doubtful (Fig. 293). These fossils are,
however, of special interest as being the

most ancient Insect larvae yet brought .

to light. A still older fossil, from the Car-
boniferous strata of Illinois called Miamia
bronsont, is considered by Scudder to have
several points of resemblance to Sialidae.

xt
Fia. 293. — Mormolucoides
articulatus, larva. Trias

of Connecticut. (After
Scudder.)

Fam. IX. Panorpidae—Scorpion-flies.

Head prolonged to form a deflexed beak, provided with palpi near

Fig. 294.—Panorpa communis, male,
Cambridge.

of the mouth-parts.

its apex; wings elongate and
narrow, shining and destitute of
hair, with numerous, slightly
divergent veins and moderately
numerous transverse veinlets (in
one genus the wings are absent).
Larvae provided with legs, and
usually with numerous prolegs
like the saw-flies: habits car-
NUVOTOUS.

The majority of the members
of this family are very readily
distinguished by the beak-like
front of the head, this being
chiefly due to enlargement of
parts of the head itself, and
in a less degree to prolongation
The upper (or front) face of the beak is

formed entirely by the clypeus, the labrum being scarcely

VOL. V

2G

450 . NEUROPTERA CHAP.

visible, though it may be detected at the sides of the tip of the
beak; the sutures between the various parts of the head are
nearly or quite obliterated, but it is probable that the sides of

the beak are formed by the genae and by the stipites of the .

maxillae, and its under-surface chiefly by the submentum: the
mentum itself is but small, the ligula is small, bifid.at the ex-
tremity, and each branch bears a two-jointed palpus, the
basal article being of very peculiar structure in Panorpa. The
mandibles are but small, and are placed at the apex of the beak ;
they have each the form of an oblong plate armed with two
very sharp teeth, and they cross freely. The maxillae are the
only parts of the mouth-pieces that are very elongated; each
cardo is articulated at the base of the head, and the stipes extends
all the length of the side of the beak; each maxilla bears a five-
jointed palpus and two small but very densely ciliated lobes.
The antennae are long, very slender, and flexible, and are many-
jointed; they are inserted between the eyes in large foramina ;
there are three ocelli, or none, and the compound eyes are
moderately large. The prothorax is small, its notum is quite
small or moderate in size, and the prothoracic stigma is placed
behind it; the side-pieces are small, and there is no chitinous pro-
sternum except a small longitudinal strip placed in the mem-
brane between the coxae; these latter are of only moderate size,
and are free and dependent. The meso- and meta-thorax are

large, their side-pieces are of considerable dimensions and bear
large, dependent coxae and supporting-pieces (Fig. 58); there is a —

stigma placed between the meso- and meta-thorax at the hind
margin of the upper part of the meso-trochantin ; both meso- and
meta-notum are transversely divided. The abdomen is elongate,
slender, conico-cylindrical, consisting of nine segments; the basal
segment is membranous and concealed; the terminal appendages
are of variable nature according to the species and sex. ‘The legs
are elongate and slender, the tarsi five-jointed. The internal
anatomy of Panorpa communis has been examined by Dufour?
and Loew.” They agree in describing the alimentary canal as
being of peculiar structure: there is a short, slender oesophagus
leading to an organ in which there is seated a remarkable
arrangement of elongate hairs; this structure might be looked
on as the proventriculus, but Loew considers it to be rather a

1 Mem, Ac, Sci. érang. vii. 1841, p, 582. 2 Linnaea entom, iii. 1848, p. 363.

_ 2 ee Te Eel

FA sa >
ae eee ee ee 2 ee ee

an tae ieee Le ieee =

xXx : PANORPIDAE 451

division of the true stomach. The particulars given by these
two anatomists as to some other parts of the internal anatomy
are very discrepant.

The Panorpidae form a small family of only nine or ten genera,

_ two or three of these being exotic and only imperfectly known ;

the three genera found in Europe are composed of very curious
Insects. The scorpion-flies—Panorpa proper—are very common
Insects, and have received their vernacular name from the fact
that the males have the terminal segments elongate and slender
and very mobile, and carry them curved up somewhat after the
fashion of the scorpions (Fig. 294). It is said that Aristotle was
acquainted with these Insects, and considered them to be really
winged scorpions.

A second European genus, Boreus, is still more peculiar; it is
destitute of wings, and has the appearance of a minute wingless
grasshopper; it is found
from late autumn to early
spring in moss and under
stones,andis said to be some-
times found disporting itself
on the surface of the snow :
the female of this Insect
has an exserted ovipositor.
The writer has found this
little creature in Scotland among moss in November, and under
stones early in March (Fig. 295). The third European genus,
Littacus, does not occur in our islands, but is common on many parts
of the Continent ; the perfect Insect has a great resemblance to a
Tipula, or “daddy-long-legs” fly, and attaches itself to the stems
of grasses, and preys on flies; according to Brauer it has the”
peculiar habit of using the hind pair of legs as hands (Fig. 296),
instead of the front pair, as is usual in Insects. This remark-
able genus is widely distributed, and species of it are found even
in the Antipodes. A species inhabiting caves has been mentioned
by M‘Lachlan.*

The early stages of the Panorpidae were for long unknown, but
have recently been discovered by Brauer: he obtained eggs of Panorpa
by confining a number of the perfect flies in a vessel containing
some damp earth on which was placed a piece of meat; when

1 Ent, Month. Mag. 1894, p. 39.

Fia. 295,—Boreus hiemalis, female. Dumfriesshire.

452 NEUROPTERA | CHAP,

the young larvae were hatched they buried themselves in the earth
and nourished themselves with the meat. or its juices. These

larvae (Fig. 297) bear a great resemblance to those of the Hymenop- —

terous family Tenthredinidae; they have biting mandibles and
palp-bearing maxillae, and show no approach to the peculiar
mouth structure found in the Hemerobiidae; there are three pairs
of feet placed on the three thoracic segments, and there is also a

pair of less perfect feet on each of the first eight abdominal —

segments, those behind being the larger. The upper surface of

Wallies

Fra. 296. —Bittacus tipularius holding Fra. 297.— Young larva of
a fly in its hind legs. Austria. Panorpa communis. .
(After Brauer.) (After Brauer.)

the body bears spines, which, however, disappear after the first
change of skin, with the exception of the larger processes on the
posterior segment, which persist throughout the life of the larva.
The larvae are active for about one month ; after this they become
quiescent, but do not change to the pupa state for several weeks ;
when this happens they change in form and cannot creep, although

their limbs are not enclosed in any pupa case. Brauer also dis-—

covered larvae of Panorpa communis at large in numbers in an
old tree stump that was quite covered with moss, and contained
many ants in the mouldering wood. The ants appeared to be on
friendly terms with. the Panorpa larvae. The earlier stages of

xx) PANORPIDAE—HEMEROBIIDAE 453

Boreus and LBittacus were also observed by Brauer; they are

- essentially similar to those of Panorpa, but the larva in Boreus is

not provided with abdominal prolegs. The Panorpidae have
been separated from the other Neuroptera by certain naturalists
as a distinct Order, called Panorpatae by Brauer, Mecaptera by
Packard; but in their structure as well as in their metamorphoses
they are not so distinct from the Phryganeidae and the Hemero-
biidae as to justify this step.

Fossil forms of Bittacus and of Panorpa have been fans in
amber and in the Tertiary strata, and Scudder has described some
forms from Florissant in which there are no cross-veinlets in the
wings. Some remains from the English Lias have been referred
to Panorpidae by Westwood under the name Orthophlebia, but it
is by no means certain that they really belong to the family.

(

Fam. X. Hemerobiidae—Ant-lions, Lacewing-flies, etc.

Head vertical ; macxillae free, with five-jointed palpi ;° labial palpr
three-jointed, Wings subequal in size, with much reticula-
tion, without anal area. Tarsi five-jointed. Metamorphosis
great ; the larvae with mandibles and mazxillae coadapted to
form spear-like organs that are.suctorial in function. Pupa,
similar in general form to the imago, enclosed in a cocoon.

KH -
J 7

a? :

WNL) ———
; Y i p ZED —SEA
So “ ‘Ss = are
TAY

Fic. 298.—Drepanepteryx sakes Scotland.

The Hemerobiidae are an extremely varied assemblage of
Neuroptera; the perfect Insects of the various sub-families are
very different in appearance, but the family as a whole is
naturally defined by the very peculiar structure of the mouth-
organs of the larvae. These Insects have, in fact, a suctorial

A454 NEUROPTERA CHAP.

mouth in their early life, and one of the ordinary biting type in
adult life.

This is a very unusual condition, being the reverse of what
we find in Lepidoptera and some other of the large Orders,
where the mouth is mandibulate in the young and suctorial in
the adult. The suctorial condition is in Hemerobiidae chiefly
due to modification of the mandibles; but this is never the case
in the Insects that have a suctorial mouth in the .imaginal
instar. Nearly all the Hemerobiidae are terrestrial Insects in all
their stages; a small number of them are, to a certain extent,
amphibious in the larval life, while one or two genera possess
truly aquatic larvae. The metamorphosis is, so far as the

changes of external form are concerned, quite complete. There —

are no wingless forms in the adult stage.
The classification given by Hagen’ and generally. adopted
recognises seven sub-families. These we shall mention seriatim.

Sub-Fam. 1. Myrmeleonides or Ant-lions—Antennae short,
clubbed, the apical space of the wing with regular, oblong
cellules,

paces
OS

Fic. 299.—Tomateres citrinus. 8, E. Africa. (After Hagen.)

The ant-lions in their perfect state are usually unattractive
Insects, and many are nocturnal in their habits; the species of the
genus Palpares and allies (Fig. 299) are, however, of more handsome
appearance, and attain a large expanse of wing. No member of the
sub-family is an inhabitant of Britain, though species of the typical
genus Myrmeleon are common in Central and Northern Europe. The

1 Stettin. ent. Zeit. xxvii. 1866, p. 369; this author has also sketched a classifi-
cation of the larvae in P. Boston Soc. xv. 1873, p. 248.

XX ANT-LIONS © 455

remarkable habits of their larvae attracted the attention of natur-
. alists so long ago as two hundred years. We owe to Réaumur an
accurate and interesting account of JZ formicarius, the species
found in the neighbourhood of Paris. The larvae are predaceous,
and secure their prey by means of pitfalls they excavate in the
earth, and at the bottom of which they bury themselves, leaving
only their elongate jaws projecting out of the sand at the bottom
of the pit. They move only backwards, and in forming their pit
use their broad body as a plough, and throw out the sand by
placing it on the head and then sending it to a distance with a
sudden jerk. When about to construct its trap the larva does
not commence at the centre, but makes first a circular groove of
the full circumference of the future pit. Burying its abdomen
in the surface of the earth, the Insect collects on to its head, by
means of the front leg, the sand from the side which is nearest to the
centre, and then jerks the sand to a distance. By making a second
circuit within the first one, and then another, the soil is gradu-
ally removed, and a conical pit is formed, at the bottom of which —
the ant-lion lurks, burying its body but leaving its formidable
mandibles widely extended and projecting from the sand. In this
position the young ant-lion waits patiently till some wandering
Insect trespasses on its domains. An ant or fly coming over the
edge of the pitfall finds the sand of the sloping sides yielding beneath
its body, and in its effort to secure itself probably dislodges some
more of the sand, which, descending to the bottom of the pit, brings
the lurking lion into activity. Availing himself of his power of
throwing sand with his head, the ant-lion jerks some in the
neighbourhood of the trespasser, and continues to do so until the
victim is brought to the bottom of the pit and into the very jaws
of its destroyer; then there is no further hope of escape; the
mandibles close, empale their prey, and do not relax their hold
till the body of the victim is exhausted of its juices. The position
chosen is in a place that will keep dry, as the larva cannot carry
on its operations when the sand is wet or damp, hence the soil at
the base of a high wall or a rock frequently harbours these
Insects. The parts of the mouth of the Myrmeleon are perfectly
adapted for enabling it to empty the victim without for a
‘moment relaxing its hold. There is no mouth-orifice of the
usual character, and the contents of the victim are brought
into the buccal cavity by means of a groove extending along

456 NEUROPTERA CHAP, —

the under side of each mandible; in this groove the elongate — es

and slender lobe that replaces the maxilla a

—there being no maxillary palpi—
buccal cavity at each movement a small

consisting in greater part of the two lobes
that support the labial palpi. The pharynx
is provided with a complex set of muscles,

tions as an instrument of suction. After the

, jerked away to a distance. When the —
ant-lion larva is full grown it forms a

grains of sand with fine silk from a
slender spinneret placed at the posterior
extremity of the body; in this cocoon it_

Fic. 300.—Larva of Myrme- changes to an imago of very elongate
leon pallidipennis. (After

plays backwards and forwards, probably — 2
raking or dragging backwards to the

quantity of the contents of the empaled
victim. The small lower lip is peculiar, — a

and, together with the buceal cavity, fune-

prey has been sucked dry the carcass is a

globular cocoon by fastening together a

Meinert.) form, and does not emerge until its meta-

morphosis is quite completed, the skin of the

pupa being, when the Insect emerges, left behind in the cocoon,

The names by which the European ant-lion has been known are
very numerous. It was called Formicajo.and Formicario by Vallis-
neri about two hundred years ago; Réaumur called it Formica-leo,
and this was adopted by some modern authors as a generic name

for some other of the ant-lions. The French people call these a

Insects Fourmilions, of which ant-lion is our English equivalent.
The Latinised form of the term ant-lion, Formicaleo, is not now
applied to the common ant-lion as a generic term, it having been
proposed to replace it by Myrmecoleon, Myrmeleo, or Myrmeleon ; —
this latter name at present seems likely to become generally
adopted. There are several species of the genus found in Europe,
and their trivial names have been confounded by various authors
in such a way as to make it quite uncertain, without reference to
a synonymic list, what species is intended by any particular writer.
The species found in the neighbourhood of Paris, and to which it
may be presumed Réaumur’s history refers, is now called Myrme-

XxX MYRMELEONIDES 457

leon formicarium by Hagen and others; M‘Lachlan renamed it
M. europaeus, but now considers it to be the IM. nostras of
Fourcroy. The popular name appears to be due to the fact that
~-ants—Formica in Latin, Fourmi in French—form a large part of
the victims ; while lion—the other part of the name—is doubt-
less due to its prowess as a destroyer of animal life, though, as
Réaumur long ago remarked, it is a mistake to apply the term
lion to an Insect that captures its prey by strategy and by
snares rather than by rapidity and strength. The imago of
Myrmeleon is of shy disposition, and is rarely seen even in
localities where the larva is abundant. It is of nocturnal pe
and is considered by Dufour to be carnivorous.

Considerable difference of opinion has existed as to the structure
of the mouth and of the alimentary canal in these larvae. Réaumur
was of opinion that there exists no posterior orifice to the alimentary
canal, but Dufour ridiculed this idea, and stated positively that
such an orifice undoubtedly exists. It is also usually said that
the mouth is closed by a membrane. Meinert has recently exam-
ined these points,’ and he states that the mouth is not closed by
any membrane, but is merely compressed. He finds that there is
no posterior exit from the stomach; that there is a compact mass
without any cavity between the stomach and the point where the
Malpighian tubes connect with the small intestine. The portions
of aliment that are not assimilated by the larva collect in the
stomach and are expelled as a mass, but only after the Insect has
become an imago. This peculiar excrementitious mass consists
externally of uric acid, and from its form and. appearance has been
mistaken for an egg by several naturalists. The posterior portions
of the alimentary canal are, according to Meinert, of a remark-
able nature. The small intestine is elongate, slender, and is
coiled. There are eight very long and slender Malpighian tubes ;
a pair of these have free extremities, but the other six: in the
posterior part of their course are surrounded by a common mem-
brane, and, following the course of the intestine, form ultimately
a dilated body seated on a coecum. These six Malpighian tubes
are considered to be partially, if not entirely, organs for the secre-
tion of silk for forming the cocoon, the coecum being a reservoir.
The canal terminates as a slender tube, which acts as a spinneret
and is surrounded by a sheath. A complex set of muscles com-

1 Ov. Danske Selsk. 1888, p. 43.

458 NEUROPTERA : CHAP.

pletes this remarkable spinning apparatus. The alimentary
canal of the imago has been described and
figured by Dufour’; it is very different
from that of the larva.

The ant-lion is capable of sustaining
prolonged fasts. Dufour kept specimens for
six months without any food. These In- .
sects are said to give off a peculiar ant-like
odour, due, it is thought, to their ant-
eating habits. Although no species in-
habits Great Britain, yet one is found in
Southern Sweden. Introduced specimens
get on very well in confinement in our
country,” and would probably flourish at
large for some. years if they were liber-
ated.

Although the number of known species
and genera of Myrmeleonides is consider-
able—that of the species being now
upwards of 300—the members of the
small genus Myrmeleon are the only forms
that are known to make pits of the kind
we have described. Other larvae? are
known similar in general form to the
Fic. 301.—Upper aspect of common ant-lion, but they walk forwards

prpraeay aie tf cr9 in the normal manner, and apparently

stomach ; ¢, free extremi- hunt their prey by lurking in a hidden
oa i hwo Malpis™ lace and, when a chance occurs, rush-
portion of other six tubes; ing on the victim with rapidity. Brauer
dh covcum 5 spimeret s has observed this habit in the case of

J, J, muscles for protruding vs é
its sheath ; gy, g, maxillary Dendroleon pantherinus in the Prater at

glands. (After Meinert.) Vianna:

The most remarkable forms of Myrmeleonides are contained
in the genus Palpares. We figure Tomateres citrinus (Fig. 299),
an allied genus found in Eastern Africa as far south as Natal.
These Insects have conspicuous blotches and marks on their
wings. The species of Méyrmeleon are similar in form, but are
smaller, more feeble, and less ornate in appearance.

1 Ann. Sci. étrang. vii. 1834, pl. 12. 2 M‘Lachlan, Ent. Month. Mag. ii. 1865, p. 73.
8 Redtenbacher, Denk. Ak. Wien, xlviii. 1884, p. 335.

xXx | - HEMEROBIIDAE 459

Pitfalls, formed in all probability by ant-lions, have been
noticed in the Galapagos islands and in Patagonia, though none
of the Insects forming them have been found.

Sub-Fam. 2. Ascalaphides.— Antennae elongate, with a knob at
the tip; the apical area of the wing with irregular cellules,

{/
UT

Fie. 302.—Ascalaphus coccajus. East Pyrenees.

The sub-family Ascalaphides is not represented by any species
in Britain, though <Ascalaphus longicornis occurs .as far north as
Paris. In the mountainous regions of Central and Southern
Europe some species of the group form a conspicuous part of the
Insect fauna, owing to their bold and active flight; they are pre-
daceous in their habits, and fly about in a hawking fashion some-
what like that of dragon-flies. Some of the larger of the numerous
exotic species of the group are very like dragon-flies, but can be
distinguished by a glance at the elongate antennae with a knob
at theend. The sub-family consists of two groups—Holophthalmi
and Schizophthalmi. M‘Lachlan says: “The eyes in the Schiz-
ophthalmous division are really double, the upper portion over-
lapping the under; if the upper portion be separated the lower

division looks like a small spherical ordinary eye.” There
appears, however, to be considerable differences in the genera in
this respect. ‘

1 J. Linn. Soc. Zool, xi. 1873, p. 227.

460 ) NEUROPTERA | CHAP.

When the weather is wet or cold the Ascalaphi repose on the
stems of grass, with their wings placed in a roof-like manner, with
the head downwards, and are then very successful in concealing
themselves by the positions they assume, and by sidling round ©
the stems to escape from enemies. Some information as to their
metamorphosis has been obtained, though knowledge of this point _
is far from complete even as regards our European species of the *
typical genus Ascalaphus. Fora long time it was supposed thata —
larva mentioned by Bonnet in his writings was that of Ascalaphus,
but Brauer’ is of opinion that such is not
the case, and as he has described the meta-_
morphoses of A. macaronius he is no doubt
s* correct. The eggs (Fig. 303, A), forty or

fifty in number, are laid in two parallel rows
on the stems of grass. The larvae (Fig. 304,
larva of Helicomitus ?) are in general appear-
ance somewhat like those of Myrmeleon ;
they are carnivorous in their habits, like
the ant-lions, and have similar extraordi-
narily developed mandibles.’ Efforts to rear
the young larvae failed, but they were
kept alive for some time by supplying them
Fie. 108 ae with Aphidides found on Centaurea jacea. The
‘Ascalaphus macaro- ©0C0On is globular, and the change from the

nius. B, Sketch of nymph state’ to the’ imago is made in the ~

oosition of the youn :
larvae of Helieonitue cocoon, the structure of the mandibles of the

rags 9 C, out- pupa being peculiar, and specially adapted to
ine of natural size. : 2
(After Westwood.) the purpose of opening the cocoon.” The larvae
of Ascalaphides, although so like the ant-lions
in appearance, do not form pitfalls for the capture of their
prey, but lurk under leaves on the ground, or under stones;
they do not move backwards, but progress forwards in an
ordinary manner; the habit of backward movement that we
noticed in Myrmeleon being probably correlative with the habit —
of forming pitfalls. Hagen states * that the larvae of Ascalaphides
and Myrmeleonides, in addition to their peculiarities of form and
mandibular structure, are distinguished from those of other
Hemerobiidae by the hind legs having the tibia and tarsus united

1 Verh. z00l.-bot. Ges. Wien, iv. 1854, p. 471. 2 Westwood, Zc. p. 12.
| p
® P. Boston Soc. xv. 1878, p. 244.

_insimulans; these were observed by Mr.

XX ASCALAPHIDES 461

without articulation. .Westwood' has recently given an account
of the young larvae of a Ceylonese Ascalaphid of doubtful
species, but possibly Helicomitus

Staniforth Green to have the very
peculiar habit of sitting together in
a long row on the stem of a plant,
with the jaws widely extended and the
body of each one covered by the head of
the individual next it (Fig. 303, B).. The
little creatures waited patiently in. this
position until a fly walked between the
mandibles of one of them, then these
formidable weapons immediately closed, 7
and did not relax their hold until the
fly was sucked dry. If Westwood is
correct, the young larva of this species
differs much from the adult one, the
back of the head being broad and the
setigerous processes of the body very rye. 304.—Larva of Helicomitus
much more developed. Nearly thirty ™s¢mwans(!). (After West-
: ‘ wood.)
genera of Ascalaphides are known.” In
the genus Haplogenius we find an exception to the usual rule
that the wings in repose are held in a roof-like manner, it having
been noticed by Bates that in the species in question the wings
are held expanded as in the dragon-flies.
Guilding has described’ a very peculiar mode of oviposition
on the part of Ulula:macleayana in the island of St. Vincent ;
the eggs are said to be deposited by the female in circles on the
extremity of a twig, and nearer the base of this there is placed a
kind of barrier to repel intruders. “The female may be seen
expelling from her ovary these natural barriers with as much
care as her real eggs.” Guilding’s description was accompanied
by drawings of the eggs, barriers and larvae, but unfortunately

these were never published, and no further information has been

obtained on the subject. Hagen * suggests that the barriers may

1 Tr. Entom. Soc. London, 1888, p. 1, pls. 1, 2.

2 Cf. M‘Lachlan, J. Linn. Soc. Zool, ii. 1873, p. 219.

3 Tr. Linn. Soc. xiv. 1825, p. 140, and xv. 1827, p. 509.
4 P. Boston Soc. xv. 1873, p. 245.

462 NEUROPTERA CHAP.

be somewhat similar to the long stalks on which the eggs of
Chrysopa (Fig. 314) are placed.

Sub-Fam. 3. Nemopterides.—AHead more or less produced and
beak-like. Hind wings of peculiar form, being elongate and
somewhat strap-like. |

The Nemopterides are a small group of delicate, graceful Insects.

(atid a CTT

ee ee ee

S—.

Fic. 305.— Nemoptera lederert. Asia Minor. Fic. 306. — Presumed larva of Nemoptera
(After Selys.) A, The imago; B, its head (Necrophilus arenarius). After Roux. Pyra-
seen from in front and magnified. mids of Egypt.

About thirty species are known. Knowledge of the group is
still very imperfect. A larva has been found of a most remarkable
nature that probably belongs to it; it was described under the
name of Necrophilus arenarius, and considered to be a fully-
developed Insect. This larva occurs in the tombs and pyramids
of Egypt where sand has accumulated. The perfect Insects of
the genus Nemoptera are, however, found in open places amongst
bushes, and flit about in a very graceful manner. Several species
are found in Southern Europe and the Mediterranean region

XX HEMEROBIIDAE - 463

(Fig. 305, WV. ledereri), but none come so far. north as Central
Europe. Formerly the genus Nemoptera was considered to be
allied to Panorpa on account of the beak-like front of the head.
The parts of the mouth are, however, different from those of
Panorpa, and it seems more probable that if the Nemopterides
have to be merged in any of the divisions of Hemerobiidae,
they will be placed in Chrysopides or Osmylides. The species
of the sub-family were for a long time believed to be. peculiar to

the continental regions of the Old. World, but a species has
recently been discovered in Northern Chili.!

Sub-Fam. 4. Mantispides.—Prothorax elongate; the raptorial
Jront legs inserted at its anterior part.

The members of this small group are readily recognised by the
peculiar structure of the front legs; these organs resembling those
of the Orthopterous
family Mantidae, so that
the earlier systematic en-
tomologists, deceived by
this resemblance, placed
the Mantispides in the ,
Order referred to. !

The Mantispides ———-
possess four ities LLM | i, i IRS

iE

<i dd ds
ous wings, either sub- ie, |
equal in size or the Y
posterior pair smaller } ‘.
than the front pair and es | -

not folded; the veins of = Fic. 307.—Mantispa areolaris. Brazil. (After
these wings are rather hi ight
numerous, as are also the cells they form; there is considerable differ-
ence amongst the species in thislatterrespect,owing to the transverse
veinlets differing in their abundance. The antennae are short, not
in the least thickened at the tip. The head is not produced into a
beak. The anterior legs, placed quite at the front part of the thorax,
have the coxae very long; the femur is somewhat incrassate, and
is armed on one side with spines ; the tibia is shaped and articu-
lated so as to fold closely on to the spines, and to thus constitute a
formidable and perfect prehensile organ, the tarsus being merely
1 M‘Lachlan, 7r. Ent. Soc. London, 1885, p. 375.

464 NEUROPTERA CHAP.

a small appendage. Only a few species of Mantispa are found in
Southern Europe; but the group has representatives in most of

the warmer regions of the world, and will probably prove to be —

rather numerous in species. The front legs are used for the
capture of prey in the same way as the somewhat similar front
legs of the Mantidae. The transformations have been observed
by Brauer * in the case of one of the European species, JL. styriaca.
The eggs are numerous but very small, and are deposited in such
a manner that each is borne by a long slender stalk, as in the
| lacewing flies. The larvae
are hatched in autumn;
they then hibernate and go
for about seven months
before they take any food.
In the spring, when the
spiders of the genus Lycosa

egos, the minute Mantispa
larvae (Fig. 308, A) find
them out, tear a hole in the
~ bag, and enter among the
egos; here they wait until
the eggs have attained a
fitting stage of development

Fic. 308.—Mantispa styriaca. A, Larva newly

aes they ate the spiders when
these were quite young, and then changed their skin for the
second time, the first moult having taken place when they
were hatched from the egg. At this second moult the larva
undergoes a considerable change of form; it becomes unfit for
locomotion, and the head loses the comparatively large size and
high development it previously possessed. The Mantispa larva
—only one of which flourishes in one egg-bag of a spider—under-
goes this change in the midst of a mass of dead young spiders
it has gathered together in a peculiar manner. It undergoes
no further change of skin, and is full fed in a few days; after
which it spins a cocoon in the interior of the egg-bag of the
spider, and changes to a nymph inside its larva -skin.

1 Verh. zool.-bot. Ges. Wien, xix. 1869, p. 831.

have formed their bags of _

before they commence to-
hatched, or first form ; B, mature larva. (After feed. Brauer found that ~

XX HEMEROBIIDAE 465

Finally the nymph breaks through the barriers—larva-skin,
cocoon, and egg-bag of the spider—by which it is enclosed,
and after creeping about for a little, appears in its final
form as a perfect Mantispa. Thus in this Insect hypermeta-
morphosis occurs; the larval life consisting of two different instars,
one of which is specially adapted for obtaining access to the
creature it is to prey on. It should be noticed that though this
Insect is so destructive to the young spiders, the mother spider
shows no hostility to it, but allows the destroying larva to enter
her bag of eggs without any opposition ; she appears, indeed, to
be so unconscious of the havoc that is going on amongst her
young that in one case she continued to watch over and protect
the egg-bag in which the destruction was taking place during
the whole of the period of the larval development and half the
period of pupation of the Mantispa.

The larval history of a second species of the Mantispides,
Symphrasis varia, is partially known ;* this Insect lives parasiti-
cally in the nests of a South American wasp, and each larva
when full fed spins a cocoon in one of the cells of the Hymen-
opteron.

Sub- Fam. 5. Hemerobiides.— Wings in repose forming an
angular roof over the body; the antennae moniliform or
pectinate, not clavate.

The Hemerobiides consist of several minor groups about
whose number and characters systematists are not very well
agreed, and about some of which very little is known. We
merely mention the latter, giving details as to some of the better
known only.

1. The Dilarina are a small group found chiefly in the Old
World, where, however, they have a wide distribution. North
and South America have each one species. They are distinguished
by their antennae, which, in the male, are pectinate somewhat like
those of many Lepidoptera, this character being of extremely rare
occurrence in the Neuroptera; the abdomen of the female termi-
nates in a long ovipositor. The metamorphoses are not known.

2. Nymphidina: Australian Insects resembling Myrme-
leonides, but having antennae without club. Metamorphoses not

known.
1 Brauer, Zool, Anz. x. 1887, pp. 212 and 218.
VOL. V 2H

466 NEUROPTERA CHAP,

3. Osmylina : a group of delicate and elegant Insects of
small or moderate size, distinguished by the possession of three

simple eyes placed on the middle of the head just above the
antennae. <A species of this group, Osmylus chrysops (maculatus
of some authors), is an inhabitant

to some extent amphibious. The
metamorphoses have been ob-
Hagen ;*
or close to the water, or in moss,
or on the stems of aquatic plants,
and pierces and empties small
Insects with its sucking-spears,
which are very elongate. The
young are hatched from the egg
in the autumn and _ hibernate
before becoming full grown;
when this moment arrives the
larva spins a round cocoon of
silk mixed with sand. The pupa,

Fia, 309.—Osmylus chrysops. A, Larva ;
B, side view of head of larva (after or nymph, in general appearance

Brauer Se Rope Neer Steere somewhat resembles the perfect

Insect, except that it is shorter and has the short wing-pads
clinging close to the body. Dufour denied the existence of

abdominal spiracles in either larva or imago, but, according to

Hagen, they are certainly present in both. It would appear
that in the larva the alimentary canal is not open beyond the
chylific ventricle, and that its terminal section is modified to
form a spinning apparatus. *

Osmylus and its allies, including Sisyra, are now frequently
treated as a separate sub-family, Osmylides, equivalent to the
Chrysopides. In it is placed a very anomalous Insect—Psectra
dispar—of great rarity. The male has only two wings, the pos-
terior pair being the merest rudiments, though the female has the
four wings normally developed. Individuals of the male have been
found’ in widely separated localities in the Palaearctic region—
Somersetshire being one of them—and also in North America. |

1 Linnaea entomologica, vii. 1852, p. 368, with plates.
2 See Albarda in Tijdschr. Ent. xvii. 1874, p. xvi.

of Britain (Fig. 212); its larva is

served by Dufour, Brauer, and —
it lurks under stones in

-
a © ey ee ee ee ee a

pine * = 7
eee ee ee ee ee ee

——

xx | HEMEROBIIDES

467 |

The genus Sisyra forms for some Neuropterists the type of a
separate group called Sisyrina, though by others it is placed, as

we have said, with the Osmylina, though
it is destitute of ocelli. The larvae of at
least one speciesof this genusareaquatic,
and have been found in abundance living
in Spongilla (Ephydatia) fluviatilis, a
fresh-water sponge; when discovered
their nature was not at first recognised,

as they possess on each ventral segment

a pair of articulated appendages, look-
ing like legs, but which are considered
to be more of the nature of gills. The
sucking-spears of this Insect are so
long and slender as to look like hairs ;
whether the little animal draws its
nutriment from the sponge, or merely
uses this latter as a place of shelter,
is hot ascertained.

4. Hemerobiina: a somewhat num-
erous group of small or more rarely
moderate-sized Insects, with moniliform
antennae, no ocelli, a complex and

\

i}

310.—A, Larva of Sisyra
JSuscatq, ventral aspect ; B, an
abdominal appendage. (After
Westwood.)

comparatively regular system of wing-nervures; the veinlets are
especially numerous at the margins, owing to the mode of forking

311.— Larva of
Hemerobius sp. from
Kent. A, The larva
bare; B, the same,
partially concealed
by the remains of

‘its victims, etc. ; a

portion of the cover-
ing has been removed
in order to show the
head.

of the nervures there (Fig. 298, Drepanepteryx phalaenoides).
The larvae of most of the species of which the habits are known

my

468 NEUROPTERA CHAP.

live on Aphides, which they suck dry, and at least one species,
in all probability several, has the habit of covering itself with
the skins of the victims it has sucked; to these remains it adds
other small debris, and the whole mass completely covers and
conceals the Insect (Fig. 311, B). The larva is furnished at
the sides with projections which serve as pedicels to elongate
divergent hairs, and these help to keep the mass in place on
the back of the Insect; some fine threads are distributed through
this curious mantle and serve to keep it from disintegration, but
whether they are fragments of spiders’ webs or are spun by the
Insect itself is not quite clear.

The genus Drepanepteryx consists of several species, and
appears to be best represented in the Antipodes; we have, how-
ever, one species in Britain—D. phalae-
noides (Fig. 298)—an extremely interest-
ing member of our fauna. This Insect
has, like several of its congeners, a
moth-like appearance, and it has a
peculiar structure for bringing the: hind
and fore wings into correlation, the costa
at the base of the hind wing being
interrupted and prominent, furnished
with setae (Fig. 312, A), and playing ina
cavity on the under-surface of the front
wing. This character is of great interest
in connexion with analogous structures
of a more perfect nature existing In various
moths. M‘Lachlan has described and
Fa, 312.—Portions of wings of fioured* a more primitive, though analo-

Drepanepteryx phalaenoides. mie . .

A, Under-face of basal parts gous, condition of the wings in Megalomus

of the two wings; a, base Airtus, also a species of British Hemero-

of front wing; 6, of hind , ,. ‘

wing. B, Portion of front blina. Another very curious feature of D.

wing, showing the apparent »haJqaenoides is shown in Fig. 312, B, there

interruption of nervures. ; ;

being a narrow space on the hind part of ;

the front wing from which the colour is absent, while the nervures
appear to be interrupted ; they are, however, really present, though
transparent; the nature of this peculiar mark is quite unknown,
but is of considerable interest in connexion with the small trans-
parent spaces that exist on the wings of some butterflies.

1 Tr. ent. Soc. London, 1868, p. 189.

,
ss) ee 4

er ae

ee

eX i
lis

"

' e

XX | HEMEROBIIDAE 469

Sub-Fam. 6. Chrysopides, Lacewing-flies.— Fragile Insects with

elongate, setaceous antennae.

The lacewing-flies—also called stink-flies and golden-eyes—are

excessively delicate Insects, of which we possess about 15 species
in Britain. Their

antennae are more , 1

slender and less dis-

tinetly jointed than Peas, 3 =

; =a te LHA

they are in Hemero- = eas | OSS
i - o< dh TP SS”

buides, and the Chry EE {7 \ 24 7 O33

sopides are more ZEA Te

elongate Insects. The <ore = 79 Waa ——

. : , Ay i its

peculiar metallic Gl TE ae i \\ LS ROS

colour of their eyes Cz ‘AL H LEAS »

is frequently very LM |

conspicuous, the eyes
looking, indeed, as if
they were composed of shining metal; this fades very much after

Fia. 313.—Chrysopa flava. Cambridge.

