h 2ERITOO TOEO OD

MOM

IOHM/1EW

”

M 4
Boston Society of Watural History.

mo IDES FOR SCIENCE-TEACHING.,
SOC

No. va y. milo.
INSECTA.

BY

ALPHEUS HYATT
AND

J. M. ARMS.

BOSTON, U.S.A.:

D. C. HEATH & CO., PUBLISHERS.
1890.

ie :
ak vi) ee Lara

é

4 on h ee

AS
rs

|

Beyond iy scschy es nay

tee,

COPYRIGHT, I8g0,
By ALPHEUS HYATT-

A222!

TyroGrapuy By J. S. CusHinc & Co., Boston.
. nt

PreEssworK BY BERWICK & SMITH, Boston.

Ye BLED ie toy

INSECTA.
[Figures refer to pages. ]

Caloptenus femoratus, a typical form, 8. Locusts and grass-
hoppers, 8; distinguishing characteristics, 9. Directions for col-
lecting material for class-work, 9,10. General characters of the
locust, 10. External skeleton, 10; colors of skeleton, Hagen’s
and Minot’s views, 11. Body described as a whole, 12; seg-
mentation, 12; use of term “ Articulata,” 12. Arthropods and
Worms contrasted, 12. Parts of body described, 13; head, 13;
motion of head, 13. Characters of prothorax, 13, 14; meso-
thorax, 15; metathorax, 16; primitive and secondary sutures,
16; origin of sutures, 16; causes of concentration of thorax,
16,17. Junction between thorax and abdomen, 17; sessile and
pedunculated abdomen, 17; characters of abdomen of male, 18;
of female, 18; “tympanal organs,” 19; Minot’s observations,
I9. Sense organs of head, 19; compound and simple eyes, 19,
20; views on the structure and physiology of the organs of
sight, 20-22. Appendages, structure and functions of antennz,
22; experiments of Trouvelot, Packard, Lubbock, Meyer,
Plateau, 22, 23. Biting mouth parts, 24; ravages of locusts,
24; functions of palpi, 25; Plateau’s experiments, 25, 26; palpi
of dragon-flies as useful organs, 26. Inference in regard to
cephalic rings, 27; concentration of sense organs in the head
correlated with concentration of nervous system, 27. Appen-
dages of thorax, 27. Structure of hind legs correlated with
habit of leaping, 28. Power of adaptation possessed by animals,
28. Structure of wings, 29, significance of term “ Orthoptera,”
correspondence between size of wings and thoracic rings, 30.
Origin of wings, 30, 31. Aérial locomotion illustrated by an arti-

A

vl SYNOPSIS.

ficial wing, 31, 32. Strigillations of insects, 33; Scudder’s
experiments, 33. Appendages of the abdomen, 33; structure
of the ovipositor, 33, 34. Internal anatomy, 35. Muscular
power of insects, 37. Respiratory system, 38; tracheze of wings,
38, 39; Moseley’s observations, 39; respiratory movements of
insects, 39, 40. Gradual development of wings, 41. Caution
against the use of theory in teaching, 42. Sexes of the locust,
42. Development of Caloptenus spretus, 42, 43. Direct and
indirect metamorphosis explained, 44; use of terms “ complete ”
and “incomplete,” 44. Structure of larva, 45; moulting, 45;
pupa, 45; adult insect or imago, 45.

CLASSIFICATION OF INSECTS.

Necessity of dealing with insects systematically in order to
make clear the underlying principles of the classification adopted
in this work, 46. Insects compared with Worms and Arthropods
in general, 47; distinctive characters of insects, 47. Campodea
the type of the primitive, wingless, ancestral form, 47; geologic
evidence wanting, 47. Bibliography of the ancestry of insects
and Thysanura, 48, 49. Scudder’s views on cockroaches, 49.
Adult characters of Lepisma appearing as transient larval stages
in groups of orders from II.—XI., 49. Generalized mouth parts
of Lepisma and Campodea, 49; biting and sucking mouth parts
modifications of Thysanuran type, 50. Different meanings of
the term “specialization,” 50; a standard of reference necessary
to fix the meaning, 50; Thysanura the standard, 50. Primitive
winged insect described, 50; its affinities with Thysanura and
insects with Thysanuriform larve, 50. Existing generalized
insects are in reality highly specialized, 50. Specialization by
addition, 51; consequent enlargement of the field of work, 51.
Specialization by reduction and narrowing of the field of work,
51; specialization by reduction the prevalent mode among the
“highest ” animals, 51. Position of degraded forms in a natural
classification, 52; parasites, 52. Proper position of an animal
in a table of classification determined by its place in the evolu-
tion of the group, 52; Meyrick’s views on lost organs, 52.
Generalized orders of insects or first series from I.-IX., inclusive,

SYNOPSIS. Vil

53; specialized orders or second series from X.—XVI., 54; terms
“ generalized”? and “specialized” substituted for “lower” and
“higher,” 54. Hypothetical ancestor of the Thysanura described,
54; characteristics of this ancestor as inherited by the Thysanura
and the larvze of the generalized orders of insects, 54; the term
*Thysanuriform” preferred to “ Campodeaform ” or “ Lepisma-
form,” 54. Characters of Thysanura the key of modern classifica-
tion, 55. Representative or parallel characters of adult insects
the cause of mis-association of forms in older classifications, 55;
bearing of the hypothesis of evolution on the subject, 55. Law
of the correlation of the transient stages of the young with the
permanent adult stages of ancestral generations, 55; cautious use
of evidence necessary, 55. Theories in regard to the origin and
development of wings, 56; Hagen’s view, 56; Fritz Miiller’s .
and Packard’s views, 56; arguments in favor of the latter, 57, 58.
Aquatic larvze not necessarily primitive, 58; adaptive characters
are secondary specializations, 58; evolution of aquatic forms of
insects from terrestrial forms, 58. ‘Tracheal system of insects
compared with respiratory system of other animals, 59. Diffi-
culties attending a linear arrangement of insect groups, 60.
Diagrams illustrating the evolution of the orders, 60; explana-
tion of diagrams, 60-63; imperfections of all graphic repre-
sentations, 63.

ORDER I.— THYSANURA.

Campodee, 64. Slight concentration of body of Campodea,
64. Possible sense organ in antennze, Kingsley’s view, 64; long
antennz of cave-inhabiting species, 65. Mouth parts of gen-
eralized structure, 65; mandibulate and suctorial mouth parts
modifications of these, 65. Similarity in structure of thoracic
legs, 65. Absence of wings, 65. Appendages of abdomen,
significance of term “ Thysanura,” 66. Bristle-tails and Spring-
tails, 66. Meinert on spiracles of Campodea, 66. Lepisma
preferable to Campodea for class instruction, 66. Structure of
body of Lepisma, of appendages, 67. Respiratory system, 67;
presence of trachez, absence of air-sacs in Lepisma and larvee
of insects, 67. Adult stages of Lepisma compared with tran-
sient larval stages of locust, etc., 67, 68.

vill SYNOPSIS.

ORDER II.— EPHEMEROPTERA.

Ephemeride, 69. Slight concentration of thoracic region
of May-fly, 69; free motion of prothorax, 69. Mouth parts
nearly obliterated, 69. Structure of wings, 69, significance of
term ‘ Ephemeroptera,” 70; reason for substituting Ephemerop-
tera for Plectoptera, 70. Moulting, 70. Lubbock’s observations
on Chloéon, 70. Oligoneuria rhenana, 70. Morse’s observa-
tions, 70. Scudder’s account of May-flies on one of the Gull
Islands of Lake Winnipeg, 71. General remarks on Epheme-
roptera, 71, 72.

ORDER III. —ODONATA.

Favorable subject for observational work. Lzbellula trimac-
ulata, 73. Directions for collecting and preserving dragon-flies,
73. Structure of head, 74; free motion of head correlated with
habit of catching food when flying, 75. Size and concentration
of thorax correlated with great powers of flight, 75. Mode of
breathing, 76. Structure of abdomen, 76; toothed ridges de-
veloped in different species as adaptations to the similar habits
of the insects, 76, 77. Large size of compound eyes, 77; small
size of antenne, 77. Mouth parts, 77, 78; carnivorous habits of
dragon-flies, 78. Structure and position of legs correlated with
peculiar habits of insect, 78, 79. Characters of the wings, 79.
Ovipositor, 79. Development of dragon-flies, 80. Structure of
larval dragon-fly, 80; simplicity of thoracic rings, 80. Mask of
pupa, 81, significance of term “ Odonata,” 82. Brehms Thierle-
ben, 82. Interesting habits of pupa, 82, 83. Respiration con-
nected with locomotion, $3. Transformation of Lzbe/lula tri-
maculata, 84-88; time required, 88. Comparative length of
life of larva, pupa, and imago, 88. Influence of surroundings
on structure of aquatic and terrestrial forms, 88. General re-
marks on the Odonata, 88, 89. Specializations of the forms of
this order, 89. Resemblances of the Odonata and Neuroptera,
89. Parallel or representative characteristics, 89.

ORDER IV.— PLECOPTERA.

Stone-flies, structure of body, 90. Character of wings, sig-
nificance of term “ Plecoptera,” 90. Tracheal gills of larva

SYNOPSIS. 1x

and pupa, 90. Pteronarcys, 90. ‘Tracheal gills of larval Pte-
ronarcys retained in the adult, 90. Resemblances of the larvz of
Plecoptera to those of Ephemeridz and Thysanura, go, 91; re-
semblances of the adults to Platyptera, 91. Aquatic larve of
orders II.-IV., 91.

ORDER V.— PLATYPTERA.

The Termitide structurally different from the Formicidae, 92.
Effects of social habits upon structure, 92. One cause of color,
92, 93. Sessile abdomen of Termites and pedunculated abdomen
of Hymenopterous ants, 93. Mouth parts of worker and sol-
dier, 93; difference in structure proportioned to amount and
kind of work performed, 93. Arrested development of workers
and soldiers, 93, absence of eyes and wings, 93. Presence of
wings in males and females, significance of term “ Platyptera,”
93. Structure and helplessness of larvee, 94; resemblance to Thy-
sanura, 94. Development of larvz into two castes of males and
females, 94; caste of complemental males and females, king
and queen caste, 94. Colorlessness of Termites correlated with
habits, 94, 95. Fritz Miiller on Termites of Brazil, 96. Dr.
Hagen on habits and destructive work of Zermes flavipes, 96.
Smeathman on African Termites, 97. Psocidz, 97. Structure
of body and appendages, 97. Characters of book-lice, 98.
Mallophagidz as examples of specialization by reduction, 98.
General remarks on the Platyptera, affinities of the Platyptera
with the Orthoptera and Dermaptera, 98, 99.

ORDER VI.— DERMAPTERA.

Structure of Forficula, 100. Peculiarities of the wings, 100,
significance of term “ Dermaptera,” 100. Forcep-like appen-
_dages of the abdomen, 100. Reasons for giving the names
Forficula and ear-wig, 100. Forficulidze of New England, roo.
Characters of larva, 100. General remarks on Dermaptera, I01;
generalized structure of ear-wigs, IOI. Position of order in the
classification, IOI.

x SYNOPSIS.

ORDER VII.— ORTHOPTERA.

Blattide, 102. UHead of cockroach, 102; unconsolidated
thoracic rings, extension and compression of abdomen, 102;
mode of breathing, 102; Plateau’s figures, 102, 103. Small
eyes and long antenne, 103. Biting mouth parts, 103. Pecul-
iar structure of legs correlated with habits, 103. Wings of male,
of female, 103. Habit of the female of forming a sac and car-
rying the eggs and young, 103. Simplicity of structure of larval
cockroach, 103. Miall and Denny on Zhe Cockroach, 104.
References to Huxley’s /zvertebrata, Rolleston’s Forms of Ani-
mal Life, and Scudder’s Paleozoic Cockroaches, 104. Lctobia
germanica, 104; remarkable habits of insect, 104. Ancient
and wild cockroaches, 105; adaptations of structure acquired
before man’s appearance on earth, 105; adaptations favorable
for a life of semi-domestication, 105; needed investigations on
the effects of domestication on structure of existing cockroaches,
105. Phasmidz, 105. Protective coloration, 105. Wallace on
the Origin and Uses of Color in Animats, 106. Unconsolidated
condition of the thorax correlated with absence of wings, 106.
Feet adapted for slow movements, 106. Gryllidz, 106. Struct-
ure of head, thorax, and abdomen, 106, 107. Mode of breath-
ing, 107. Structure of appendages, 107. Manner of produc-
ing the “chirp,” 107. Effects of habit of burrowing upon
structure illustrated by Gryllotalpa borealis, 108. Locustide,
108. Comparative work on the locust and meadow grasshop-
per, an instructive lesson for children, 108, 109. Acrididee, 109.
Caloptenus spretus, 109; ravages in the West, 110. Tettix
or grouse locust, 110; prothorax performing the work of wing-
covers, consequent reduction of the latter, 110. General re-
marks on Orthoptera, 110; similarity in habits and habitats
correlated with corresponding similarity in structure and devel-
opment, 110. The Thysanuriform stage shown in generalized
Orthoptera, absent in specialized forms, 111. Resemblances of
the young of specialized forms to the adults, 111. Objections
urged against the derivation of these insects from a Thysanuran
form, 111. Statement of the law of acceleration in develop-
ment, 112. Adequacy of this law to meet objections and to
account for absence of the Thysanuriform larva, 112,

SYNOPSIS. x1

ORDER VIII. —THYSANOPTERA.

Thripide, 113. Plants frequented by Thrips, 113. Mouth
parts intermediate between mandibulate and suctorial organs,
113. Structure of feet, 113. Fringed wings, 113, significance
of term “ Thysanoptera,” 113; similar modifications of wings in
Pterophoridz and Proctotrupide, 113. General remarks on
Thysanoptera, resemblance of larve to Thysanura, 114; adults
more widely removed from young than adults of Dermaptera,
114. Affinities of Thysanoptera with Hemiptera generally ad-
mitted, 114.

ORDER IX.— HEMIPTERA.

Order divisible into two groups, Heteroptera and Homoptera.
Anasa tristis the type of the order, 115. Plan adopted in this
Guide, description of type and common forms of order followed
by general statements, 115. Method of teaching Natural His-
tory, 115. Directions for collecting squash-bugs, 115. Struc-
ture of head, 115. Form of prothorax in correlation with
sucking habits of insect, 116. Characters of mesothorax and
metathorax, 116; liquid-secreting glands, 116. Sessile abdo-
men, 117. Spiracles and mode of breathing, 117. Sucking
mouth parts, 117; difficulties of pupils in determining their
number and homologies, specimens of the harvest-fly helpful,
117, 118. Legs adapted for walking and running, 118. Struc-
ture of wings, significance of term “ Hemiptera,” 118. Absence
of abdominal appendages, 118. Abundance of larve and pup
in August, 118. Structure of larva, 119; dark color of working
antenne, sucking-tube, and legs, 119. Thoracic rings of pupa,
I19, 120. Aquatic Heteroptera, 121. Interesting habits of
Notonecta, 121; caution in handling, 121. Large size of meta-
thorax correlated with large size of swimming-legs, 121. Peculiar
mode of respiration, Comstock’s experiments, 122. Belostoma
useful to teachers, 122; general structure, 122; habit of sting-
ing with beak, 122. Dimmock on Fish-destroying Bugs, 122.
Legs adapted for catching fish and frogs, 123. Mode of
forming a claw in Insecta contrasted with that in Crustacea, 123.
Destruction of young fish in the breeding ponds, efforts of the

xl SYNOPSIS.