A .
Fic. 314.—Eges of Chrysopa. A, Five Fic. 315,—Larva of Chrysopa sp. Cambridge.
eggs on a leaf; B, one egg, more A, The Insect magnified; B, foot more
magnified. (After Schneider.) magnified ; C, terminal apparatus of the

claws, highly magnified.
death. Although not very frequently noticed, the Chrysopides
are really common Insects, and are of considerable importance

470 NEUROPTERA CHAP.

owing to their keeping “ greenfly ” in check, The eggs are very
remarkable objects (Fig. 314), each one being supported at the ~—

top of a stalk many times as long as itself; in some species
(C. aspersa) the eggs are laid in groups, those of each group
being supported on a common stalk. The larvae (Fig. 315) are
of a very voracious disposition, and destroy large quantities of
plant-lice by piercing them with sucking-spears, the bodies of
the victims being afterwards quickly exhausted of their contents
by the action of the apparatus connected with the spears. The
larvae of two or three species of Chrysopa cover themselves with
the skins of their victims after the manner of the larvae of
Hemerobius ; but most of the larvae of Chrysopa are unclothed, and
hunt their victims after the fashion of the larvae of Coccinellidae, to
. which these Chrysopa larvae bear a considerable general resemblance,
These larvae have a remarkable structure at the extremity of their

feet, but its use is quite un-

Some larvae of the genus
make use of various sub-
stances as a means of dis-
guise or protection. Dewitz

he denuded of their clothing

ing the head, placed the
morsels on their backs;
here the pieces remained in
consequence of the exist-
ence of hooked hairs on
the skin. Green algae
or cryptogams are much
used for clothing, and

Fie. 316.—Chrysopa (Hypochrysa) pallida, :
larva. (After Brauer.) Dewitz supposes that the

Insect spins them together
with webs to facilitate their retention. According to Constant
and Lucas* the larvae of Chrysopa attack and kill the larvae

1 Biol. Centralbl. iv. 1885, p. 722.
2 Bull. Soc. ent. France (6), i. 1881, pp. xxi. and xxxi.

known (Fig. 315, B, ©).

noticed! thatsomespecimens —

and placed in a glass, seized —
small pieces of paper with —
their mandibles and, bend- —

ee ee

fp ee a Tee @ = be

a ——-— es.

XX HEMEROBIIDAE 471

of Lepidoptera and Phytophagous Hymenoptera. The curious

’ form we figure (Fig. 316) has been hatched from eggs found by

Brauer on Pinus abies in Austria. The eggs were of the stalked
kind we have described; the young escaped from them in the
autumn, twelve days after deposition, but did not take any food
till the following spring.

The Chrysopides are widely distributed over the earth’s sur-
face. They form an important part of the fauna of the Hawaiian
islands.

Sub-Fam, 7. Coniopterygides.—Minute Insects with very few
transverse nervules in the wings ; having the body and wings
covered by a powdery efflorescence.

These little Insects are the smallest of the Order Neuroptera,
and have the appearance of winged Coccidae; their claim to be

considered members of the Neuroptera was formerly doubted,

but their natural history is quite concordant with that of the
Hemerobiid groups, near which they are now always placed. Low
has made us acquainted
with the habits and
structure of an Austrian
species, Coniopteryx lutea
Wallg., but for which he
has proposed the new |
generic name Aleurop-
teryx; the larvae are
found on Pinus mughus
at Vienna feeding on
Aspidiotus abietis, which | |
they pierce with sucking- Fic. 317. Coniopteryx psociformis. Cambridge.
spears, after the fashion Sbiet Cute) “e Bt — xe vee sf
of the Hemerobiides S ae ed, magnined ; BD, Wl wings ciosea, natura
when full fed they spin

a cocoon formed of a double layer of silk, in which meta-
morphosis takes place in a manner similar to that of other
Hemerobiidae. The better-known genus Coniopteryx differs
from <Aleuropterye in having the sucking-spears short and
nearly concealed by the front of the head, which is somewhat
prolonged.

Ps ae NEUROPTERA CHAP. X3

We may conclude this sketch of the Hemerobiid groups 1
remarking that fossil remains of specimens of most of them ha’

; Cc if
Fig, 318.—A, Larva of Coniopteryx tineiformis(?). (After Curtis.) B, Head and pro-—
thorax of larva of Coniopteryx sp.; ©, upper surface of head of larva of Ooniopter: a
(after Low), much magnified.

been detected in the Tertiary strata, and that in the Seconda ry
strata these groups are represented by only a small number of —

pe |

fossils, which are referred specially to Hemerobiina, Nymphidina, -
and Chrysopides. a

CHAPTER XXI

NEUROPTERA CONTINUED-—TRICHOPTERA, THE PHRYGANEIDAE OR
CADDIS-FLIES

Fam. XI. Phryganeidae—Caddis-flies.

(TRICHOPTERA OF MANY AUTHORS)

Wings more or less clothed with hair, nervures dividing at very
acute angles, very few transverse
nervules ; hind pair larger than — | s
the front, with an anal area which |
is frequently large and in repose
plicately folded. Antennae thread-
like, porrect, of many indistinct
joints. Mandibles absent or obso-
lete. Coxae elongate and free but
contiguous. Metamorphosis great ;
larvae caterpillar-like, usually in-
habiting cases of their own con-
struction. Pupa resembling the
perfect Insect in general form, becoming active previous to
the last ecdysis. Wingless forms of the imago excessively
rare.

Fic. 319.—Halesus guttatipennis.
britain. (After M‘Lachlan.)

THE caddis-flies are Insects of moth-like appearance, found in the
neighbourhood of water; their larvae live in this element, where
they may sometimes be found in abundance. Phryganeidae are
not very attractive Insects, and there are few of large size;
Hence they have been much neglected by entomologists, and very
little is known about the exotic forms of the family. The
habitations constructed by the larvae are, many of them, of a

474 NEUROPTERA CHAP.

curious nature, and usually attract more attention than do the
creatures they serve to protect.
. The Phryganeidae form the division or series Trichoptera ;
the two terms are therefore synonymous; those entomologists
who consider these Insects to form a distinct Order use the latter
appellation for it.
The perfect Insect, though the wings are usually ample, has
but feeble powers of flight, and rarely ventures far from the
water it was reared in; it has a moth-
._. like appearance, and the wings in
repose meet, at an angle, in a roof-like
manner over the back (Fig. 326, E).
The head is small, with the front in-
flexed ; it has two large compound eyes,
and usually three ocelli; the antennae
Fic, 820.— Hydroptila angustella aye slender,thread-like, and occasionally
?. Britain. (After M‘Lachlan.) i
attain a great length. The parts of the
mouth are very peculiar, the labrum and the palpi—cspeci-
ally the maxillary palps—being well developed, while the

lobes of the maxillae and labium are amalgamated and therefore —

indistinct. The labrum is more or less elongate, and is more
mobile than is usual in mandibulate Insects; it is held closely
applied to the maxillae. These latter are small, have usually
only a single small free lobe; they are united to one another and
to the labium by membrane in such a manner as to form a
channel along the middle of the mouth, the labrum forming the
roof of this channel. The palpi are in some cases (Sericosto-
matides) of a remarkable nature; their joints vary in number
from three to five, and differ sometimes in the sexes of the same
species. The lower lip appears as a plate supporting the labial
palpi, which are three-jointed and do not exhibit any peculi-
arities of structure comparable with those we have mentioned as so
frequently existing in the maxillary palps. Difference of opinion
exists as to the mandibles, some entomologists declaring them to
be entirely absent, while others state that a small tubercular pro-

cess that may be seen in some species on each side of the labrum.

is their representative. The prothorax is very small, the notum
is the largest piece but is quite short, the side-pieces are very

small, and the sternum appears to consist only of membrane. The

mesothorax is much the largest segment of the body; its sternum

XXI - PHRYGANEIDAE 475

is large, but is nearly perpendicular in direction, and is much
concealed by the elongate, free front coxae, which repose against
it. The metathorax is intermediate in size between the pro- and
meso-thorax ; its side-pieces are rather large, but the sternum is
membranous, with a heart-shaped piece of more chitinous consist-
ence in the middle, entirely covered by the middle coxae. The
side-pieces both of the meso- and meta-thorax are large, and are
closely connected; the middle and posterior coxae are very large,
elongate, and prominent, and the middle pair slope backwards,
so that their tips are in contact with the tips of the hind
pair. The abdomen is cylindric and rather slender; it looks as if
formed of eight segments in addition to the terminal segment ;
this latter in the male usually bears remarkably modified
appendages. The first ventral plate is sometimes, if not always,
entirely membranous; indeed the texture of the segments is in
general very delicate, so that they
shrivel up to an extent that renders
their comprehension from dried
specimens very difficult. The legs
are always elongate, the coxae attain-
ing in some forms a remarkable
length, and the tibiae and tarsi are
armed with many spines; the tarsi
are five-jointed, slender, frequently
very elongate, terminated by two
large claws and an _ apparatus,
placed between them, consisting of :
a pair of hair-like processes with a Fic. 321.— Front view of head of

membranous lobe after removal
The structure of the mouth-parts

of the Phryganeidae has given rise

to much difference of interpretation ;
it has recently been investigated by
R. Lucas? in connexion with <Ana-
bolia furcata (Fig. 321). He agrees

| with other observers that mandibles

are present in the pupa, but states

that no rudiment of them exists in the imago.

Anabolia furcata
of labrum. o0, Ocellus ; an, base
of antenna ; au, eye ; cm, cardo ; st,
stipes ; 7, external lobe ; pt, sup-
port of palpus; pm, palpus of
maxilla ; g, condyle of articulation
of the absent mandible ; ha, channel
of haustellum ; A, haustellum ; sp,
apex of channel of haustellum (not
explained by Lucas) ; ch, chitinous
point of external lobe of second
maxilla; pl, labial palp. (After
Lucas. )

He ealls the

peculiar structure formed by the combination of the maxillae and
1 Arch. Naturges. lix. 1893, Band I. p 285.

476 NEUROPTERA CHAP,

labium a haustellum. He looks on the Trichoptera as possess-
ing a mouth intermediate between the biting and sucking types
of Insect-mouths. He considers that the Phryganeidae take
food of a solid, as well as of a liquid, nature by means of the
haustellum, but the solid matter must be in the form of small
particles, and then is probably sucked up by the help of saliva
added to it. Lucas says also that in the larvae certain parts of
the salivary glands serve the function of spinning organs, and it
is from these that the salivary glands of the imago are formed;
those salivary glands of the larva that are not. spinning glands
disappearing entirely.

The eggs are deposited in a singular manner; they are ex-
truded in a mass surrounded by jelly; there may be as many as
one hundred eggs in such a mass. This is sometimes carried
about by the female after its extrusion from the interior of the
body, but is finally confided to a suitable place in stream, spring,
or pool. It is said that the female occasionally descends into the

water to affix the egg-mass to some object
therein, but this requires confirmation,
and it is more probable that the egg-mass
is merely dropped in a suitable situation.
As soon as the larvae are hatched they
begin to provide themselves with cases ;
they select small pieces of such material
as may be at hand in the water, and
connect them together by means of silk ~
spun from the mouth. Particulars as to
' these tubes we will defer till we have
considered the larvae themselves. These ©
have ‘the general appearance of cater-—
pillars of moths; in order to move about
they must put their head and the three
| pairs of legs at the front of the body out
Fic. 322.—Anabolia nervosa, Of their tube or case, and they then look

A, Larva extracted from yery like case-bearing caterpillars. The

its case; B, one of the .

dorsal spaces of the ab- part of the body that usually remains

dominal segments more ynder cover is different in texture and

strongly magnified. .

colour, and frequently bears outstanding
processes, or filaments, containing tracheae for the purpose of
extracting air from the water. Some peculiar spaces of a

xxI CADDIS-FLIES 477

different texture may be seen on certain larvae (Fig. 322, B);
these may possibly be also connected with respiration. On
each side of the extremity of the body there is a rather
large hook by which the creature attaches its dwelling to its
body, and there are also frequently present three large bosses
on the anterior abdominal segment, which are supposed to
assist towards the same end. The hold it thus obtains is so
firm that it cannot be dragged out by pulling from the front ;
fishermen have, however, discovered a way of extracting it by a
strategic operation: the cases are, as a rule, partially open
behind, and by putting a blunt object in and annoying the
larva it is induced to relax the hold of its hooks and advance
forwards in the case, or even to leave it altogether. The firm
hold of the larva is maintained in spite of the fact that the body
does not fill the case. It is necessary that water should pass
freely into and out of the case, and that there should be some
space for the respiratory filaments to move in. The mouth of
the case is open, and the posterior extremity is arranged by the
larva in such manner as to allow a passage for the water; various
ingenious devices are adopted by different species of larvae with
the object of protecting the hind end of the body, and at the
same time of permitting water to pass through the case.

The mode of changing the skin, or the frequency with which
this occurs in the larval state of the caddis flies has not been
recorded, The duration of life in this
stage is usually considerable, extending
over several months: indeed in our
climate many species pass the winter in
this stage, completing the metamorphosis
in the following spring or summer; and
' aS one generation each year appears to
be the rule, it may be assumed that the
larval condition in such cases lasts from
seven to ten months. During this stage
the Insects are chiefly vegetable feeders,
some being said to feed on minute algae ; : ake CObr ee wie
animal diet is not, however, entirely B, Mandibles of pupa of
avoided, and it is said by Pictet that “rma angustata.
not only do some of the Phryganeidae eat other Insects, but that
they also sometimes devour their companions.

478 NEUROPTERA 7 CHAP.

At the end of the larval period of existence the creature
closes its-case by a light web spun at each end, taking care not
to prevent the ingress and egress of the water; it sometimes adds
a stone or piece of stick, and having thus protected itself, changes
toanymph. During the first part of this metamorphosis the

creature is completely helpless, for there is so great a difference

between the external structures of the larva and nymph as to
make the latter a new being, so far as these organs are concerned.
The changes take place in the interior of the larval skin, and as

they are completed this latter is shed piecemeal. The resulting

pupa or nymph greatly resembles the perfect Insect, differing
consequently very much from the larva. Pictet, who paid
special attention to the nymph condition of these Insects, con-
cludes, however, that many of the organs of the nymph are
actually formed within the corresponding parts of the larva, and
has given a figure that, if trustworthy, shows that the legs of
the nymph, notwithstanding the great difference between them as
they exist in the larva and in the perfect Insect, are actually

formed within the legs of the larva; each nymphal leg being

rolled up in the skin of the corresponding larval leg, in a
spiral, compressed manner, and the only articulations that can be
detected in the leg being those of the tarsus. The head of the
nymph is armed in front with two curious projections that are,
in fact, enormously developed mandibles (Fig. 323,B); they serve as
cutting implements to enable the nymph to effect its escape from
its prison; they are cast off with the nymph-skin, the perfect
Insect being thus destitute of these organs. The abdomen of the
nymph differs from that of the perfect Insect in possessing
external respiratory filaments; the nymphs of some species have
also the middle legs provided with swimming-hairs, that do not
exist in the imago.

As a rule the larvae bring the respiratory filaments into con-

tact with the water by moving the abdomen, but Fritz Miiller

found * that those of a Macronema move the gills themselves—after
the manner of Ephemeridae—with much rapidity. Many kinds
of larvae of Phryganeids possess at the posterior extremity of the
body exsertile pouches in the form of finger-like, or even branched,
processes into which tracheae do not enter. Miiller observed that
in the Macronema alluded to these pouches were generally not

1 Ent. Nachr. xiv. 1888, p. 274.

er CADDIS-FLIES 479

exserted ; when, however, the larva ceased to move the tracheal
gills, then these pouches were protruded. He is inclined to con-
sider them blood-gills. Similar structures are found in Lristalis
and some other Dipterous larvae that have to breathe under
difficulties.

The imagines of certain species possess filaments—or some-

thing of the sort—on the abdomen. Palmén, who has examined

these organs in Hydropsyche, thinks that they are the remains
of gills that existed in the larva and pupa, and that they are
functionless in the imaginal instar. M‘Lachlan thinks that in
Diplectrona, where the filaments are elongate, they may be
functionally active even in the imago.* —

The skin of the nymph is at first very soft, but it soon
hardens, and when about fifteen or twenty days have elapsed the
nymph opens its case by means of the mandibular processes, and

swims through the water with its back downwards till it reaches

some solid object by which it can ascend to the air; the nymph
skin then swells and splits, and the thorax of the imago’ pro-
trudes ; this is soon followed by the disengagement of the head
and other parts, and the imago having thus escaped, the nymph
skin remains a complete model of the external structure of the
nymph, and contains a considerable number of tracheae. This
sketch of the metamorphosis of a caddis-fly does not apply |
in all its’ details to all the forms of caddis-flies, there being
exceptions, as we shall mention hereafter. —

Dewitz has described? the first appearance and development
of the wings in larvae of Phryganeidae. Each one appears at
first in the form of a small thickening of the hypodermis, accom-
panied outwardly by a minute depression of the chitin (Fig.
324, A). He compares the structure in the earliest stage to the
entothoraciec projections into the interior of the body. The
rudiment grows as.the larva increases in size, the chitinous por-
tion being duly shed at the ecdyses. When the rudiment is larger
and more complex, a mesoderm layer appears in it (Fig. 324, B);
this is derived from a nerve-sheath near the rudiment. During
the resting state of the larva—after its case has been closed, but
before the pupal form has appeared—the wing assumes the form
and position shown.in C, Fig. 324. Dewitz’s description of the
process leaves much to be desired, and it is doubtful whether in

1 Trichoptera europ. 1878, p. 356, note. 2 Berl, ent. Zeitschr. xxv. 1881, p. 54

480

NEUROPTERA

CHAP.

C the position of the wing on the exterior of the body is due
to the stripping off of the chitinous integument, or to a process

of eversion, or to both.

Fic. 324,— Development of wings

of Phryganeidae. (After Dewitz.)
A, Portion of body-wall of
young larva of Trichostegia;
ch, chitin, forming at 7 a pro-
jection into the hypodermis m ;
ry and d. forming thus the first
rudiment of the wing. B, The
parts in a largely grown larva ;
a, ¢, d, b, the much grown hypo-
dermis separated into two parts
by 7, the penetrating extension
of the chitin ; v, mesoderm. C,
Wing-pad of another Phryganeid
freed from its case at its change to
the pupa ; 0, d, outer layer of the
hypodermis, m, of the body-wall ;
v, inner layer without nuclei.

There are about 500 species of this family of Insects known as
inhabiting the European region, and about 150 of this number occur

in Britain.

These are arranged by M‘Lachlan '—whose zealous

and persevering work at this neglected family of Insects is beyond
praise—in eight sub-families, on a system in which the structure
of the maxillary palpi plays a principal part; they are called

Phryganeides, Limnophilides,
Sericostomatides, Leptocerides,
Oestropsides, Hydropsychides,
Rhyacophilides, Hydroptilides.
The first three of these form
the division “ Inaequipalpia,”
in which the number of joints
in the maxillary palpi differs
in the two sexes, but is always
five in the female.
Phryganeides.—This group
includes the largest forms of
the family, and appears to be
almost confined to the tem-

perate regions of the northern hemisphere.

-

Fia. 325.—Cases of British Trichoptera. A,

Of Odontocerum albicorne ; A}, its ter-
mination ; B, quadrangular case of Orun-
oecia irrorata ; B', mouth of case.

This feature in

1 Monograph of the British Trichoptera in 7. ent. Soc. London, third series, vol.
v. 1865 ; and Monographic Revision of the European Trichoptera, 1874-1880.

of the Limnophilides are

+ CADDIS-FLIES 481

their geographical distribution is, however, by no means peculiar
to them, for a similar discontinuity of distribution exists in
numerous other groups of Insects, and even in other divisions
of the Phryganeidae.

The Phryganeides almost without exception inhabit still waters,
and it is more specially to them that the brief sketch of meta-
morphosis given in the preceding pages will be found to apply.
The larva always has the respiratory filaments simple and thread-
like, though elongate, and lives in a case that it carries about ;

this case is open at both ends, and the larva is said to occasionally

cut off the end having the least diameter and increase the other
end, thus accommodating the habitation to its own growth.
Limnophilides.—These Insects have only three, instead of four,

3 joints in the maxillary palpi of the male, but in most other respects

agree with the Phryganeides. There is, however, greater variety
in the habits of the larvae, though all live in free cases. In the
genus Hnoicyla (Fig.
326) we meet with the
anomaly of a Trichopter-
ous Insect that lives
amongst moss and dead
leaves, far away, it may
be, from water. The cases

al

een

} é
as
s

constructed of a great
variety of materials, and
are often decorated with
shells containing living

Inmates. Fic. 326.— Metamorphoses of Enoicyla pusilla.
In the genus Apa- (After Ritsema. ) A, Case of full-grown larva ; B,

; larva and case magnified ; C, larva extracted ; D
tania the phenomenon wingless adult female ; E, male. ine
of parthenogenesis is
thought to occur, there being at least two species in which no
male specimen has ever been discovered, though M‘Lachlan has
made special efforts to discover the sex of A. muliebris. It
should, however, be stated that these species have not been ex-
tensively investigated ; A. arctica has been detected in the Arctic
regions, and A. muliebris has occurred in several localities in
Europe, in Britain chiefly near Arundel in a lake of intensely
cold water.

VOL. V eae

482 NEUROPTERA CHAP.

Sericostomatides, like the Limnophilides, is a group rich in
species; the larvae are chiefly found, in streams. They form

portable cases out of sand and stones

© (Fig. 325, B, case of Crunoecia irrorata)
in preference to vegetable matter. It
is here that the genus Helicopsyche,
which for jong was an enigma to
naturalists, is now placed.. This genus
consists of Insects whose larvae form
ira, 897:-—Uoea’ ot Hedeopeyens spiral cases, similar to small snail shells,
shuttleworthi. (After von Sie- Of sand or minute stones. These objects
bold.) A, Natural size; B,C, occur in various parts of the world. ©
magnified, ¢ ; ;

Fritz Miller! has informed us that the
larva inhabiting one of them, when it withdraws entirely within
its abode to repose, takes the precaution of anchoring its snail-
like habitation, fixing it to a rock or stone by spinning some
temporary silken threads. The respiratory filaments in this
group are filiform.

Leptocerides.—The first group of the division Acunipalaal ;
so that there are five-jointed maxillary palpi in both sexes;
these organs are frequently developed in a remarkable manner.
The antennae are usually extremely long and slender. . The case
of the larva is portable (Fig. 325, A, case of Odontocerwm) ;
the respiratory filaments are not very conspicuous; they form
short tufts placed on various parts of the abdomen. Miiller * has
called attention to a species whose larva lives in Brazil between
the leaves of Bromeliae on trees.

- The Oestropsides is a small group, and has recently been
reduced by M‘Lachlan to the rank of an inferior division.

Hydropsychides.—An extensive group, in which the larvae
are believed to be chiefly of carnivorous habits. They vary,
according to species, as to the nature of the respiratory
filaments, and live in fixed abodes; these are less tubular than is —
the rule with the portable cases, and are formed from pieces of —
sand and stone spun together and fixed to. larger stones under —
water. Sometimes several larvae live together in loosely compacted
structures of this kind, and only form true cases when about to
undergo their metamorphosis. Miiller describes’ a Brazilian species _
of Kkhyacophylax as forming a case in which the mouth-end has a

1 Zeitschr. wiss. Zool. xxxv. 1881, Pl. IV. fig. 6.

XXI CADDIS-FLIES 483

large funnel-shaped verandah, covered by a beautiful silken net..
This larva lives in the rapids of various rivulets, and the entrance
to the verandah is invariably directed towards the upper part of
_ the rivulet, so as to intercept any edible material brought down
by the water. Several of these larvae, moreover, build their cases
so that they form a transverse row on the upper side of a stone;
as many as thirty cases may be placed in one of these rows, and
sometimes several rows are placed parallel with one another.
This same larva has the habit of coming out of its case when
necessary, and suspending itself in the water—as some caterpillars
do in the air—by means of a silken thread. Other members of
the Hydropsychides form tubes or covered ways of silk, earth and
mud attached to stones, and in which they can move freely about.
Some of the Hydropsychidae have been ascertained with certainty
to be carnivorous in the larval state. A species of the genus
Hydropsyche has been found by Howard! to help itself in the
task of procuring food by spread-
ing a net in the water in con-
nexion with the mouth of its
case. This net is woven in wide
meshes with extremely strong
silk, and supported at the sides
and top by bits of twigs and
small portions of the stems of
water - plants. Small larvae Fic: 328.—Case, with head of larva’ and
brought down by the current pa fn fecpreraongrsté ea ne ms
are arrested by this net for

the advantage of the larva that lurks in the tube. The
breathing organs of the larvae of Hydropsychides are apparently
of a varied character, and would well repay a careful study. Mr.
Morton informs the writer that some of our British species of
Philopotamus and Tinodes have no gills either in the larval or
pupal state, and probably respire by means of modified tracts in
the integument. In some of the allied genera, e.g. Polycentropus,
the larvae are destitute of gills, but the pupae possess them.

The Rhyacophilides is another group in which the larval
habitations are fixed. Some of these larvae have no respiratory
filaments, breathing only by means of the stigmata, but others
have tufts of filaments. These Insects have a peculiarity in their

SS
SS <
—=

i \
i Nu \
| iy

.
>,
—

1 Rep. of the Entomologist, 1886, p. 510, Washington.

484 NEUROPTERA ' CHAP,

2

metamorphosis inasmuch as the larva, instead of lying free, con-
structs a cocoon in its case or other habitation in which to change

toa nymph. In the larvae that do not make use of a portable —

case the abdominal hooks are not essential, and are replaced —

by other organs differing much in structure, being sometimes
apparently of a sensitive nature, in other forms possibly respira-
tory. Miiller tells us of a carnivorous larva of this group in

which the anterior legs are armed with powerful forceps for pre- |

datory purposes.
The Hydroptilides comprise the most minute of the

Phryganeidae, and their species will prob-—
ably prove to be very numerous in well- —

watered tropical regions, though few have
yet been described from there. The per-
fect Insects (Fig. 320) bear an extreme
resemblance to small moths of the group

titute of respiratory filaments, and con-
struct portable cases of a variety of
forms, some resembling seeds. Miiller has
given particulars of a curious nature as
to the cases of some Brazilian Hydrop-
tilides; one species moors its dwelling
to a stone by means of a long silken
pigre 21) Pi vat, Cable, by this artifice combining safety

larva magnified; A, larva with the power of ranging over a con-

Kunin he (After siderable extent of water. In Diaulus

there is only a narrow slit at each end

of the case, but one side of it is provided with two chimneys to
permit the flow of water for respiratory purposes.

The larva of Oxyethira (Fig. 330) is a curious form, possess-
ing comparatively long legs, and a head and thorax slender in
comparison with the distended hind body. The cases are
fastened, for the purposes of pupation, to a leaf of a water-lily.

Some very curious anomalies as regards the development

of the wings exist in the Phryganeidae ; Anomalopteryx, for —

instance, has the wings quite short and useless for flight in
the male, while in the other sex they are ample; in Hnoicyla
—the curious Insect figured on p. 481, in which the larvae
are of terrestrial habits—we find the females with only rudiments

Tineidae. The larvae (Fig. 329) are des- —

ee ee ee ee ee ae ee

XXI+ - CADDIS-FLIES 485

of wings, while in Zhamastes the posterior wings are absent in
both sexes. These anomalies are |
at present quite inexplicable; and
we may here mention that we
are in complete ignorance as to
the functional importance of
many of the peculiarities of the
Phryganeidae. We do not know 4
why the mouth is reduced from
the normal state, the maxillary
palpi being, on the other hand,
extraordinarily developed ; we do
not know the importance of the
numerous spines and of the |
spurs on the legs, nor of the mye, 330.—Ozyethira costalis, A, Larva
hairs on the wings, although — * “5 vr nets Kisotick) Acat fy
these are amongst the most

characteristic of the special features of this group ‘of Insects.

Fossils—Abundant remains of Phryganeidae belonging to
the Tertiary epoch have been discovered. They are common in
amber, and it is a remarkable fact that a larval case has been
found in amber. This seems almost inexplicable, except on the
assumption that such larvae were of arboreal habits, a condition
that, at the present time, must be excessively rare, though the
terrestrial habits of Hnoicyla warrant us in believing it may
occur. -In the Tertiary Lake Basin at Colorado the remains of
Phryganeidae in the imago state are extremely abundant, so
that it is curious that but few such remains have been found in
Europe.. In Auvergne the so-called indusial limestone, which
is two or three yards thick over a wide area, is considered to be
composed chiefly of the cases of larvae of this family.

In the Mesozoic epoch some wings found in the lower Purbeck
strata are considered to be those of Phryganeidae; similar wings
have been found in the Lias, but this is the only evidence of
the existence of the family at that period except a tube, supposed
to. be a tarval case, detected in the Cretaceous of Bohemia.
Earlier than this nothing has been discovered that can be
connected with the family, so that at present the palaeontological
evidence appears unfavourable to the view held by some that
the Phryganeidae may be considered forms allied to the early

> =
™
ae

486 NEUROPTERA CHAP. XXI

conditions of the Lepidoptera. It should be noted that the

3

head in Phryganeidae is the most important part from a

systematic point of view, and that fossils have been chiefly
identified from the wings; this is a much more doubtful
character,;as the wings of the Phryganeidae have a simple
system of neuration, and in shape have nothing very charae
teristic.

Extinct Order Palaeodictyoptera.

This seems to be the fittest place to notice the existence of
some fossil remains from the Palaeozoic rocks that cannot be
fitly, or certainly, assigned to any of our existing Orders, and to
which the above name has consequently been given. These
remains consist chiefly of wings in a more or less imperfect state
of preservation, and it is therefore quite doubtful whether the
course of assigning them to a separate Order supposed to be ex-
tinct be correct. This is all the more doubtful when we recollect
that an Insect fossil, Zugereon bockingi, having the head with
mouth-parts of a Hemipterous or Dipterous nature, has been found,
the wings attached to it being such as, had they been found
separate, would have been considered to be Neuropterous, or at
any rate allied thereto. “About forty-two forms of Palaeodicty-
optera are assigned by Scudder to a section called Neuropteroidea,
and may therefore be considered to have’a special resemblance
to our Neuroptera. These Neuropteroidea comprise numerous
genera and no less than six families. Scudder’s view -is at
the best tentative, and is not very favourably received by some
entomologists. Brauer has, indeed, objected altogether to the
formation of this Order Palaeodictyoptera, and Brongniart has
published a list of the Palaeozoic Insects in which a system
of arrangement different to that of Scudder is adopted. In his
most recent work’ Brongniart assigns some of these Neur-
opteroidea to the families Platypterides and Protodonates, which
we have previously discussed. The whole subject of these
Palaeozoic Insect remains is still in its infancy, and it would
not be proper to accept any view as final that has yet been
stated, nor would it be fair to dismiss the subject as unimportant
because of the great divergence of opinion amongst the authorities
who have investigated it.

1 Insectes fossiles des temps primaires, 1893, p. 38.

ee Se ee ee

CHAPTER XXII

HYMENOPTERA——HYMENOPTERA SESSILIVENTRES—-CEPHIDAE—
ORYSSIDAE——SIRICIDAE——TENTHREDINIDAE OR SAWFLIES

Order IV. Hymenoptera.

Wings four, membranous, without scales, usually transparent, never
very large, the posterior pair smaller than the anterior ; the
cells formed by the nervures irregular in size and form, never
very numerous (less than twenty on the front, than fifteen on
the hind, wing). Mandibles conspicuous even when the other

parts of the mouth form a proboscis. The side-pieces of the
prothorax are disconnected from the pronotum and overlap
the prosternum, usually entirely concealing tt. The females
are furnished at the extremity of the body with either saw,
sting, or ovipositor ; these parts may either be withdrawn
into the body or be permanently protruded. The metamor-
phosis is great and abrupt, the chief changes being revealed
in the pupa disclosed at the last moult of the larva ; this moult
is frequently delayed till long. after growth has been com-
pleted. In the pupa the parts of the perfect Insect are seen
nearly free, each covered in a very delicate skin.

THE term Hymenoptera includes ants, bees, wasps, sawflies, and
the tribes of innumerable Ichneumon-flies. The Order is of
enormous extent, consisting even at present of tens of thousands
‘of described and named species, and yet .these are but few in
comparison with those that remain-unknown. It has good claims
to be considered the “highest” Order of Insects. Sir John
Lubbock says: “If we judge animals by their intelligence as
evinced in their actions, it is not the gorilla and the chimpanzee,
but the bee, and above all the ant, which approach nearest to

488 HYMENOPTERA CHAP.

‘

1

man.’ * The mechanical perfection of the structures of the
individuals, and the rapid and efficient manner in which their
functions are discharged, are very remarkable. In many species
of Hymenoptera the individuals have the habit of living together
in great societies, in
which the efforts of
the members are com-
bined for the support
of the whole society
and for the benefit
of a younger genera-
tion. To fit them
for this social life
the bodies of the
larger number of the
individuals are more
or less changed in
structure, so that
S Ss they become workers.
Tie he These workers are in
igo . all cases imperfect
females; besides
Fic. 331.—Bombus lucorum. A, Adult larva; B, pupa ; carrying on the
C, imago, female. Britain. ordinary work of the

society, they tend and feed the young. The duty of reproduc-

tion is restricted to a single female, called a queen, or to a small —

number of such individuals in each society. The males occupy
an unimportant position in the society, and are usually much
shorter-lived than the workers and queens. The social Hymen-
optera do not form a single zoological group, but are of three
different kinds—wasps, bees, and ants. There are numerous
non-social, or solitary, wasps and bees.

In the Order Hymenoptera—especially in the higher forms.

—the males and females are often different in appearance and
structure. In the ants, one of the social groups, the workers, or
imperfect females, are quite wingless. There are numerous other
groups in which species, not social, are found, having the females
wingless while the males have wings. In a few species there is
an apterous condition of the male, perhaps usually only as a

1 P. ent. Soc. London, 1866, p. Ixv.

XXII EXTERNAL STRUCTURE 489

dimorphic form. In the parasitic division there are species that
are apterous in both sexes. The structure of the outer skeleton,
or external part of the body, exhibits some peculiarities, the chief
of which is the detachment of the side-pieces of the prothorax and
their great development. Not less remarkable is the abstraction
of a segment from the abdomen to become, as it were, part of
the thorax; while between the first and second true segments of
the abdomen there exists a joint, or articulation, of the utmost
mechanical perfection, enabling the operations of stinging and
piercing to be executed with an accuracy that cannot be surpassed.
As a result of the detachment of the thoracic side-pieces, the
front legs and the structures connected with them are disjoined
from the notum, as shown in
Fig. 332, and act in connex-
ion with the head, while the
dorsal portion of the segment _
remains attached to the great.
thoracic mass. The head is
quite free from the thorax
and very mobile; the upper
organs of the mouth—the
labrum and the mandibles—
are not subject to modifica-
tions equal to those exhibited | :
by the maxillae and lower F!l® 332:—Tenthredo, with head fully ex-
. tended: «a, pleuron; 0%, pronotum; c¢,
lip, which parts in the bees membrane ; d, mesonotum.
are prolonged to form a suc- 7
torial apparatus that may exceed in length the whole body of
the Insect. The mandibles remain cutting or crushing imple-
ments even when the maxillae and lower lip are modified to
form a suctorial apparatus of the kind we have mentioned; so
that in the higher forms—ants, bees, and wasps—the mouth-
pieces are completely differentiated for two sets of functions, one
industrial, the other nutritive. 3
Behind the head there is a large consolidated mass represent-
ing the thorax of other Insects, but made up, as we have already
indicated, in an unusual manner, and which therefore may be
called by a special name, the alitrunk (Fig. 333). The pronotum
forms the anterior part of the alitrunk, with which it is usually
very closely connected, being indeed frequently immovably soldered

490

HYMENOPTERA

thereto.

Fic. 333.—Alitrunk of Sphex

chrysis. A, Dorsal aspect :
a, pronotum ; 0, 7, mesono-
tum; c, tegula; d, base of
anterior, ¢,of posterior, wing ;
g, division of metanotum ; A,
median (true first abdomi-
nal) segment ; 7, its spir-
acle; k, second abdominal
segment, usually called the
petiole or first abdominal
segment. B, Posterior as-
pect of the median seg-
ment: a, upper part; 34,
superior, c, inferior abdomi-
nal foramen; d, ventral
plate of median segment ;
€, COxXa.

It exhibits, however, considerable variety, and is seen

in its simplest and least soldered state in
Cephus. In the higher bees the pro-
notum takes on a form not seen in any
other Insects, being one of the most
beautiful sclerites to be found in the

class (Fig. 334, pronotum of ylocopa).

We have already remarked that in
Hymenoptera the lower portions of the
prothoracic segment are detached from
the upper, so ,

that the pro-
notum is not
supported be-

neath by a

sternum as xa

usual, In the py¢, 334.—Pronotum of a car-

bees in ques- penter bee, Xylocopa sp.
| East India.

tion the pro-

notum makes up for the removal of the

corresponding side-pieces and sternum,
by becoming itself a complete ring,
its sides being prolonged and meeting
in the middle line of the under sur-
face of the body. At the same time
a large lobe is developed laterally on
each side, overlying and protecting the
first breathing orifice. The intermediate
stages of this remarkable modification
may be observed by dissecting a small
series of genera of bees.

Although the prosternum of a Hymen-
opterous Insect is not usually visible
owing to its being overwrapped by the

CHAP.

side-pieces, it is really, as shown in Fig. 335, B, of complicated
form. In Cimbex and some other sawflies the side-pieces are not so
large as usual, but the prosternum is larger and is exposed. The
prothoracic spiracle is rarely visible externally, but its position
is remarkably constant, and is usually indicated by a peculiar
lobe or angle of the pronotum projecting backwards just below

“XXII EXTERNAL STRUCTURE 491

the insertion of the front wing. This stigmatic lobe is frequently
fringed with short hairs.

The mesothorax is the largest of the three divisions of the
thorax proper; its notum is large, and usually divided into two
parts by a transverse suture. The side-
pieces are so placed that the epimeron is
rather behind than below the episternum.
The mesosternum forms the larger part of
_the under-surface of the alitrunk. A very
large phragma projects from the meso-
thorax into the interior of the body. The
mesothoracic spiracle is usually not visible ;
its existence was unknown to the older
entomotomists, who were in consequence led
to consider the spiracle of the median seg-
ment as belonging to the thorax. The meso-
thoracic spiracle is, however, easily seen in
Cimbex, placed in the suture between the
mesothoracic epimeron and the metathoracic

Fic. 335.—Articulation of
front legs of the hornet
(Vespa crabro, 2). A:
a, side-piece of pro-

episternum, a little below the insertion of
the front wing; close to this spot the meso-
phragma, just spoken of, comes, in Cimbex,

thorax overlying the
prosternum ; 0}, coxa ;
¢, trochanter. B, pro-
sternum proper, as seen

from front when ex-

to the surface. The mesothoracic spiracle
tracted.

is generally conspicuous in the worker ant.
The parts of the metathorax are usually small, but so much variety
prevails in this respect that no general description can be given.
The structure of the posterior part of the alitrunk has given
rise to an anatomical discussion that has extended over three-
quarters of a century, with the result that it is now clear that
the posterior part of what appears to be thorax in Hymenoptera
is composed of an abdominal segment. This part has been called:
“Latreille’s segment,” the “median segment,” and the “ pro-
podeum.” The latter term was proposed by Newman, under the
form of propodeon,? and appears to be on the whole the most

1 For a history of this complex question, see Gosch, Naturhist. Tidskr. (Rk. 3)
vol. xiii. 1881 ; and also Brauer, Sitzb. Ak. Wien, \xxxv. 1882.

2 Introd. hist. Insects, 1841, p. 143. The names proposed by Newman may be
adopted when it is specially requisite to use terms that are morphologically correct.
According to his nomenclature the true whole abdomen of petiolate Hymenoptera
consists of three anatomical parts: 1, the petiole or podeon ; 2, the propodeon or
part in front of the petiole ; 3, the metapodeon or part behind the petiole.

492 HYMENOPTERA CHAP.

suitable term for this part, which is of great importance in
systematic entomology, owing to the extreme variety of characters
it affords. Although it is clear that the propodeum is, in large
part, an abdominal segment, yet its morphology is still uncertain ;

what parts are pleural, what tergal, and what may be chitinised -

spiracular area, or portions of the metathorax, being undetermined.

The ventral portion of the propodeum affords a strong contrast —

to the dorsal part, being so small that it has frequently been
described as absent; it 1s, however, not difficult to detect it in
the position shown at d, Fig. 333, B..

Although the true first segment of the abdomen is detached from
its normal position and added to the thorax, yet the term abdomen
is conventionally restricted to the part
that commences with the true second
segment, which, in counting the number
of abdominal segments, is reckoned as
being the first. There are two modes
of articulation of the Hymenopterous
abdomen with the alitrunk; in one

remains of the calibre usual in Insects,
. while in the other (Fig. 336, B) it is
Fic. 336.—Articulation of abdo-
wen, pnd altemee ee at cae greatly contracted, so that the two
hex, B, Vespa. a, Propodeum parts are connected only by a slender
or median segment; 0, dorsal : ; ;
plate Be iMae Glee se stalk, the petiole. The petiole, besides
abdominal segment or petiole; articulating in a very perfect manner
2 spate of the propodeum with the propodeum by means of cer-
, hind coxa; e, ventral plate : . : é
of first (second true) abdomi- tain prominences and notches, is also
ee connected therewith by means of a
slender ligament placed on its dorsal aspect and called the
funiculus, shown in Fig. 333, A, just at the extremity of the
pointing line % This mode of articulation gives great freedom
of motion, so that in some Petiolata (Ampules) the abdomen can
be doubled under the body and the sting brought to the head.
It is worthy of note that even in the Sessiliventres—as the sub-

Order with broad-based abdomen is called——-some amount of

movement exists at the corresponding spot; while, as shown in |

Fig. 336, A, between a and 0, there exists an exposed membrane,
the homologue of the funiculus.
The number of abdominal segments that can be seen in the

(Fig. 336, A) the base of the abdomen

XXII EXTERNAL STRUCTURE 493

perfect Insect varies greatly. In Tenthredinidae nine can be
distinguished, while in some of the Chrysididae it is difficult to
detect more than three behind the petiole. These distinctions
are, however, superficial or secondary, being due to changes in
the later life in connexion with the stings or borers; in the
larvae that have been examined thirteen segments behind the
head have usually been detected. |

Nothing is more remarkable in the Hyménoptera than the
great differences that exist in the form of the petiole. This may
be very short, as in the bees, so that the abdomen when not
deflexed does not appear to be separated from the thorax (Fig.
831, C); in this condition it is said to be sessile, a term which
it would be well to replace by that of pseudosessile. In many
of the solitary wasps the petiole is very long. In ants it is re-
placed by one or two curiously-shaped small segments called
nodes (Fig. 60, B, 2,3), and in many ants these are provided
with structures for the production of sound. The abdomen is
formed by a system of double imbrications; each dorsal plate
overlaps each ventral plate, and the hind margin of each segment
embraces the front part of the one following; thus this part of
the body has not only great mobility, but is also capable of much
distension and extension. The pleura are apparently absent, but
each one has really become a part of the dorsal plate of the seg-
ment to which it belongs. This is shown to be the case by
Cimbex, where the division between pleuron and dorsal plate
exists on each segment except the basal one. Owing to this
arrangement, the abdominal stigmata in Hymenoptera appear
to be placed on the dorsal plates.

The organs for mechanical purposes existing at the extremity -
of the body in Hymenoptera exhibit a great diversity of form ;
they are saws, borers, piercers, or stings. Notwithstanding
their great differences they are all, in their origin, essentially
similar, and consist’ of six parts developed from limb-like pro-
longations on the penultimate and antepenultimate segments of
the larva, as described by Packard and Dewitz These processes
have by some been-thought to be not essentially different from
abdominal legs, and Cholodkovsky has recently advocated this
opinion.”

1 Zeitschr. wiss. Zool. xxv. 1874, p. 184.
2 Ann. Mag. Nat. Hist. (6) x. 1892, p. 442.

494 HYMENOPTERA CHAP.

The legs of bees exhibit modifications for industrial purposes.
In the stinging Hymenoptera the trochanters are usually of a
single piece, and these Insects are called monotrochous ; but in most
of the other forms the trochanters are more or less distinctly
divided into two parts (Fig. 345, 0). The usual number of joints
in the tarsus is five, but is subject to diminution in many cases.
In the bees and ants the first joint is altered in form; in the
bees to act as an instrument for gathering or carrying pollen; in
the ants to act, as it were, as a second tibia. Between the

claws there is a very perfect pad, already described and figured

on p. 106.

The wings are remarkable for the beautiful manner in whielt

the hinder one is united to the
anterior, so that the two act in
B flight as a single organ. The
hind wing is furnished with a

series of hooks, and the hind
margin of the front wing is

curled over so that the hooks
catch on to it. In some of the
parasitic forms the wings are
almost destitute of nervures,
and have no hooks. The powers
~ of flight in these cases are prob-
ably but small, the wings merely
serving to float the Insect in
the air. In some Hymenoptera,
- especially in Pompilides and
Fic. 337.—Wings of a carpenter bee. A, Xylocopa, the wings may be

The pair of wings separated ; a, posi- deeply pigmented or even me-
tion of the hooks: B, the same wings P

when united by the hooks. C, Portions tallic; and in some forms of

of the two wings: a, the series of Tenthredinidae, Ichneumonidae,
hooks ; 6, marginal hairs ; c, portion of a ;
edge of front wing, of which the other and Braconidae the pligmenta-
part has been broken away in order to tion assumes the form of definite
show the hooks.

patterns.

The studies of the internal anatomy of Hymenoptera are at
present by no means numerous or extensive. The alimentary canal
(Fig. 69) possesses a crop, gizzard, and chylific stomach in addition
to the oesophagus and intestine. The social Hymenoptera have

the power of disgorging matter from the alimentary canal for the

wal Me a a

XXII ANATOMY 495

purpose of supplying food for their young. The crop—which
is situated in the anterior part of the abdomen—is the reser-
voir that contains this matter. The mode of disgorgement is
believed to be pressure exerted on the crop by contraction of the
abdomen. Salivary glands are present in remarkable variety.
The tracheal system possesses, in the higher winged forms, large
saccular dilatations situated at the side of the abdomen. The
nervous system is of peculiar interest on account of the high
intelligence of many of the members of this Order; and on this
point of the anatomy, Brandt’ has made rather extensive inves-

Fic. 338.— Central nervous system

. (supra-oesophageal ganglion and ven-
tral chain) of a worker ant, Cam-
ponotus ligniperdus. (After Forel.)
a, Cerebral hemisphere ; 6, primor-
dial cerebral lobe or pedunculate
body (depressed so as to show other
parts); ¢, olfactory lobe (raised
from natural position); d, nerve
to labrum; e, antennary nerve; /,
scape of antenna; g, eye; A, optic
nerve ; 7, longitudinal commissures
connecting the hidden sub-oesopha-
geal ganglion with k, the prothoracic
ganglion ; 7, mesothoracic, m, meta-
thoracic ganglion ; s, ganglion of the
petiole ; , nerve from petiole to
other part of abdomen ; 7, qg, 0, 2nd,
3rd, 4th abdominal ganglia; p, ter-
minal nerve to cloaca; ¢ bases of
legs. “

tigations, having examined it in the adult of seventy-eight
species, and in the larva of twenty-two. In the adult there are
two cephalic—the supra- and the sub-oesophageal—two or three
thoracic, and from three to seven abdominal ganglia. The bees,
wasps, and some other of the Aculeata have only two thoracic
ganglia, while some ants have three. The supra-oesophageal
ganglion is very large. The most remarkable fact revealed by
Brandt’s investigations is the. great difference that exists between
the sexes and the worker caste in the same species. The pedun-

1 OR. Ac. Paris, \xxxiii. 1876, p. 613, and Ann. Mag. Nat. Hist. (4) xviii. 1876,
p- 504; also Horae Soc. Ross. xv. 1880, pp. 20 and 31.

496 HYMENOPTERA CHAP.

culate bodies of the supra-oesophageal ganglion are considered to
be in their development correlative with that of the intelligence
or instinct. In the workers of the social Hymenoptera these
bodies are very large, while in the males and females they are
small. The workers and females of Bombus have six abdominal
ganglia, while the males have only five; and the worker of the
honey-bee has five abdominal ganglia, while the male and the
queen-bee have but four. In the leaf-cutting bee (Megachile) the
male has four abdominal ganglia and the female five, and in the
wasps the workers have five, the males and females six. The
nervous system in the larvae shows but little difference between
the ganglia, which are thirteen in number, eight being abdominal.
In the embryo of the bee Kowalewsky has observed seventeen
ganglia. The changes that take place from the embryonic
to the imago condition are therefore. dirécted to the reduction
in number of the ganglia, which is accomplished by the
fusion of some of them. In the adult Hymenopterous Insect it
would appear that the first abdominal ganglion is always joined
with the last thoracic. |

Sub-Orders.—The distinction in the form of the abdominal
articulation, previously alluded to (p. 492, Fig. 336, A, B),
divides the Hymenoptera into two great sub-Orders, the members
of which are very different in their habits and life-histories.
The Sessiliventres are plant-eaters ; their larvae (Fig. 343, A) are
provided with legs, and are able to procure their vegetable food
for themselves. The larvae of the Petiolata are maggot-like

and helpless, and are dependent for food on supplies afforded

them by their parents or companions. It is said by Dewitz that
although the larvae of the Petiolata appear to be legless, there are
thoracic legs within the body. The metamorphosis, so far as it
is known, and the early life-history of the Sessiliventres are very
similar to those of butterflies and moths, except that the pupa is
soft and has no hard external skin. A few of these plant-eating
Sessiliventres become carnivorous in the perfect state—a change
of habit that is most unusual in Insects, though the reverse
occurrence is common. The larvae of the Petiolata exhibit, in
the cases that have been examined, the peculiarity that the
alimentary canal has not any outlet posteriorly until the ter-
mination of the larval stage of existence is approaching. In
some cases there is no anal orifice; in others this orifice exists,

XXII HYMENOPTERA 497

Te

but there is no communication between the stomach and the
posterior intestine.

Packard informs us! that in Bombus the larva, after it is
full fed, passes into the pupa state (Fig. 331, A, B) by a
series of transformations accompanied by moultings of the skin.
Packard’s statements have been confirmed by others, but details
have not been fully given, so that the number of the moults,
their intervals and other particulars, are still unknown. We
have remarked that the pupal instar is very like the perfect instar,
except that it is colourless and soft, and that each of the members
is wrapped in a very delicate skin; the colour appears gradually.
This metamorphosis exhibits important differences from that of
the Lepidoptera. Packard calls the Insect, during the stages of
transformation from the full-fed larva to the pupa, the semi-pupa ;
the later stages of the pupa, when the colouring has appeared, he
terms the subimago. Altogether he considers there is a series of
at least ten moultings of the skin. His ideas were apparently
derived from examination of a series of specimens after death
rather than from observation of the development in living indi-
viduals. The parasitic forms of Hymenoptera have apparently
extraordinary metamorpheses of very varied kinds.

Parthenogenesis.—One of the most remarkable facts con-
nected with this Order is the prevalence of parthenogenesis in a
considerable number of widely separated species. In many of
these Hymenoptera it is not a mere occasional occurrence, but
plays an important part in the continuity of the species; in-
deed, it is believed that in some. members of the Order the
reproduction is entirely parthenogenetic. We shall give par-
ticulars as to some of these cases in subsequent chapters, and
will here make some remarks on the different forms of partheno-
genesis existing in the Order. The three forms of parthenogenesis
mentioned on p. 141 all occur in Hymenoptera. In the gall-
making Cynipidae parthenogenesis is frequently accompanied with
alternation of generations, a generation consisting of the two sexes
being followed by another consisting entirely of females, which
in its turn gives origin to a bisexual generation. In this case
deuterotokous parthenogenesis is established as a part of the normal
economy of the species. This same form of parthenogenesis also
occurs in other species of Cynipidae unaccompanied by alternation

1 P. Boston Soc. x. 1866, p. 279.
VOL. Vv 2K

498 HYMENOPTERA _ CHAP.

of generations. Thus in Fhodites rosae the generations resemble
one another, and the male is very rare, but is still occasionally

produced,’ and the same condition exists in other Cynipidae.
According to the observations of Adler, we may assume that the’

male, in the latter cases, is useless, the continuation of the species
being effected by virgin females although males exist. Deutero-
kous parthenogenesis also occurs.in the sawflies, but as a com-
paratively rare phenomenon.?

Thelyotokous parthenogenesis is common in sawflies, and it

also occurs in some Cynipidae. There are several species of this —

latter family in which no males have ever been found.’ The
phenomena in Lhodites rosae we have mentioned, give rise to
the idea that in that species deuterotokous parthenogenesis occurs
as an exception, the species being usually thelyotokous. <A
most remarkable case of thelyotokous parthenogenesis is said to
exist in the case of the parasitic ant Z'omognathus. This species
is said to be monomorphic, only the female existing, and repro-
ducing by uninterrupted parthenogenesis. |

Arrhenotokons parthenogenesis—z.¢. parthenogenesis in which
the progeny is entirely of the male sex—occurs in several species
of sawflies. We find it also occurring in the case of the social
Hymenoptera; the workers of ants, bees, and wasps occasionally
produce eggs parthenogenetically, and the progeny in these
cases is always of the male sex. In the honey-bee the queen

sometimes produces eggs before she has been fertilised, and

the parthenogenetic young are then always of the male sex.
Some species of Hymenoptera exhibit two forms of partheno-
genesis. In Nematus curtispina the parthenogenetic generation is
generally of the male sex, but a female is occasionally produced ; *
while in Hemichroa rufa parthenogenesis may result in either
deuterotokous or thelyotokous progeny. No case is yet known
of a species exhibiting the three forms of parthenogenesis. From
this review we may conclude that parthenogenesis does not
favour the formation of one sex more than another; but it is
clear that it decidedly favours the production of a brood that is

1 Adler, Deutsche ent. Zeitschr. xxi. 1877, p. 209.

* Cameron, Brit. Phyt. Hym. Ray Society, i. 1882, p. 29, and ii. 1885, p. 218.

> Cameron, op. cit. iv. 1893, p. 9.

4 Brit. Phyt. Hym. i. p. 27. . Fletcher’s record, referred to by Cameron, men-
tions V. miliaris, but this name was probably erroneous.

a es

XXII PARTHENOGENESIS AND SEX 499

entirely of one sex, but which sex that is differs according to
other circumstances.

Production of Sex.—lIt is believed that a very peculiar form
of parthenogenesis exists in the honey-bee, and it is confidently
stated that the drones, or males, of that species are always pro-
duced from unfertilised eggs. These views are commonly called
the Dzierzon theory, and are widely accepted. They assume
that the eggs are male till fertilised, and then become female.
After the queen-bee is fertilised most of the spermatozoa soon
find their way into a small chamber, the spermatheca, near the
posterior orifice of the body; it is believed that each egg may
be fertilised as it passes the door of this chamber, and that the
eggs that produce females (i.e. workers or queens) are so ferti-
lised, but that the eggs that produce drones are not fertilised.
Hence it is supposed that the sex is determined by this act of
fertilisation, and Cheshire has described what he calls an appa-
ratus for differentiating the sexes. It is also confidently stated
that no male honey-bee ever has a father.

The facts we have stated as to the sexes resulting from
parthenogenetic reproduction in Hymenoptera generally, are
extremely opposed to the Dzierzon theory, in so far as this
relates to the production of sex. There have always been
entomologists’ who have considered this view unsatisfactory,
and the observations of several recent French naturalists* are
unfavourable to the idea that the sex of an egg is determined by
its fertilisation.

There can be no doubt that the queen honey-bee frequently
produces males parthenogenetically, and the error of the views
we are alluding to consists in taking the parthenogenesis to be
the cause of the sex of the individual. It must be recollected
that the laying of an unfertilised egg by a fertilised female may
be different physiologically from the laying of an egg by an
unfertilised female; for, though both have as result an un-
fertilised egg, it is possible that the fertilisation of the female
may initiate processes that modify the sex of the eggs produced
by the ovaries, so that though these may produce previous to
fertilisation only male eggs, yet after fertilisation they may
produce eggs of the opposite sex or of both sexes. In other

1 See Perez and Cameron, 7. Nat. Hist. Soc. Glasgow, n.s. ii.1889, p. 194.
2 Fabre, Marchal, Nicolas.

500 IIYMENOPTERA CHAP. XXII

words, the act of fertilisation may initiate a different condition
of nutrition of the ovaries, and this may determine the sex of
the eggs produced.

Polymorphism, or Castes.—The question of the causes of

the modified individuals forming the various castes of the social —

Hymenoptera has been much discussed. These individuals are
many of them very different in size and structure from-either of
their parents, and are also different in their habits and instincts.
This difficult subject is far from being completely elucidated.
In the case of the honey-bee it is well established that an egg of
the female sex can, after deposition, be made either into a queen
or a worker-bee by the mode of nutrition—using that word in
the largest sense. On the other hand, Dewitz thought that in
the case of the ant Formica rufa, the caste—whether worker or
winged female—is already determined in the Insect before leay-
ing the egg’ Weismann and others associate the caste with
‘some hypothetic rudiments they consider to exist at the pi
earliest stage of the embryonic, or oogenetic process.

Herbert Spencer says:” “Among these social Insects the sex

is determined by degree of nutrition while the egg is being
formed,” and “after an egg, predetermined as a female, has been
laid, the character of the produced Jnsect as a perfect female or
imperfect- female is determined by the nutrition of the larva.

That is, one set of differences in structure and instincts is deter-
mined by nutrition before the egg is laid, and a further set of

differences in structures and instincts 1s determined by nutrition
after the egg is laid.”

Spencer’s generalisation is not inconsistent with the facts
hitherto brought to’ light, though it is possible that the progress
of knowledge may show some variety as to the periods of the
development at which the commencements of the modifications
occur.

Fig. 339 represents the chief castes, or adult forms, existing

in a community of one of the most highly developed of the—

species of social Hymenoptera, the leaf-cutting ant, Atta cepha-
lotes. We shall, when dealing with Formicidae, enter into some
details as to these and other cases of polymorphism. Our object

0% Rajeinder to Professor Weisser; p- i. eee from Contemporary Review,
December 1893.

a ee Oe ee eS ee ee ee ee ee ee ee eee

Fig. 339.—Adult forms of Atta (Oecodoma) cephalotes, taken from a nest in Trinidad
by Mr. J. H. Hart, 25th June 1895. A, male; B, winged female; C-F, various
forms unwinged; C, so-called soldier; D, large worker; E, smaller worker; F,
smallest worker or nurse. All equally magnified (one and half times),

502 ‘ HYMENOPTERA CHAP.

at present is to bring to the eye of the reader the great diversity
of outer form that is believed, rightly or wrongly, to result from
the mode of treatment of the young. And we will also take this
opportunity of more fully illustrating the remark we made on
p. 85 as to the profound distinctions that exist between ants
and white ants, or Termites, notwithstanding the remarkable
analogies that we shall find to exist in many of their social
arrangements. | .

The analogies we allude to, coupled with the fact that there
is a certain general resemblance in outer form between the
workers of Termites and ants, and even between the extra-
ordinary castes called soldiers in the two groups, have given rise
to the idea that there is a zoological relationship between the
social forms of Neuroptera and Hymenoptera. The two are,
however, zoologically amongst the most different of Insects.
The external skeleton in Termites is remarkable for its im-
perfect development, the sclerites being small and isolated, while
the segmental differentiation of the body is low (Fig. 225, ete.),
so that there is no difficulty in counting the segments. In ants
the reverse is the case as regards both these facts, the various
segments being most unequal, so that their homologies have only
*been detected after prolonged studies, while the chitinisation and
articulation of the various parts is so complete that the ant may

be described as cased in armour, fitting together so exactly that
it is difficult anywhere to introduce the point of a needle into —

its chinks. The wings of the two kinds of Insects are also
extremely different. The differences between the modes of
growth and development of the two sets of Insects are as pro-
found as the distinctions in their anatomy. Termitidae belong
to the division of Insects in which the wings are developed
outside the body; Hymenoptera to the division’ in which they
are developed inside the body. In Termites the growth of
the individual is slow, and the final form is reached gradually.
In the ants the growth is carried on with great rapidity, and
during it the Insect is a helpless maggot absolutely dependent
on the attentions of its seniors, while the difference in form and
structure between the. ant-larva and the ant are enormous.
Both anatomy and ontogeny are profoundly different in ants
and Termites. To these distinctions must be added, as of much
importance, the fact that in Hymenoptera only the female sex

ee, Fe ee ee

XXII SUB-ORDERS *503

is modified for the division of labour, while in Termites both
sexes undergo this change. Hence it is impossible to suppose
that the remarkable analogies that exist between the societies of
ants and those of Termites are due to any common origin. It
is probably to some similar physiological susceptibilities in the
ancestors, at an extremely remote epoch, of both groups that we
must look for an explanation of the interesting resemblances in
the social lives of ants and Termites.

The Hymenoptera are no doubt one of the largest Orders of
Insécts, the species of the parasitic tribes being apparently
innumerable. No doubt 250,000 species of the Order exist; and
possibly the number may prove to be very much larger. Up to
the present time 25,000 or 30,000 have been discovered. No
remains of Insects of this Order, of older age than the Lias,
have been brought to light; it is indeed doubtful whether the
fossils considered to be Hymenopterous of the period referred
to are really such.

The Order, as already mentioned, consists of two very distinct
sub-Orders, viz. :—

1. Hymenoptera Sessiliventres.—Insects with the abdomen broad at the base,
its first segment not completely amalgamated with the thorax,

2. Hymenoptera Petioliventres or Petiolata.—The abdomen connected with
what appears to be the thorax by a slender joint, the posterior
part of the apparent thorax consisting of an abdominal segment.

Hymenoptera Sessiliventres.—This group has been variously

called Hymenoptera phytophaga, H. securifera, H. sessiliventres,
Hi. serrifera, H. symphyta. We prefer an old term, taken from
a character that enables us to recognise at a glance which group
a species belongs to. The division or sub-Order may be formally
defined as follows :— |

Abdomen nearly continuous in outline with the thorax, the two
parts having a broad connexion instead of a small highly
mobile articulation. Anal lobe of hind wings usually of
considerable size. Trochanters «ditrochous (transversely
divided into two, Fig. 345). Hatremity of body of female
furnished with saws or boring instruments, usually concealed,
in some cases visible in part. Larvae with complex mouth-
parts; three parrs of thoracic legs (imperfect in Cephidae and

504 HYMENOPTERA CHAP.

Siricidae), and frequently with numerous abdominal _ legs,
which are destitute of hooks. Food vegetable.

The Insects of this sub-Order never exhibit the highly
specialised habits and activity of the better known petiolate
Hymenoptera. Though the food in the larval stages is always

vegetable, there is considerable variety in the larvae and their

habits ; some feed in galls, some in the twigs of plants, some in
the hard wood of trees and shrubs. The majority, however, live
on the leaves of plants. Those that live in wood (Fig. 342, C)
resemble in appearance Coleopterous larvae that have similar
habits, and those that live on leaves (Fig. 343, A) resemble
Lepidopterous larvae that do likewise. There are four families
included in the sub-Order, viz. Cephidae, Oryssidae, Siricidae,
Tenthredinidae. ;

The British Sessiliventres—under the name Phytophagous
Hymenoptera—have recently been monographed by Mr. Peter
Cameron in a series of vols. published by the Ray Society.’
These contain many figures and many details relating to natural
history, in addition to the descriptions of genera and species.

Fam. I. Cephidae—Stem Sawflies.

Slender Insects, with weak integument ; free, more or less elongate
pronotum ; one spine on the front tibia. Larvae living in the
stems of plants or in the tender shoots of trees and shrubs.

The obscure little Insects composing this family have slender
antennae of peculiar form, composed of eighteen to thirty joints,

two of which are short and. stout; then come several long joints, |

with more or less power of movement, the terminal portion
consisting of an elongate club of many joints with little power
of movement. The pronotum is longer than is usual in the

Hymenoptera, and instead of being very closely connected with —

the mesonotum, it is free and mobile, although its -base over-
wraps the front of the mesonotum. The median plate (7.e. the
dorsal plate connecting the thorax and abdomen) is divided to
the base along the middle, the divisions being separated by a
membranous piece broader behind; the anal lobe of the posterior

1 Mon. Brit. Phyt. Hym. 4 vols. 1882 to 1893.

a

an§

eo eee

XXII CEPHIDAE 505

wings is small but distinct. The female bears a saw at the
extremity of the body, but it is covered by two flaps; these
form a short, terminal projection. Although too much neglected,
the Cephidae are really of great interest
as being of more imperfect or primi-
tive structure than any of the other
families of Hymenoptera. The larval
history has been traced in_ several
species. C. pygmaeus is sometimes very
injurious to corn crops on the con-
tinent of Europe, and even in our own
country its effects in this respect are
considered to be occasionally serious.
The egg is laid in the stem of the corn
plant; the larva soon hatches and eats
its way upwards in the stem. It is a soft mem a ee
grub, apparently footless, but really pos- female imago. _ Britain.
sessing six small projections in place of — After Curtis)
thoracic legs. It occupies all the summer in feeding, and when
full fed and about to prepare for its metamorphosis, it weakens
the stem by a sort of girdling process below the ear; it then
descends in the stem to near the root, where it constructs a
transparent cocoon, in which it passes the winter as a larva,
changing to a chrysalis in the month of May, and completing
its development by appearing as a perfect Insect shortly there-
after. The girdling operation is very injurious, and causes the
corn stem, when ripe or nearly so, to break in two under the
influence of a strong wind, so that the ears fall to the ground.
The history of C. integer has been given by Riley. This
Insect attacks the young shoots of willows in North America.
Riley states’ that by a wonderful instinct the female, after she
has consigned her ege to the twig, girdles the latter, preventing
it from growing any further, and from crushing the egg. by so
doing. The larva after hatching eats downwards, sometimes
destroying-a length of two feet of the twig; when full grown it
fills the bottom of the burrow with frass, and then previous to
making its cocoon eats a passage through the side of the shoot
about a quarter of an inch above the spot where the cocoon will
be placed, thus making it easy for the perfect Insect to effect its

1 Insect Life, i. 1888, p. 8.

506 IIYMENOPTERA | CHAP.

escape ; it leaves the bark, however, untouched, and is thus pro-

tected in its retreat. A delicate transparent cocoon is then spun
in which the larva passes the winter, changing to a pupa in the
following March, and emerging as a perfect Insect about six
weeks thereafter.

Somewhat less than 100 species of this family are at present
known; the great majority are found in the Mediterranean —
region, but there are several in North America. As a single species”
is known from Mexico and another from Japan, it is probable
that the family may prove to have a wider geographical exten-
sion than at present appears to be the case.

Fam. II. Oryssidae.

The median plate behind the metanotum entire, not divided in the —
middle; antennae inserted below the eyes immediately above
the mandibles, under a sharp edge.

This family consists of the genus Oryssus, and includes only
about twenty species, but is nevertheless very widely distributed
| over the world. They are very
rare Insects, and little is known
as to their habits; one species,
O. abietinus, was formerly found
in England. Should any one
be so fortunate as to meet with
it, he can scarcely fail to re-
cognise it on noticing the
peculiar situation of the base
of the antennae. In this re-
spect the Chrysididae somewhat
resemble Oryssus, but in that
group of Hymenoptera the hind
body or abdomen is remarkably
mobile, so that the Insects can
coil themselves up by bending
Fic, 341.—Oryssus sayi. North America. at this joint ; whereas in Oryssus

A, The female Insect; B, head seen the hind body is very closely

Reece amalgamated with the thorax—
more so, in fact, than in any other Hymenopterous Insect—and
has no power of independent movement.

XXII : HYMENOPTERA 507

Oryssus abietinus very closely resembles C. sayi (Fig. 341);
it has indeed been recently suggested by Mr. Harrington that
the two supposed species may really be identical.

Fam. III. Siricidae or Uroceridae.

Pronotum closely connected with the mesonotum, perpendicular in.
JSront ; the anterior lobe of the latter not separated by the
lateral lobes from the posterior lobe: the median plate (behind
the metathorax) is divided longitudinally along the middle.
The female is provided at the extremity of the body with an
elongate, cylindrical boring instrument. The larvae live in
the wood of trees.

Fic. 342.— Zremex
columba. North
Americu A,
Imago, female:
B, pupa, female,
ventral aspect :
C, larva ; a, im-
perfect legs: D,
parasitic larva of
Thalessa. (B
and D_ after
Riley.)

The Insects of this family are usually of large size and of
bright conspicuous colours; these, however, frequently differ
greatly in the sexes of the same species, and may be very vari-
able even in one sex. The antennae are filiform and usually
elongate ; the head is usually contiguous with the thorax, but in
one division, Xyphidriides, it is exserted and separated from the
thorax by a well-marked neck. The pronotum is attached to
the mesonotum, and possesses very little, if any, freedom of
movement; it varies. in its size, being sometimes conspicuous

508 HYMENOPTERA CHAP. ~

from above; in the Xyphidriides it is smaller, and in the middle —

is entirely vertical in its direction. The mesonotum is moderate
in size, and its divisions are delimited by broad vague depressions.
The prosternum appears to be entirely membranous, but the
prosternal plates (pleura) are large, and meet together accurately
in the middle, so as to protect the greater part of the under-

surface of the neck. The abdomen is cylindrical or somewhat.

flattened above; it has seven dorsal plates in addition to the
spine-bearing terminal segment. The trochanters are double,
the outer division being, however, short; the anterior tibia has
only one spur; the anal lobe of the posterior wings is large.
The “ borer” or ovipositor of the female is a remarkable organ ;
it is held projecting directly backwards from the extremity of
the body, and has the appearance of being a powerful sting. The
apparatus is much longer than it appears, for it proceeds not
from the apex of the body, but from.the under-surface far for-
wards, so that the part exposed is only about one-half of the total
length ; it consists of a pair of elongate sheaths, which are easily
separable though they wrap together, and enclose a slender tube.

This tube is rigid and quite straight; though appearing solid, it

is really composed of two very perfectly adjusted laminae and a
third arched piece or roof. The two lower laminae are called
the spiculae; they aré serrated or grooved in a peculiar manner
near the tip, and although ‘so closely adjusted to the borer or
upper piece of the tube as to appear to form one solid whole
with it, they are said to be capable of separate motion. In
addition to these parts, the termination of the abdomen bears
above a shorter piece that projects in a parallel plane, and forms
a sort of thick spine above the ventral pieces we have described ;
this process is very strong, and has in the middle of its under-
face in Sirex gigas a membranous cavity, replaced in S. juvencus,
according to Westwood, by a pair of minute pilose styles. The
Insect, by means of this powerful apparatus, is enabled to deposit
her eggs in the solid wood of trees, in which the larva sometimes
penetrates to the depth of eight inches.

Sirex gigas is one of the most remarkable of our British
Insects, but is little known except to entomologists, being usually
rare. On the continent of Europe it is, however, an abundant
Insect, especially in the neighbourhood of forests of fir-trees,
and is a cause of considerable terror. As the Insect is not

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_ XXII SIRICIDAE 509

capable of inflicting much injury to the person, it is probable that
the peculiar ovipositor is believed to be a sting. The eggs are
laid—it is said to the number of 100—in the solid wood of fir-
trees, but not in perfectly healthy wood; the reason for this, it
is thought, being that in a healthy tree the great affluence of sap
caused by the burrows and presence of the Insect would be in-
jurious to the latter. The Strea will, however, attack a perfectly
healthy tree immediately after it has been felled. The larva, small
at first, enlarges its burrows as itself grows larger, and thus the
wood of a tree may be rendered completely useless for trade pur-
poses, although there may be’ very little outward indication of
unsoundness. The larva (Fig. 342, C, larva of Zremesz) is a pallid,
maggot-like creature, with six projections representing thoracic
legs; there are no other legs behind these, but some slight pro-
tuberances take their place; the terminal segment is enlarged, and
bears a hard spine. There is a difference of opinion as to the
duration of the life of the larva, Kollar saying that in seven
weeks after the deposition of the egg the maggot is full fed,.
while others consider that it takes two years to attain this con-
dition; the latter statement is more probably correct, it being
the rule that the life of wood-feeding larvae is more than usually
prolonged. After becoming full fed, the Insect may still pass a
prolonged period in the wood before emerging as a perfect Insect.
As a result of this it not infrequently happens that the Insect
emerges from wood that has been carried to a distance, and used
for buildings or for furniture. A case is recorded in which large
numbers of a species of Sivex emerged in a house in this country
some years after it was built, to the great terror of the inhabi-
tants. The wood in this case was supposed te have been brought
from Canada.

Fabre has studied! the habits of the larva of Sirex augur,
and finds that it forms tortuous galleries in the direction of the
longitudinal axis of the tree or limb, and undergoes its meta-
morphosis in the interior, leaving to the perfect Insect. the task
of finding its way out; this the creature does, not by retracing
its path along the gallery formed by the larva, but by driving a
fresh one at right angles to the previous course, thus selecting
the shortest way to freedom. By what perception or sense it
selects the road to the exterior is quite unknown. Fabre is not

1 Souvenirs entomologiques: quatriéme série, 1891, p. 308.

510 HYMENOPTERA CHAP,

able to suggest any sort of perception that might enable the larva

to pursue the right course, and considers it must be accomplished
by means of some sensibility we do not possess. Fabre’s observa-
tion is the opposite of what has been recorded in the case of 8.
gigas, where the larva is said to prepare the way for the exit of
the perfect Insect. |

Individuals of Sivex are often found in dried and solid wood,

encased by metal. When the Insect finds itself so confined; it
gnaws its way through the metal, if this be lead, and escapes.
The perseverance displayed by the Insect in these circumstances
seems to indicate a knowledge of the direction in which liberty
is to be found.