Mass. Fish Commissioners, 123. ‘Terrestrial Heteroptera, 124.
Habits of Prionidus cristatus, Glover’s observations, 124. Sting
of Opsicetus personatus painful, 125. Podisus spinosus, diet
of vegetable and animal juices, 126. Scutelleridz, 126. Extraor-
dinary size of mesothoracic scutellum, 126. Degraded forms
of Heteroptera, 126; habits and structure of Cimicidz transi-
tional to true parasitic habits and structure, 127; reduction of
fore-wings to scales, absence of hind-wings, condition of wings
correlated with condition of thoracic rings, 127, 128. Existence
of Cimicidz in a wild state considered doubtful, 128. Pyreth-
rum powder a preventive against the attacks of Cimex, 128,
Parasitica, 128. The Pediculina regarded by Packard and
Comstock equivalent to Heteroptera and Homoptera, 129. De-
graded structural characters of Pediculus not comparable with
simple, Campodea-like forms or larval forms, examples of special-
ization by reduction, 129. Adaptation in color to the races of
men infested, 129, 130. Homoptera, 131. Cicada an instruc-
tive insect for class-work, 131. Peculiarities of head and neck,
lateral motion of head reduced to a minimum, 132. Develop-
ment of thoracic region, huge size of the mesothorax correlated
with large size of first pair of wings, and small size of meta-
thorax with reduction of hind-wings, 132. Markings of the
thorax, Hagen’s view, 132. Broad junction of the thorax and
abdomen, 132. Musical apparatus of the male, absence of ap-
paratus in the female, 132. Structure of the appendages of the
head, 132, 133. Membranous character of both pairs of wings,
133. Seventeen-year and thirteen-year Cicada, 133. New
England species, Cicada dibicen, 133. Grub-like form of larva,
133. Transformation of pupa into imago, 134. Children en-
couraged to make collections illustrating different stages in the
development, 134. Aphidide, 135. Color a means of protec-
tion, 135. Structure of winged and wingless female, 135. Ab-
dominal tubes and “ honey-dew,” 136. Parthenogenesis, 136.
Development of Aphis, 136. Effects of change of temperature
and failure of food on development, 137. Aphides in the
school-room, 137. Phylloxera, 138. General characters of tree-
hoppers, 138. Coccidz, 138. Adult female scale-insect an
example of specialization by reduction, 138. Development of

SYNOPSIS. Xlll

Aspidiotus conchiformis, 138; activity of larva, remarkable
changes in structure, 139. Indirect metamorphosis of male
scale-insect, 140. Wings and halteres of male, characters in
common with Diptera, 140. Parallel or homoplastic forms, 141.
Dactylopius or mealy bugs, 141. Cochineal bug and dyes, 141.
Lac insect and shellac, 141. General remarks on Hemiptera,
142; greater diversity of habitat, and consequently of structure,
observable in this order than in Orthoptera, 142. Development
of Heteroptera more direct than that of Homoptera, 142.
Larve in both groups differ from Thysanuroid type on account
of early development of sucking-tube, 142. Sucking mouth
parts derived from biting mouth parts, 142. Loss of biting
mouth parts in Hemiptera probably due to excessive accelera-
tion in development, 143. Larve and adults of Homoptera
farther removed from generalized Thysanuran type than those
of Heteroptera, 143. Resemblance of larvee of Cicada to those
of Coleoptera with similar burrowing habits, 144. Thysanuroid
larval stage replaced by adaptive, grub-like stages, 144.

ORDER X.—COLEOPTERA.

Favorable subject for observation-work, abundance of mate-
rial, 145. Lachnosterna fusca a typical form, 145. Directions
for collecting May-beetles and other Coleoptera, 145. Wedge-
shaped form of May-beetle adapted for burrowing, 146. Large
size of prothorax, small size of mesothorax, 146. Complex char-
acter of metathorax, 146. Broad junction of thorax and abdo-
men, flexibility of the abdomen an aid in respiratory movements,
146. Structure of antenne, significance of term “ Lamellicorn,”
147; remarkable form of these organs among beetles, 147.
Biting mouth parts, 147. Legs adapted for running, 147;
manner of using legs, 147. Peculiar structure of wing-covers,
significance of term “ Coleoptera,’ 147. Flight of beetles, 148.
Metamorphosis, 148. Lintner on the White Grub of the
May-Beetle, 148. Immature condition of larva when hatched,
148; habit of lying upon its side, 148. Length of life of larva,
149. Injury done to plants, 149. Pupa state passed in a rude
cocoon, 149; changes in structure, 149. Time of appearance

XIV SYNOPSIS.

of the imago, 149. Chrysomelidz, 149. Rapid spread of the
potato-beetle, 149. Structure and development, 150. Original
home of insect, 150. Scarabzeidee, 151. Huge size of the
South American Dynastes, 151. Stag-like horns of the males
of some Lamellicorns, 151. Darwin’s figures, 151. Lampyride,
151. Luminous organs, 151. Views on cause of phosphores-
cence, 151. Dimmock’s observation, 152. Wingless females or
“ glow-worms,” 152; larva-like condition of these adults, 152.
Dermestidz, 153. Size and markings of the carpet-beetle, 153.
Characters of the larvae; preventives against their attacks, 153,
154. Pollen-feeding habits of the adults, 154. Entomological
collections destroyed by species of Dermestidz, 154; disinfect-
ing cones, bisulphide of carbon and other preventives, 154. Coc-
cinellidz, 155. Structure of the adult and larva, 155. Gyrinidee,
155. Interesting habits observed in the schcol-room, 155. Pe-
culiar structure of eyes, 155. Respiration, 156; abdominal respi-
ratory organs of larva, 156. Remarkable modification of mouth
parts in Dytiscide, 156. Carabidze and Cicindelide, 156, 157.
Parasitic Coleoptera, 157. Effects of specialization by reduction
resulting from parasitic habits of the larva, 157. Life-history of
Epicauta, 157-159. Significance of term “ hypermetamor-
phosis,” 159. Reduction in size and number of wings in Meloé
and Hornia, 159. Life-history of Meloé and Sitaris, 159, 160.
Quiescent stage a natural consequence of a gorged condition of
the tissues, 160; period of development, but not of growth, 160;
habits leading to quiescent larval or pseudo-pupal stage in
Meloé and Sitaris comparable to those which precede the true
pupal stage in other groups, 160. Nemognatha, a Coleopteron
with a Lepidopterous proboscis, 161; H. Miiller’s view, 161.
Stylopide, 161. Degraded structure of the female Stylops, 161.
Mesothorax of the male with halteres, metathorax with fan-
shaped wings, 162. The Stylopidz viviparous, 162; young
larva hexapod, mature larva a footless grub, 162. Ceramby-
cidz or Borers, 163. Characters of thorax, 163. Structure of
antenne, significance of term “ Longicorns,” 163. Grubs with
scarcely perceptible feet, or entirely footless, 164. Curculionidee,
164. Proboscis performing the additional work of an oviposi-
tor, functions of organs not invariable, 164; unexpected modi-

SYNOPSIS. XV

fications like the vertical motion of the jaws of Balaninus, 165.
Footless grubs, 165. General remarks on the classification of
the Coleoptera, 165; affinities with Orthoptera and Hemiptera,
166; retention in many groups of Thysanuriform larva, and of
generalized characters in the adults, 166. Tendencies to pro-
duction of wing-covers, and differentiation of prothorax shown
in orders VI., VII., and IX. carried to an extreme in Coleop-
tera, 166. Sessile abdomen possessed by beetles in common
with the more generalized insects, 166. Larvze with biting
mouth parts, consequently less widely removed from Thysanuran
standard than sucking larve of Hemiptera, 166, 167. Larvee
of other Coleoptera cylindrical grubs with few Thysanuran char-
acters, 167; larve of most weevils footless grubs with no Thysa-
nuran characters, 167. Development of Meloé and Sitaris tend
to prove that the hexapod grub is a derivative from the Thysa-
nuriform larva, and the footless grub from the hexapod form,
167. Evolution of the Rhynchophora, 168.