About 100 species of Siricidae are known. They form two

sub-families :—

1. Stricides: back of head nearly or quite contiguous with the pronotum.
2. Xyphidrvides: back of head separated from the pronotum by an elonga
neck. $

We are reputed to possess in Britain two species of each of

these sub-families, but it is doubtful whether more than one

Siricid is truly native. Sirex gigas is frequently brought over
in timber, and certainly breeds at times freely in Britain. Mr.
Leech has recorded the occurrence of the larvae in abundance
in fir-trees in the neighbourhood of Dublin. Sirex juvencus
is more rarely met with. Xyphidria camelus is doubtless a
native, though now apparently rare. It used to occur about eld
willows, near London, in the New Forest, and, I believe, also
in the neighbourhood of Cambridge.

Fam. IV. Tenthredinidae—Sawflies.

Hymenoptera Sessiliventres, having the pronotum small, accurately
adapted to the mesonotum ; the anterior lobe of the latter is
widely separated from the posterior; there are two spurs on
the anterior tibiae. The larvae usually live on leaves after
the manner of caterpillars, but a few inhabit galls.

The sawflies are an important family of Insects, their species
being numerous, while some of them are, in the larval state, very
destructive to vegetables and fruit. Being quiet creatures, rarely
seen on the wing, they are, though common Insects in this

ra

a fk ee ee ee

mite | Lat

XXII SAWFLIES 511

country, but little known, and few persons recognise a sawfly as
such. They are usually of small or moderate size, and the
numerous species have a great family resemblance. This remark
requires some qualification in the case of the Cimbicides, they
being Insects of larger size—usually surpassing the honey-bee—
of more robust structure,
and with greater powers of
flight.

The antennae are re-
markably variable in form
and structure. Cameron
considers that nine should
be taken as the normal
number of their joints;
but there are only three
in Hylotoma, while in Lyda
there may be forty or more.
The head is usually held
closely applied to the
thorax, but is really borne
Fic. 343.—Lophyrus pini. Britain: A, Larva; 00 @ neck capable of much

B, ventral aspect of pupa; C, imago, male- elongation (Fig. 332).

(After Vollenhoven.)

The pronotum forms .a
part of the alitrunk, but is not soldered thereto. Usually the
prosternun is more or less completely concealed by the side-
pieces, but in Cimbicides it is larger and conspicuous, the side-
pieces being in this group smaller than -usual. The dorsal
pieces of the mesothorax have their relative proportions different
to what we find them in the other families of Sessiliventres, and
even in most of the other Hymenoptera. There is first an
antero-median lobe of triangular shape projecting, like a wedge,
far backwards, into the great lateral lobes. ‘These latter form
the larger part of the area of the mesonotum ; they meet together
in the middle line, and behind are separated by a deep depression
from the posterior lobe, or scutellum of the mesothorax, which
is frequently divided into two parts, the anterior being the so-
called scutum. The pieces of the metanotum are short and
obscure, owing to the great unevenness of their parts; on each
side of the middle there is a small membranous space of pallid
colour. The cenchri, as these spaces are called, are, in Lyda,

512 HYMENOPTERA CHAP. .

delicate, membranous, depressed spaces, in front of each of which .

there stands up a flap of membrane. The function of the cenchri

is quite unknown. The median plate is fastened to the hind -

margin of the metanotum, and looks quite like one of the dorsal
plates of the following abdominal segments, from which, however,
it is separated by a more or Jess conspicuous membrane. In
the majority of the Tenthredinidae the median plate is divided
along the middle, but in the Cimbicides this is not the case.
The mesosternum is very large, and the metasternum small,
so that the middle‘and hinder pairs of coxae are placed close

together. The abdomen consists of nine segments, there being

eight dorsal plates in addition to the median plate, and seven
ventral plates besides the terminal armature. There is a pair of
short cerci, each of a single segment. The trochanters are
divided; each tibia bears two spurs at the extremity, and the
tarsi are 5-jointed.

The most characteristic and interesting of the structures with
which the Insects of this family are provided is the apparatus
from which the name of sawfly is derived. As long as two
centuries ago these instru-
ments excited the admira-
tion of Vallisnieri and of
Réaumur, who deseribed
them at length; and it is
truly astonishing that any
part of a living being
should be changed into
tools so mechanically per-
fect as these saws are
(Fig. 344). They serve
the purpose of assisting
the. female in depositing
the eggs in a suitable
situation, the place selected
being frequently the ten-
der stems of shrubs or

pair spread out and placed in a horizontal posi- ;
tion ; a, the lower margin of the saw proper; other plants, or the in-

b, the upper margin of the support: B, two

teeth of the saw more highly magnified. terior of leaves. These

organs are therefore of
course possessed only by the female. They are placed on the

XXII : SAWFLIES 513

lower aspect of the hinder extremity of the body, where they
are enclosed and protected by a pair. of sheaths, from which
they can be made to protrude by a little pressure exercised on
the parts immediately in front of them. Each female possesses
a pair of these saws; they consist of thin laminae of very
hard consistence, and are not only toothed at their edge, but in
many cases each tooth is itself serrate; at the same time the
outer face of the saw is sculptured or plicate in a remarkable
inanner, so that the saw in this way acts as a file or rasp. The
Insect having selected a suitable place, uses the saws by placing
the extremity of the abdomen against a twig or leaf, protruding
the blades, which, moving with an alternate motion, one being
thrust forward while the other is retracted, act on the plant so
as to make an incision. Each saw is directed in its movement by
the support, the pair of supports being united at the base by
- membrane as shown in Fig. 344. In the case of some species,
—Hylotoma rosae, the common sawfly of our rose-bushes, for
instance—there is no difficulty in observing the operation ; in-
deed old Réaumur, when speaking of the placid disposition of the
sawflies, suggests that it was given them so that we may easily
observe their charming operations. We cannot but regret that
in these days we are unable to take so complacent a view of the
arrangements of. nature. There is much variety in the details
of the structure of these saws; so much indeed that it is possible —
to identify most of the species by means of the saw alone.
According to certain observers, the eggs are laid by some kinds
on, not in, the leaves, so that we may conclude that in, these
cases the saws are not used by their possessors. An_ incision
having been made, an egg is placed in it, and also a drop of some
liquid matter. The egg is at first small, but soon increases till
it becomes twice or three times its former size, and the develop-
ment of the embryo commences.

The larvae of the Tenthredinidae exhibit great variety, and
are indeed in this respect more interesting than the perfect
Insects. The usual rule is that the larvae much resembles
those of Lepidopterous Insects, and feed exposed on plants in
the same way as Lepidopterous larvae do. But the exceptions
are numerous; sometimes the larva is covered with slime, and’
thus protected from various enemies. In other cases it is very
depressed, a broad creature, of irregular outline, living closely

VOL. V 21

514 , HYMENOPTERA CHAP.

attached to the leaf, somewhat after the fashion of a huge scale-
Insect. Some larvae mine between the layers of a leaf, others roll
up leaves; a few live in the stems of plants, and one or two inside
fruits. Even this does not complete the list of their habits, for
a few species of Vematus live in galls caused by the deposition of
the egg. <A species of Lyda forms for itself a case out of bits of
leaves, and carries this habitation about with it after the fashion
of the Phryganeidae. The number of legs in these larvae is
unusually great, varying from eighteen to twenty-two—that is,
three pairs of thoracic legs and eight of abdominal or pro-legs.
This character offers a ready means of distinguishing, in the majority
of cases, these larvae from those of the Lepidoptera in which the
number of legs varies, but is only from ten to sixteen; moreover,
the pro-legs in sawflies are destitute of the circles of hooklets
that exist in Lepidoptera. This mode of identifying the
immature stages of the Tenthredinidae is not, however, always
satisfactory, as there are some of these larvae that have no pro-
legs at all, but only the three thoracic pairs. Another point of
distinction exists, inasmuch as the larvae of the sawflies have
only one ocellus on each side of the head, whereas in the Lepi-
dopterous caterpillars the rule is that there are several of these
little eyes on each side. In addition to this, we should mention
that the Lepidopterous larva never has any pro-legs on the fifth
body-segment, whereas in the sawflies when pro-legs are present
there is always a pair on the segment in question.

These larvae are of various colours, but the patterns and —
markings they exhibit are not quite like those of the Lepidoptera,
though it would be difficult to make any correct general state- —
ment as to the nature of the differences. The variety of their
postures is very remarkable; and in respect of these also
Tenthredinidae differ considerably from Lepidoptera. Some of
them hold the posterior part of the body erect, clasping the
leaf by their anterior legs; others keep the posterior part of the
body curled up (Fig. 343, A), and some combine these methods
by curving the posterior part of the body and holding it away
from the food. These attitudes, like the general form, are
characteristic for each species. The Nematus larvae that inhabit
galls possess all the characteristics of those that feed externally.
As arule the skin of the larva is naked and free from hair, but
it is often minutely tuberculate, and in a few species it is armed

XXII SAWFLIES 515

with remarkable forked spines. These spines may exist during
part of the larval life, and completely disappear at one of the
moults. The creatures are as a rule very sluggish, and move
about much less than Lepidopterous larvae ; many of them, when
alarmed, have the power of exuding a disagreeable liquid, either
from the mouth or from pores in the skin; in the latter case it
may be sent as a sort of spray to some little distance from the
body. This operation is said to be very efficacious as a means
of protecting the larvae from the attacks of parasitic flies that
are desirous of laying eggs in their bodies. One peculiarity as
to their colour has attracted the attention of Réaumur and sub-
sequent naturalists, namely, that in the case of many species a
great change takes place in the colour during the life of the
larva, and more especially at the period of the last moult. The
change to the pupal state usually takes place in a cocoon, and
some species have the peculiar habit of forming a double cocoon,
the outer one being hard and coarse, while the inner is beauti-
fully delicate. The cocoon is sometimes formed in the earth,
and in that case it may be to a large extent composed of earthy
matter. The Insect frequently remains a long time in its cocoon
before emerging as a perfect Insect; however long this time may
be, it is nearly all of it passed in the larval state; when the
Insect does change to a pupa it speedily thereafter emerges as a
perfect Insect. In the pupa the parts of the imago may be seen
enveloped in a very delicate, transparent skin.

In Brazil Dielocerus ellisii, a sawfly allied to Hylotoma,
constructs a nest in which the cocoons of many specimens
are crowded together, being packed side by side like the cells
in the comb of the bee, while the whole mass is protected by
a thick outer wall. It is not known in what manner this
communal work is carried out, but it is interesting to note that
the cocoons assume to a considerable extent the hexagonal form
of the cells in the comb of the bee. Some doubt was expressed
as to the interpretation put on this structure by Curtis, but his
observations have been confirmed by Smith and Peckholt.

Several species of sawflies are known to be very injurious to
crops. One of these—the sawfly of the turnip, Athalia spinarum
(centifoliae Panz.)—sometimes commits excessive depredations
on the turnip crops in this country as well as on the continent of
Europe; its life-history and anatomy were described by Newport

516 HYMENOPTERA CHAP.

in an essay published by the Entomological Society in 1838.
The .eggs, it appears, are laid singly at the edges of the leaves
in the month of May, as many as 200 or 300 being deposited by
one female; as the parent flies are usually gregarious, appearing
in large numbers in fields of turnips, it is not difficult to form an
idea of the serious nature of their depredations. The egg grows
very considerably; the development of the embryo is rapid,
occupying, even in unfavourable weather, only seven or eight days,
while in quite congenial circumstances it is probable that the
eggs may hatch about the fourth day after their deposition. The
young grub immediately begins to feed, and in about five days
changes its skin for the first time; it. repeats this operation twice
at similar or slightly longer intervals, the third moult thus oceur-
ring when the larva is three or four weeks old; it is then that the
larva begins to be most destructive. Sunshine and warm weather
are very favourable to it, and under their influence it grows so
rapidly that in a few days a field may be almost completely
stripped of its foliage. This larva is of a sooty black colour,
and will live on other Cruciferous plants quite as well as on the
turnip. When full grown it buries itself to a slight depth under
the surface of the earth,-and forms an oval cocoon of a firm
texture, and with many particles of earth closely adherent to it.

The perfect fly emerges towards the end of July, and a second

brood will be produced in the same season if circumstances
are favourable; in that case- the resulting larvae enter the
ground for the formation of their. cocoons in September or
October, and pass the winter in their cocoons, but still in the
larval state; changing to pupae in the following spring, and
appearing as ‘perfect Insects in May. From this account
appears not improbable that the offspring of a single female
existing in the April of one year may amount by the following
May—three generations having been passed through in the
interval—to as many as 27,000,000 larvae. Fortunately the
creatures are, as Frauenfeld observed, destroyed in very large
numbers by a parasitic fungus and by a Nematode (/ilaria).

We have, earlier in the chapter, alluded to the fact that the
phenomena of parthenogenesis prevail somewhat extensively
among sawflies. It is the rule in the family that males are
very much less numerous than females, and there are some species
of which no males have been discovered. This would not be of

oa SAWFLIES 517

itself certain evidence of the occurrence of parthenogenesis, but
this has been placed beyond doubt by taking females bred in con-
finement, obtaining unfertilised eggs from them, and rearing the
larvae produced from the eggs. This has been done by numerous
observers with curious results. In many cases the partheno-
genetic progeny, or a portion of it, dies without attaining full
maturity. This may or may not be due to constitutional weak-
ness arising from the parthenogenetic state. Cameron, who has
made extensive observations on this subject, thinks that the
parthenogenesis does involve constitutional weakness, fewer of
the parthenogenetic young reaching maturity. This he suggests
may be compensated for—when the parthenogenetic progeny is
all of the female sex—-by the fact that all those that grow up
are producers of eggs. In many cases the parthenogenetic young
of Tenthredinidae are of the male sex, and sometimes the abnormal
progeny is of both sexes. In the case of one species—the com-
mon currant sawfly, Vematus ribesii—the parthenogenetic progeny
is nearly, but not quite, always, entirely of the male sex; this.
has been ascertained again and again, and it is impossible in
these cases to suggest any advantage to the species to compensate
for constitutional parthenogenetic weakness. On the whole, it
appears most probable that the parthenogenesis, and the special
sex produced by it, whether male or female, are due to physio-
logical conditions of which we know little, and that the species
continue in spite of the parthenogenesis, rather than profit by it.
It is worthy of remark that one of the species in which partheno-
genesis with production of males occurs—Nematus ribesii—is
perhaps the most abundant of sawflies.

Although many kinds of Insects display the greatest solicitude
- and ingenuity in providing proper receptacles for’ their eggs, and
in storing food for the young that will be produced, there are
extremely few that display any further interest in their descend-
ants; probably, indeed, the majority of Insects die before the
eggs are hatched, one generation never seeing the individuals of
another. It is therefore interesting to find that a fairly well
authenticated case of maternal attachment, such as we have
previously alluded to as occurring in earwigs, has been recorded
in Perga lewisii, an Australian sawfly of the sub-family Cim-
bicides. The mother, having deposited about eighty eggs on
the leaf of a Eucalyptus, remains with them until they hatch,

518 SAWFLIES CHAP. XXII

after which she sits over her brood with outstretched legs, and |

with admirable perseverance protects them, so far as she is able,
from the attacks of parasites and other enemies; she quite
refuses to be driven away from her charges. Mr. Lewis, to
whom we are indebted for this account,’ states that the sawfly
does not recognise her own special brood, but will give equal
attention to another brood if she be transferred thereto; and he
adds that many of the batches of larvae were destitute of any
maternal guardian.

There are about 2000 species of sawflies known. A large
majority of them are found in the European and North American
regions ; still, a good many are known to live in South America,
and Perga—one of the genera of the family containing many
species of large size—is peculiar to the Australian region.
Although the family includes so many species, very few anomalies
of structure have been detected in it; one species, Pompholyx
dimorpha Freymuth, is described as being apterous in the female,
and as having the thorax curiously modified in its form. There
are no very small Insects in the family, and none over the middle
size. Nearly 400 species. have been detected in Britain; this
number could certainly be increased by persevering researches.
The palaeontological record has hitherto given only a very
meagre evidence about sawflies. Several species have been
preserved in amber, and three or four are known from Tertiary
strata in Europe and North America.

1 Tr. ent. Soc. London, i. 1836, p. 232.

CHAPTER XXIII

HYMENOPTERA PETIOLATA——PARASITIC HYMENOPTERA-——CYNIPIDAE
OR GALL-FLIES——-PROCTOTRYPIDAE——CHALCIDIDAE——ICHNEU-
MONIDAE — BRACONIDAE — STEPHANIDAE — MEGALYRIDAE—
EVANIIDAE——PELECINIDAE—-TRIGONALIDAE.

WE now pass to the consideration of the Hymenoptera of the
sub-Order Petiolata, or Apocrita, as they are styled by Brauer.
We should make use of the term Petioliventres, for it contrasts
naturally by its termination with Sessiliventres, were it not that
the word is so uncouth that we think it better to adopt the
shorter and more euphonious expression, Petiolata.

The members of this sub-Order, without exception, have the
hind body connected with the thorax by means of a deep con-
striction, so that the base of the abdomen (Fig. 336, B, 5) is
very narrow; the articulation between the two parts is effected
by means of a complex joint allowing great play, and facilitating
the operations of boring and stinging, processes that are of
extreme importance in the economy of the great majority of the
species. The petiole is sometimes extremely short, but it may
be so long that it appears like a stalk, at whose extremity is
borne the remaining part of the abdomen (Fig. 369). When
the petiole is very short the abdomen reposes close to the back
of the thorax (Fig. 331, C), and in this case the abdomen is
usually described as sessile; while, when it is evidently stalked,
it is said to be petiolete. These terms are, however, unsuitable,
as the words sessile and petiolate should be reserved for the
conditions characteristic of the two sub-Orders. We shall
therefore use the terms pseudo-sessile and pedicellate for the
two conditions of the Petiolata.

The Hymenoptera Petiolata comprises an enormous majority

520 HYMENOPTERA CHAP.

of the Order. Although it includes many of the most interest-
ing and important of Insects, its classification
is but little advanced, for a great many of
the forms are still rare or unknown. ‘Three
series may be adopted for the purposes of
nomenclature.

ane 1. Parasitica—tTrochanters of two pieces,

female with an ovipositor. |
2. Tubulifera—Trochanters undivided ; ab-
domen consisting of only three, four, or five
visible segments. |
3. Aculeata.—Trochanters undivided; abdo-
men consisting of six or seven visible segments ;
female furnished with a retractile sting.
: In the absence of’ any clear distinction
Fic. 345.—Divided (di- between sting and ovipositor, these groups are
trochous) trochanter , :
of an Ichneumon: merely conventional. The character furnished
4 coxa s 0, the two by the trochanters is unfortunately subject to
ivisions of the tro- ; ‘ oye
chanter ; c, femur. SOme exceptions, there being a few parasitic
(For monotrochous forms in which the trochanters are not divided,
trochanter see lig. ‘ 5
385, A, c.) and a few aculeates in which the reverse
is more or less distinctly the case; moreover,
the division, when it exists, is in some cases obscure, and the two
pieces are of unequal size. Ratzeburg calls the upper division,
which is frequently much larger than. the other, the trochanter,
and the lower division the apophysis. There is much reason
for believing that the apophysis is really merely a secondary
division of the femur. The Tubulifera are a comparatively small
group, and will probably be merged in one of the other two,
when the anatomy and morphology of the abdomen have been

more thoroughly elucidated.

Series 1. Hymenoptera Parasitica or Terebrantia.

This is one of the most extensive divisions of the class
Insecta. There can be little doubt that it contains 200,000
species, and possibly the number may be very much greater than
this. It is, however, one of the most neglected of the great
groups of Insects, though it is. perhaps of greater economic
importance to mankind than any other. |

XXIII» PARASITES —. 521

Insects derive their sustenance primarily from the vegetable
kingdom. So great and rapid are the powers of assimilation of
the Insect, so prodigious its capacity for multiplication, that the
Mammal would not be able to compete with it were it not: that
the great horde of six-legged creatures has divided itself into two
armies, one of which destroys the other: The parasitic Hymen-
optera are chiefly occupied in destroying the tribes of vegetarian
Insects ; the parasites do this by the simple and efficient device
of dwelling in the bodies of their hosts and appropriating the
nutriment the latter take in. The parasites do not, as a rule,
eat the structures of their host,—many of them, indeed, have
no organs that would enable’ them to do this,—but they
absorb the vegetable juices that, in a more or less altered state,
form the lymph or so-called blood of the host. The host could
perhaps starve out his enemies by a judicious system of absten-
tion from food; instead, however, *of doing this, he adopts the
suicidal policy of persistent eating, and as the result of his
exertions, furnishes sufficient food to his parasites, and then
dies himself, indirectly starved. Ratzeburg considers that the
traditional view that the larvaé of parasitic Hymenoptera live.
by eating the fat-body of their host is erroneous. They imbibe,
he ccnsiders, the liquid that fills the body of the parasitised
Insect." ; 3

The wide prevalence of Insect parasitism is appreciated .only
by entomologists. The destructive winter moth—Cheimatobia
brumata—is known to be subject to the attacks of sixty-three
species of Hymenopterous parasites. So abundant are these
latter that late in the autumn it is not infrequently the. ‘case
that the majority of: caterpillars contain these destroyers. -Al-
though Lepidoptera are very favourite objects with parasitic
Hymenoptera, yet other Insects are also pertinaciously attacked ;
there is quite a host of Insect creatures that obtain their susten-
ance by living inside the tiny Aphididae, or “ green-tflies,” that
so much annoy the gardener. A still larger number of parasites
attack eggs of Insects, one or more individuals finding sufficient
sustenance for growth and development inside another Insect’s
‘egg. As Insects have attacked Insects, so have parasites attacked
parasites, and the phenomena called hyperparasitism have been
developed. These cases of secondary parasitism, in which another

' Ichneumonen der Forstinsecten, i. 1844, p. 86. _

522 HYMENOPTERA CHAP.

species attacks a primary parasite, are extremely numerous. It
is also pretty certain that tertiary parasitism occurs, and Riley
is of opinion that even quaternary destruction is not outside the
range of probability.

The physiological problems connected with Insect parasitism
are of great interest to the entomologist ; the modes of nutrition
and respiration of these encaged creatures could not fail to be
most instructive were we fully acquainted with them. It is
obvious that when an Insect-egg is laid inside another Insect’s
egg, and the parasite has to undergo the whole of its growth
therein, it is in the strangest condition as regards nutrition. It
is unnecessary for the intruded egg to have yolk of its own ;
moreover, the embryonic mode of nutrition may be continued
during what would, with other Insects, be the larval period.
And it seems to be the case that both these conditions are
actually met with in the lives ‘of egg-parasites. The embryology
and post-embryonic development of parasitic Hymenoptera have’
already been ascertained to be of the most extraordinary nature.
Great variety, however, will no doubt be found to exist, as will be
readily understood if we tabulate’the conditions of the early life
of various parasitic Hymenoptera.

1. The egg may be laid outside a larva, and the embryonic
and larval developments may both be passed on the exterior.

2. The egg may be laid and the embryonic development
passed through, outside the host, but the parasite on hatching
may enter the host, so that the post-embryonic development is
passed in the lymph of the host.

3. The egg may be laid inside the host, both embryonic and
post-embryonic developments being gone through in the fluids of
the host.

4. The egg may be laid inside another egg, the embryonic
and post-embryonic developments being passed therein.

We shall find that all these conditions exist in the Insects
we are about to consider.

We shall treat the series as composed of ten families; but
we must remind the student that this great subject ‘is still in a ~
very unadvanced state; the combined efforts of generations of
naturalists will be required to perfect it. Of the ten families
five are comparatively insignificant in number of species. Many
of the Cynipidae are not parasitic in habits, but live in galls.

XXIII GALL-FLIES | 523

After what we have said as to the mode of nutrition of parasites
it will be understood that the physiological conditions of life
may not be so different in a gall-dweller and a parasite as would
at first be supposed; and it is perhaps not a matter for much
surprise that good characters cannot be found to separate the
gallicolous from the parasitic forms.

Fam. I. Cynipidae—Gall-flies.

Wings with very few cells, with no dark patch (stigma) on the
anterior margin ; pronotum fixed to the mesonotum, and at
each side extending back to the point of insertion of the
Jront wing. Antennae not elbowed but straight, composed of
a moderate number (12-15) of joints. Early stages passed
either in galls or as parasites in the bodies of other Insects.

The Cynipidae are always small, frequently minute, Insects ;
usually black or pitchy in
colour. The simple struc-
ture of the antennae and
thenumber of their joints are
of importance as an aid in
identifying a Cynipid. The
mesonotum is usually re-
markably convex, and_ has,
behind, a prominent scutel-
lum, which more or less over-
hangs the small metanotum
and the median segment ;
these are perpendicular in their direction ; the sculpture of these
posterior parts of the alitrunk is usually deep and remarkable.
The abdomen has usually only a short petiole, so as to be pseudo-
sessile; but there are some genera in which this part is rather
long. The abdomen is generally so very much changed in outer
form that its structure is not easily understood. The visible por-
tion is frequently in larger part made up of the greatly enlarged
dorsal plate of the second or third segment, or of both. These
large plates are really chiefly composed of free flaps, and on lift-
ing them up the large ventral plates are disclosed, although these
appeared previously to be nearly or quite absent. In the female

Fig. 346.—Neuroterus lenticularis. Britain.

524 HYMENOPTERA CHAP.

there is a very slender ovipositor, of which only a small part pro-
trudes, although the organ is really elongate ; it is drawn into the
abdomen by means of a peculiar
series of structures, the modi-
fied terminal segments to which
it is attached being folded over

in such a way that the pos-
terior part becomes situated
anteriorly. In conformity with
this arrangement, the oviposi-
Fig. 347.—Ovipositor of Neuroterus laevius- tor is bent double on itself,
culus. (After Adler. ) a, d, The ovi- the anterior and the middle
penitor partially cole & extemity °F portions of the borer being
carried into the body, leay-

ing only a small part projecting beyond the extremity. The
Cynipid ovipositor is an instrument of much delicacy, and
is capable of a great deal of movement; it is usually serrate
just at the tip, and although it looks so very different from the

cutting apparatus of the sawflies (Fig. 344), it seems that it is”

really composed of pieces similar 3 in their origin to those of the
Tenthredinidae.

The wings frequently bear fp hairs; the paucity of nerv-
ures and the absence of the “stigma” are of importance in
the definition of the family. The most important of the cells is
one called the radial cell, situate just beyond the middle of the
front part of the wing.

We cannot enter into a consideration of the classification of
. the family, as authorities are not agreed on the subject. As
regards their habits Cynipidae are, however, of three different
kinds: (1) the true gall-flies, or Psenides, which lay an egg or
eggs in the tissues of a growing plant, in the interior of which
the larva lives after it is hatched; this mode of life may or
may not, according to the species, be accompanied by formation
of a peculiar growth called a gall: (2) Inquilines,’ or guest-tflies ;

1 See Cameron, Brit. Phiyt. Hym. iii. Ray Soc. 1890, p. 152. :

° The term inquiline is applied in entomology to a great variety of conditions
covered by the Latin word ‘*inauilinus” (incolinus), signifying a tenant or dweller
in another’s property. ‘The term parasite is used in a still wider and vaguer sense,

being in fact applied to a large number of cases, in many of which we do not at
present understand the exact reiations between the two parties con¢erned. This

into the interior of the body |

elt te meals i

XXIII GALLS ’ 525

these lay their eggs in the galls formed by the gall-makers
subsequent to the growth of the galls, of which they obtain
the benefit: (3) Parasites; these live, like most Ichneumon-flies,
in the interior of the bodies of other living Insects; they prey
on a considerable variety of Insects, but chiefly, it is believed, on
Aphididae, or on Dipterous larvae. These parasitic flies belong
to the sub-family Figitides.

A great deal of discussion has occurred relative to the nature
and origin of galls, and many points still remain obscure. Con-
siderable light has been thrown on the subject by the direct
observations of modern naturalists. Previous to Malpighi, who
wrote on the subject two hundred years ago, it was supposed that
galls were entirely vegetable productions, and that the maggots
found in them were due to spontaneous generation, it having been an
article of belief in the Middle Ages that maggots in general arose
from the various organic substances in which they were found, by
- means of the hypothetical process called, as we have said, spon-
taneous generation. Malpighi was aware of the unsatisfactory
- nature of such a belief, and having found by observation that
galls arose from the punctures of Insects, he came to the further
conclusion that the growth of the gall was due to the injection
by the Insect into the plant of a fluid he termed Ichor, which
had, he considered, the effect of producing a swelling in the plant,
something in the same way as the sting of a bee or wasp
produces a swelling in an animal. Réaumur also made observa-
tions on the gall-Insects, and came to the conclusion that the
latter part of Malpighi’s views was erroneous, and that the swell-
ing was not due to any fluid, but simply to irritation caused by
the prick; this irritation being kept up by the egg that was
deposited and by the subsequent development of the larva.
Observations since the time of Réaumur have shown that the
matter is not quite so simple as he supposed, for though in the
case of some galls the development of the gall commences immedi-
ately after the introduction of the egg, yet in other cases, as in
the Cynipidae, it does not occur till some time thereafter, being
delayed even until after the hatching of the egg and the com-
mencement of the development of the larva. Galls are originated

subject is no doubt destined to become a most interesting department of entomology.
See Riley, P. ent. Soc. Washington, ii. 1893, p. 397 ; and Wasmann, Zusanvmengesetz-
ten Nester, etc., 1891.

526 HYMENOPTERA CHAP.

by a great variety of Insects, as well as by mites, on many plants ;
and it must not be concluded that a gall has been formed by
Hymenoptera even when these Insects are reared from one.

Extremely curious galls are formed by scale-Insects of the sub-.

family Brachyscelides on Eucalyptus trees in Australia; they are

much inhabited by parasitic Hymenoptera, and Froggatt has -

obtained 100 specimens of a small black Chalcid from a single dead
Brachyscelid.* The exact manner in which many of these galls
originate is not yet sufficiently ascertained; but the subject of
the galls resulting from the actions of Cynipidae has received
special attention, and we are now able to form a conception
of their nature. They are produced by the meristematic or
dividing tissue of plants, and frequently in the cambium
zone, which is caused to develop to an unusual extent, and
in a more or less abnormal manner, by the presence of the
Insect. The exact way in which a Cynipid affects the plant is
perhaps not conclusively settled, and may be found to differ in
the cases of different Cynipidae, but the view advocated by Adler
and others, and recently stated by Riley,’ seems satisfactory ; it
is to the effect that the activity of the larva probably affects
the meristem, by means of a secretion exuded by the larva.
The mere presence of the egg does not suffice to give rise to the
gall, for the egg may be deposited months before the gall begins
to form. It is for the same reason improbable that a fluid injected
by the parent fly determines the gall’s growth. It is true that
the parent fly does exude a liquid during the act of oviposition,
but this is believed to be merely of a lubricant nature, and not to
influence the development. It is said that the gall begins to form

in some cases before the larva is actually hatched, but the eggs of _

some Hymenoptera exhibit remarkable phenomena of growth, so
that the egg, even during development of the embryo in it, may
in these cases, exert an influence on the meristem. It is to
reactions between the physiological processes of the meristem
and the growing Insect that the gall and its form are due.

The investigations of several recent naturalists lend support
to the view that only the meristematic cells of the plant can
give rise to a gall. Riley says that the rate of growth of the
gall is dependent on the activity of the meristem, galls on cat-

1 P. Linn. Soc. N. S. Wales (2), vii. 1892, p. 357.
2 Science (n.s.), i, 1895, p. 457.

aed
i

XXIII -BEDEGUAR 527

kins developing the most quickly ; those forming on young leaves
also grow with rapidity, while galls formed on bark or roots’ may
take months to attain their full size.

It is a curious fact that Cynipid galls are formed chiefly on
oaks, this kind of tree supplying a surprising number and variety
of galls. The plants that furnish Cynipid galls in Europe are
not numerous. A list of them is given by Cameron.’ Several
species, of the genus /hodites, attack rose-bushes.. One of the
best known of our British galls is the bedeguar, found in various
parts of the country on both wild and cultivated rose-bushes (Fig.
348), and caused by Rhodites rosae (Fig. 349). This gall has

Tic. 348. —Bedeguar
on rose, cut across
to show the cells
of the larvae; in
some of the cells
larvae are seen.

the appearance of arising from a twig or stem, but it is really a
leaf gall. Pazlavsky”* has described the mode of formation of
the bedeguar. The female Rhodites in the spring selects a rose-
bud—not a flower-bud—that should produce a twig and leaves,
and pricks this bud in a systematic manner in three places. The
three spots of the bud pricked by the Insect are the three unde-
veloped leaves that correspond to a complete cycle in the phyllo-
taxis of the plant. The three rudiments do not develop
into leaves, but by a changed mode of growth give rise to the
bedeguar. Usually this gall, as shown in our figure, is of
_ large size, and contains numerous cells; but abortive specimens
are not infrequently met with; sometimes a small one is seated
on a rose-leaf, and it is thought that these are due to a failure
on the part of the Insect to complete the pricking operation.

1 Ray Soc. vol. iv. 1893, p, 24.
2 Term. Fiizetek, v. 1882, p. 198, and Biol. Centralbi, ii, 1882, p. 617.

528 HYMENOPTERA CHAP.

Cynipidae will not go through their gall-making operations except

under natural conditions. Giraud’ attempted to obtain oviposi-
tion, on gathered twigs of oak,
from flies in confinement; but,
although he experimented with
thousands of specimens, they on

disposal, but discharged their
eggs in little heaps, without
attention to the twigs. The

attention to the fact that after
being deposited in a bud the eggs

Fic. 349.—Rhodites rosae, female. _ Of certain species of Cynips will

parestizbonss - remain dormant without produc-
ing, so far as can be seen, any effect on the tree for a period
of fully ten months, but when the bud begins to develop and
ihe egg hatches then the gall grows.

The exact mode in which the egg is brought to the requisite
spot in the plant is still uncertain. The path traversed by the
ovipositor in the plant is sometimes of considerable length, and
far from straight; in some cases before it actually pierces the
tissues, the organ is thrust between scales or through fissures, so
that the terebra, or boring part of the ovipositor, when it reaches
the minute seam of cambium, is variously curved and flexed.
Now as the canal in its interior is of extreme tenuity, and
frequently of great length, it must be a very difficult matter for
the egg to reach the tissue where it should develop. The eggs
of Cynipidae are very remarkable bodies; they are very ductile,
and consist of a head, and of a stalk that in some cases is five or
six times as long as the head, and is itself somewhat enlarged at
the opposite end. Some other Hymenoptera have also stalked
eges of a similar kind (Fig. 357, A, egg of Leucospis). It has
been thought that this remarkable shape permits of the contents
of the egg being transferred for a time to the narrower parts, and
thus allows the broader portion of the egg to be temporarily
compressed, and the whole structure to be passed through a very
narrow canal or orifice. It is, however, very doubtful whether

1 Ann. Soc. ent. France (4), vi. 1866, p. 198,

no occasion laid their eggs in
the fresh shoots placed at their ©

same observer has also called

ee ee

tee ey ae ee

XXIII GALL-FLIES 529

the egg really passes along the canal of the borer. Hartig
thought that it did so, and Riley supports this view to a limited
extent. Adler, however, is of a different opinion, and considers
that the egg travels in larger part outside the terebra. It should
be remembered that the ovipositor is really composed of several
appendages that are developed from the outside of the body;
thus the external orifice of the body is morphologically at the
base of the borer, the several parts of which are in longitudinal
apposition. Hence there is nothing that would render the view
of the egg leaving the ovipositor at the base improbable, and
Adler supposes that it actually does so, the thin end being
retained between the divisions of the terebra, Riley is of opinion
that the act of oviposition in these Insects follows no uniform
system. He has observed that in the case of Callirhytis clavula,
ovipositing in the buds of Quercus alba, the eggs are inserted by
the egg-stalk. into the substance of the leaf, and that the ege-
fluids are at first gathered in the posterior end, which is not
inserted. “The fluids are then gradually absorbed from this
exposed portion into the inserted portion of the egg, and by the
time the young leaves have’ formed the exposed [parts of the]
shells are empty; the thread-like stalk has disappeared, and the
ege-contents are all contained within the leaf tissue.” He has
also observed that in Biorhiza nigra the pedicel, or stalk, only is
inserted in the embryonic leaf-tissue, and that the enlarged portion
or egg-body is at first external. The same naturalist also records
that in the case of a small inquiline species, Ceroptres politus, the
pedicel of the egg is very short, and in this case the egg is thrust
down into the puncture made by the borer, so that the egg’ is
entirely covered.