ORDER XI.—NEUROPTERA.

Structure of Corydalus, 170; unconsolidated wing-bearing seg-
ments, large size of wings, slow movements, 170; power of flight
not wholly dependent upon comparative size of wings, 171;
significance of term “ Neuroptera,” 171. Egg-mass of Corydalus,
171; larval characters, tracheal gills, and spiracles, 171, 172.
Hemerobidz, 172. Structure of lace-winged fly, 172. Manner
of laying eggs, 173. Carnivorous habits of larvee, 173. Cocoon of
pupa, 173. Habits of ant-lions, 174. Brauer on life-history of
Mantispa, 174. General remarks on Neuroptera, 174, 175; the
primitive form of larvae as compared with larve of succeeding
orders, 175. Derivation from a Thysanuroid ancestor through
some intermediate winged insect, 175; difficulty of determining
with certainty this intermediate winged form, 175.

ORDER XII.— MECOPTERA.

Structure of Panorpa, 176; small prothorax like that of Lepi-
doptera, 176. Length of wings, significance of term “ Mecoptera,”
176. Biting mouth parts at the end of a rostrum, 176. Cater-

XVi SYNOPSIS.

pillar-like form of larva,177. Boreus,177. Remnants of wings
in male, no wings in female, 177. General remarks on Mecoptera,
177. Classification of Mecoptera, 177. Absence of Thysanuri-
form larva in this and succeeding orders, 177. Theoretical
considerations, 177.

ORDER XIII. — TRICHOPTERA.

Living caddis-worms in the school-room, 178. Resemblance
of caddis-fly to generalized Lepidoptera, 178. Reduced size of
sucking mouth parts, 179; Hagen’s view on the food of Phry-
ganeide, 179. Structure of wings, significance of term “ Tri-
choptera,” 179. Caterpillar-like form of larval Anabolia, 179.
Habit of making an artificial covering, 180. Exception to general
statement in regard to eyes and antennz, 180. Mastication and,
in part, locomotion performed by mandibles, 180. Respiratory
abdominal organs, 180. Structural changes in pupal stage, 181.
Native caddis-fly larvee in streams near Boston, 181. General
remarks on Trichoptera, 182. Order of relations found in
Mecoptera reversed in Trichoptera, 182. Disappearance of
abdominal legs through disuse, 182, 183. Resemblance of adult
caddis-flies to Microlepidoptera, 183. Probability that the
Trichoptera and Lepidoptera had a common origin, 184.

ORDER XIV.— LEPIDOPTERA.

Phenomenon of indirect metamorphosis best illustrated in the
school-room by the Lepidoptera,-185. Natural order of lessons,
185. Directions for collecting and preserving butterflies, 186.
Preparations of specimens for class-work, 186. Structural feat-
ures of milkweed butterfly, head, small size of prothorax, 186;
mesothorax with shoulder lappets, 187. Freedom of motion of
wing-bearing segments, 187. Butterfly apparently an excep-
tion to law that power of flight is correlated with tendency to
consolidation of thoracic region, 187; explanation found in
wave-like flight of butterfly and structure of hind-wings, 187;
light thrown on the subject by the structure and rapid flight of
the hawk-moth, 188. Burgess on the thorax of Danais Archip-
pus, 188. Structure of abdomen, probable scent-organ, 188.

SYNOPSIS. XV

Number of facets of compound eyes, 188; Scudder’s figures,
188. Characteristic form of antenne, 188. Burgess on S¢zc-
ture and Action of a Butterfiy’s Trunk, 189. Legs supporting
rather than locomotive organs, 190. - Reduction of first pair of
legs correlated with reduction of prothorax, 190; brush-footed
butterflies or Nymphalidz, 190. Distinguishing characteristic
of wings, significance of term “ Lepidoptera,” 190. Scudder’s
Butterflies recommended to teachers, 191. Migrations of milk-
weed butterfly, 191. Metamorphosis, 192. Markings of eggs,
192. Voracious habit of larva, 192. Structure of mature larva,
spinneret, thoracic legs and abdominal prop-legs, 192, 193.
Transformation of larva into pupa, of pupa into imago, 193-195.
Length of life of milkweed butterfly, 195. Heterocera, 196.
Telea Polyphemus the type, 196. Broad junction of thorax and
abdomen, 196. Characteristic form of antennz, 196. Reduc-
tion of mouth parts, 196. Forward legs useful as organs of
support, 196. Habits of the caterpillar, 198. Trouvelot’s ob-
servations on food plants of larva, 198. Poulton on young Le-
pidopterous larvz forming special relations with food plants, 198.
Amount of food consumed by larve of Telea, Trouvelot’s experi-
ments, 199. Pupa and cocoon, 199. Effects of temperature on
development, 200. Tineidz, 200. Structure of 77%xea pelli-
onella, 200. Fringed wings, 201. ‘Tineidz with footless larve,
effects of habit of mining leaves upon structure, loss of loco-
motive organs and power of motion, 202. Resemblance of the
larva of Nepticula to larva of a Dipteron, 202. Absence of
footless larvae among butterflies, 202. Phalenidz, 203. Differ-
ences between the fall and spring canker-worm, 204. Position
taken by larva a probable means of protection, 204. Noctuide,
205. ‘Travelling of army-worm an abnormal habit, 205. Rav-
ages in 1770, 1861, 1875, 206, 207. Length of life of larva de-
pendent upon temperature, 207. Cut-worms, 207. Bomby-
cidze, 207. Effects of domestication upon Bombyx mort, 208.
Sphingidz, 208. Consolidation of thoracic rings correlated
with rapid flight, 208. Length of sucking-tube, 208. Legs as
supporting organs, 208. Ingenious contrivance for fastening
wings together and increasing power of flight, 208. Compari-
son of ruby-throated humming-bird and humming-bird moth,

xvill SYNOPSIS.

216. Food plants of larva, 210. Rhopalocera, 212. Scudder’s
classification of butterflies, 212. Hesperide, 212. Resem-
blances of skippers to moths, 212. Habits of larve, 213. Pop-
ular names, 214. Papilionidz, 214. General characteristics,
2r4. Remarkable migrations of the cabbage butterfly, 215.
Social Lepidoptera, 216. Effects of temperature upon struct-
ure illustrated by Papz/io ajax, 216-218. Lyczenidze, 218. Re-
duction of forward legs in male, 218. Manner of attaching
chrysalis, 219. Slug-like appearance of Thecla, 219. Nymph-
alidz, 219. Vanessa Antiopa, 219. Mimicry, 219. Aasi-
larchia Disippus imitating Danais Archippus, 219. The Sus-
pensi and Succincti, 220. Importance of making collections
to illustrate all the stages of development, 221. General re-
marks on the classification of the Lepidoptera, 221; complete
possession of the earlier stage by secondary larval form, conse-
quent absence of Thysanuriform larva, 221. Close proximity of
Lepidoptera to Trichoptera and Mecoptera, 221. Scudder’s ob-
servations on crescent-shaped bands of chrysalids, probability
that archaic butterflies had direct metamorphosis, 221, 222.

ORDER XV.—HYMENOPTERA.