Some Cynipidae bore a large number of the channels for their
egos before depositing any of the latter, and it would appear that
it is the rule that the boring of the channel is an act separate
from that of actual oviposition. Adler distinguishes three stages :
(1) boring of the canal; (2) the passage.of the egg from the base
of the ovipositor, where the egg-stalk is pinched between the two
spiculae and the egg is pushed along the ovipositor; (3) after the
point of the ovipositor is withdrawn, the egg-body enters the
pierced canal, and is pushed forward by the ovipositor until it
reaches the bottom."

1 Adler and Straton, Alternating Generations, 1894, p. 119.
VOL. V 2M

530 HYMENOPTERA CHAP.

About fifty years ago Hartig reared large numbers of certain
species of gall-flies from their galls, obtaining from 28,000 galls
of Cynips disticha about 10,000 flies, and from galls of C. folit
3000 or 4000 examples of this species; he found that all the
individuals were females. His observations were subsequently
abundantly confirmed by other naturalists, among whom we
may mention Frederick Smith in our own country, who made
in vain repeated attempts to obtain males of the species of the

genus Cynips. On one occasion he collected in the South of —

England 4410 galls of C. kollari (at. that time called C. ligni-
cola), and from these he obtained 1562 flies, all of which were
females. A second effort was attended with similar results. Hartig,
writing in 1843, after many years’ experience, stated that though
he was acquainted with twenty-eight species of the genus Cynips,
he had not seen a male of any one of them. During the course
of these futile attempts it was, however, seen that a possible
source of fallacy existed in the fact that the Insects were reared
from collected galls; and these being similar to one another,

it was possible that the males might inhabit some different gall. —

Adler endeavoured to put the questions thus raised to the test
by means of rearing females from galls, and then getting these
females to produce, parthenogenetically, galls on small oaks planted
in pots, and thus completely under control. He was quite
successful in carrying out his project, and in doing so he made a
most extraordinary discovery, viz. that the galls produced by these

parthenogenetic females on his potted oaks, were quite different

from the galls from which the flies themselves were reared, and
were, in fact, galls that gave rise to a fly that had been previously
considered a distinct species; and of this form both sexes were
produced. Adler’s observations have been confirmed by other natu-
ralists, and thus the occurrence of alternation of generations, one
of the two generations being parthenogenetic, has been thoroughly
established in Cynipidae. We may mention one case as illustrat-
ive. <A gall-fly called Chilaspis lowit is produced from galls on

oak-leaves at Vienna at the end of April, both sexes occurring.

The female thereafter lays eggs on the ribs of the leaves of the
same kind of oak, and thus produces a different gall from that
which nourished herself. These galls fall off with the leaves in
the autumn, and in July or August of the following year a gall-

fly is produced from them. It is a different creature from the

s

Sa A RN BO el gi 5 al et

XXIII GALL-FLIES 531

mother, and was previously known to entomologists under the
name of Chilaspis nitida. Only females of it occur, and these
parthenogenetic individuals lay their eggs in the young buds of the
oak that are already present in the autumn, and in the following
spring, when the buds open and the leaves develop, those that
have had an egg laid in them produce a gall from which Chilaspis
lowit emerges in April or May. In this case therefore the cycle
of the two generations extends over two years, the generation
that takes the greater part of the time for its production con-
sisting only of females. Adler’s observations showed that, though
im some species this alternation of generations was accompanied
by parthenogenesis in one part of the cycle, yet in other species
this was not the case. He found, for instance, that some gall-
flies of the genus Aphilothriz produced a series of generations
the individuals of which were similar to one another, and were
all females and parthenogenetic. In some species of the old
genus Cynips no males are even yet known to occur. A very
curious observation was made by the American, Walsh, viz. that
of galls gathered by him quite similar to one another, some pro-
duced speedily a number of both sexes of Cynips spongijica, while
much later on in the season the remainder of the galls gave rise
to females only of an Insect called Cynips aciculata. It is be-
lieved that the galls gathered by Walsh’ were really all one
species ; so that parts of the same generation emerge at different
times and in two distinct forms, one of them parthenogenetic, the
other consisting of two sexes. It has, however, been suggested
that Cynips spongifica and C. aciculata may be two distinct species,
producing quite similar galls.

Turning now to the questions connected with. inquiline or
guest-flies, we may commence with drawing attention to the
great practical difficulties that surround the investigation of
this subject. If we open a number of specimens. of any kind of
gall it is probable that several kinds of larvae will be found.
In Fig. 350 we represent four kinds of larvae that were taken
out of a few bedeguar galls gathered on one day in a lane near
Cambridge. It is pretty certain that No. 1 in this figure repre-
sents the larva of Rhodites rosae, and that Nos. 2 and 3 are
larvae of inquilines, possibly of Synergus, or of a parasite; while
No. 4, which was engaged in feeding on No. 3 in the position

1 P. entom. Soc. Philadelphia, ii. 1864, pp. 447, etc.

$32 HYMENOPTERA CHAP. |

shown, is possibly a Chalcid of the genus Monodontomerus, or
may be Callimome bedequaris. It is clear that, as we cannot
ascertain what is inside a gall without opening it, and thereby
killing the tenants, it is a most difficult matter to identify the
larvae; the only safe method is that of observation of the act of
oviposition ; this may be supplemented by rearing the flies from

galls, so as to ascertain what variety of flies are associated with —
each kind of gall. This last point has been well attended to;

but the number of cases in which oviposition of inquiline gall-

flies in the galls formed by the Psenides has been ascertained by —

direct observation is still very small; they are, however, sufficient
to show that the inquilines deposit their eggs only after the
galls are formed.

Fic. 350.—Larvae in-
habiting bedeguar
gall at Cambridge.
1, Rhodites rosae
in cell; 2 and 3,
larvae of inqui-

opteron.

Bassett recorded the first case of the kind in connexion with a
North American species, Cynips (Ceroptres) quercus-arbos Fitch.
He says: “On the first of June galls on Quercus ilicifolia had
reached their full size, but were. still tender, quite like the
young shoots of which they formed part. Examining them on
that day, I discovered on them two gall-flies, which I succeeded
in taking. They were females, and the ovipositor of each was
inserted into the gall so deeply that they could not readily free
themselves, and they were removed by force.”

The great resemblance of the inquiline gall-fly to the fly that
makes the gall both dwell in, has been several times noticed by
Osten Sacken, who says “one of the most curious circumstances
connected with the history of two North American blackberry
galls is, that besides the Diastrophus, which apparently is the
genuine originator of the gall, they produce another gall-fly, no
doubt an inquiline, belonging to the genus Aulaz, and showing
the most striking resemblance in size, colouring, and sculpture to
the Diastrophus, their companion. The one is the very counterpart

lines; 4, larva of |
a parasitic Hymen-

XXIII GALLS 533

of the other, hardly showing any differences, except the strictly
generic characters! This seems to be one of those. curious
instances, so frequent in entomology, of the resemblance between
parasites and their hosts! By rearing a considerable number of
galls of D. nebulosus I obtained this species as well as its parasite
almost in equal numbers. By cutting some of the galls open I
ascertained that a single specimen of the gall frequently con-
tained both species, thus setting aside a possible doubt whether
these Insects are not produced by two different, although closely
similar galls.” 4

_ The substance of which galls are composed, or rather, perhaps,
a juice they afford, is apparently a most suitable pabulum for the
support of Insect life, and is eagerly sought after by a variety
of Insects; hence by collecting galls in large quantities many
species of Insects may be reared from them; indeed by this
means as many 4s thirty different kinds of Insects, and belong-
ing to all, or nearly all, the Orders, have been obtained from a
single species of gall. Some galls are sought by birds, which
open them and extract their tenants, even in cases where it
might be supposed that the nauseous flavour of the galls would
forbid such proceedings.

Not more than 500 species of Psenides and Inquiline Cyni-
pidae are known from all parts of the world; and of. described
Parasitic Cynipidae there are only about 150 species. The
British forms have recently been treated by Cameron in the
work we have already several times referred to.’

A few Cynipidae have been found in amber; and remains of
members of the family, as well as some galls, are said by Scudder
to have been found in the Tertiary strata at Florissant.

Fam. II. Proctotrypidae, or Oxyura.

Small Hymenoptera, with few, or even no, nervures in the wings:
’ the pronotum closely adherent to the mesothorax, and at the.
sides reaching backwards to the points of insertion of the
wings. The abdomen is pointed, and the pointed apex is
frequently deflexed; the ovipositor is not coiled, but is
retractile, and when extruded is of tubular form, and appar-

1 P. ent. Soc. Philad. ii. 1863, p. 34.
_ * Brit. Phyt. Hym. vols. iii. and iv. Ray Soc, 1891 and 1893.

534 HYMENOPTERA | CHAP.

ently a continuation of the tip of the body. The earlier stages
are passed in the bodies, or in the eggs, of other Arthropods.

The Proctotrypidae is one of the most difficult groups of
Hymenoptera to define; some of its |

members exhibit a great resemblance
to Aculeate Hymenoptera. This is

(Fig. 351). It, however, is an
undoubted Proctotrypid, but there
are other forms that approach very
closely in appearance to the Acu-
leata, or stinging Hymenoptera; so
that until a better comprehension
is reached as to the distinction
between a sting and an ovipositor
Fra; $81.~=Helonus aneiatinde the separation between Proctotry-

Britain. pidae and Aculeata must be con-

sidered somewhat arbitrary.

There is extreme variety in the family; the wings differ
considerably in shape and neuration; they are not infrequently
altogether absent in one or both sexes. The chief distinction of
the family from other parasitic Hymenoptera is the tubular form

of the ovipositor ; which part appears to be a continuation of the —
tip of. the body. This latter is more definitely acuminate than —
usual, and has given rise to the term Oxyura, by which name ~
the Proctotrypidae are distinguished in many books. From the-

Chalcididae they are distinguished also by the angles of the
pronotum attaining the tegulae. In this character they agree
with the Cynipidae, but the ovipositor and abdomen are very
different in form in these two groups, and the Proctotrypidae
very frequently have a pigmented spot or stigma on the front
wings which is absent in Cynipidae. As if to add to the diffi-
culties the systematist meets with in dealing with this family,
some of its members have the trochanters undivided, as in the case
of the stinging Hymenoptera. The larvae of all that are known
lead a completely parasitic life in the bodies or eggs of other
Insects or of Spiders. Sometimes half a dozen specimens may
find the means of subsistence during the whole of their develop-
ment in a single Insect’s egg. Usually Proctotrypids pupate in

the case with the Insect we figure —

j
a ee ro

cance al

a a ——T 2

at

“XXIII PROCTOTRYPIDAE 535

the position in which they have fed up, enclosed each one in a
more or less dis- _
tinct cocoon. In
Fig. 352 we re-
present a very
remarkable case
of Proctotrypid
pupation; a
larva of some
beetle has nourished many specimens of a species of the genus
Proctotrypes, and the pupae thereof project from the body of the
host, a pair of the parasites issuing from each segmental division
in a remarkably symmetrical manner.

Comparatively little is known as to the habits of the members
of this family, but such information as has been obtained leads
to the conclusion that great variety will be found to exist in
this respect. We have already mentioned that numerous species
have been ascertained to feed inside the eggs of Insects or of
Spiders; others have been reared from larvae or from galls of
the minute Dipterous midges of the family Cecidomyiidae ;
others have been obtained from Cynipid galls, a few from ants’
nests and from green-fly; some .species are known to attack
Coleoptera. The distinguished Irish entomologist, Haliday, has
written an account of the proceedings of a species of Bethylus,
from which it has been supposed that this Insect carries off living
caterpillars, and stores them in a suitable receptacle as food for
its progeny, thus anticipating, as it were, the habits of the
fossorial division of the Aculeata, in which group this instinct
has, as we shall subsequently relate, attained an astonishing
degree of perfection. Haliday’s observation was unfortunately
incomplete and has not been subsequently confirmed. The
Bethylides are remarkable for their great approach in structure
to the Aculeates, so much so that entomologists are not agreed
as to whether. certain Insects are Proctotrypids or Aculeates.
Pristocera, with a very wide distribution, may be mentioned as
illustrative of these doubtful forms; but other genera of the
Bethylides are in many respects very similar to the Aculeates,
and it is not matter for surprise that Haliday should have con-
sidered the Bethylides to be a tribe of the stinging Hymenoptera.

1 Entom. Mag. ii. 1835, p. 219.

Fic. 352.—Pupation of Proctotrypes sp. in body of a beetle
larva.

HYMENOPTERA CHAP.

5 36

The genus Scleroderma consists of small Insects much resembling
ants, and, as well as some of its allies, is of great interest from

the remarkable phenomena of polymorphism presented by certain

species. The males in this genus are winged, the females com-
pletely apterous; yet at times winged females are produced—as
exceptional individuals in a brood of wingless specimens—the
females in these cases being not only winged, but possessed of

ocelli like the females of other winged Hymenoptera. Particulars’

of a case of this kind have been given by Sir Sidney Saunders,'
and Ashmead also mentions” the exceptional occurrence of these
winged females. Westwood * was of opinion that there are three
forms of the female sex. This subject is of importance in con-
nexion with the production of the various castes in ants.
Although the -presence of wings in these Insects is always

(which, it will be remembered, are normally
absent from the wingless individuals), yet
the converse is not always the case, for a
form of the female of Cephalonomia jor-
mieiformis, without any wings, yet having
ocelli, as well as eyes, well developed, is
figured by Westwood.*

The development of some of the Proec-
totrypids has been partially described by
Ganin and others, and is of an extra-
ordinary character.. Ganin’s observations °

Fig. 353.—Cyclops form of

.
es Se ee er ee eee

accompanied by the existence of ocelli-

larva of Platygaster sp.
(After Ganin.). a, Mouth;
6b, antenna; c¢, claw-
limb; d, lower lip (the
pointing line is a little
too short); e, doubtful
“ zapfenformig” organ ; f,
wing-like lobe; g, branch
of the tail.

were most complete in the case of a
species of Platygaster, which he found in
the larva of a very minute Dipteron of
the genus Cecidomyia.
larva changes its form very much in the
course of its life, resembling at first a
minute Crustacean rather than an Insect-

larva; it has a very large rounded anterior portion, while

behind it terminates in two, or more, tail-like processes.

By a

1 Tr. ent. Soc. London, 1881, p. 109.

* Bull. U. 8. Museum, No. 45, 1893, p. 28.

® Tr. ent. Soc. London, 1881, p. 117.

+ Tr. ent. Soc. London, 1881, pt. vi. f. 3; pp. 120, 126.

° Zettschr. wiss. Zool. xix. 1869; Ganin’s observations are described by
Lubbock, Origin and Metamorphoses of Insects, 1874, p. 34.

The Platygaster

ee

XXIII PROCTOTRYPIDAE 537

very peculiar kind of metamorphosis this Cyclops-like larva
changes into an almost unsegmented, oviform larva, destitute of
appendages ; by a second change this creature assumes a third
condition, in which it is similar to the ordinary form of para-
sitic Hymenopterous larvae.. Sometimes several of the Platy-
gaster larvae are found in a single host, but only one of them
reaches this third stage. Afterwards the third larval instar
passes into the pupal stage, which lasts five or six days, and
then the perfect Insect appears. It is worthy of remark that
the internal organs undergo quite as remarkable a change as the
outer form does. . The metamorphoses of some other Proctotry-
pidae have been examined by Ganin, and appear to be of an
equally interesting character.’

There is reason to suppose that these Platygaster parasites
are of great economic importance as well as of scientific interest,
for Platygaster herrickwi is one of the enemies of the larva of the
destructive Hessian fly, Cecidomyia destructor.

The Proctotrypidae are no doubt extremely numerous in species,
but as yet they have been very little studied; a good work on
the British species is much required. A valuable contribution
has recently been made to the study of the family by Ashmead,
in the book we have already referred to. This volume includes
much information on
the natural history of

Qy “A
these Insects, and the S\\, | \

outline figures give EM NX
some idea of the great —\y
variety of external a)

form.

Many entomologists
include the Mymarides
in Proctotrypidae, but
Ashmead considers Y | HIMNNS’
that they should be Uf : ; \
treated as a separate ag Bie!
family. Alaptus excisus
Westw. (Fig. 354)
has been frequently said to be the smallest known Insect, the

Fic. 354.— Alaptus excisus, Westwood. Britain.
(Probable size about 4 millim.)

1 See also Kulagin, Zool. Anz. xiii. 1890, p. 418 ; xv. 1892, p. 85 ;-and Congr,
internat. Zool. ii. 1892, pt. i. p. 258. ;

538 | HYMENOPTERA CHAP.

measurement given for it by Westwood * being a length of 2 of a
millimetre—about ++ 5 of an inch. Mr. Enock has recently
examined Westwood’s type in the Museum at Oxford, and from
his information we may conclude that this Insect is probably
the same as Alaptus fusculus Hal., and that the measurement
mentioned by Westwood is erroneous, the Insect being really

about half a millimetre long. The Mymarides are, however,

very minute, some of them not exceeding one-third of a milli-
metre in length. Whether any of them are smaller than the
beetles of the family Trichopterygidae, some of which are only
one-fourth of a millimetre long, may be doubted.

The Mymarides are recognisable by their very minute size,
and by their peculiar wings. These are slender, destitute of
nervures, fringed with long, delicate hairs, and stalked at the

base. Probably Mymarides may all prove to be dwellers in eggs —

of other Insects. The group is remarkable from the fact that it
contains some of the very few Hymenoptera with aquatic habits.
Two species were discovered in their winged condition in the
water of a pond near London by Sir John Lubbock*; one of
them—Polynema natans Lubbock—probably, according to Mr.
Enock, the same as Caraphractus cinctus Hal. uses its wings
freely for swimming under water, while the other—Prestwichia
aquatica—performs this operation by the aid of its legs. This
latter Insect seems to be very anomalous, and its position quite
doubtful. The embryogeny of Polynema is very peculiar, and
takes place in the egg of a’ dragon-fly—Calepteryx virgo—under
water. According to Ganin,’ in the earliest stages the develop-
ments of the embryos of the Calepteryx and of the Polynema

progress simultaneously, but that of the dragon-fly does not pro-_

ceed beyond the formation of the ventral plate. The Polynema

appears to leave its own egg at an extremely early stage of the.

embryonic development. It would appear, in fact, that there is
no definite distinction between embryonic and larval stages.
The information given by Ganin leads to the conclusion that a
complete study of this remarkable mode of development is
necessary before forming any general ideas as to the nature of
Insect embryogeny and metamorphosis.

1 Tr. Linn. Soc. (2) Zool. i. 1878, p. 587.
2 Tr. Linn. Soc. xxiv. 1863, p.135. 3 Zeitschr. wiss. Zool. xix. 1869, p. 417. °

XXIII _ PARASITICA 539

Fam. III. Chalcididae.

Pronotum with some freedom of movement, its angles not extend-
ing to the insertion of the front wings. Antennae elbowed,
consisting of from seven to thirteen joints. Wings without
a system of cells; with a single definite nervure proceeding
from the base near the front margin, or costa; afterwards
passing to the costa, and giving off a very short vein more or
less thickened at its termination. The species are, with few
exceptions, of parasitic habits.

The Insects of this family—the Pteromalini of Ratzebure—
are frequently of brilliant colours and of remarkable form; the
Species are very numerous, some 4000 or more having already
been described. Of this number nearly 3000 are European,
and as there is good reason for supposing that Chalcididae are
quite as numerous in the Tropics and in the New World as they
are in Europe, the family will probably prove to be one of the
largest in the class. About twenty sub-families have already been
proposed for the classification of the group; they are based
chiefly on the number of joints in the tarsi, and the details of
the antennae and of the ovi-
positor. This latter exhibits
great variety in external ap-
pearance, due chiefly to the -
modification in form of the ©
basal, or of the following ven- °
tral abdominal plates, one or
more of which may be pro-
longed and altered in form or
direction, giving rise in this
way to considerable diversity fe
en shape of bhie podommien: Fic. 355. — Eurytoma abrotani, male.
Correlative with this is a Britain. Hyper-parasite through Micro-
great variety in the mode iw of Ligure dignr, and according
of parasitism of the larva. and other gall-flies in Britain. x 10.
Many live in galls, feeding on ‘AMer Ratzeburg.)
the larvae of the makers of the galls or on those of the inquilines ;
others attack caterpillars, others pupae only; some flourish at
the expense of bees or other Hymenoptera, or of Coccidae

540 HYMENOPTERA CHAP,

and Aphididae, and some deposit their eggs in the egg-cases of
Blattidae. The details of the life-history are well known in
only a few cases.
The career of Leucospis gigas has been inveinttonted by Fabre,
and exhibits a very remarkable form of hypermetamorphosis."
This Insect is of comparatively
large size and of vivid colours,
wasp-like, black contrasting with
yellow, as in the case of the
wasps; and like these it has the
' wings folded or doubled. The
female bears a long ovipositor,
which by a peculiar modification
Fic. 356.—Leucospis gigas, female. is packed in a groove on the
pees i - back of the Insect. This species
lives in Southern Europe at the expense of Chalicodoma muraria,
a mason-bee that forms cells of a hard cement for its nest, the
cells being placed together in masses of considerable size ; each cell
contains, or rather should contain, a larva of the bee, and is closed
by masonry, in the construction of which the bee displays much
ability. It is the mission of the Leucospis to penetrate the
masonry by means of its ovipositor, and to deposit an egg in the
cell of the bee. The period chosen for this predatory attack is
the end of July or the beginning of August, at which time the
bee-larva is in the torpid and powerless condition that precedes
its assumption of the pupal state. The Leucospis, walking about
leisurely and cireumspectly on the masonry of the nest, tests it
repeatedly by touching with the tips of the antennae, for it is
most important that a proper spot should be selected. The bee’s
cell is placed in a mass of solid masonry, a considerable part—
but a part only—of whose area is occupied by the group of cells;
every cell is closed by hard mortar, making an uneven surface,
and the face of the masonry is rendered more even by a layer of
hardened clay outside the rougher material; it is the task of the
Leucospis to detect a suitable spot, in the apparently uniform
external covering, and there to effect the penetration so as to
introduce an egg into a cell. By what sensations the fly may
be guided is unknown. After a spot has been selected and the
ovipositor brought into play, the masonry is ultimately pierced

1 Sowvenirs entomologiques. Troisiéme série, 1886, p. 155.

XXIII INSTINCT 541

by patient work ; sometimes a quarter of an hour is sufficient for
the purpose, but in other cases three hours of uninterrupted
effort are required before the end is attained. Fabre expended
much time in watching this operation, and after the Insect had
completed it, he marked with a pencil the exact spot of the
masonry that was penetrated, and the date on which it was done,
and he states that he afterwards found that without any excep-
tion a proper spot had been selected, and a cell consequently
penetrated. Admirable as the instinct of the parasite appears
from this point of view, it is nevertheless accompanied by a
remarkable deficiency in two other respects. The first is that
though the spot selected by the Leucospis invariably gives
entrance to a cell, yet in the majority of the cases the selected
cell is not a suitable one; a large number of the cells of the
Chalicodoma are not occupied by living larvae on the point of
pupation—though in that case only can the egg of the Leucospis
hatch and successfully develop——but by dead and _ shrivelled
larvae, or by mouldy or dried-up food. And yet, in each case of
penetration, Fabre believes that an egg is deposited, even though
it may be impossible that it can undergo a successful develop-
ment. Strange as this may appear, it is nevertheless rendered
less improbable by the second deficiency in the instinct of the
parasite. The Insect has no power of recognising a cell that
has been previously pierced either by itself or by another of its
species. One bee larva can only supply nourishment for a single
larva of the parasite, and yet it is a common occurrence for a
cell to be revisited, pierced again and another egg introduced ;
indeed Fabre, by means of the cells he had marked, was able to
assure himself that it is no uncommon thing for this to be done
four times; four eggs, in fact, are sometimes deposited in a cell
that cannot by any possibility supply food for more than one
larva. The egg of the Leucospis is a curious object (Fig. 357,
A), very elongate oval, with one end drawn out and bent so as
to form a hook; ‘it is not placed at random in the cell of the bee,
but is suspended on the delicate cocoon with which the Chalico-
doma larva is surrounded at the period of pupation. Fabre
allowed sufficient time to elapse for the hatching of the larvae
from the eggs, and then opened some cells where Leucospis eggs
had been deposited, in order to obtain the larvae; when doing
- this he was surprised that he never found more than one Lew-

542 HYMENOPTERA CHAP,

cospis larva in a cell. Even in cells where he had observed
more than one act of oviposition, and which he had marked at
the time, only one larva existed. This induced him to think
that it was possible that no egg was deposited by the Leucospis
at the second penetration. He accordingly examined cells soon
after the eggs were laid, and thus discovered some that contained

more than one egg,—indeed in one cell he observed no less than.

five eggs suspended from the cocoon of the Chalicodoma ; he was
also able to demonstrate that eggs were actually deposited in some
cells that contained no means of support for the larva. How then
could these two facts be reconciled—four or five eggs deposited in
a cell, only one larva present afterwards? It is of course impos-
sible to observe the operations of a larva shrouded in the obscurity
of a cell formed of masonry, so he transferred some bee larvae
with their destructive companions to glass tubes, in which he was
able to note what took place. He found that the egg deposited
by the Leucospis hatches and produces a very peculiar larva,
having little resemblance to the Leucospis larva that he had found
eating the Chalicodoma larva. The primary larva (Fig. 357, B)
of the Leucospis is an arched worm, moderately deeply segmented,
a millimetre or a little more in length, with a remarkably large

and abruptly-defined head. The body bears —

erect setae, the most remarkable of which
are a pair on the ventral aspect of each of
the segments, each of these ventral setae
being borne on a small conical prominence.
SSS These prominences and setae serve as ambu-
latory organs, and are supplemented in their
function by a protuberance at the posterior
extremity. The little creature has consider-
Frc. 357.—Leucospis gigas, “Lie powers of locomotion; it moves, after
: : pis gigas. :
A, Egg; B, primary, the fashion of many other larvae, by con-
me Bg eee larva. tracting and arching the body so as to bring
the posterior part nearer to the anterior ;
then fixing the hinder part, the anterior is extended and fixed, the
posterior being again brought nearer to the front. The Lewcospis
larva when hatched does not at once attack the bee larva which is
to be its future food, but every few hours makes excursions over

its surface, and even explores the walls of the cell; returning, .

however, always to the cocoon for repose. The object of these

ee ee sees

ry -" : —
ae ee ee ee ee eS

ee et

XXIID | LEUCOSPIS 543

excursions is, Fabre believes, to ascertain if another Leucospis egg
has been laid in the cell, and in that case to destroy it. For
the food, as we have said, being only enough for one larva, and
the mother Lewcospis frequently laying more than one egg in a
cell, it is necessary that all the eggs except one should be destroyed.
Fabre did not actually observe the act of destruction, but he
found repeatedly in his glass tubes that the supernumerary eggs
were destroyed, being, in fact, wounded by the mandibles of the
first-hatched larva. After several days of this wandering life
the tiny destroyer undergoes a first moult, changing its skin
and appearing as a very different creature (Fig. 357, C); it
is now completely destitute of any means of locomotion, very
deeply segmented, curved at one extremity, with a very small
head, bearing-extremely minute, scarcely perceptible, mandibles.
The sole object of its existence in this state is to extract the
contents of the Chalicodoma larva, and appropriate this material
to the purposes of its own organisation. This it accomplishes
not by wounding, tearing, or destroying the larva, for that ap-
parently would not answer the purpose; the contents must be
conveyed while still-in their vital state to itself; and this it
effects by applying its mouth to the extremely delicate skin of
the victim, the contents of whose body then gradually pass to
the destroyer, without any visible destruction of the continuity
of the imtegument. Thus the Leucospis larva gradually grows,
while the bee larva shrinks and shrivels, without, however,
actually suffering death. The process of emptying the bee larva
apparently does not occupy the Leucospis more than two or three
weeks, being completed by about the middle of the month of
August; afterwards the larva remains in the cell by the side of
the shrivelled skin of its victim for ten or eleven months, at the
end of which time it assumes the pupal condition, and very
shortly thereafter appears as a perfect Insect.

Monodontomerus cupreus is another member of the Chalcididae
that lives parasitically at the expense of bees of the genus Chali-
codoma. Its habits have been sketched by Fabre, and exhibit
considerable difference from those of Lewcospis. It is much less
in size, and can accommodate itself to a greater variety of food ;
it will, in fact, eat not only the larva of Chalicodoma, but also
that of another bee, of the genus Sée/is, that is frequently found

1 Souvenirs entomologiques. Troisieme série, 1886, p. 179.

544 HYMENOPTERA CHAP,

shut up in the cell of the Chalicodoma, at whose expense the ,

Stelis also lives parasitically. The Monodontomerus bores. a hole —

through the masonry of the bee and deposits its eggs in the cell
after the fashion of the Lewcospis; one bee larva is, however,
sufficient food for several individuals of the young of this smaller
parasite. There is no hypermetamorphosis, the early larval
condition resembling the later. This Insect attacks not only
Chalicodoma and Stelis, as already mentioned, but also other bees ;
anda single larva of some of the larger kinds will afford sufficient
food for fifty young of the Monodontomerus. They feed on the
bee larva, as the Leucospis does, without wounding it. This fly
has the power of recognising what is suitable provender for its
young by the use of the antennae, even when the conditions are
so changed that it is clear the sense of sight has nothing to do
with the recognition. Fabre relates that he had extracted a
number of the bee larvae from their cells of masonry, and that
as they were lying on his table enclosed in their cocoons, the
Monodontomerus recognised the latter as containing the desired
provender for its young by examining them with its antennae;
after which, without hesitation, the Monodontomerus pierced the
cocoon with its ovipositor and deposited the eggs in a suitable
position. This observation, together with those made on Leucospis,
seem to indicate that it is neither by sight nor smell that these
Insects discover the desired object, but by some sense we do not

understand, though its seat is ‘clearly in the antennae of the —

Insect.

Newport discovered a Monodontomerus, which he. described
as MM. nitidus,’ in the cells of the bee Anthophora retusa, and
demonstrated that the alimentary canal, as is usual in Petiolate
Hymenoptera, is closed behind until the Insect is about to enter
the pupal state, when it becomes perforated and faecal matters
are for the first time passed from it. “These matters were com-
posed of the refuse of digestion and of epithelial cells accumulated
during the period of feeding, and retained in the digestive sac
until the period of its perforation. In this way the food and
abode of the Insects are maintained pure and uncontaminated,
and the digestive apparatus is completed, and the refuse of
nutrition ejected only when the whole of the food has been
consumed.”

1 Tr. Linn. Soe. xxi. 1855, p. 67.

.
i a oo

XXII CHALCIDIDAE 545

In the cells of the same bee Newport discovered another
curious parasitic Chalcid, Anthophorabia retusa. The male has
short wings, and the compound eye is replaced by an ocellus
on each side of the head, the female having fully developed
wings and eyes. A variation may occur in the metamorphosis
of this Insect, inasmuch as when the growth is completed during
the month of August, the Insect changes to a pupa, the imago
appears ten or twelve days thereafter, and the perfect Insect then
hibernates for seven or eight months; but should the completion
of growth be deferred till after the end of August, hibernation
takes place in the larval condition. A large and brilliant Chalcid
Lucharis myrmeciae, has been described by Cameron as preying
on the formidable Australian ants of the genus Myrmecia.

The development. of Smicra clavipes has been partially de-
scribed by Henneguy.” This Insect lives in the interior of the
aquatic larva of Stratiomys strigosa, a Dipterous Insect. As
many as fifty eggs of the parasite are found in one larva, but a
large number of embryos die during development, so that he has
never found more than two or three well-grown larvae in one
Stratiomys larva. It has been ascertained that the eggs of many
of these parasitic Insects are deficient in yolk, and the ovum of
Smicra is said to obtain the nutritive materials necessary for
the development of the embryo from the blood of its host by
endosmosis. For a long time after the assumption of the larval
condition, the larva appears to nourish itself only at the expense
of the blood of its host. The segmentation of the ovum is total,
and a single embryonic membrane appears at an early period,
before the formation of the embryo, by a process very different
from that giving origin to the amnion of the majority of
Insects. |

A very interesting sketch of the development of Lncyrtus
fuscicollis has been given by Bugnion.? This small parasite
passes its earlier stages in the interior of the larva of Hypono-
meuta cognatella or other Lepidoptera. The female Encyrtus
deposits her eggs in the interior of a caterpillar, in the form of
a series of 50 to 100 or more eggs enclosed in a sac; the origin

1 According to Ashmead, P. ent. Soc. Washington, ii. 1893, p. 228, this genus
should take the name of Melittobia.

2 Ann. Nat. Hist. (6) x. 1892, p. 271. -

8 Rec. Zool. Suisse, v. 1891, pp. 435-534. Cf. Koulaguine, Congr. internat. Zool.

ii. 1892, pt. i. p. 265.
VOL. V 2N

RYO HYMENOPTERA CHAP. |

of the sac is obscure, but the embryonic development and the

early part of the larval life are passed in the sac, which contains —

a supply of nutritive matter. The larvae of the Hncyrtus are
at first entirely confined to this sac, but when they have con-
sumed all the nutritive matter in it, they leave it and pass the
remainder of their larval and pupal existence in the body-cavity
of the caterpillar. They live at first on the lymph (blood) of
the Insect, and apparently do it no harm; nevertheless the
strength of the caterpillar is so much enfeebled that it fails
to undergo the transformation to a pupa; the parasites then

devour its interior, and use the empty skin as a nidus for their
own pupation ; they form cocoons which divide the area into com- —

partments. Usually the individuals disclosed from one Hypono-

meuta are all of one sex, which may be either male or female.

Unfortunately the most interesting points of this development,

viz. the history of the common sac for the larvae, the nature of —

the eggs, the earlier embryonic stages, and the nutriment in the
sac, are still without elucidation. The account given by Bugnion
raises a great desire for information on these points.

We have in a previous page described the remarkable mode —

of oviposition of Mantis. Captain Xambeu’ has made a very
curious observation to the effect that a minute Chalcid, Podagrion
(Palmon) pachymerus, shelters itself under the wings of the

Mantis so as to be in a position to oviposit in the eggs of the —

latter when it shall be forming its peculiar ootheca.

The genus Jsosoma consists of Insects that differ in habits
from their congeners, being phytophagous instead of parasitic.
I. tritict and J. hordei live in the stalks of corn, and in North
America, where they are known to the agriculturist as joint-
worms, are frequently very injurious to crops. They are some-

ye

times obtained in large numbers without any males appearing, and ~

a wingless as well as a winged form of the female occurs. Owing
to the fact that the allies of these Insects are parasitic, it has
been frequently maintained that this may also prove to be the
case with Isosoma, but the observations of Riley * and others leave

no doubt that the Insects of this genus are really plant- —

feeders.

1 Bull. Soc. Ent. France (5) vii. 1877, p. Ixix. ; also André, Feudlle Naturail. vii.
1877, p. 136, and Riley and Howard, Insect Life, iv. 1892, p. 242.
* Insect Life, i. 1888, p. 121.

=_—er ©

aia Mg
‘

XXIII FIG-INSECTS 547

Riley has called attention? to some facts in connection with
T. tritict and J. grande, that make it clear that these two supposed
species are really alternate generations, and that both generations

_are probably in larger part, if not entirely, parthenogenetic.
Some species of the genus Megastigmus are known to be of
phytophagous habits.’

The most interesting of all the forms of Chalcididae are
perhaps those called fig-Insects. A considerable number of species
are now known, and amongst them we meet with the unusual
phenomenon of species with wingless males, the females possessing
the organs of flight normally developed. The wingless males
exhibit the strangest forms, and bear no resemblance whatever to
their more legitimately formed partners (Fig. 358, A, B). Many
of the fig-Insects belong to a special group called Agaonides.
Others belong to the group Torymides, which contains likewise
many Chalcididae of an ordinary kind; possibly some of these
may be parasitic on the Agaonides. Some of these Torymid fig-
Insects have winged males, as is normal in the family, but in
other cases winged and wing-
less forms of the male of one
species may be present.