Worker-bee a typical form, 223. Directions for collecting
bees, 223. Large size of head, prothorax unconsolidated and
capable of motion like that of the Lepidoptera, 223. Meso-
thorax and metathorax consolidated, 223. Specialized ring or
first abdominal segment fastened to thorax, 223. Pedunculated
abdomen correlated with use of sting, probable explanation for
the wasp-like waists of Hymenopterous insects, 224. Senses of
bees, Lubbock’s observations, 224. Jelations of insects to
flowers, 224. Observations of Henslow, Miiller, and Darwin,
225. Henslow’s views especially recommended to teachers, 225.
Caution against the free use of explanations which the doctrine
of natural selection seems to furnish, 225; this doctrine inade-
quate to account for the origin of structures and their modifica-
tions, 225; views of Packard, Riley, Cope, Ryder, and Hyatt,
225. Specialization by addition finely illustrated by structure of
mouth parts, 226, Adaptations of the legs for collecting and

SYNOPSIS. X1xX

carrying pollen, 226. Membranous character of the wings,
significance of term ‘‘ Hymenoptera,” 227. Adaptations of wings
for swift flight, 227. Modification of ovipositor into sting, 227.
Home-making instinct of bees, 227. Specialization of function
illustrated by a colony of bees, consequent specialization of
structure, 228. Cells of the comb not mathematically exact,
228. Darwin’s observation on progress in cell-making in pass-
ing from humble to hive bee, 228. Helplessness of larve, 228.
Tender treatment of old bees towards their young compared
with indifference of locusts and fostering tare of the more
specialized vertebrates, 229. Length of pupal stage, 229. Length
of life of worker and queen, 229; habits acquired during adult
life, 229. References on bees, 230; Hymenoptera Terebrantia,
231. Tenthredinidz, 231. Broad junction of thorax and abdo-
men, 231. Biting mouth parts, 231. Ovipositor modified into
a saw, 231. Habits and structure of larve similar to those of
Lepidoptera, 231. Uroceride, 232. General characters, 232.
Tendency of first abdominal ring to join thorax, 232. Ovipositor
modified into a borer, 232. Absence of abdominal prop-legs in
larve, 233. Cynipide, 233. General characters of gall-flies,
233. Galls the homes of the larvae, 233. Degraded condition
of mouth parts, 233. Oak-apples, 233, 234. Spring and fall
gall-flies, 234. Osten Sacken on Cynipide of North American
oaks, 234. Chalcididz, 235. Males of Blastophaga, wingless,
females winged, 235. Ichneumonidze, 235. Power possessed
by Zhalessa atrata of raising and lowering its abdomen, conse-
quent aid given the ovipositor, 235, 236. Method of oviposition,
236. Riley’s observations, 236. Ichneumon-flies with short ovi-
positors, 237. Snellen Van Vollenhoven’s Pinacographia, 237.
Hymenoptera Aculeata, 238. Formicide, 238. Thoracic rings
of wingless worker and soldier more loosely connected than in
winged male and female, 238. Pedunculated abdomen of sting-
less and stinging ants, 238. Organs of sight, 238. Adaptations
of mandibles to work performed, 238. Architecture of ants,
239. Specialization of function and structure illustrated by a
colony of ants, 239. Helplessness of larva, 239. Cocoon of
Formica fusca, 239. Short duration of pupa stage, 239. Social
life resulting in habits of co-operation, 239. Lubbock’s experi-

XX SV Oris.

ments on the intelligence of ants, 240; structure and develop-
ment, not mental qualities, the basis of a classification, 240.
References on ants, 240. Sphegide, 240. Habit of paralyzing
insects, 240. Adaptations of mandibles and legs for digging
nests in the earth, 240. Diet of the larva, 240. Preference of
different species for different kinds of insects, 240. Other fos-
sorial Hymenoptera, 241. Habits and structure of Pompzlus
formosus, 241; Lincecum on the 7arantula — Killer of Texas,
242. Vespidee, 242. Structure of Vespa maculata, 242; shoulder
lappets similar to those of Lepidoptera, 242. Social habits, 243.
Construction of paper nests, 243. Larval characters, 244. Size
of forward end of body adapted to size of cell, 244. Apide,
244. General remarks on the classification of the Hymenoptera,
244; reasons why this order is placed at the head of the insect
series, reasons why it should not be given this position, 244, 245.
Tenthredinide more closely allied to Lepidoptera than any
other family of its order, 246. Possibility that Lepidoptera and
Hymenoptera had a common ancestor, 246. Reasons for the
obliteration of the caterpillar-like stage in Hymenoptera, 247;
replacement of this stage by the grub-like form, 247. Other
evidence of the convergence of the Hymenoptera and Lepidop-
tera, Walter’s investigations, 247.

ORDER XVI.— DIPTERA.

Adult and larval stages of flies characterized by interesting
modifications of structure, 248. Tabanus a good type, 248.
Marked concentration of parts of body, 249; prothorax immov-
ably consolidated with mesothorax, large size of mesothorax,
complex structure of metathorax, 249. Discussion on the thorax
of Hymenoptera and Diptera, 249; Gosch’s paper, 249; La-
treille’s theory, 250. Views of Weismann, Hammond, and Pal-
mén, 250. Pseudo-sessile abdomen of Tabanus, 251; difference
between this and the true sessile abdomen of the generalized
orders of insects, 251. Specialization of function correlated
with complexity of mouth parts, 252. Degraded structure of
mouth parts of Musca, 252. Peculiar adaptations of feet,
Home’s figures, 252, Number of wings, significance of term

SYNOPSIS. XX1

* Diptera,” 253. Strength of wings and size of mesothorax cor-
related with swift flight, 253. Alulets, 253. Halteres, 253.
Gradual reduction in size and efficiency of the hind-wings in
passing from the Lepidoptera to the Hymenoptera and Diptera,
this change correlative with the reduction of the wing-bearing
segments and their muscles, 253. Cause of the buzzing of the
fly, 254. Larval characteristics of Tabanus, 254. Development
of Musca domestica, 254; larva not a generalized but an ex-
tremely specialized form, shape of body adapted for boring, 254;
forward end of body not differentiated into a head, 254. Brief
duration of larval and pupal life, 255. Time of appearance of
the imago, 255. bBrauer’s classification of the Diptera based
upon larval and pupal characteristics, 255. Position of the semi-
parasitic fleas and true parasites, 256. Tipulidz, 257. Resem-
blances of the adult to Lepidoptera, 257. Thoracic region wholly
exposed, 257. Absence of a sting the probable cause of absence
of pedunculated abdomen, 258. Presence of an external, horny
ovipositor, 259. Biting mouth parts and diet, 259. Resem-
blances of Tipulid larve to the generalized larval forms of Lepi-
doptera and Hymenoptera, 259; resemblances to the specialized
larvee of Hymenoptera, 259. Culicide, 259. Thoracic region
shortened. but wholly exposed, 259. Dimmock on the mouth
parts and diet of the Culicidz, 260, 261. Eggs of mosquitoes,
261; larvee with differentiated head and abdominal respiratory
tubes, 261. Thoracic breathing-tubes of pupa, 261. Motions
of pupa produced by muscles of abdomen, 261. Asilidze, 262.
Posterior part of thoracic region partly concealed, 262. Carniv-
orous habits of robber-flies correlated with peculiarities of struct-
ure, 262. Tabanidz, 263. Extreme concentration of parts of
body, 263; posterior portion of thorax entirely concealed, 263.
Cecidomyidz, 263. Aberrant characters of family, 263. Resem-
blances to Hymenopterous gall-flies, 263. Degraded structure
of mouth parts, 263. Peculiar mode of escaping from the
puparium, 263. Cyclorhapha, 264. Junction of the abdomen
in Syrphus, 264. Larve without a differentiated head, 265.
Habit of devouring Aphides correlated with sucking mouth
parts, 265. Rat-tailed larva of Zréstalis tenax, 265. Muscide,
265. Junction of abdomen in Musca, 265. Krzpelin on mouth

XX SYNOPSIS.

parts of Musca domestica, 265. Characters of larve, 266. Light
thrown on the subject of the systematic position of the Diptera
by Weismann’s observations on the development of the Musci-
dee, and M. Ganin’s views on the post-embryonal development
of insects, 266. (stride, 267. Thoracic region uncovered by
abdomen, 267. Larvz parasitic on mammals, 267. Life-his-
tory of (estrus ovis, 267. Modifications of structure peculiar to
different species of bot-flies, 268. Verrill on Gastrophilus equt,
268. Pulicidz, 268. Semi-parasitic habits of the adult, conse-
quent modification of structure, 269. Loss of power of flight
compensated for by increased power of leaping, 269, 270. Diet
of the larve, 270. Pupipara, 271; significance of term, 271.
Degraded structure of the Braulinidz and Nycteribidz, 271.
Hippoboscidz, 272. Adaptations of legs, 272. Development
of Hippobosca equina, 273. General remarks on the classifica-
tion of the Diptera, 273. Larvze farther removed from the Thy-
sanuriform type than those of any other group, 273. The absence
of thoracic legs in larvz which live in situations that seem to
demand them, a peculiarity inherited from an ancestral form
whose larvee had lost the thoracic legs, 274; inflexibility of larvze
sufficient to show a wide gap between existing Diptera and other
orders of insects, 274. Extreme specialization of the adults in
Diptera, 274.

GENERAL REMARKS.

In the first series of orders the direct mode of development
unites the Thysanuriform larva closely with the adult stages;
traces of this close connection are shown by retention of cer-
tain primitive characters, 275. Mouth parts of first series
adapted for biting; suctorial mouth parts of Hemiptera are
exceptional, 275; primitive form of larva retained in Hemip-
tera, 275. Complicated modes of development in second series
of orders, 275, introduction of secondary larval stages, 275;
these stages degraded modifications of the Thysanuriform larva,
275. Pupa stage of second series identical with that of first
series, with the exception that it is incapable of motion, 276.
Use of the terms “ Ametabola”’ and “ Metabola,” 276. Voracity
of larvee of second series of orders, 276; fatty accumulations

SYNOPSIS. XXIl1

used by pupa in building up the organs of the imago, 276; in-
activity of pupa in the second series a prolongation of the
shorter periods of inactivity accompanying every moult, 277;
want of any common structural differences in quiescent and
active pupe, 277; quiescence, therefore, a habit of resting from
exertion, 277. Replacement of Thysanuriform stage in orders
XII.-XVI. by secondary larval stages in accordance with law
of acceleration in development, 278; tendency toward accelera-
‘tion shown in the more specialized forms of the orders I.-IX.,
278; adult characters inherited by certain Orthoptera, 278.
Extraordinary importance of the functions of larval life in orders
XI.-XVL., 278. Larval life less variable than the adult stage in
many other classes of animals, 278; in insects larval life as eff-
cient for the manifestation of new modifications as the adult
stage, 278, 279; modifications probably due to the plastic nature
of the organism in adapting itself to its surroundings, 279;
parasites as good illustrations, 279; extraordinary metamorpho-
ses often accompanied by corresponding acceleration and loss
of primitive stages, 279, 280. Transformation of Echinoder-
mata, 280; adaptations of the larvee to a free life in the water,
280. Explanation for the hypermetamorphoses of Epicauta,
Sitaris, Meloé, etc., 280. Laws of heredity subservient to the
effects of habit and use of parts, 280. Degraded character of the
secondary larval forms, apparent rudimentary condition of these
forms, 280, 281. Argument offered against the derivation of
Coleoptera from Thysanura, 281. Researches of Brauer, Packard,
and Lubbock, 282. Composite nature of the process of indirect
development, 283; stages of development in individuals are
abbreviated records of the stages of evolution in the history of
the group to which the individual belongs, 283. Specialized
forms in each group evolved from generalized forms, 283. Later
acquired and useful characteristics replace primitive and useless
characters, 284; law illustrated by sucking mouth parts of
Hemiptera, adult characters in larval locusts, and the Pupipara,
284, 285. Adult and pupal characters remarkably constant in
orders X.-XVI., 286. Lubbock’s views on the rank of meta-
morphoses, 286. Confusion caused by the use of the words
“higher” and “lower,” 287, 288; reasons why they should not
be used, 288.

~ 5 tA

ad

7 hs
rg

th er Sao ae ee

: es:
a

ee

EIST OF LETTERS AND: SIGNS USED IN

THIS

A, head.

a, egg-pod.

a', cluster of eggs.
a'' site of egg-pod.
abt}—8, abdominal trachez.
ant, anterior.

at, antenne.

B, thorax.

é', prothorax.

6!', mesothorax.
6!'", metathorax.

dc, bursa copulatrix.
é6¢, mentum.

C, abdomen.

cl-l), abdominal rings.
ca, cardo.

cl, clypeus.

cn, central canal.
cs, cushions.

ct, cephalic trachea.
cw, claws.

cx, COXxa.

d, spine.

dt, dorsal trachea.
dz, dorsal muscles.
eé, fleshy membrane.
ea, ears.

eg, egg-guide.

ep, epicranium.
epx, epipharynx.
ey, eyes.

ey’, cornea of eye.

GUIDE.

f; chitinous margin.
Jr, femur.
jr', teeth of femur.

/%, frontal muscles.
a

}

ae fori sterna.
oI

5

el, galea.

gn, gena.

gu, guia.

i

hi } episterna.

A3

hph, floor of pharynx.
hs!

ie epimera.

hs?

hyp, hypopharynx.

if, infra-cesophageal ganglion.
j; abdominal folds.
21-3, abdominal sterna.
k, subgenital plate.

/’, Ist pair of legs.

i!', 2d pair of legs.
Z'', 3d pair of legs.

Za, \abrum.

/ae, labrum-epipharynx.
lc, Jacinia.

dg, ligula.

de', swelling of ligula.
7p, shoulder lappets.
ds\-1s°, prop-legs.

2 LETTERS AND SIGNS.

lv, larva.

/z, lateral muscles.

m, mouth.

mad, mandibles.

mx', Ist pair of maxillee.
mx'', 2d pair of maxillee.
m, tergum of 11th ring.
n', tip of tergum.

mr, nervous cord.

nr', nerve.

0, podical plate.

oc, median ocellus.

oc', lateral ocellus.

oe, cesophagus.

oeb, cesophageal bulb.
os, OVipositor.

os!

os'! ¢ parts of ovipositor.
ost

of, ocular trachea.

ov, ovary.

ov.t., oviduct.

ov.t.', site of oviduct.

iD, CCFL.

pst, paraglossz.

ph, pharynx.

4, pulvillus.

post, posterior.

pv, pharyngeal valve.

g Rab

7 t thoracic air-sacs.
g>_', abdominal air-sacs.
vr, neck of egg-pod.

ro, chitinous rods.

si19, spiracles.

sal, salivary gland.

sb, sebaceous gland.

sc, scale.

sd, salivary duct.

se, caudal setz.

sg, ganglion.

sm, sympathetic nerve.

| sf, supra-cesophageal ganglion.
spn, spinneret.

st, stigmatal trachea.

| su, sucking-tube.

suz, suture.
Zi
at scutum of thoracic rings.
B

tb, tibia.

tc, trochanter.

th, trachee.

Zn, tongue.

tp, stipes.

¢r, tarsus.

= rings
=

tu, respiratory tubes.

ubt, submentum.

ur, urinary tubes.

v, horny spikes.

vm, velum.

vt, ventral trachea.

w!, Ist pair of wings.

w!', 2d pair of wings.

x!, palpi of Ist pair of maxillze.
x!!, palpi of 2d pair of maxillze.
x'lz, muscles of x”.

y, horny plate.

z, muscles.

g., male.

©, female.

9, worker bee.

2, enlarged two diameters.

¢sl :
ore of thoracic

INSECTA.

mat

Sih

INTRODUCTION.

Tuis Guide is a series of replies to questions which
have arisen in the minds of its authors while teaching.
Many of the answers appear in the unsatisfactory form
of quotations from various observers. ‘These are often
contradictory, and for this reason sometimes confusing
to ordinary minds which demand certainty; and to
teachers and scholars who are inclined to rely upon
definitions. In the sciences of observation, except
where experience has accumulated, certainty is un-
attainable and definitions often fuller of error than of
truth.