The most notorious of these
fig-Insects is the one known
as lastophaga grossorum (Fig.
358), this being the chief agent —
in the custom known as capri- ~
fication of the cultivated fig-
tree. This process has been
practised from time immemorial,
and is at the present day still
carried on in Italy and the
Grecian archipelago. The Greek
writers who describe it say that Fic. 358.—Blastophaga grossorum. A,
the wild fig-tree, though it does bpd nay ae tNeape, Bigs aay
not ripen its own fruit, is ab-
solutely essential for the perfection of the fruit of the cultivated
fig. In accordance with this view, branches from the wild fig

1 Report of the Entomologist, Dep. Agriculture, Washington, 1886, p. 542.
2 Wachtl, Wien. ent. Zeit. xii. 1898, p. 24, and Howard, P.U.S. Nat. Mus. xiv.
_~ 1892, p. 586.

548 HYMENOPTERA cam

are still gathered at certain seasons and suspended amongst the
branches of the cultivated fig-trees. The young fig is a very —
remarkable vegetable production, consisting of a hollow, fleshy
receptacle, in which are placed the extremely numerous and
minute flowers,.the only admission to which is by a small orifice —
at the blunt end of the young fig; this orifice is lined with pro-—
jecting scales, that more or less completely fill it up or close it;
nevertheless inside this fruit the Blastophaga grossorum develops
in large numbers. The males are, as we have seen, wingless ;
creatures, and do not leave the fruit in which they were bred,
but the females make their way out of the wild fig, and some
of them, it is believed, enter the young fruit of the cultivated ©
trees and lay their eggs, or attempt to do so, therein; and it

has been supposed by various writers that these proceeding are
essential to the satisfactory development of the edible fruit. It
‘ ; J
1s a curious fact that the Blastophaga develops very freely in
the wild fig—so much so, indeed, as to be a means of preventing -
it from coming to maturity ; but yet the Insect cannot complete .
its development in the cultivated fruit. This is due to the fact
that the fly must lay its egg in a particular part of the fig-

ovule, so that when the egg hatches the larva may have a proper ©
supply of food. In the cultivated fig the structure of the flower
differs somewhat from that of the caprificus, as the wild fig is
called, and so the egg, if deposited at all, does not reach a proper
nidus for its development. Hence the Blastophaga can never liye
exclusively on the cultivated fig, and if it be really necessary for
the development of the latter, must be brought thereto by means
of the caprifig. Whether the Blastophaga be really of use, as has
been for so long supposed, is, however, a matter for doubt. The
reasons for this are (1) that those who think caprification bene
ficial do not agree as to the mode in which they suppose it to be
so; (2) that there is but little reason for believing that when

ingradaea amongst the cultivated figs the Blastophaga occupies -
itself to any, great extent therewith; and (3) that in some parts j
of the world caprification is not partici but the cultivated fig
nevertheless ripens its fruit there. Hence many writers on the
subject—Solms-Laubach,! Mayer,’ and Saunders *—entertain cl.
siderable doubt as to whether caprification is at present anything | ‘

<

1 Abh. Ges. Gottingen, xxviii. 1882. 2 Mitt. Stat. Neapel, iii. 1882, p. 55.
3 Tr. ent. Soc. London, 1883. p. 389.

. vee

XXIII FIG-INSECTS 549

more than an old custom destitute of practical utility. On the
other hand, Riley states! “that the perfect Smyrna fig, the most
esteemed of the edible species, can be produced only by the
intervention of the Blastophaga psenes [grossorum].”

Although the questions connected with the effect the Slasto-
phaga is supposed to produce on the fruit are of a botanical
rather than a entomological nature, we may briefly say that two
views have been held: (1) that, as in the fruit of the cultivated
fig, only female flowers are produced, the lastophaga is necessary
for their fertilisation and the subsequent development of the
fruit; (2) that the Insects stimulate the fig by biting parts
thereof or by burrowing in it, and so give rise to the processes
that have as their result the edible fruit. There seems to be
little doubt that the Insect agency is necessary to the fertilisa-
tion of some species of figs. Cunningham, who has recently
carried out an elaborate investigation as to the fertilisation
of Ficus roxburghii, concludes that in this fig, and probably
also in other kinds, the perfect development is dependent on
the access of the fig-Insects to the interior of the receptacular
cavity. Should access fail to occur, both male and female
flowers abort, without the formation of pollen grains by the
former or seeds by the latter. The access of the Blastophaga is
thus as necessary for the perfect evolution of the normal male
and female flowers as it is for that of the modified 9 or. gall-
flowers, with their contained ova and Insect-embryos. Whether
the successful fertilisation of the flowers is really essential to the
production of the edible fig is not a question for our discussion.

Fig-Insects are apparently more numerous in South America
than they are in any other part of the world; and Fritz-Miiller
has discovered * a number of species there of a very extraordinary
character, several of them possessing two forms of the male, one
winged like the female, the other wingless and so different in
character that they were considered to belong to a different genus.
The wingless male of a species found in Madagascar, Kradibia
_cowant, has the peculiarity of possessing only four legs, the middle
pair being represented merely by minute two-jointed rudiments.
Some of these Insects live in galls on the figs. The fig-Insects

1 P, biol. Soc. Washington, vii. 1892, p. 99. -
2 Ann. Botan. Garden, Calcutta, i. 1889, Appendix L.
3 P. ent. Soc. London, 1886, p. x.

550 HYMENOPTERA ! CHAN

were formerly considered to belong to the Proctotrypidae or to —

the Cynipidae (gall-makers), but there can be no doubt, not-
_ withstanding they differ so much in their habits from the para-
sitic Chalcididae, that they probably belong to the same family.
If treated as different from Chalcididae, they should be separated
as a distinct family rather than united with the Cynipidae.'

It is impossible for us to do more than allude to the extra- —
ordinary shapes exhibited by some —

Chalcididae. The genus Zhoracantha

of the family Mordellidae, and has the
wings concealed by false wing-cases—
really projections from the thorax—so

Fic. 359.—Thoracantha latreillei. that from above the Insect bears no
Bahia. A, Upper, B, lateral

aspect. (After Waterhouse.) Yresemblance to the other Insects of the —

Order it really belongs to.

Howard has called attention to some peculiarities in the
pupation of Chalcididae.? Like the Cynipidae, they do not make —

a silken cocoon, but some of them that change to pupae inside
the victims on which they were nourished have the power of
forming oval cells in which to undergo their transformation,

and they thus cause a peculiar inflation of the skin of their de- —
ceased victim, which after death still continues to serve as a
protection to the destroyers. The statement made by Haliday,
and repeated subsequently in various works, to the effect that —
Coryna spins a cocoon under the Aphis in which it has lived, is —
an error, the cocoon being really formed by Praon, a Braconid |
that is a parasite of the Aphis, and on which the Chalcid Pachy-_

crepis (Coryna) lives as a hyperparasite. The pupae of some

species differ from those of other Hymenoptera, in that the
integument is hard, and the limbs are soldered to the body as in ~

Lepidoptera. These forms pupate external to the victim.

Fritz Miiller has recorded that the pupa of an unnamed species :
of Chalcid that attacks a Brazilian ant (Azteca instabilis Forel)
is suspended on the wall of the cell the ant lives in by its —

posterior extremity, just like the chrysalis of a butterfly.

1 For a systematic memoir refer to Mayr, Verh. zool.-bot. Ges. Wien, xxxvy. 1885,

p- 147, ete.
2 Insect Life, iv. 1891, p. 193.

is specially remarkable in this respect. —
7. latreillet is said to resemble a beetle —

—

XXIII: PARASITICA 551

Notwithstanding the small size of Chalcididae, their remains °
have been detected in the tertiary strata of both Europe and
North America. |

Fam. IV. Ichneumonidae (Ichneumon-flies).

Wings with a well-developed series of nervures and cells; the
space on the front wing separating the second posterior cell
from the cubital cells is divided into two cells by a transverse
veinlet. The abdomen is attached to the lower or posterior
part of the median segment. Larvae parasitic in habits.

The Ichneumonidae form a family of enormous extent, con-
taining nearly 6000 described species. The study of the family
is but little advanced, owing to their parasitic habits and to
this bewildering multiplicity in their
specific forms. Most of the species, in the:
larval state, live inside the larvae of Lepi-
doptera, and they thus keep the myriads
of caterpillars within bounds, the number
of these destroyed by Ichneumons being
prodigious. Some of the family are,
however, external parasites, and some are
known to attack Spiders and Insects of
other Orders than Lepidoptera. Their
antennae are not elbowed and are many-
jointed, the joints being closely compacted,
especially towards the extremity. This
character readily distinguishes Ichneu-
monidae from the families we have ¥14360.—Lissonota setosa, °.

ritain. Parasite of the
previously considered. The ocelli are — goat-moth, ete. (After
well developed even in the apterous forms, >™:)
and are placed in a triangular position on the vertex. The pro-
notum is small in front; and extends backwards at the sides to
the points of insertion of the front wings; it is fixed to the
mesonotum. The wings (Fig. 367, A) have a more complex
neuration than those of most of the other parasitic Hymenoptera,
but are occasionally absent in one or both sexes of a species. The
metathorax is very small, and the middle and hind legs are
placed close together. The propodeum is very large, and is

552 HYMENOPTERA CHAP. |

frequently covered with a highly-developed sculpture. The hind
body springs from the lower part of the propodeum; it is usually
of slender form, and its segmentation is very conspicuous. The
females bear an ovipositor, which differs greatly in length accord-

ing to the species, and is known in the case of one species. to

attain a length six times that of the whole of the rest of the
body The egg is deposited by some species on the skin, by
others within the body of the victim ; it varies much in form and
colour, some eggs being stalked and of peculiar shape. The

larvae issuing from the eggs are legless maggots with a delicate

integument of pallid white or creamy colour. If the eggs are laid
on the surface of the body, the result-
ing larvae (except in the cases of the

interior of their victim, and disappear
therein. The changes that take place
) in the lifetime of the larvae have
been studied in only a few cases; but
if we can judge from Ratzeburg’s
history? of the changes that take
place in Anomalon, they are of great
interest. From observation of the

number of larvae of A. cirewmflecum
he distinguished four stages. It is of
course impossible to follow directly
the growth of one individual, be-
cause it is concealed in the interior

and to open this involves the death
, ; of both caterpillar and Ichneumon-
Fra. 361.— Anomalon circum- larva, The life history must therefore

Jlecum, larval development.
(After Ratzeburg.) A, First be constructed from a great number of

instar ; B, second instar ; ©, the separate observations; and it is not —

larva in the third or encysted

stage extracted from its cyst; ascertained that the four instars de- —
scribed by Ratzeburg represent the —

D, the mature larva ; E, pupa.

number of moults of the larva that actually take place. He,
however, entertained no doubt that all the forms he observed

1 Tosquinet, Ann. Soc. ent. Belgique, xxxviii. 1894, p. 694. -
2 Ichnewm. Forst. Ins. 1844, p. 81.

external parasites) soon bore into the ©

differences existing amongst a great

of the caterpillar in which it lives,

— ts? Pun

~

XXIII ICHNEUMON-FLIES 3 553

were stages in the development of one species. In the earliest
stage, when only one millimetre in length and about as thick
as a horse-hair, the larva is free in the interior of the cater-
pillar’s body, and has a small head armed only with a pair of
mandibles. There are, in addition to the head, thirteen segments,
and the last of these is an elongate tail forming nearly one-
half the length of the creature. No trace of tracheae can be
discovered. In the second stage the larva is still free, an elon-

gate tracheal tube exists, the tail has diminished to half the

length, the head has become much larger, and rudimentary
antennae of one joint are visible; possibly stigmata are present
at this stage, though they cannot afterwards be detected. In
the third stage (Fig. 361, C) the larva is encysted, the head is
large, the parts of the mouth are all developed, the tracheal
system is extensive, and the caudal termination of the body is quite
short ; notwithstanding the extensive development of the tracheal
system, no stigmata can be found. In the fourth stage the
larva is still encysted, the tail has disappeared, the head and
mouth parts are reduced in size and development, and the creature
has now the appearance of a normal larva. The changes to pupa
and perfect Insect take place within the body of the victim, in
some cases, if not usually; after it has undergone its metamor-
phosis into a chrysalis. Very little information is extant as to
the duration of the various stages, but it appears to be the rule
that only one generation appears annually, though in some cases
there are pretty certainly two.

It is very difficult to observe the. act of oviposition; the
Ichneumon-flies usually decline to notice caterpillars with which
they are placed in confinement. Ratzeburg thinks they will only
attack caterpillars that are in a deficient state of health or vitality.
Occasionally we may by a happy chance observe the act in
Insects at large, and from the records of observers it may be
deduced with tolerable certainty that the sense of sight takes no
part in the operation. Ratzeburg relates that he saw a Pimpla
alight on a leaf of Rhus and thrust its ovipositor through the
leaf. On looking to the under-side of the leaf he found that a
cocoon of Bombyx neustria was concealed there in such a position
that it could not have been seen by the Ichneumon.

Among the most remarkable of the Ichneumon-flies are the
Insects of the genera Rhyssa and Thalessa. These fine Insects

554 HYMENOPTERA CHAP.

have an ovipositor three or four inches in length, and are parasitic
on species of the family Siricidae, which, as we have previously
described, live in solid wood. In order therefore to deposit
the egg in a suitable place, the wood must be pierced by the
Ichneumon. The ovipositor is not only of extreme length, but is
also furnished with serrations on its apical part, so that it forms a —
very effective boring apparatus. It is brought into use by being
bent on itself over the back of the Insect (Fig. 362), so as to bring
the tip vertically down on to the wood, through which it is then
forced by a series of efforts; the sheaths do not enter the wood.
The egg is laid anywhere in the burrow of the Sirex ; the young
larva seeks its prey, and lives on it as an external parasite (Fig.
342,D). Erne, however, states’ that the young larva of Rhyssa
persuasoria enters its victim, and remains within the latter till its
death occurs. This happens
when the young Rhyssa is —
two or three lines in length,
and it then makes its exit from
the interior of the body and
gradually eats it up. Should
the larva it has attacked be of
large size, it of itself affords
sufficient food for the comple-
tion of the growth of the
Rhyssa. Should the Rhyssa,
however, have attacked a small
larva, this does not furnish it
« With sufficient food, and it con-
sequently dies without seeking
; Pi another larva. Erne says,
Fra. See aie Re Oviposition. Sndeod,| that at will Gees ie
another if offered to it, so that
in order to rear the Rhyssa in captivity, the victim it has first
attacked must always be given to it. The same observer states
that the Rhyssa larva is sometimes transported by the Sirex
deep into the wood, so that when it has completed its metamor-
phoses the Ichneumon-fly may find itself buried in solid wood to
a depth of about two inches.- In that case it excavates the wood
with its mandibles, and should it fail to gain the exterior after

1 Mitt. schweizer. ent. Ges. iv. 1876, p. 518,

XXIII ICHNEUMON-FLIES 555

three days of work, it dies. In the case of Zhalessa it is stated
that it sometimes bores into wood where there are no larvae, but
Riley thinks this erroneous; it is, on the other hand, certain
that the Insect after penetrating the wood is frequently unable
to withdraw the ovipositor, and consequently dies.

Packard has recorded, without mentioning the species, the
oviposition of an Ichneumon of which the egg is deposited
externally. It was placed on the head of the caterpillar, and
speedily hatched; the young larva at once bored through the
prothoracic slack of the victim, the head of the latter then
became swollen, and covered the opening into the prothorax, made
by the parasite.

The history of an Ichneumon larva that feeds as an external
parasite has been sketched by De Geer and Newport. The
observations of the latter? refer to Paniscus virgatus; he
found small, shining, black bodies attached to the skin of the
larva of a moth, Mamestra pisi; these were the eggs of the
Ichneumon. They are furnished with a short peduncle, which
is implanted in the skin of the victim; the egg, according to De
Geer, being retained more firmly by the peduncle subsequently
swelling, so as to form two knobs. The hatching takes
place by the egg-shell splitting longitudinally, while from the
split protrudes: the little head of the destroying larva. This
becomes fixed to the caterpillar, from which the nutriment is
to be drawn; the Paniscus larva does not, however, leave the
egg-shell, but, on the contrary,
becomes adherent to it, so that
the parasite is in this manner
fixed by the two ends to its
victim. In fifteen days the
parasite jessy full-grown, and had Fie. 363.—Young larva of Paniscus in
become half an inch in length. position of feeding on the skin of Mam-
At first no tracheae were ea (After Newport.) a, The egg-
to be seen, but these were

-- detected after the second day. Moulting took place three

times, and in a peculiar manner, very different from that.
described by Ratzeburg as occurring in the internal parasites
(which, he states, change their very delicate skin by detaching it
in almost imperceptible fragments). In the external parasite the

1 Fifth Rep. U.S. Ent. Comm. 1890, p. 15. 2 Tr. Linn. Soc. xxi. 1852, p. 71.

556 HYMENOPTERA CHAP.

skin remains entire, and is shuffled down to the extremity of the
body, but cannot be completely detached owing to the anchoring
of the posterior part of the body to the caterpillar; the cast

skins thus remain as envelopes to the posterior part of the body.

Newport states that if the mouth of the parasite be detached, it
usually cannot again seize hold of the victim, and consequently
perishes. It is a curious fact that more eggs than one caterpillar
can support are habitually placed on it, and some of the resulting
larvae of necessity perish during the period of growth. Poulton,
who has recently made some additional observations on the
development of Paniscus} says that if three larvae are close
together, it is the middle one that perishes, and suggests
that this is due to some simple physical condition. From
Newport’s account it may be gathered that the Mamestra

retains sufficient vitality to form its cocoon, and that the —

Paniscus larvae likewise construct their own cocoons within
that of the Mamestra. In the case of Paniscus cephalotes
feeding on Dicranura vinula, Poulton relates that the latter died
after the twelfth day of attack. The parasites, having relaxed
their hold on the victim just previous to this event, then thrust
their heads into the dead body, and devoured the larva, leaving
only a dried and empty integument. These larvae span a loose
sort of web in which to undergo their metamorphosis. In a
natural state, however, they form cocoons inside the cocoon of
the Dicranura. The period passed in the pupal condition was
about four weeks. This parasite only attacks the Lepidopterous
larva during the last stage of its existence as a larva, but the
eggs may be laid on the victim in an earlier stage; and in such
ease De Geer has stated, and Poulton has confirmed the observa-
tion, that though the larva sheds its skin it does not get rid of
the eggs.

The little Ichneumons of the genus Pezomachus are quite
destitute of wings and somewhat resemble ants; they are
common Insects in Britain. Only the female sex is known, and
it is believed that the winged Ichneumons assigned to the genus
Hemiteles—of which no females are known—are the males of
Pezomachus. Repeated efforts have been made to place this
beyond doubt, but they have usually failed, for when a brood of
these parasites is reared, the individuals generally prove to be

' Tr. ent. Soc. London, 1886, p. 162, and 1887, p. 303.

.’ ‘
scares SC ae

a Te vaee a) ee eee ee ee ee eee ee

~

XXIII ICHNEUMON-FLIES | 557

either all Hemiteles or all Pezomachus. It is to be hoped that

this interesting case will be fully elucidated.
Although the Ichneumonidae are perhaps the most purely
carnivorous of all the great families of Hymenoptera, there is

nevertheless reason for supposing that some of them can be

nourished with vegetable substances during a part at any rate of

_ the larval existence, Giraud and Cameron * having recorded observa-

tions that lead to the conclusion that some species of the genus
Pimpla may inhabit galls and live on the substance, or juices
thereof.

Over 1200 species of Ichneumonidae are known to inhabit
Britain, and there can be no doubt that this number will be
increased as a result of further observation. Unfortunately no
general work has yet been published on this department of our
fauna, and the literature is very scattered.2 The species of
North America have not received so much: investigation as those
of Europe, and the Ichneumon fauna of the tropics remains almost
uninvestigated. Six sub-families are recognised: Agriotypides,
Ichneumonides, Cryptides, Tryphonides, Pimplides, Ophionides.
Of these the first is the most remarkable, as it consists of an
Insect having aquatic habits. It
has for long been known that the
unique species Agriotypus armatus, a
rare Insect in our islands, is in the
habit of going under water and re-
maining there for a _ considerable
period, and it has now been satis-
factorily ascertained that it does this
for the purpose of laying its eggs in
the larvae of Trichoptera.® The re-
sultant larva lives inside the cases
of species of Stilo, Goéra, etc. It eet htt 5 dager Curtis)
undergoes a sort of hypermetamor-
phosis, as its shape before assuming the pupal condition

1 Ent. Month. Mag. xiii. 1877, p. 200.

2 A catalogue, with references, of the British Ichneumonidae was published by
the Entomological Society of London in 1872. Since then many additional species
have been detected and recorded, by Mr. Bridgman and others, in the Z’7ransactions
of the same Society.

8 Klapalek, Ent. Month. Mag. xxv. 1889, p, 339, and Arch. Landesdurchforschung
Bohmen, viii. No. 6, 1893, p. 53.

558 HYMENOPTERA CHAP.

is very different to what it was previously. It changes to
a pupa inside the case of the Trichopteron in a cocoon attached
to the walls. of the case. Previous to making this, however, the
Agriotypus forms a curious, elongate, string-like process attached
to the anterior extremity of its cocoon. The use of this is
unknown. Full information as to the life-history of this aquatic

Hymenopterous larva, especially as to its respiratory functions, 7

Fic. 365.—Metamorphosis of Agriotypus. (After Klapalek.) A, Larva ; B, sub-nymph ;
C, case of the Silo with the string of attachment formed by Agriotypus ; D, section
of the case: v', operculum of case ; v’, cocoon ; ag, pupa of Agriotypus ; e, exuvia
of Agriotypus ; w?, wall of cocoon ; s, remains of Silo; w', closure of case.

would be of great interest. The affinities of this remarkable
Insect are still doubtful. It may probably prove to be between
Proctotrypidae and Ichneumonidae.

Remains of Insects that may be referred with more or less
certainty to Ichneumonidae have been found in some abundance
in various tertiary strata both in Europe and North America, but

nothing indicative of the existence of the family has yet been
found in the older rocks.

Fam. V. Braconidae—Supplementary Ichneumon-flies.

Antennae with many (nearly always more than fifteen) joints, not
geniculate. Wings with a moderate number of cells, which
on the anal part of the front wing are more or less imper-
fect, the anal (i.e. the second posterior) cell being separated
from the cubital cells by a large space in which there is no
cross-nervure. Abdomen with but little mobility between the
segments ; the suture between the second and third usually

i

t ice eis a ees

r

—, eee ee ee

eg ee ao

|
:
}
}

XXIII BRACONDIDAE 559

absent, or obsolete. Larvae living parasitically in—possibly
exceptionally outside—the bodies of larvae or pupae of Insects.

Y i}
—< i <

4 (= “
——

wi
\/

Fic. 366.— Bracon palpebrator, Fic. 367.—Diagram of wing of Ichneu-
female. Europe. (After Ratze- - monid (A) and of Braconid (B). 1, 2,
burg. ) 3, 4, series of cells extending across

the wing; a, 0, divided cell of the
Ichneumonid wing, corresponding with
a, the undivided cell of the Braconid
wing.

The Braconidae are the Ichneumones, or Ichneumonides,
adsciti of the older Hymenopterists. They are extremely similar
to the Ichneumonidae, but the hind body has a much less degree
of mobility of its segments, and there are some constant distinc-
tions in the wings. Although there is a great deal of difference
in the various forms of each of the two families, yet there are
two points of distinction easily appreciated; the series of cells
running across the wing (Fig. 367) being only three in the
Ichneumonides (Fig. 367, A), but four in the Braconids (Fig. 367,
B); besides this the space a of the Braconid wing is divided
into two (a, b) in the Ichneumonid wing. A glance at these
characters enables us at once to separate correctly the thousands
of species of the two families.

The habits of the Braconidae are similar to those of Ichneu-
monidae, it being believed that all are parasites. Usually they
attack larvae, but they are bred in great numbers from pupae,
and even from imagos of other Insects. Hlasmosoma is one
of the few parasites. known to attack ants. As many as 1200
specimens of Microgaster have been reared from a single Lepi-
dopterous larva. Although such parasitism raises a feeling of
repulsion, yet there is reason for supposing that there may be

little or no cruelty or acute suffering connected with this mode of
life. The victim attacked is not eaten, the parasites in the in-
terior taking in the lymph of the caterpillar either by the mouth
or by endosmosis, but not biting their host. The latter displays
no sign of sickness, but eats voraciously, so that it serves merely
as a sort of intermediary between the juices of the plant and the

larvae inside itself. It is only when the metamorphosis is at

hand that the host sickens, but this does not always happen:
parasitised larvae frequently change to pupae, and they may
occasionally even become perfect Insects. Cases are known in
which imagos have appeared with some of the small parasites
embedded in some of the outer parts of their bodies. These
cases are, however, very rare; in the enormous majority of
instances the host is destroyed either when it is in the larval
stage or before the pupa has. advanced to any great extent on
its metamorphosis to an imago. Particulars as to various species
will be found in the valuable work of Ratzeburg we have already
referred to. Reference may also be made to Goureau’s account
of Microgaster globatus, this latter including some suggestions
by Dr. Boisduval on some of the difficult physiological questions
involved in the lives of these parasites.

The metamorphosis of Microgaster fulvipes has been studied
by Ratzeburg, and an epitome of his observations is given by
Marshall.? The larva goes through a series
of changes somewhat similar to those we
have already sketched in Anomalon cir-
cumflecum. Usually these Insects after
emerging from the body of their host spin

connected together. A most curious case
- has, however, been recorded by Marshall ®

Fic. 868.—Stalked cocoon formed as an exceptional act by Apanteles
of Apanteles formosus. a
(After Marshall.) Sormosus. Mr. Marshall has recently re

ceived other specimens of this cocoon as

well as the Insects reared therefrom in France, and inclines to

the opinion that the stalked cocoon may be the usual form, and
is sometimes departed from by the Insect for unknown reasons.

1 Ichnewm. Forst. Ins. 1844. 2 Ann. Soc. ent. France (2), iii. 1845, p. 355.
® Tr. ent. Soc. London, 1885, pp. 224, 219.

a mass of cocoons more or less loosely

of a stalked cocoon (Fig. 368) being

|

560 HYMENOPTERA CHAP. |

\
|

Gee PARASITICA 561

‘This family is of enormous extent; we have several hundred
‘species of it in Britain,’ and there are no doubt many thou-
sands of undescribed exotic forms. To Apanteles glomeratus. we
are indebted for keeping our cabbages and kindred vegetables
from destruction by the caterpillars of the white butterflies.
The larvae of the various species of Pieris, as well as those of
other Lepidoptera, are attacked by this little Insect, the masses of
whose cocoons may frequently be found in numbers in and near
cabbage gardens. The tropi-
eal species of Braconidae are
greatly neglected, but many
large and remarkable forms
—some of brilliant colours
—have been brought from
there, so that we are justified
in believing that Insects of 7.0

this family will prove to be |
very numerous. ‘There are
but few apterous Braconidae.
Both sexes of Chasmodon
apterus are destitute of wings;
the females of one species of
Spathius, and also those of (

Pambolus and Chasmodon are

apterous ; in a small number ,
of species of various genera
the wings are so minute as
to be incapable of serying as | |
organs of flight. In the |
genus Alloea the wings of
the male are shorter than
those of the female. |

Nae

Fic, 369.—Stenophasmus ruficeps, female.
Fam. VI. Stephanidae. Aru Islands.. (After Westwood.)

Antennae composed of many (thirty to seventy) joints; hind body
attached to the lower and posterior part of the median dorsal

1 A monograph of the British Braconidae was commenced by the Rey. T. A.
Marshall in 1885, and is still in progress, in. the Transactions of the Entomological
Society of London ; cf. op. cit. 1885, 1887, 1889, 1891, 1894.

VOL. V 20

ia
:

le ae a ee Pai ene. eee

5 62 HYMENOPTERA

‘|e

plate. Wings with a distinet costal cellule ; head globose,
posterior femora frequently toothed.

This is a doubtful family, consisting of a few onomalaaa
Insects. Schletterer assigns to it only two genera, Stephanus and ©
Stenophasmus;! both have a wide distribution over the world, —
though we have no species in Britain. Nothing is known of
their habits, and they are apparently all very scarce Insects.
The definition is compiled from those of Cameron and Schlet-_
terer. There seems Py. little to distinguish these Insects from
Braconidae. , :

Fam. VII. Megalyridae.

Hymenoptera with short broad hind body, which is not separated |
by a pedicel from the thorax. The female has a very long
bristle-like ovipositor. Antennae with fourteen jornts.

This family is constituted by the Australian genus Megalyra,?
one of the most interesting of the numerous extraordinary Insect-_
forms found in that region; the species appear to be very rare
and not numerous. Apparently nothing is known as to their
habits. It is quite possible that these Tnsects will prove to be
anomalous Braconidae.

ee ee ee

Fam, VIII. Evaniidae.

Petiole of the abdomen attached to the upper part of the median
dorsal plate; antennae not elbowed, of thirteen or fourteen
joints. Wings with a moderate number of nervures. Larva
of parasitic habits.

a a ee eS ee, ne id

This family is composed of only three genera—Zvania,
Gasteruption, and Aulacus, each possessing a considerable number
of species; they agree in the characters mentioned above, and
may be readily recognised by the peculiar insertion of the
hind body. This character occurs outside the limits of the
_Evaniidae only in one or two genera of Chaleididae and
Braconidae ; it is to this latter family that the Evaniidae must ;
be considered most closely allied. '

The species of the genus Evania are believed to live at

a)

a

j
1 Berlin entom. Zeitschr. xxxiii. 1889, p. 197. 2 Ibid. 7 |

CU PARASITICA 563

the expense of cockroaches (Blattidae), and to deposit their
eggs in the egg-capsules of those Insects. The species of
Gasteruption live, in the larval state, on the larvae of other
Hymenoptera, more especially of such as form nests in wood.
Very little is known as to the habits of the species of Aulacus,
but it is believed that they are parasitic on members of the
Hymenopterous families, Siricidae and Oryssidae. Only the
most meagre details as to the life history of any of the Evaniidae
have been recorded, The species of Evania are met with most
freely where cockroaches abound, and. are said, hence, to be
frequently observed on board ship. Two or three species of
each of the two genera Hvania- and Gasteruption occur in .
Britain. The latter genus is |

. more widely known under the |

name of Foenus.'

Fam. IX. Pelecinidae.

Sexes very different ; the female ) ‘ ’ ]
without exserted ovipositor, a a eh
but with extremely long ge rat | \
abdomen. Articulation — Bis |
between the femur and /
trochanter oblique and | :
elongate, but without divi-
sion of the trochanter.

|

This family at present com- |
prises, according to Schlet- )
terer,? only the three genera |

Pelecinus, Ophionellus, and
Monomachus. The systematic
position of the Insects is very
doubtful, and their habits are
pate rdithde Bown: ripest Fie, 370.—Pelecinus polyturator, q.
polyturator (Fig. 370) appears, patty

however, in the female sex, —

to be acommon Insect over a large part of the warmer regions

1 Monograph, Schletterer, Verh. zoo/.-bot. Ges. Wien, xxxv. 1885, p. 267, ete. ;
xxxvi. 1886, p. 1, etc. ; and Ann. Hofmus. Wien, iv. pp. 107, ete.
2 Berlin. entom. Zeitschr. xxxiii. 1889, p. 197.

564 HYMENOPTERA ¢ APL

of the New World; it is in all probability parasitic in its habits,
the elongate ovipositor of the female Ichneumon being in ie
Insect replaced by an extraordinary linear extension of the abdo- —
men itself. Doubleday has recorded that he saw twenty ¢
thirty specimens of this species that had perished with thei
elongated hind bodies inserted into the stem of a tree, fre nm I
which they could not extricate themselves. On the other hand, —
Patton thinks they are parasitic on locusts.’ hie 3

The male in Pelecinus has the proportions of the nani of
the body normal, there being no elongation of the abdomen; oa
thus differs very much in appearance from the female. Theiy
seems to be very little to distinguish Pelecinus from Procto- —
trypidae. The undivided trochanters have led to these Insects —
being placed, by some, among the Aculeate Hymenoptera, This"
character, as we have already shown, occurs ale in Procto- —
nee ,

Fam. X. Trigonalidae.

Abdomen ovate, not separated by a pedicel from the thorax.
Antennae twenty-five-jointed. Trochanters imperfectly two- —
jointed. Both the anterior and posterior wings provided with
a well-developed neuration. Abdomen composed of only five —
apparent segments. Larva (in some cases) parasitic on Aculeate —
Hymenoptera. a

fe
\
\

This family is chiefly constituted by the very rare Insects —
contained in the genus 7'rigonalys, of which we have one species —
in Britain. Although, so far as appear-
ance goes, they have little in common —
with the parasitic Hymenoptera, and _
look quite like members of the Acu- —
leata, yet the late F. Smith found a —
species in the cells of Polistes lanio, —
thereby showing it to be of para- —
sitic habits. Although some Aculeate —
Hymenoptera are also of parasitic —
Fic. 871.—Trigonalys maculi- habits, yet the characters of Trigonalys

[ron ah ee perhaps agree, on the whole, better —
with the Hymenoptera parasitica. The British species is very
Y Amer. Nat. xxviii. 1894, p. 895. See also Forbes, Rep. Ins. Illinois, xix. 1896, p. 79.

¥

XXIIT | PARASITICA 565

rare. The South American genus, Vomadina, looks still more like
a bee, and the trochanters are even more imperfectly divided
than they are in some of the Aculeate group, Nyssonides, the
outer portion being merely a small piece imperfectly separated
from the base of the femur.

Note——tThe citation of Saint Augustine on p. 85 is made in the words
used by Wasmann in Der Trichterwickler, eine naturwissenschaftliche Studie
diber den Thierinstinkt, 1884.

The authenticity of the passage we have adopted as the motto for this
volume is somewhat doubtful. It is explained in an “ admonitio ad lectorem ”
of the soliloquy, that this work is probably a compilation by a later writer,
from two, or more, works of Saint Augustine. Father Wasmann has been so |
kind as to inform the writer that the idea of the passage quoted occurs
frequently in the undoubted works of the Saint, as, for instance, de Civitate
Dei, lib. xi. cap. 22 ; Serm. ccxiii. in traditione symboli II. cap. i. ; contra
Faustum, lib. xxi. cap. v. etc. The passage quoted is, however, the only one
in which “angeli” and “vermiculi” are associated.

INDEX

Every reference is to the page: words in italics are names of genera or species ;

figures

in italics indicate that the reference relates to systematic position ; figures in thick
type refer to an illustration ; f. = and in following page or pages.

ABDOMEN, 109 ; of Hymenoptera, 492 f.

Abdominal appendages, 188, 189, 190

Acantherpestes, 74, 76, 80

Accessory glands, 392, 404

Acheta, 330, 338

Achorutes murorum, 194

Acini, 126

Acoustic orifice, 317

Acridiidae, 201, 279-310, 309

Acridiides, 310

Acridium peregrinum, 298 ; growth, 156 ;
at sea, 297—see also Schistocerca

Acrophyllides, 278

Aculeata, 520

Aculeates and Proctotrypids, 535, 564

Adler, on alternation of generations, 530 ;
on galls, 526 f. ; on useless males, 498

Aeschna cyanea, 412 ; A. grandis, labium,
411 ; nymph, 420, 421

Aeschninae, 416, 426

Agaonides, 547

Agathemera, 274, 276

Agrion nymph, 426

Agrion pulchellum, 412

Agrioninae, 412, 426

Agriotypides, 557

Agriotypus armatus, 557

Air sacs, 128, 282, 283, 294, 495

Alaptus excisus, 587; A. fusculus, 538

Alar organs, of earwigs, 206 ; of Blattidae,
225 ; of Mantidae, 245 ; of Phasmidae,
269 ; of Acridiidae, 281 ; development
of, in earwigs, 212; in Mantidae, 248
—see also Tegmina, Wings, Elytra

Alary muscles, 134

Albarda on Raphidiides, 448

Alder flies, 444

Aleuropteryx, 471

Alimentary canal, 123-127, 403, 446; of
may - flies, 438 f.; of Panorpa, 450;
closed, 457, 466, 496, 544

Alitrunk, 489 f., 490, 492

Alloea, 561

Alternation of generations, 497, 530

Amber, Myriapods in, 74, 76, 77 ; Insects,
179; Aptera, 196; Blattidae, 239;
Mantidae, 258; Phasmidae, 276; Pso-
cidae, 397 ; Perlidae, 407 ; Phryganeidae,
485 ; Tenthredinidae, 518; Cynipidae,
533.

Ambua, 40

Ameles, 245

Ametabola, 158, 174

-Amnion, 148, 545

Amnios, 291

Amorphoscelides, 251, 259

Amorphoscelis annulicornis, 251

Amphibiotica, 342

Amphientomum paradoxum, 397

Ampulex, abdomen, 492

Ampulla, 290

Amylispes, 76, 80

Anabolia furcata, mouth-parts, 475; A.
nervosa, larva, 476

Anabrus purpurascens, 321

Anaplecta azteca, folded wing, 227

Anaplectinae, 240

Anatomy — see External Structure and
Internal Anatomy

Anax formosus, 410, 414

Anderson, Dr. J., on Gongylus, 254

Anechura scabriuscula, 208

Anisolabis maritima, 205 ; A. moesta, 205,
A. tasmanica, 216

Anisomorpha pardalina, 274

Anisomorphides, 278

Anisopterides, 412, 414, 426; nymphs,
421

Anomalon, metamorphosis, 552

Anomalopteryx, 484

Anostostoma australasiae, 326

Anoura, 190

568

PERIPATUS-—MYRIAPODA——INSECTA

Ant, brain, 119; nervous system, 495 ;
castes, 500

Ant destroyer, 545, 559

Ante-clypeus, 93

Antennae, 97 ; growth of, 212

Anthophora retusc, parasites of, 544, 545

Anthophorabia retusa, 545

Ant-lions, 453, 454

Anurida ‘maritima, 194, 195

Aorta, 135, 134

Apanteles glomeratus, 561

Apatania, 481; A. arctica, A. muliebris,
481

Apex, 112

Aphilothriz, 531

Apocrita, 519

Apodeme, 103

Apophysis, 103, 520

Appendages, 91, 188, 189, 190

Aptera, 172, 180-189

Apterous Insects, 205, 216, 217, 220, 234,
235, 252, 261, 262, 264, 269, 272, 274,
277, 299, 302, 303, 307, 321, 322, 323,
324, 325, 326, 329, 518, 556, 561—see
also Wingless Insects

Apterygogenea, 175, 196

Aquatic Acridiidae, 301, 303; Aq. Hymen-

optera, 538, 557 ; Aq. Phasmids, 272
Arachnides antennistes, 77
Archidesmidae, 76
Archidesmus, 76
Archijulidae, 76
Archipolypoda, 74, 76
Arolium, 105, 223
Arrhenotoky, 141, 498
Arthromeres, 87
Arumatia ferula, anatomy, 262
Ascalaphides, 459 f.

Ascalaphus coccajus, 459 ; A. longicornis,

459 ; A. macaronius, 460 ; eggs, 460
Aschipasma catadronus, 263, 266
Aschipasmides, 278
Ashmead, on Mymarides, 537 ; on Procto-

trypids, 537 ; on Scleroderma, 536
Astroma, 300
Asymmetry, 216
Athalia (centifoliae) spinarum, 515
Atropinae, 394 f.

Atropos divinatoria, 394 f., 396

Atta (Oecodoma) cephalotes, 501

Attitude, 248, 250, 256, 268, 514
Attraction of light, 230

Auditory organ, 400; of Calotermes, 358

—see also Ear
Audouin on thorax, 100, 101
Aulacus, 562
Aulax, 532
Avicenna, 41
Axes of body, 113

BacILLIDES, 278
Bacillus patellifer, 263

“Ts

| Bittacus, 451, 453; B. tipularius, 452

Blaberides, 247

- Blood-gills, 479 @

Bacteria, 276

Bacteriides, 277

Bacunculides, 277

Baétis, 433

Ballostoma, 196

Ballowitz on spermatozoa, 140

Barber, Mrs., on 8. African locust, 294 —

Barbitistes yersini, 321

Barnston on Perlidae, 402, 405

Barriers with eggs, 461

Base, 112

Basement membrane, 162

Bassett on oviposition of inquilines, 532 *

Bataillon, on metamorphosis, 131, 168;
on reversed circulation, 135 4

Bates, on singing grasshopper, 319 ; on
Termites, 375 :

Bateson, on forceps of earwig, 209 ; on ;
antennae of same, 212 4

Batrachotettiz whiti, 305

Bedeguar, 527, 531

Bees killed by Locusta, 321 | :

Belt on domestic cockroaches, 231 ©§ |

Bermuda, 33

Bertkau, on Psocus, 391 ; on micropterous
Psocidae, 394

Bethylus habits, 5395

Bherwa, 326

Bird eaten by Mantis, 250

Bird-lice, 345, 351 a

Biting-lice, 345, 351

Blabera, 235; wings, 237; B. gigantea, iW
222 i

Black beetle, 221

Blanjulidae, 44

Blanjulus, 44

Blastoderm, 147

Blastophaga grossorum, 547 f.

Bilatta, 240 ;

Blattidae, 201, 220-241, 240; parasites
of, 563 ‘

Blattinae, 240 ; a

Blind Insects, 217, 233 ~

Blood, 132 é,

Blowfly, egg, 1453 roctainaraivaelel 163
Bolivar on eyes of Machilis, 185 id
Bombus, -dorsal vessel of, 133 ; metamor-
_ phosis, 497 ; B. ducorwm, 488
Bombyliidae, 291

Bonnet and Finot on Lugaster, 324
Book-lice, 390 f. ;

Boreus hiemalis, 451 ; larva, 453 ox
Boutan on concealment of leaf-like Tar “9
sects, 323

Brachyscelides, 526

Brachystola magna, 308
Brachytrypes megacephalus, 332
Bracon palpebrator, 559
Braconidae, 558 f.

INDEX

569

Bradford Cave, Myriapods in, 34

Brain, 118,120; of ant, 119; of Perlidae,
404

Branchiae, 401, 421—-see also Gills

Brandt on nervous system, 119, 495

Brauer, on classification, 175 ; on median
segment, 491 ; on hypermetamorphosis,
160 ; on Menorhyncha, etc., 161; on
Ascalaphus larva, 460; on development
of Mantispa, 464; on Palaeodictyop-
tera, 486; on Panorpa larva, 452; on
tegmina of Phyllium, 270

Breitenbach on Proscopiides, 299

Bridgman on British Ichneumonidae, 557 -

Brindley on growth of cockroach, 229

British, Myriapods, 36 ; Orthoptera, 201 ;
earwigs, 215; grasshoppers and locusts,
308; crickets, 339; Psocidae, 395;
Perlidae, 406 ; Odonata, 424 ; Sialidae,
444, 448 ; Chrysopides, 469 ; Trichop-
tera, 480 ; Phytophagous Hymenoptera,
504; Siricidae, 510; Cynipidae, 533 ;
Ichneumonidae, 557 ; Braconidae, 561

Brongniart, on fossil Insects, 428; on
fossil Neuroptera, 343;-on Neurop-
teroidea, 486; on post-embryonic de-
velopment of locust, 287; on young
Mantis, 247 f.

Brongniart and Becquerel on chlorophyll
in Phyllium, 268

Bruner on variation of Orthoptera, 804

Brunner, on Hypertely, 322 ; on classifica-
tion of Orthoptera, 202; of Blattidae,
240 ; of Mantidae, 259; of Phasmidae,
277; of Acridiidae, 309 ; of Locustidae,
328 ; on variation of Oedipoda, 304

Bryodema tuberculata, 281

Bugnion on histolysis, 166; on Hncyrtus,
545

Buller on Weta-punga, 326

Burchell on Mantis, 249

Burgess on. Psocus, 391 f.

Burmeister on Mantidae, 250

Bursa copulatrix, 139

CADDIS-FLIES, 473 f.
Caecum, 125
Caenis dimidiata, 442
Calcares, 104
Calepteryginae, 422, 426
Calepteryx, 417, 420, 422 ;
site, 538
Callimenides, 318, 329
Callimome bedeguaris, 532
Caloptenus spretus, 288 f., 289, 298, 303 ;
development, 289
Calotermes flavicollis, 362, 363, 371, 376 ;
C. nodulosus, 359; C. rugosus, 358,
382, 383
Calvert on Odonata, 412
Calvisia atrosignata, 266, 273 |
Calyx, 283, 439

its eggs’ para-

Cameron, on ant-parasite, 545; on gall-
producing plants, 527; on partheno-
genesis, 498, 499, 517; on Pimpla
larva, 557

Camerano on earwig, 211, 213

Campodea, 61; C. ert ylinus, 182, 183,
197

Campodeidae, 183

Camponotus, nerves, 495

Cannibalism, 425, 477

Cantharidae, 291

Capnia vernalis, 405

Caprification, 547 f.

Capsule of eggs, 201—see also Egg-capsule

Caraphractus cinctus, 538

Carboniferous, Myriapods, 75,76 ; Insects,
196, 238 f., 259, 276, 408, 428, 442 f.,
449

Cardiophorus larva, 90

Cardo, 95

Carnivorous and vegetarian, 250

Carpenter bee wings, 494

Carruthers on locust swarm, 292 .

Case, Hymenopterous, 514

Cases, caddis-fly, 476 f., 480, 481, 482,.
483, 484, 485

Castes, 500, 501

Caudal branchiae, 423

Cave, Myriapods, 34, 37; Insects, 197,

' 451; Locustidae, 321; cockroach, 232,
233

Cecidomyia, parasites of, 536, 537

Cenchri, 511

Centipedes, 30, 36, 40

Cephalocoema lineata, 299

Cephalonomia formiciformis, 536

Cephidae, 504 f.

Cephus integer, 505 ; C. pygmaeus, 505

Cerci, 110,183, 216, 257, 337, 400; of Blat-
tidae, 224, 238

Cermatia, 35

Ceroys saevissuma, 264

Cervical sclerites, 99, 99, 409

Chalcididae, 539

Chalicodoma muraria,
540 f,

Changing colour, 288, 253, 267, 268

Chasmodon apterus, 561

Chatin on labrum, 93 ; on mandibles, 95

Chauliodes, 447

Cheeks, 94

Cheimatobia brumata, parasites, 521

Chelidura dilatata, 205

Cheshire on fertilisation of bee, 499

Chilaspis lowii, 530; C. nitida, 531

Chilian Insects, 447, 463

Chilognatha, 30, 43, 47, 76 ; developmext
of, 63-72; structure of, 52-56, 53;

. double segments, 58, 70

Chilopoda, 30, 33, 44, 47, 52, 74, 74;
structure of, 56-59; development of,
70-72

nest, " parasites,

570 PERIPATUS——-MYRIAPODA—HINSECTA

Chitin, 162

Chitinogenous cells, 162

Chlorophyll in tegmina, 269

Choeradodis cancellata, 252

Cholodkovsky, on head, 87; on styles of
cockroach, 224; on embryolog y of

' Phyllodromia, 237; on morphology of
sting, 493

Chordeuma, 31

Chordeumidae, 44, 54

Chordeumoidea, 80

Chordotonal organs, 121

Chorion, 144

Chorisoneura, 240

Chromosomes, 146

Chrysopa eggs, 469 ; larva, 469; C. aspersa,
470; C. flava, 469 ; 0, pallida larva;.470

Chrysopides, 469 f., 472

Chun on rectal gills, 422

Chyle, 133

Chylific ventricle, 125, 228

Cimbex abdomen, 493 ; abdominal articu-
lation, 492; dorsal vessel, 134; C. syl-
varum, saws, 512

Cimbicides, 511, 517

Cinura, 182

Circulation, 132 f.; in caudal setae, 435

Cladomorphides, 278

Cladonotus humbertianus, 301

Classification, 171 f.; of Blattidae, 240;
of Mantidae, 259; of Phasmidae, 277 ;
of Acridiidae, 309 ; of Locustidae, 328 ;
of Gryllidae, 340

Claws, 105, 106, 469

Chitumnides, 278

Cloéon, eyes, 430; C. dimidiatum, larvule,
432; C. dipterum, nymph, 432 ; respira-
tion of nymph, 435

Clothilla, 395; C. pulsatoria, 395, 396 ;
anatomy, 392

Clypeus, 92, 93

Cockroaches, 220

Cocoons of sawfly, 515

Coeloblast, 149

Coleoptera, 173

Collembola, 782, 189 f.

Collophore, 193

Colobognatha, 44

Colour, 200

Commissures, 116

Common cocoons, 515

Compass Termite, 386

Complementary Termites, 361

Compound eyes, 97,430 ; (=facetted eyes)
in Myriapods, 36

Concealment by movement and position,
288 ; by selection of place, 308

Coniopterygides, 471

OConiopteryx lutea, 471;
471; OC. tineiformis, 472

Conocephalides, 313, 327, 328

Copiophora cornuta, 313

C. psociformis,

Cordulegaster, 415 ; C. annulatus, 415

Cordulegasterinae, 426

Corduliinae, 426

Correlative variation, 536

Corrodentia, 175, 389

Corrosion by Termites, 360

Corydalis, 447 ; C. crassicornis, 447

Corydaloides scudderi, 344

Corydia, 221; C. petiveriana, 233

Corydiides, 241

Coryna, 550

Corynothrix borealis, 191

Costa, 108

Cotes on Indian locusts, 298

Cotylosoma dipneusticum, 272

Coxa, 88, 104

Craspedosoina, 76

Crawlers, 447

Creepers, 407

Cretaceous Myriapods, 75; Insects, 485

Creutzberg on circulation, 436

Cricket, 330, 338

Crioceris asparagi, legs of larvae, 106

Crop, 114, 124, 495

Crunoecia irrorata, case of, 480

Cryptides, 557

Cryptocerus, abdomen of, 109

Cryptops, 36, 41

Crystalline cone, 98

Cuculligera flexuosa, 304

Cunningham on fig fertilisation, 549

Cursoria (Orthoptera), 201

Cuvier, 77

Cyclops form, 536

Cylindrodes campbellii, 336 ; C. kochi, 336

Cynipidae, 523

Cynips aciculata, 531; C. disticha, 530;
C. folii, 530; C. kollari, 530; ¢. lignt-
cola, 530 ; C. spongifica, 531

Cyphocrania aestuans, 266

Cyprus, 32

Cyrtophyllus concavus,320; C.crepitans,311

DaHt and Ockler on feet, 105

D’Albertis on may-flies, 441

Damsel-tlies, 417

Dancing may-flies, 439 f.

Dasyleptus lucasii, 196

Death-watch, 395 f.

Decaux on cannibalism of mole-cricket, 336
Deception, 250, 265

Decoys, 257

Decticides, 329

De Geer on earwigs, 214

Degeeriidae, 190

Deinacrida heteracantha, 326
Demoiselles, 417

Dendroleon pantherinus, 458

Denny on Mantis in England, 258
Derham on death-watches, 396, 397
Dermaptera, 202, 216
Dermatoptera, 202

‘
. ae
a

“ said

INDEX .

571

Derocalymma, 235

Deroplatys sarawaca, 248

De Saussure, on Orthoptera, 202 ; on wings
of Blattidae, 226 f.; on classification
of Gryllidae, 340 ; on Hemimerus, 217 ;
on nomenclature of Blattidae, 240; on
oceans as barriers to migration, 297

Desert Insects, 253, 304

Deuterotoky, 141, 497 f.

Deuto-cerebron, 118

Development, of alar organs of Platycleis,

312; of crickets, 332—see also Em-

‘bryology and Metamorphosis

Devonian, 428, 442

Dewitz on caste, 500; on ovipositor of
Locusta, 314; on morphology of sting,
493 ; on internal legs, 496 ; on develop-
ment of wings of Phryganeidae, 479,
480; on dragon-fly nymphs, 423; on
Chrysopa larva, 470

Diaphana fieberi, 226

Diapheromera femorata, 263, 264, 265, 267

Diastrophus, 532

_ Diaulus, 484

Dicranota, larva, glands of, 142

Dictyoneura, 277, 344

Dictyopteryz microcephala, 406; D. sig-

_ nata, 401

Dielocerus ellisii, 515

Digestion, 127

Dilarina, 465

Dilke, Sir Charles, on Orchis-like Mantis,
254

Dimorphic cocoons, 560 ; males, 547,549

Diplectrona, 479

Diploglossata, 217

Diplopoda, 43, 53, 74

Diploptera silpha folded wing, 227

Diptera, 172

Disgorgement, 495

Distant on §. African locust, 298

Ditrochous, 494, 520

Divided eyes, 409

Docophorus fuscicollis anatomy,
D. wterodes, D. cygni, 349

Dog, biting-louse of, 349 —

Dohrn on tracheal system of Gryllotalpa,
132; on embryology of Gryllotalpa,
336

Dolichopoda palpata, 322 °

Dorsal vessel, 133, 134; reversed action,
435

Dorsum, 100

Dragon-flies, 409

Drakes, 441

Drepanepteryx phalaenoides,
wings, 468

Drones, 499

Drummers, 237

Dubois on decapitated Mantis, 250

Duchamp on egg-capsule of cockroach, 228

Ductus ejaculatorius, 140

348 ;

453, 468 ;

Dudley and Beaumont on Termites, 372,
387

Dufour, on alimentary canal, 124; on tra-
cheal system, 129; on air sacs of Acri-
diidae, 283; on sexual organs, 138,
139; on testes, 140; on phonation,
286; on Tridactylus, 338; on Man-
tidae, 246; on earwigs, 210; on ana-
tomy of cockroach, 228 ; on anatomy of
Gryllotalpa, 335; on anatomy of Ter-
mites, 360; on anatomy of Panorpa,
450 ; on larva of Sialis, 446 ; on Myrme-
leon larva, 458

Duns, 441

Dust-lice, 390 f.

Dwellings of Termites, 385 f.

Dytiseus, mesothorax, 101 ; egg-tube, 138,
199)

Dzierzon theory, 499

Ear, 101, 121 ; of Acridiidae, 285 f., 285 ;
of Locustidae, 316 f., 316, 317; of
crickets, 332 ; of Gryllvtalpa, 333, 334

Earliest pre 238

Earwig, 202 f., 211, 213,.214; forceps,
208 f., 209 ; wing, 206; the name, 214

Eaton, on nymph, 157 ; on Ephemeridae,
435, 437, 440

Ecdysis, 156, 162; nature of, 169

Ectobia, 236 ; E. lapponica, egg-capsule, 229

Kctobiides, 240

Ectoblast, 149

Ectoderm, 148 ; of Peripatus, 20 f., 22

Ectognathi, 189

Ectotrophi, 189

Eggs, 143-145 ; of Peripatus, 19 ; of Myria-
pods, 38, 39, 64; of Ascalaphus, 460;
growing, 513; of parasites, 552 ; of egg-
parasites, 545 ; of Corydalis, 447 ; of Cyni-
pidae, 528 ; of Limacodes, 153; of Mallo-
phaga, 348 ; of Microcentrum, 314; of Phas-
midae, 265, 270 f., 270; of Perla, 404;
of Sialis, 445 ; of Trichoptera, 476 —

Egg-capsule, 265, 290 ; of Phylliwm, histo-
logy, 271

Egg-parasites, 522, 586, 538

Egg-tubes, 137, 139, 392—see also Ovaries

Eileticus, 76, 80

Eisig on chitinous excretion, 180, 163

Ejaculatory duct, 392, 414

Ejection of fluid, 264, 324, 399, 515

Elasmosoma, 559

Elater larva, 29

Elipsocus brevistylus, 393

Elytra, 108

Embia, 352, 353

Embidopsocus, 395

Embiidae, 351, 395

Embryology, 145-153 ; of Peripatus, 19 f.;
of Myriapods, 63 f. ; of parasites, 522:
of earwig, 216; of Blattidae, 237 ; of
Encyrtus, 546 ; of Gryllotalpa, 336 ; of

572

PERIPATUS—-MYRIAPODA—-INSECTA

Polynema, 588; of Smicra, 545; of
Proctotrypidae, 536 f.

Emergence from egg, 263, 264, 290,291, 313

Empodium, 105

Empusa pauperata, 245, 257

Empusides, 259

Encyrtus fuscicollis development, B45

Endoblast, 149

Endoderm, 148; of Peripatus, 20 f., 22

Endolabium, 97

Endo-skeleton, 399

Eneopterides, 340

Enock on Alaptus and Cansohemeds 538

Enoicyla pusilla, 481

Entognathi, 189

Entomology, 86

Entothorax, 103, 114, 116

Entotrophi, 189

Eocene, 407

Eoperipatus, 24 n.

Eoscolopendridae, 80

Ephemera, 434; H. danica, 429, 441;
wing, 431; #. vulgata, 441; nymph, 433

Ephemeridae, 429-443

Ephippigera Malpighian tubes, 335; £.
rugosicollis, 323

Ephippigerides, 318, 329

Epiblast, 65, 149

Epicranium, 92, 93, 93 ©

Epidemes, 107

Epilamprides, 240

Epimeron, 100, 101, 104

Episternum, 88, 100, 101, 104

Epistome, 92

Epithelium of stomach, 126

Eremiaphila, 2438, 253 ; E. vs bien 253

Eremobiens, 304

Erianthus, 301

Erichson on Neuroptera, 342

Erne on Rhyssa, 554

Etoblattina manebachensis, 238, 239

Eucharis myrmeciae, 545

EKuchroma, head and neck 99

Eucorybas, 37

Eugaster guyoni, 324

Eugereon bockingi, 486

Eumegalodon blanchurdi, 327

Eumegalodonidae, 327

Euorthoptera, 216

Euphaea, 422

Euphoberia, 76, 80

Euphoberiidae, 73, 76

Euprepocnemis plorans, 303

Eurycantha australis, 274

Eurypauropidae, 47

EKurytoma abrotani, 539

Eusthenia spectabilis, 407 .

Eutermes, 374 ; EL. ripperti, 388

Euthyrhapha, 296

Evania, 562

Evaniidae, 562

Exner on sight, 416

Exodus, locust of the book of, 298 ©

Exsertile blood-saes, 132

External parasite, 555

External structure, 87; diagram, 88; of
earwigs, 203 f. ; of cockroaches, 221 ; :
‘of Mantidae, 242 £3) ef Phasmidae,
260 f. ; of Acridiidae, 280 f.; of Odon-
ata, 409 f. ; of Ephemeridae, 430 f. ; of
Panorpa, 450; of Phryganeidae, 474 ;
of Hymenoptera, 489 f.; of Tenthre-_
dinidae, 511 é

Eyes, 97—see also Compound Eyes and aa,
Ocelli ;

FABRE on Leucospis, 540; on Monodon-
tomerus, 543; on Sirex, 509 :

Facetted eyes—see Compound Eyes:

Family, 177

Fasting, 448, 458

Fat-body, 136

- Feeding, by Termites, 376 ; young, 495

Femur, 88, 104

Fenestra, 221

Fenestrate membrane, of eye, 98 ; of aie
cardium, 134

Fertilisation, 499 ; of fig, 549

' Field- cricket, 332

Fields of wings, 206
Fig-Insects, 547 f.

. Figitides, 525
- Finot on Japyx, 196

Fire-brats, 186

. Fischer on instars, 158

Fish destroyed, 425

Fletcher on parthenogenesis, 498

Flight, 416

Floral simulators, 254 f.

Flying-machine, model for, 417

Foenus, 563

Foetus of Hemimerus, 218

Foramen, occipital, 92, 94.

Forbes on Blattid, 235

Forceps of earwigs, 208, 209 . .

Forel on nervous system of ant, 495

Forficula auricularia, 202 f., 204, 209,
211; F. gigantea, 210

Forficulidae, 201, 202

Formica-leo, 456

Formicajo, 456

Formicario, 456

Fossil, Insects, 178, 472, 485, 486 ; Acri-

diidae, 308 ; Blattidae, 238 ; : cricket,
340; dragon-flies, 427; earwigs, 216 :
Locustidae, 328 ; Mantidae, 258 ; may-
flies, 442, 443; Phasmidae,. 276;
Panorpidae, 453; Perlidae, 407 ; Siali-
dae, 449; Termites, 389; Thysanura,
196 ; Myriapods, 72 £.; Palaeozoic Neu-
roptera, 343

Founding communities, 381

Fourmilions, 456

' Fowl, biting-louse of, 350

INDEX

573,

Fritze on Ephemerid alimentary canal, 439
Frons, 94

Front wings absent, 260 f.

Fungus chambers, 387

Fungus-growing Termites, 885, 387
Funiculus, 492

Furea, 103

Fureal orifices, 399, 402

GALAPAGOS Islands, 459

Galea, 95

Gall- flies, 523 f.

Galls, 514 f. ; nature of, 525 f., 533

Ganglia, 116.
anin, on metamorphosis, 162 ; on embry-
ology, 536 f., 538

Gasteruption, 562

Gena, 94

Geophilidae, 46, 58, 7%

Geophilus, 33, 36, 39, 46; marine, 30 ;
phosphorescent, 34

Geoscapheusides, 241

Gerascutigeridae, SO

Gerephemera simplex, 428

Gerstaecker, on Neuroptera,
mouth of Odonata, 411

Giebel on Mallophagea, 347

Gigantic Insects, 276, 306, 428

Gilbert White, on mole-cricket, 333; on
field-cricket, 339

Gills, 132, 400, 421, 432f., 478; jointed, 445,
446, 467; filamentous, 476; spongy,
447 ; prothoracic, 443; of pupa, 483 ;
on imago, 401, 479 ; blood-gills, 479

Giraud on Cynipid oviposition, 528

Gizzard, 124, 125

Glacier water, 405

Glande sébitiqne, 139

Glands, 139, 142 ; conglobate, 229 ; maxil-
lary, 458; mushroom, 258—see also
Salivary Glands

Glandulae odoriferae, 31, 36, 54

Glomeridae, 43, 76, 8O

Glomeridesmidae, SO ~

Glomeris, 33, 43, 52

Gnathites, 94, 97

Golden-eyes, 469

Géldi on eggs of Phasmidae, 265

Gomphinae, 426

Gomphocerus, 308

Gomphus, 415

Gonapophysis, 110

Gongylus gongyloides, 254 f., 255

Gosch on median. segment, 491

Goureau on Microgaster, 560

Graber, on dorsal vessel, 134; on blood
cells; 137; on embryology, 148-151 ;
on ears, 286; on ears of Locustidae,
316, 317; on chordotonal organs, 121 ;
on blood, 133; on phonation of Steno-.
bothrus, 284 ; on Platycleis, 312

Grassi, on Myriapoda, 47 ; on Campodea,

343; on

163; on Hinbia, 353 ;
361 f.
Grassi and Rovelli on Thysanura, 182
Green grasshoppers, 311
Green, Mr. Staniforth, on
larva, 461 ;
Gromphadorhina portentosa, 235
Grosse on Mallophaga,. 346
Growth of wings, 393; of Mantidae, 248

on Termitidae,

Helicomitus

-Gryllacrides, 329

Gryllidae, 201, 330-340, 340

Gryllides, 340

Gryllotalpa, 332; dorsal vessel, 134 ;
Malpighian tubes, 127 ; tracheal system,
132

Gryllotalpides, 340

Gryllus, head, 93; G. campestris, 332,
339 ; G. domesticus, 330, 338

Guilding on Ulula, 461

Gula, 88, 93 4

Gyri cerebrales, 119

Gyropus, 350

HAASE on abdominal appendages,
192

Haemocoele, 22, 23

Hagen, on segments, 88; on wing-rudi-
ments, 395 ; on respiration of immature
dragon-fly, 423 f. ; on larvae of Ascala-
phides, 460 ; on amber Psocidae, 397 ;
on Platephemera, 428; on Perlidae,
401; on Psocidae, 393 f. ; on Termites,
360 f.

Haldmanella, 308

Halesus guttatipennis, 473

Haliday on Bethylus, 535

ITalobates, 83

Halteres, 108

Iiansen on Hemimerus, 217

Haplogenius, 461

Haplophlebium, 345

Haplopus grayi, egg, 265

Harpagides, 259

Harpalus caliginosus, head, 92

Harpax ocellata, 253; H. varieyatus, 244

Harrington on Oryssus, 507

Harris on Katydids’ music, 320

Hart on forms of Atta, 501

Hartig on gall-flies, 530

Harvesting Termites, 383

Harvey on metamorphosis, 168

Hatchett Jackson on ecdysis, 162; on
oviduct of ee tae 139

Haustellata, 94

189,

Haustellum, 476

Haviland on Termites, 368, 373, 384
Hawaiian Islands, 354, 395, 425, 471
Head, 92-94

Heart, 133

Heat, 131

Helicomitus insimulans, 460, 461
Helicopsyche shuttleworthi, cases of, 482

574

PERIPATUS—MYRIAPODA——-INSECTA

Hellgrammites, 447

Helminthomorpha, SO

Helorus anomalipes, 534

Hemerobiidae, 453 f.

Hemerobiides, 465 f,

Hemerobiina, 467, 472

Hemerobius larva, 467

Hemichroa rufa, 498

Hemimeridae, 207, 217

Hemimerus hanseni, 217 ; foetus of, 218 ;
H. talpoides, 218

Hemimetabola, 158

Hemiptera, 173

' Hemiteles, 556

Henking on embryology, 145

Henneguy on egg-capsule of Phyllium,
271 ; on embryology of Smicra, 545

Heptagenia, 440; H. longicauda, 437

Hessian-fly, parasites, 537

Heterogamia, 222; H. aegyptiaca, 220;
egg-capsule, 229

Heterometabola, 158

Heteromorpha, 158

Heterophlebia dislocata, 427

Heteropteryx grayi, 262

Hetrodides, 329

Hexapoda, 86

Heymons on earwig embryology, 216

Hind body, 109

Hind wings absent, 429

Histoblasts, 167

Histogenesis, 165

Histolysis, 165, 166 -

Hodotermes japonicus, 383;
landi, 384; H. mossambicus, 356 ;
brunneicornis, 359 ;
371

Hoffbauer on elytra, 108

Holocompsa, 226, 235

Holometabola, 158

Holophthalmi, 459

Homomorpha, 158

Hooks for wings, 494

Hoplolopha, 303

Hose, 393

Howard, on pupation of Chalcididae, 550 ;
on Hydropsyche, 483

Hubbard and Hagen on Termites, 388

Humboldt, 31

Humpback, 445

Huxley, on head, 87 ;
99

H. havi-
H.

on cervical sclerites,

Hydropsyche, 479
Hydropsychides, 482 ;
Hydroptila an gustella, 474 ;

lant, larva, 484
Hydroptilides, 484
Hylotoma rosae, 513
Hymenoptera, 173, 487-565
Hymenoptera phytophaga, 503 f.
Hymenopus bicornis, 253
Hyperetes, 395, 397

larva, 483 ‘
H, maclach-

H, quadricollis, -

Hypermetamorphosis, 158, 159, 465, 540,
552, 557

Hyperparasitism, 521

Hypertely, 323

Hypnorna amoena, 234

Hypoblast, 65, 149

Hypocephalus, 99

-Hypochrysa, 470

Hypodermis, 162, 480
Hypoglottis, 96

Hyponomeuta cognatella, parasite of, 545 |

Hypopharynx, 96—see also Lingua

ICHNEUMONES ADSCITI, 559

Ichneumon-flies, 265, 531; uninjurious
264 ; supplementary, 558

Ichneumonidae, 551-558

Ichneumonides, 557

‘| Ictinus, 419
Ilyodes,. 80

Imaginal, dises, 165, 166 ; folds, 165
Imago, 157

| Imbrications 493

Imhof on Perla, 403 f.

Inaequipalpia, 480

Indusial limestone, 485

Infra-oesophageal ganglion, 11

Inner margin of wing, 108

Inocellia, 447

Inquilines, 373, 524, 531, 533

Insecta, definition, 86

Instar, 155, 158

Instinct of Leucospis, 541

Integument, 162

Internal anatomy, 186 f. ; of f Acridiidae,
282 f.; of earwigs, 210; of Gryllotalpa,
335 ; of Hymenoptera, 494 ; of Libel-
lula, 414; of Mantidae, 246; of Myr-

meleon larva, 457, 458; of Odonata,

~ 414; of Stylopyga orientalis, 228 ; of
Phasmidae, 262; of Raphidia, 448 ; of
Sialis larva, 446 ; of Thysanura, 187 f.

Intestine, 114, 124

Involucrum alarum, 206

Iris oratoria, 248

| Isogenus nubecula, 405, 406

| Isopteryx, 400

Isosoma, 546

Isotoma, 190

JAMAICA, 388

Japygidae, 184

Japyz,abdomen of,109; J.solifugus, 184,196

Jhering, Von, on Termites, 387 .

Joint, 105

Joint-worms, 546

Joly on Ephemeridae, 431; on anatomy

* of Phyllium, 262

Julidae, 34, 43, 71, 73, 77

Juloidea, 80

Julopsis, 74 ;

Julus, 36-39, 52; J. nemorensis, 43; J.
terrestris, 37, 70, 773; breeding, 37;

}

INDEX —

575

development, 66-69 ; heart, 50; ovum,
63, 64; eye, 69

Jurassic, 216, 259, 407, 442

Jurine on pieces at base of wing, 102

KAMPECARIS, 76

Karabidion, 274

Katydids, 319, 320

King, 361, 378

Klapalek, on Trichopterous larvae, 484 f. ;
on Agriotypus, 557.

Knee, 104

Koch, 42

Koestler on stomatogastric nerves, 120

Kolbe, on entothorax, 103 ; on wings of
Psocidae, 394

Kollar on Sirex, 509

Korotneff on embryology of Gryllotalpa,
336

Korschelt on egg-tubes, 138

Korschelt and Heider on regenerative
tissue, 167

Kowalevsky, on phagocytes, 166; on re-
generative tissue, 167 ; on bee embryo,
496

Kradibia cowani, 549

Krancher on stigmata, 111

Krawkow on chitin, 162

Kulagin, on embryology, 537 ; of Encyrtus,
545

Kiinckel d’Herculais, on histoblasts, 167 ;
on emergence of Stawronotus, 290

Labia minor, 214

Labidura riparia, 210, 211, 214, 215

Labium, 95; of Odonata, 410, 411; of
O. larva, 420

Laboulbéne, on Anurida maritima, 194 ;

on Perla, 399

Labrum, 93, 93

Lacewing flies, 453, 469

Lachesilla, 395

Lacinia, 95

Laemobothrium, 347

Lamarck, 77

Lamina, subgenitalis, 224 ; supra-analis, 224

Landois on stigmata, 111 —

Languette, 96

Lankester, 40

Larva, 157 ; (resting-larva), 164 ; oldest, 449

Larvule, 431, 432

Latreille, 30

Latreille’s segment, 491

Latzel, 42, 77

Latzelia, 80

Leach, 30, 77

Lead, eating, 510

Leaf-Insects, 260

Legs, 104 ; internal, 496 ; four only, 549;
of larvae, 106, 110

Lendenfeld, on dragon-flies, 416, 417 ; on
muscles of dragon-fly, 115

Lens, 98

Lepidoptera, 173

Lepisma, 185, 196; L. saccharina, 186; L.
niveo-fasciata, 195

Lepismidae, 185

Leptocerides, 482

Leptophlebia cupida; 430

Lespés on Calotermes, 364°

Leuckart on micropyle apparatus, 145

Leucocytes, 137

Leucospis gigas, 540;
habits, 540 f.

Lewis, Geo., on luminous may-fly, 442

Lewis on Perga, 518

Leydig, on brain, 119, 120 ; on Malpighian
tubes of Gryllotalpa, 335 ; on ovaries,
137, 142 ; on glands, 142

Lias, 216, 236, 340, 427, 428, 453, 485, 503

Libellago caligata, 413

Libellula quadrimaculata, 411, 425

Libellulidae, 409

Libellulinae, 416, 426

Lichens, resemblance to, 253

Liénard on oesophageal ring, 118

Light, attraction of, 441

Ligula, 96

Lilies and dragon-flies, 426

Limacodes egg, 153

Limacomorpha, 80

Limnophilides, 487

Lingua, 95, 96, 391, 411, 420, 437

Linnaeus quoted, 84

Liotheides, 346, 350

Lipeurus heterographus, 346 ; L. bacillus,
347; L. ternatus, 349

Lipura burmeisteri, 190 ; L. maritima, 194

Lipuridae, 190

Liquid emitted, 264, 324, 399, 515

Lissonota setosa, 551

Lithobiidae, 45, 70, 75

Lithobius, 32, 36-39, 41, 45, 58; breeding,
38 ; structure, 48, 49, 57

Lithomantis, 259 ; L. carbonaria, 344

Locusta, ovipositor, development and struc-
ture, 315; L. viridissima, 318, 319, 321,
324, 327

Locustidae, 201, 311-329, 328

Locustides, 329

Locusts, 291 f.; of the Bible, 298; in
England, 299; swarms, 292-299 ; eggs,
292

Loew on anatomy of Panorpa, 450 ; of
Raphidia, 448

Lonchodes duivenbodi, ege, 265; L. nema-
todes, 260, 261.