Teacher and scholars should, recognize that science
is infinite, and demands from all its votaries a modest
acknowledgment of this fact. ‘They should work more
as companions learning from each other’s observa-
tions, and less as teacher and pupils, than in those
studies which can be taught from written treatises.

The frequent reiteration of the statement, that a
person does not know a certain fact or series of facts
will cause no distrust in scholars who are trained to
study the things themselves, and are thus led to realize
the vast extent of the field of work in every organism.

A teacher need not be discouraged because a library
is not accessible; specimens of some kind, and gen-
erally of many kinds, can be obtained. These are

5

6 INTRODUCTION.

nature’s own books, which can be studied by teacher
and pupil together, both learners at the same source.
Some of the best results in the teaching of Natural
History have been ultimately attained by those who -
have started in their work by encouraging their stu- ‘
dents to collect, and many have gained considerable
knowledge and owe their success to this method.

This Guide could not have been completed if Miss
J. M. Arms had not joined the undersigned in the
work, and if it had not been for the free gift of the
illustrations. These were paid for by the same ap-
preciative but unknown friend, who also gave the
drawings used in the Guide on WVorms and Crusta-
cea. ‘The number and value of the drawings con-
tributed in the present work very much exceed those
used in any previous Guide, because Insects form the
most favorable, and are apt to become the favorite,
means for the teaching of observation in the schools.
For the same reason, the text of this Guide has been
prepared with greater care than that of the preceding
Guides, and discussions of some questions of more
advanced scientific character have been brought for-
ward in its pages. Teachers are beginning to demand
explanations ; and while theoretical considerations are
largely out of place in the school-room, they are not
out of place in a treatise addressed, as this is, to
teachers themselves.

We desire to return thanks to the entomologists
who have assisted us in various ways, — Dr. A. S.
Packard, Dr. Hermann A. Hagen, Professor C. H.
Fernald, Mr. Edward Burgess, Dr. C. V. Riley, and
especially Mr. Samuel Henshaw, who has been con-

’

INTRODUCTION. 7

stantly called upon for specimens and for information
and advice, and Mr. Samuel H. Scudder, who has most
kindly read the proofs.

Figs. I-2, 4, 6, 7-12, 34-35, 37-49, 59, 52; 56, 63;
Ge 07, 72-00, 84-87, 124-127, 134-135, 172, 176-
177, 183, 186-189, 197-198, were drawn by Mr. S. F.
Denton.

Figs. 21, 28, 31, 33, 334, 36, 42, 424, 43, 54-55,
68, 69, 75, 76, 151, 153, 185, 185@, 194-195, were
drawn by Mrs. Katharine Peirson Ramsay ; and Figs.
35 5, 32, 64, by Miss J. M. Arms.

Diagrams I.-III. and Figs. 206, 206a, 215, were
drawn by Mr. J. H. Emerton.

Fig. 14 is an original drawing by Edward Burgess,
kindly given by him. Figs. 71, 73, 83, 91, 93-94, 96,
118-120, 154-160, 168-171, 184, 214, 217, were bor-
rowed from Dr. C. V. Riley. °

Pigs2707077,.61, 82, 92,95, 114-11 7a, 0, 121, 122,
14a, 050; 153¢, 0, c, 161, 1612, 1616, 182, 182a, 185%;
193, 216, 218, 222-223, were given by Dr. A. S. Pack-
ard. These figures, excepting 182, 182a, 185x (taken
from Zodlogy, Amer. Sci. Ser., 1881) are from Dr.
Packard’s valuable Guzde to the Study of Insects.

Figs. 162, 165-167, 175, were given by Mr. S. H.
Scudder.

Figs. 128-133 were given by the Boston Society of
Natural History.

Woodcut 149 was loaned by the late Mr. C. L. Flint.

The remaining figures are either copies from various

authors or original drawings.
ALPHEUS HYATT,
JULY 1, 1890. (Spey, ieee

INSECT.

THE locust, or “ grasshopper,” as it is called in this —
country, is a good type of the class of Insects, and its
wide range throughout the United States will enable
teachers in any part of the country to obtain speci-
mens without difficulty. In New England there are
many species ; but one of the commonest and largest
kinds is the yellow-striped locust, Ca/opienus femora-
tus; Burm. (PI. 1., Figs. 1,°2,.3, p. 10.) “Thetenees
locust, Dictyophorus reticulatus,’ common at the South,
«shows the parts more plainly, owing to its large size.
Specimens can be obtained from Florida; but when
this is inconvenient, our native locusts can be used.

Confusion has arisen in regard to the names “locust ”’
and “ grasshopper.” ‘The former has been incorrectly
applied by some authors to the cicada, or harvest-fly
(Fig. 78), a form well known by its shrill, trilling note.
The cicada, however, does not even belong to the
same order as the true locust, it being one of the
Hemiptera, or Bugs (see p. 131).

The name “ grasshopper” has also been applied by
Americans to certain species of true locusts which are
known by their appropriate name in Europe and other

1 For figures of this locust (also named Romalea micropiera)
see Science, Vol, II., No, 47.
8

INSECTA. 2

parts of the world. The true grasshoppers (PI. IV.,
Figs. 59, 60, p. 102), and the katydids belong to a dif-
ferent family from our “ grasshopper.” Unfortunately,
popular nomenclature in this case has not only become
different in America and Europe, but in Europe it is
the reverse of the scientific. Thus the locusts of his-
tory belong to the family Acridide, and the true grass-
hoppers belong to the Locustide.

Locusts can be readily distinguished from grass-
hoppers, as they have stout antennz which are usually
shorter than the body. They are generally reddish
brown or dull green in color, and live for the most
part on the ground. ‘They are found in great numbers
in open fields and along roadsides. ‘The grasshoppers
have long, slender, and tapering antenne which when
turned back, as one ordinarily sees them in cabinets,
usually extend beyond the abdomen. Those living in
grass, bushes, and trees are mostly of a bright green
color ; while the wingless forms which live in caves,
among rocks, and under stones, are generally different
shades of gray and brown."

Not only is it true that our yellow-striped locust
belongs to the same family as the destructive Rocky
Mountain locust, but also to the same genus, the two
being separated only by specific differences.

During July and August insects are very abundant,
and material should then be collected and preserved
‘for the winter’s use. Insects which are preserved in
alcohol are more pliable and easier to study, but

1 Some western wingless Locustarians living on the prairies
are almost black.

10 INSECTA.

should be accompanied also by some dried and
pinned specimens, since the former are apt to lose
their colors, and if at all hairy are very unsightly ob-
jects.’ It will be found convenient to pin the body
to a small piece of cork to facilitate observation and
prevent mutilation in handling.

Scholars who have taken the lessons on Mollusks
and Crustacea ought to be able to place the body of
the locust (Pl, I., Fig. 1, p. 10) in the most favorable
position for observation and comparison; viz. with
the head turned from them and the back uppermost
(see Guide No. WII. pp. 17, 18). In this position
the insect is seen to be bilaterally symmetrical. An
imaginary vertical plane passed longitudinally through
the body divides it into two equal lateral parts, and an
equal number of appendages project on either side.

The obvious peculiarities of the locust are as fol-
lows: It is a winged creature with a more or less
elongated body, supported on jointed legs, and pro-
tected by an external horny skeleton. ‘This skeleton
is one of the most noticeable features to scholars
already familiar with the external calcareous skeleton
of the Crustacean.

It is, in reality, the outer layer of the skin, known as the
cuticula and is an excretion from the soft, underlying cel-

! Further details for preserving the necessary material for
class-work are given under the different orders. See also
* Directions for Collecting and Preserving Insects,” Packard,
Smithsonian Miscellaneous Collections, 261, [Distributed free. ]
Packard, Entomology for Beginners, Chap. VI, Morse, Ferst
Book of Zoblogy.

PLATE Tf.