Lonchodides, 277

Longevity, 377, 429, 438; of cockroach,
229

Lopaphus cocophagus, 264

Lophyrus pini, 511

Low on Coniopteryz, 471, 472

Low, F., on snow Insects, 194

larva, egg, 542 ;

576

PERIPATUS—MYRIAPODA—INSECTA

Lowne, on embryonic segments, 151; on
integument, 162; on stigmata, 111; on
respiration, 130

Lubbock, Sir John; on Pawropus, 62; on
aquatic Hymenoptera, 538 ; on auditory
organs, 121; on sense organs, 123 ; on
respiration, 180; on stadia, 1653; on
Cloéon, 432, 437 ; on Collembola, 192 ;
on Insect intelligence, 487

Lucas on mouth-parts of Trichoptera, 475

Luminous may-flies, 442

Lycaenidae, eggs, 144

Lyonnet on muscles, 115

Lysiopetalidae, 76

MACHILIDAE, 184

Machilis maritima, 185 ; M, polypoda, 184
Macronema, 478

Malacopoda, 77

Mallophaga, 342, 245-350

Malpighi on galls, 525

Malpighian tubes, 114, 124, 127, 187,

358, 360, 392, 403, 414, 421, 448, 457, ©

458; of Gryllotalpa, 335; of Ephippigera,
335; of Mantis, 246; of Myriapods,
48

Malta, Myriapods at, 35

Mandibles, 94, 95; absent, 474, 475

Mandibulata, 94

Manticora, 304

Maatidae, 201, 242-259, 259

Mantides, 259

Mantis, immature tegmina, 248 ; parasite,
546; M. religiosa, 246, 247, 258

Mantispa areolaris, 463; M. styriaca larva,
464

Mantispides, 463 f.

Mantoida luteola, 251

Marchal on Malpighian tubes, 127

Marine Myriapods, 30

Marshall, on Apanteles cocoons, 560; on
Braconidae, 561

Mask, 420

Mastacides, 301, 309

Mastax guttatus, 301

Maternal care, 214, 336, 517

Maxilla, 95, 96 ; of Odonata, 411 ;
190

May-flies, 429 ; number of, 442

Mayer, on Apterygogenea, 196 ;
fication, 547, 548

Mazon Creek, Myriapods at, 75

M‘Coy on variation of ocelli, 267

M‘Lachlan, on Ascalaphides, 459; on
Oligotoma, 354; on Psocidae, 395; on
Trichoptera, 480 f.

Mecaptera, 174, 453

Mechanism of flight, 416

Mecistogaster, 412

Meconema varium, 321

Meconemides, 328

Mecopoda, 319

absent,

on capri-

Mecopodides, 328

Mecostethus grossus, 285, 299, 308
Median plate, 504, 506, 507, 512
Median segment, 109, 490, 491
Megachile, nervous system, 496
Megaloblatta rufipes, 235
Megalomus hirtus, 468
Megalyra, 562

Megalyridae, 562

Meganeura monyi, 428
Megasecopterides, 344
Megastigmus, 547

Meinert, on earwigs, 210, 211, 212; on

Myrmeleon larva, 457 ; on stink-glands,
210

Melittobia, 545

Melliss on Termite of St. Helena, 389

Melnikow on eggs of Mallophaga, 348

Membranule, 413

Menognatha, 161

Menopon leucostomum, 348 ; M. pallidum,
350

‘Menorhyncha, 161

Mentum, 95, 96, 96
Mesoblast, 20, 65, 149
Mesoderm, 20, 149
Mesonotum, 88

_ Mesopsocus unipunctatus, I94

Mesothoracic spiracle, 491
Mesothorax, 101

‘Mesozoic, 309, 449, 485

Metabola, 158, 174

Metagnatha, 161

Metamorphosis, 153-170 ; of Hymenoptera,
497 ; of nervous system, 495 f.

Metanotum, 88

Metapodeon, 491

Methone, 200; M. anderssoni, 305, 206

Miall, on imaginal discs, 165, 167 ;
unicellular glands, 142

Miall and Denny, on pericardial tissue,
135; on epithelium of stomach, 126;
on spermatheca of cockroach, 228; on
stigmata, 111 ; on stomato-gastric nerves,
120

-Miamia bronsoni, 449

Microcentrum retinerve, 313, 314, 320

Microgaster, 559; M. fulvipes, 560; M.
globatus, 560

Micropterism, 339, 394, 405 f., 484

Micropyle, 145 ; apparatus, 404

Migration, 293, 425

Migratory locusts, 292, 297

Millepieds, 41

Millipedes, 30, 40, 41

Miocene, 216, 258, 407

Molanna angustata, mandibles of pupa,
477

Mole-cricket, 333 ; leg, 333

Moniez on Anurida maritima, 194

Monodontomerus, 532; M. cupreus, 543;
M. nitidus, 544

‘

ee A eT ee ee ee &.

HT

INDEX

577

Monomachus, 563

Monomorphic ant, 498

Monotrochous trochanters, 494, 520, 564,
565

Mordella eye, 98

Mormolucoides articulatus, 449

Morton, on gills of Trichoptera, 483 ; on
Perlidae, 406

Moult, 156

Moulting, 437 ; of external parasite, 556

Mouth-parts, of dragon-fly, 411 ; of dragon-
fly nymph, 420; atrophied, 430 .

Miiller, Fritz, on caddis-flies, 482 f.; on
fig-Insects, 549 ; on Termites, 358, 360,
374, 381, 382

Miiller, J., on anatomy of Phasmidae, 262

Murray, on Phyllium scythe, 263; on
post-embryonic development of Orthop-
tera, 265

Musca, metamorphosis, 163, 167

Muscles, 115

Music, of Locusta, 318; of Tanana, 319;
of Katydids, 319—see also Phonation

Mylacridae, 239

Mymarides, 537, 538

Myoblast, 149

Myriapoda, 27, 42, 74; definition, 29; as
food, 31 ; habits, distribution, and breed-
ing, 29-40 ; locomotion, 40 ; names for,
41 ; classification, 42-47 ; structure, 47-
63; embryology, 63-72; fossil, 72-77 ;
affinities, 78

Myrmecoleon, 456

Myrmecophana fallax, 323

Myrmecophilides, 340

Myrmeleo, 456

Myrmeleon, 456; M. europaeus, 457 ; M.
Sormicarius, 455, 457; M. nostras, 457 ;
M. pallidipennis, 456

Myrmeleonides, 454 f.

Nasutt, 370

Necrophilus arenarius, 462

Necroscides, 278

Needham on locusts at sea, 297

Nematus, 514; .V. curtispina, 498

Nemobius sylvestris, 339

Nemoptera ledereri, 462; NV. larva, 462

Nemopterides, 462

Nemoura, 401; N. glacialis, 405

Neoteinic Termites, 362, 380

Nervous system, 116

Nervures, 107, 108, 206 ; of Psocidae, 393 ;
of Embiidae, 352 ; of Termitidae, 359

Neuroptera, 172, 341-485; N. amphibio-
tica, 342; N. planipennia, 342

Neuropteroidea, 486

Neuroterus lenticularis, 523

Neuters, 137

Newman on abdomen, 491

Newport on <Anthophorabia, 545; on
Monodontomerus, 544; on Paniscus,

WOT

‘Nymph, 157);

555; on Pteronarcys, 399 f.; on turnip
sawfly, 515

Nicolet on Smynthuridae, 191

Nietner on Psocidae, 395

Nirmus, 346 f.

Nitzsch, on Mallophaga, 346 f.; on Psocidae,
392

Nocticola simoni, 232

Nodes, 493

Nodus, 413

Nomadina, 565

Notophilidae, 45

Notophilus, 45

Notum, 91, 100

Number of species, of Insects, 83, 171, 178 ;
of Cephidae, 506 ; of Chalcididae, 539 ;
of gall-flies, 533 ; of Hymenoptera, 503 ;
of Parasitica, 520; of Ichneumonidae,
551; of Odonata, 424; of Orthoptera,
201; of earwigs, 215; of cockroaches,
236; of Mantidae, 258; of Phasmidae,
272; of migratory locusts, 297; of
Perlidae, 407; of Psocidae, 395; of
sawflies, 518

Nurseries of Termites, 387

Nusbaum on embryology, 149, 152

Nyctiborides, 240

of dragon-fly, 418, 419,
420, 422, 426; of Ephemeridae, 432 f,,
432, 433, 434, 435, 436

Nymphidina, 465, 472

Nyssonides, 565

OAK-GALLS, 527

Occiput, 94

Ocelli, 97, 282, 313, 400, 409, 430;
variation in, 267, 536

Odonata, 409 £

Odontocerum albicorne, case of, 480

Odontura serricauda, 316

Oecanthides, 340

Vecanthus, 339

Oecodoma—see Atta

Oedipodides, 304, 309

Oenocytes, 137

Oesophageal ‘‘ bone,” 391

Oesophageal nervous ring, 118, 121

Oesophagus, 114, 124, 403

Oestropsides, 482 ;

Oligonephria, 175

Oligoneuria garumnica, nymph, 434

Oligotoma michaeli, 351, 354 ; O. sawndersi,
352; O. insularis, 354

Ommatidium, 98

Oniscigaster wakefieldi, 442

Oniscomorpha, 80

Ontogeny, 153

Onychophora, 4

Oolemm, 144

Oolitic, 239

Ootheca of Mantis, 246, 247

‘Ophionellus, 563

578

PERIPATUS—MYRIAPODA—INSECTA

Ophionides, 557

Opisthocosmia cervipyga, 215

Opisthopatus, 24, 24 n.

Orders, 172

Orientation, 112

Origin of wings, 206

Orl-fly, 445

Ormerod, Miss, onimportation of locusts, 299

Ornament, 200, 215, 233 f., 243, 244,
282, 302, 313, 339

Orphania denticauda, 321

Orthodera ministralis, 249

Orthoderides, 251, 259 ~

Orthophlebia, 453

Orthoptera, 772, 198-340, 407

Oryssidae, 506

Oryssus abietinus, 506; O. sayi, 506

Osborn on Menopon, 350

Osmylides, 466

Osmylina, 466

Osmylus chrysops, 341 ;
maculatus, 466

Osten Sacken on similar gall-flies, 532

Ostia, 48 f., 133, 435 :

Oudemans on Thysanura, 182

Oustalet on Odonata, 422, 423

Outer margin of wing, 108

Ovaries, 137, 138; of earwigs, 211; of
Oedipoda, 283, 284; of Perla, 404; of
Thysanura, 188

Oviduct, 139, 392

Oviposition, 229, 246, 265, 290, 291, 440;
of Agriotypus, 557; of Cynipidae, 527
f., Adler on, 529; of Hncyrtus, 545;
of Ichneumon, 555; of inquiline gall-
flies, 532 ; of Meconema, 321; of Pele-
cinus, 564; of Pimpla, 553; of Poda-
grion, 546 ; of sawflies, 513; of Sirex,
509; of Xiphidium, 321

Ovipositor, 110, 552, 554; Cynipid, 524;
of Locusta, development, 314, 315

Owen, Ch., 40, 78

Oxyethira, 484; O. costalis, larva, 485

Oxyhaloides, 234, 241

Oxyura, 533, 534

larva, 466; O.

PACHYCREPIs, 550

Pachytylus cinerascens, 298, 297, 298, 299,
308 ; P. marmoratus, 298 ; P. migrator-
toides, 298 ; P. migratorius, 298, 299,
308; P. nigrofasciatus, 285, 298

Packard, on caye-Myriapods, 34; on air
sacs of locusts, 283, 294; on classifica-
tion, 173; on development of Diplaz,
419; on may-flies, 430; on metamor-
phosis of Bombus, 497 ; on scales, 397 ;
on spiral fibre, 129

Pad, 105-

Paedogenesis, 142

Pagenstecher on development of Mantis, 247

Palaeacrididae, 309

Palaeoblattariae, 239

-Panorpa, 450, 453;

. Pedicellate, 519

Palaeoblattina douvillei, 238 f.
Palaeocampa, 73
Palaeodictyoptera, 486
Palaeomantidae, 259
Palaeontology, 178
Palaeophlebia superstes, 427
Palaeozoic, Myriapods, 76 ; Insects, 343, 486
Palenarthrus, 80 *
Palingenia bilineata, 430; P.feistmantelit,
443; P. papuana, 441 P. virgo, 431 —
Palmén, on dragon-fly nymphs, 423; on
Ephemeridae inflation, 439 ; on gills of ©
Perlidae, 402; on rectal gills, 422; on
tracheal system of immature Ephe-
meridae, 436 _
Palmon, 546 re
Palmula, 105
Palophus centaurus, 275
Palpares, 454
Palpiger, 95
Palpus, 95 ; of Pieris brassicae, 122
Pambolus, 561 _
Pamphagides, 303, 310 1%
Panchlora viridis, 229
Panchlorides, 241
Panesthiides, 247
Paniscus virgatus larva, 555 f. 4
leg, 104; P. com-
munis, 449 ; larva, 452
Panorpatae, 175, 453
Panorpidae, 449, 451
Pantel on phonation of Cucullinera, 304
Papiriidae, 191 -
Paraderm, 164
Paraglossa, 95, 96, 96 . iy
Paraperipatus, 24 n. .
Parapteron, 100, 101, 102 i
Parasites, 540 f., 543 ; external, 555 fs 1
Parasitica, 520, 521 \ “a
Parasitism, 521 f., 535, 559, 560 ;
Parthenogenesis, 141, 481, 497, 516 f.
530 f., 547 ; utility, 517°
Passalidae, mandibles, 95
Patagia, 102, 103 .
Patagonia, 459 |
Paunch, 348, 360, 446, 448
Paurometabola, 158, 199
Pauropidae, 33, 42, 47
Pauropoda, 47, 57, 77, 79, 80 ; ; structure, 62
Pauropus, 47
Pazlavsky on bedeguar, 527

..

Pedunculate body, 495
Pelecinidae, 563
Pelecinus polyturator, 563
Pelopaeus spinolae foot, 105, 106
Perez on ‘Termes, 366, 382
Perga lewisii, 517
Periblast, 149
Pericardial septum,
tissue, 135
Peringueyella jocosa, 325

134; sinus,

134 ;

INDEX

579

Peripatoides, 24 n.

Peripatopsis, 24 n.

Peripatus, 1, 6, 23, 77, 79; teanhene: 3;
14, 15; affinities, 4; external features,
53 head, 6; tail, 6; colour, 6; jaws,
7; legs, 8; habits, food, 9; breeding,
10, 19; alimentary canal, 11; nervous
system, 12, 22 ; body-wall, 13 ; muscles,
vascular system, 15 ; haemocoele, 22, 23 ;
body-cavity, 16, 22; nephridia, 16, 17,
22 ; reproductive organs, 18; develop-
ment, 10, 19, 20, 22; species, 24; dis-
tribution, 24-26

Periplaneta americana, 236; P. austral-
aside, 221, 236, 239

Periplanetides, 241

Perisphaeriides, 241

Perla, anatomy, 403 f. ;
P. cephalotes, 406; P.
406; P. parisina, 399

Perlidae, 398 f.

Perris on Termes, 366, 374

nymph, 400;
maxima, £00,

_ Petasia, 303

Petiolata, 496, 503, 519

Petiolate, 519

Petiole, 492, 493, 519

Petioliventres, 503, 519

Peyrou on atmosphere in bodies, 131

_ Peytoureau on styles of cockroach, 224

Pezomachus, 556

Phagocytes, 137, 165

Phaneropterides, 323, 328

Pharynx, 114, 124

Phasgonuridea, 311

Phasma, 276

Phasmidae, 201, 407, 260-278, 277

Phasmides, 278

Phasmodes ranatriformis, 324

Philopotamus, 483

Philopterides, 346, 350

Phonation, 200, 257, 302, 306; of Acri-
diidae, 284, 304; of Locustidae, 318,
319, 320, 324, 327 ; of Gryllidae, 331 f. ;
of Gryllotalpa, 334 ; of Brachytrypes, 332

Phosphorescent Myriapods, 34 ; may-flies,
442

Phragma, 103, 491

Phryganeagrandis, 422; P. pilosa,pupa,477

Phryganeidae, 398, 473 f.

Phryganeides, 480

Phylliides, 267, 278

Phyllium, 262, 263, 267 f.; P. crurifolium,
269 f.; egg-capsule, structure, 271;
P. scythe, 267, 268 ; egg, 270; P. sicci-
Solium, egg, 265

Phyllodromia germanica, 229, 236; egg-
capsule, 229

Phyllodromiides, 240

Phymateus, 303

Phytophagous Parasitica, 522, 546,547,557

Pick, of death-watch, 391

Pictet on nymphs of Ephemeridae, 433

Pieris, palpus, 122; instars, 156; para-
sites 561

Pigment, of iris, 98 ; retinal, 98

Pillared eyes, 430

Pimpla, 553, 557

Pimplides, 557

Pitfalls of ant-lions, 455, 459

Planipennia, 342

Plantula, 105

Plateau, on marine Myriapods,
digestion, 127 ; on sight, 416

Platephemera antiqua, 428

Platyblenmus lusitanicus, 339

Platycleis grisea, 312

Platycnemis, 413; P. pennipes, 418, 417

Platycrania edulis, egg, 265

Platygaster, embryology, 536

Platyptera, 174

Platypterides, 259, 344, 428

Plecoptera, 775, 407

Plectoptera, 174, 442

Plectopterinae, 247

Pleura, abdominal, 493

Pleuron, 88, 91, 100

Plica of earwig, 209

Pneumora scutellaris, 302

Pneumorides, 299, 302, 309

Pocock on Myriapods, 33, 80

Podacanthus wilkinsoni, 272

Podagrion, parasitism of, 546

Podeon, 491

Podura, 194; P. aquatica, 194

Poduridae, 290

Poecilimon affinis, 200

Poisers, 108

Poison-claws, 36, 58, 60

Poletajewa, Olga, on dorsal vessel, 133 ;
on Odonata, 414

Polistes lanio, parasite of, 564

Polycentropus, 483

Polydesmidae, 34, 36, 44, 76

Polydesmoidea, 80

Polydesmus, 36, 39, 44

Polymitarcys, 440

Polymorphism, 500, 536

Polynema natans, 538

Polynephria, 175

Polyxenidae, 43, 53, 59, 77

Polyxenus, 33, 37, 48, 55, 72;
section, 56 ; sense-organ, 51

Polyzoniidae, 44, 53

Polyzonium, 44, 48

Pompholyx dimorpha, 518

Pompilides, 494

Porthetis, 280, 282

Post-clypeus, 93 ‘

Post-embryonic development, 154

Post-scutellum, 100, 101

Potamanthus, 433

Potts on Mantis, 249

Poulton on Paniscus, 556

Praescutum, 100, 101

-30; on

transverse

580

PERIPATUS—-MYRIAPODA——INSECTA

Praon, 550

Pratt, on imaginal dises, 167

praying Insects, 242

Prestwichia aquatica, 538

Primary larva, 542

Primary segmentation, 150

Prisopus, 272

Procephalic lobes, 97, 150

Prochilides, 328

Prochilus australis, 324

Proctodaeum, 123, 151 ;

Proctotrypidae, 633-538

Production of sex, 499

Pro-legs, 514

Pronotal wing-rudiments, 344, 395

Pronotum, 88, 100 ; of Xylocopa, 490

Pronymph, 164

Propleuron, 100, 489

Propodeon, 491

Propodeum, 491, 492

Proscopiides, 299, 309, 325

Prosopistoma punctifrons, 435

Prostemmatic organ, 195

Prosternum, 88, 100; of Vespa crabro, 491

Protection, 518, 515

Protephemerides, 443

Prothoracie dorsal appendages, 443

Prothorax, 102

Protoblast, 149

Proto-cerebron, 118

Protocranium, 92, 93

Protodonates, 428

Protoperlidae, 408

Protosyngnatha, 75

Prototracheata, ix, 4

Proventriculus, 114, 124, 125, 450

Psalis americana, 215

Psectra distra, 466

Pselapsognatha, 43

Psenides, 524, 533

Pseudoglomeris fornicata, 235

Pseudoneuroptera, 342

Pseudonychium, 105 ©

Pseudophyllides, 328

Pseudo-sessile, 493

Pseudotremia, 34, 35

Psilocnemis dilatipes, 413

Psocidae, 390 f.

Psocus fasciatus, 390; P. heteromorphus,
391

Pteromalini, 539

Pteronarcys frigida, 398; P. regalis, 402

Pteroplistus, 331

Pterygogenea, 175, 196

Pulvillus, 105

Pupa, 157, 169 ; active, 448, 465, 473, 479

Pupation, of Chalcididae, 550 ; of Encyrtus,
546 ; of Proctotrypids, 534, 535

Pupipara, 143

Pygidicrana hugeli, 202

Pygidium, 205

Pylorus, 127

in Musca, 124

Pyramids of Egypt, 462
Pyrgomantis singularis, 252
Pyrgomorpha grylloides, 308
Pyrgomorphides, 303, 309

QUEEN, 144, 361, 378

RaDIAat cell, 524
Raphidia, 447 ;
448

Raphidiides, 444, 447

Raptorial legs, 242 f., 257, 463, 484
Ratzeburg, on. Anomalon, 5535; on tro-
- chanter, 520
Ravages of Termites, 388

Réaumur, on ant-lions, 455; on circula-

R. notata, 447; larva,

tion of silkworm, 135; on galls, 525 ;_

on may-flies, 438, 441; on sawflies,
512, 513 ; on spheroidal condition, 164

Receptaculum seminis, 139, 404

Rectal, gills, 421 f. ; respiration, 435

Rectum, 125

Redtenbacher, on migratory locust, 297
on wing, of Oligotoma, 353 ; of Termes,
359

Reduviid egg, 145

Reflex action, 250

Reproduction of lost parts, 213, 265,

266

Reproductive organs of Ephemeridae, 439

Resemblance, of eggs to seeds, 265, 270,
271; of one part to another, 208, 266 ;
of parasite to host, 532; histological,
271; of Trichoptera to moths, 484; to
bark, 251; to flowers, 254, 255, 256 ;
to inorganic things, 253, 304, 307; to
leaves, 255, 267, 268, 322 f., 323; to
lichens, 253; to other creatures,
to other Insects, 197, 215, 225, 251,
274, 300, 301, 323, 324, 504, 513, 550;
to vegetation, 200, 260, 274

Respiration [and respiratory organs], 128-

132, 431;
setae, 435 ;
420 f.; of Perlidae, 401 f.

Respiratory chamber, 434

Retinula, 98

Reuter on ventral tube, 192

Rhabdom, 98

Rhipipteryx, 337, 338

Rhizotrogus egg-tubes, 138

Rhodites rosae, 498, 527, 528, 531 ;
532 ; parasite, 539

Rhyacophilides, 453

Rhyacophylax, 482

Rhynchota, 175

Rhyparobia maderae, 237

Rhyssa persuasoria, 554

Riley, on caprification, 549 ; on Cophus,
505 ; on development of Caloptenus, 28,
289; on galls, 526 f.; on Katydids,
320; on locust swarms, 293 ; on Micro-

by integument, 483; by

larva,

235 > |

of nymphs of Odonata, ©

LD ye ate ae ON a

INDEX

581

centrum, 313 ; on ovipositing of locust,
290 ; on subimago, 437; on Thalessa,
554

Ritsema on Hnoicyla, 481

Ronalds on anglers’ flies, 441

Roux on Necrophilus, 462

Royal pairs, 377 :

Riihl on earwig, 213

Sacs—see Air Sacs

Sagides, 328

Salivary glands, 124, 126, 187, 210, 228,
246, 283, 335, 348, 353, 403, 414, 495 ;
of Peripatus, oa s0f ‘Myriapods, 48,
49

Salivary receptacle, or reservoir, 126, 228,
246, 335, 348, 360

Saltatoria (Orthoptera), 201

Sandwich Islands—see Hawaiian Islands

Saunders, Sir Sydney, on. Scleroderma,
536 ; on caprification, 548

Saussure, H. de—see De Saussure

Savage on Termites, 368

Saw, 493, 512

Sawflies—see Tenthredinidae

Scales, 185, 189, 397

Scapteriscus, 334

Scelimena, 301

Schindler on Malpighian tubes,
Gryllotalpa, 335

Schistocerca peregrina, 298 ; development,
287 ; S. americana, 298, 308

Schizodactylus monstrosus, 325

Schizophthalmi, 459

Schizotarsia, 35, 46, 57, 58, 70,75 ;
ture, 59

Schletterer on parasitic Hymenoptera, 562,
563

Sclerite, 91

Scleroderma, 536

Scolia, ovaries, 138

Scolopendra, 30, 31, 32, 41, 78

Scolopendrella, 47, 61

Scolopendrellidae, 33, 42, 46

Scolopendridae, 31, 33, 39, 45, 75;
matophores, 39

Scorpion-flies, 449 f.

Seudder, on grasshopper music, 287 ; on
Katydids’ music, 320; on locusts at
sea, 297 ; on reproduction of lost limbs,
265; on fossil Insects, 486; on fossil
earwigs, 216 ; on fossil may-flies, 443 ;
on fossil Sialidae, 449; on Tertiary
Insects, 179 .

Scutellum, 100, 101

Scutigera, 35, 36, 48 ; sense organ, 51

Seutigeridae, 35, 36, 40, 46, 50

Scutum, 100, 101

Secondary, 427, 472 ;

Securifera, 503

Segmentation,
Smicra, 545

246; of

struc-

sper-

larva, 542

149, 237; of ovum of

Segments, 88, 90 ; number of, 87

Selys, De, on dragon-flies, 425, 427

Semi-pupa, 497

Sense organs, 121-123

Senses, 541, 544, 553

Sericostomatides, 474, 482

Series, 177, 201

Serosa, 148.

Serrifera, 503

Sessile abdomen, 493

Sessiliventres, 492, 496, 503

Sex, 498, 499, 500

Sexes, 137

Sexual organs, external, 141

Shaw on Orthoptera, 201

Sialidae, 407, 444

Sialides, 444

Sialis lutaria, 444 ; eggs, 445, larva, 445 ,
tracheal gill, 446

Silk, 127

Silo, parasite of, 558

Silurian Insect, 238

Silver fish, 186

Simple eyes, 97, 184—-see also Ocelli

Sinel, on marine Geophilus, 30

Siphonaptera, 174, 175

Sirex, habits of its parasite, 554; S. augur,
509; S. gigas, 508, 510; S. juvencus,
508

Siricidae, 507; parasites of, 563

Siricides, 510

Sisyra, 467 ; S. fuscata larva, 467

Sisyrina, 467

Sitaris humeralis, early stages, 159

Sloane, Sir Hans, on locusts at sea, 297,

Smallest Insect, 537

Smeathman on Termites, 366 f., 381, 383,
387

Smicra clavipes embryology, 545,

Smith, F., on Cynips, 530; on Trigonalys,
564

Smynthuridae, 797

Smynthurus. variegatus, 19155 S. fuscus,
192

Snow-Insects, 194

Social, Insects, 85, 361, 369 ; Gb TIeT eS:
488, 500 f.

Soldiers, 370, 371, 372

Somites, 87

Sommer on Macrotoma, 163, 195

Soothsayers, 242

Sound production, 358—see also Phona-.
tion

Spathius, 561

Species, number of—see Number

Spencer, Herbert, on caste and sex, 500

Spermatheca, 139, 228, 499

Spermatophores, 10, 39

Spermatozoa, 140

Sphaeropsocus kunowii, 397

Sphaerotherium, 43

Sphex chrysis, 490

582

PERIPATUS—MYRIAPODA—INSECTA

Spiders eaten, 464, 465

Spinneret, 458

Spinners, 441

Spiracles, 89, 111, 128 ; number of, 186 ;
of dragon-fly nymph, 423: absent, 436
—see also Stigmata

Spiral fibre, 128

Spongilla fluviatilis, larva in, 467

Spontaneous generation, 525

Spring of Collembola, 191

Spurs, 104

Stadium, 155, 158

Stalked, cocoons, 560; eggs, 469

St. Augustine quoted, 85, 565

Stein on Raphidia larva, 448

Stelis, parasitic, 544 ; parasitised, 543

Stem sawflies, 504

Stenobothrus, 308 ;
284

Stenodictyopterides, 344

Stenopelmatides, 321, 329

Stenophasmus ruficeps, 561

Stenophylla cornigera, 257, 258

Stephanidae, 567

Stephanus, 562

Sternum, 91, 100

St. Helena, 389

Stick-Insects, 260

Stigma of wing, 524, 534

Stigmata, 88, 89, 111, 204 ; position, 493 ;
on head, 193 ; 8. repugnatoria, 36—see
also Spiracles

Sting, 493 ; and ovipositor, 534

Stink-flies, 469

Stink-glands, 31, 125, 210, 264, 335

Stipes, 95

Stoll on spectres, etc., 254

Stomach, 114, 124, 125

Stomato-gastric nerves, 120, 121

Stomodaeum, 123, 151

Stone-flies, 407

Stratiomys strigosa parasite, 545

Stridulation, 304—see also Phonation

Stummer-Traunfels on Thysanura and
Collembola, 189

St. Vincent, island of, 461

Styles, 224, 238

Stylopyga ortentalis, 223, 228, 231, 236

Sub-imago, 429, 437 ;

Sub-Order, 177

Subulicornia, 426

Sucking spears, 466, 467, 470, 471

Suctorial mandibles, 453, 456

Super-Orders, 177

Supplementary Ichneumon-flies, 558

Supra-oesophageal ganglion, 117

Sutures, 92

Swarms: of locusts, 299-299 ; ; of may-flies,
441; of Termites, 362

Sympathetic nervous system, 120 ;
353

sound - instruments,

absent,

Symphrasis varia, 465

Symphyla, 42, 46, 77, 79, 80 ; structure,
61 ;

Symphyta, 503
Sympycna fusca, 415
Synaptera, 175
Synergus, 531
Syngnatha, 44

TANANA, 319

Tarachodes lucubrans, 249

Tarsus, 88, 104, 106

Taschenberg on. parthenogenesis, 141

Tausendfiisse, 41

Teeth, 95

Tegmina, 108; leaf-like, of Pterochrow,
322 ; of crickets, 331; of earwigs, 205,
212; of Phyllium, 269 : ; of Schizodacs

tylus, 325

Tegula, 103, 108

Teleganodes, 442

Telson, 205

Temples, 94

Templeton on Lepisma, 195

Tendons, 116

Tenthredinidae, 570-518

Tenthredo sp., 489 ; testes, 140

Tentorium, 99

Tepper on fossorial Blattid, 241

Terebrantia, 520

Tergum, 91, 100

Termes, 378, 380 ; 7. lucifugus, 359, 360,
364, 365, 373, 374 ; ; T. mossambicus, 356 ;
T. bellicosus, 366, 371 ; trophi, 357 ; cell
of, 367; 7. occidentis, 371; T. armiger,
371; T. tenuis, 389; T. cingulatus, 3713
T. dirus, 371; T.debilis, 371 ; T. viarum,
383

Termitarium, 386, 387 ‘

Termites, 357 f.; distinctions from ants,
502; wings, 359 ; anatomy, 360

Termitidae, 356; number of species,
389

Tertiary, 196, 216, 239, 276, 309, 340,
398, 427, 442, 449, 453, 472, 485, 533,
551, 558

Testes, 18, 49, 140, 404, 440 ; of Psocidae, —
392; of Stilopyga orientalis, 228

Tetrophthalmus chilensis, 346

Tettigides, 299, 300, 309

Tettix bipunctatus, 300

Thalessa larva, 507 ; oviposition, 554

Thamastes, 485

Thamnotrizon apterus, 316

Thecla egg, 145

Thelyotoky, 141, 498

Thermobia furnorum, 186

Thliboscelus cumellifolius, 319 i.

Thoracantha latreillei, 550 S|

Thorax, 99-103, 101, 103

Thorax porcellana wing, 227

Thyrsophorus, 395

Thysanoptera, 173

=e --”.—

‘= Pe’. - eww

INDEX 583

ee E

Thysanura, 782 f.; distinctions from Sym-
phyla, 61, 77, 79

Tibia, 88, 104’

Tillus elongatus larva, 90

Tinodes, 483

Titanophasma fayoli, 276, 428

Tomateres citrinus, 454, 458

Tomognathus, 498

- Tongue, 96—see also Lingua

Torymides, 547

Toxodera, 253; T. denticulata, 254

Trabeculae, 345

Tracheae, 128 ; absent, 553, 555

Tracheal gills, 400 f., 401—sée also
Branchiae

Tremex columba, 507

Trias, 449

Triassic, 239

Trichijulus, 76, 80

Trichodectes, 350 ; T. latus, 349

Trichoptera, 342, 473 f.

Trichostegia, 480

Tricorythus, 434, 436

Tridactylides, 340

Tridactylus variegatus, 337

Trigonalidae, 564

Trigonalys maculifrons, 564

Trigonidiides, 340

Trimen on Trachypetra bufo, 304

Trinidad, 501

Trinoton luridum, 345, 347

Trito-cerebron, 118

Trochanter, 88, 104, 491, 494, 520

Trochantin, 104; of cockroach, 222

- Trophi, 91, 94

Tryphonides, 657

Tryxalides, 303, 309, 325
Tryxalis nasuta, 279

Tubulifera, 520

Tympanophorides, 328
Tympanum, 285 f.

Tyndall on grasshopper music, 286

Uxtoa, 33

Uroceridae, 507

Useless wings, 199, 394, 484, 561
Uterus, 18, 392

‘VAGUS nervous system, 120
Van Rees on metamorphosis, 162, 164

Variation, 536 ; of colour, 252, 288, 304,

308; in desert Insects, 305; in ocelli,
267, 395, 536

Vatides, 259

Vas deferens, 18, 140, 187, 392

Vayssicre, on nymphs of Ephemeridae, 434 ;
on lingua, 438

Veins, 206

Ventral chain, 116, 187. 414; of Perlidae,
404

Ventral plate, 148 ; tube, 191, 192

Verhoeff, 38

Verlooren on circulation, 436

Vertex, 94

Vesicula seminalis, 140, 392 ; absent, 404,
414

Vespa crabro prosternum, 491

Vestibule, 112

Viallanes, on head, 87; on brain, 118,
119 ; on metamorphosis, 162

Visceral nervous system, 120

Vitellophags, 147, 152, 168

Viviparous Insects, 217, 229, 143,
218

Voetgangers, 295 f.

Vom Rath on sense organs, 122

Voracity, 250, 258

Vosseler on stink-glands, 210

WALKER, J. J., on Australian Termites,

386

Walking-leaves, 267

Walking on perpendicular and smooth
surfaces, 106

Walsh on galls, 531

Wasmann on St. Augustine’s works, 565

Wattenwyl, Brunner von—see Brunner

Weismann, on caste, 500; on meta-
morphosis, 162, 166 ; on imaginal discs,
167

Westwood, on Forficula, 204; on Helico-
mitus larva, 460, 461; on Lachesilla,
395 ; on Scleroderma, 536

Weta-punga, 326

Wheeler, on Malpighian tubes, 127 ; on
embryology of. Orthoptera, 199; on
embryology of Xiphidium, 321; on
vitellophags, 147, 152, 168; on seg-
mentation, 150

White ants, 356—-see Termites

Wielowiejski on blood-tissue, 133, 137

Will on brain of Aphididae, 118

Wingless : caddis-fly, 481; earwigs, 205 ;
Insects, 345, 352, 356, 451, 488, 536,
547 ; wingless Psocidae, 394 f.—see also
Apterous

Wings, 107 ; origin and function, 394 ; of
Blattidae, 225 f., 227; development of,
in locust, 288; in Trichoptera, 479, 480 ;
of dragon-fly, 413; of earwigs, 206 ;
of Ephemera, 431; growth of, 418;
of Ichneumon and Bracon, 559; pos-
terior absent, 466, 485; wing-hooks,
494 ; veins, 107—-see also Tegmina and
Alar Organs

** Wire-worm,” 29, 36

Wistinghausen on tracheae, 129

Wood-Mason on Cotylosoma, 272; on
mandibles, 95 ; on Mantidae, 251, 253;
on Oligotoma, 352; on phonation of
Mantidae, 258

Woodworth on embryology, 146, 153

Workers, 361, 374, 488, 495

Wyandotte Caves. Myriapods in, 34

Xptidhun eerie 321

Aye 404 494 ; metamorphosis, 110 S “pro
Xyphidviides, 507 f,510 oat Dygonterites,

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