ANY

INSECTA. 11

lular layer, the epidermis. It is homologous with the
cuticle of the earthworm and the crust of the lobster, but
differs from the latter in having no layers of calcareous
matter. It is entirely composed of tough, horny matter,
called chitine, which prevails in the Articulata; z.e. Worms,
Crustacea, and Insects. The colors of the skeleton are
generally considered to be due to pigment in the epidermis
shining through the cuticula.2, They vary from reddish
brown to olive-green, passing from dark, rich shades above
to lighter tints below, as is the case in most deeply colored
animals.

Upon looking at the body of the locust, one sees
that the integument exhibits a series of constrictions
dividing the body into rings, and these rings are
grouped into three regions separated by soft, pliable
membrane not stiffened by chitine. The anterior region

1 Also called “ hypodermis ” by many entomologists,who speak
of the cuticle as the epidermis. This is a misuse of terms, the
true epidermis being a true cellular layer and never an excretory
product.

2 Dr. Hagen (Proc. Amer. Acad., Vol. XVIL., 1882, pp. 242-
245) says there are two kinds of colors: one belongs to the
cuticula, the other to the hypodermis. The colors of the cuticula
are persistent, while those of the hypodermis are not.

Dr. Minot (“Zur Kenntniss der Insektenhaut.” Archiv. fiir
mikroskop. Anatomie., Bd. XXVIII.) gives a few observations
on the structure of the outer cuticle, especially of caterpillars.
“In the larve of many insects a part of the coloring is caused
by the pigmenting of the cuticle. The pigment may extend
through the whole cuticle, but is generally confined to the ex-
treme outermost layer, and is found there in connection with
peculiar modelings of the surface arranged in microscopic fig-
ures, which claim our interest not only on account of their ele-
gance, but also their variations, which are characteristic for each
species.”

a2 INSECTA.

is the head (Pl. I., Fig. 2, 4), the enlarged middle
region the thorax (Fig. 2, 4), and the posterior region
the abdomen (Fig. 2, C). The scholars should observe
the distinctness of these regions, and the marked de-
velopment of the head which especially characterizes
insects as a whole and separates them from the Spiders
and Crustacea, and they ought to detect in the seg-
mented body, especially in the posterior region, one
of the structural characteristics common to these three
classes and to the Worms. ‘This characteristic of being
composed of segments, or successive rings, possessed
in common by the Worms, Crustacea, Spiders, Myrio-
pods, and Insects, led Cuvier to bring these five types
together under the name of the Articulata. ‘The last
four classes are now usually grouped together as the
Arthropoda, or animals with jointed appendages.
These, as one type, are contrasted with the Worms,
which either possess simple, unjointed appendages, or
none at all, as stated in Guide No. VII., p. 16, and
the use of the term “ Articulata” has been discon-
tinued."

1 While this is a statement of current views, it does not repre-
sent the unanimous opinion of investigators. Some naturalists,
among them the authors of this Guide, are disposed to uphold a
modified form of the Cuvierian classification. The old names
Radiata, Mollusca, and Articulata, like the name Vertebrata, rep-
resent obvious relations, and a legitimate grouping of forms.
The groups Crustacea, Scorpions and Spiders, Myriopods, and In-
sects have astiff skeleton, and as swimming and walking animals
necessarily have jointed appendages. The Worms, being crawl-
ers and burrowers or swimmers, do not need a hard skeleton.
Their integument being soft, they do not have articulated or
jointed legs, but soft paddles and sete. The division of the
Arthropoda and Vermes may be used to show such distinctions,

4
INSECTA. 13

In accordance with the plan heretofore pursued,
and which we think presents certain advantages, we
shall now describe the regions of the body, neglecting
for the present all the appendages. In considering
these regions it is better to begin with the head (PI. L.,
Figs. 2, 3, 4; Fig. 4), as by so doing the distinctive
features of the Insecta are brought out more clearly.
This part is long and narrow in shape and is set at
right angles upon a fleshy neck, so that it moves freely
upward, downward, and sideways. It is marked by
sutures, but no inference as to the number of rings
composing it can be drawn till the number of append-
ages has been determined.

The epicranium (Pl. I., Fig. 4, ef) extends from the
upper part of the head to the broad, short, immovable
plate or clypeus (c/) below; the gena, or cheeks (gv),
occupy the sides of the head.

The forward part of the thorax is known as the pro-
mamas (Fl 1. Vigs.~3, 7, 6"; Fig. 4, side view of
Caloptenus spretus). Vhe dorsal and lateral portions
form a cape which extends backward from the neck,
and is free along its posterior margin. There is a slight
longitudinal ridge through the middle, and it is marked
by three distinct grooves, which divide it into four
parts.

Pl. I., Fig. 3, 4 is the scutum, ¢s! the scutellum. The
part in front of the scutum is the prascutum, and that
back of the scutellum the postscutellum. These two parts

but we should not blind ourselves to the more obvious relations
of both groups, as members of the Articulata or segmented
animals.

*

14 INSECTA.

are small in most insects and difficult to make out. The
ventral or sternal portion (Pl. I., Fig. 5, ¢’) consists of a
hard, crescent-shaped ridge (which here extends into a
blunt tubercle (@) at the middle), a soft, pliable mem-
brane (¢), and a stiffened posterior margin (/).

The prothorax moves freely, apparently only con-
nected with the middle segment, or mesothorax (PI. L.,
Figs. 3, 7, 4"), by soft skin. While this is true of the
back, the sternal and lateral connections (PI. I., Figs.
5, 6, swf) are immovable, lying back of the pliable
membrane. Pl. I., Fig. 6 represents the prothorax
with a portion on one side cut away, exposing the
fleshy membrane (¢), the chitinous margin (/), and
the spiracle (s'), which will be described farther on.
Practically, however, the prothorax is independent of
the mesothorax, and also of the head, as it is only
connected with the latter by fleshy membrane and
two chitinous jointed bands which extend downward
on either side of the face. With the exception of
these bands, the neck yields readily to pressure. The
weakness of this part of its armor sometimes costs the
locust its life. The sharp, dry grass-blades are as
dangerous as steel-pointed spears to the naked skin,
and when one accidentally enters between the plates
of the cheek and the prothorax, it readily pierces the
soft neck, so that the insect is impaled and often dies.
One such unfortunate is figured by Morse.’ Such parts
can be used to show pupils the suitability of the horny
crust to resist collisions while in flight, and the con-
stant attrition of the grass and other vegetation. A

1 First Book of Zovlogy, p. 91.

INSECTA. 15

calcareous shell would have been too heavy as well as
too stiff and unwieldy. ‘The insect’s armor is, there-
fore, composed wholly of the single substance chitine,
the lightest and toughest material excreted by the
epidermis, and capable of fully protecting, while not
embarrassing by its weight, the body of this essentially
aérial type. It is not a wonderful material of new and
mysterious origin, but probably an adaptation of the
outer part or horny cuticula, a layer similar to that
found in the Worms and Crustacea. |

Upon cutting away the prothorax, the upper or
tergal part of the mesothorax (Pl. L., Fig. 3, 4") bear-
ing the first pair of wings, is exposed.’

The mesothorax is divided into the scutum (7?) and
scutellum (7s). The sides consist of two parts, the epi-
sternum (PI. I., Fig. 7, #7) and epimerum (/s?), which
extend downward and backward. The sternum (PI. I.,
Fig. 5, 2’) is a flat, stiff piece. In Guide No. VII. Fig.
8, D, is a drawing of a typical crustacean ring in which
the epimeral plates are above the episternal. In the locust
the epimera have been crowded downward and backward,
so that they no longer lie above, but behind the episterna.

The mesothorax is separated from the third and
last segment, the metathorax, with some difficulty, as

1 Scholars will understand the structure of the locust far bet-
ter after they have separated the parts; and if several in the
class fasten these parts on cardboard, the preparations are
useful for reference, and valuable additions to the school cabi-
net. This process enables them to see, that, although each ring
of the thorax is apparently subdivided by sutures into two or
three rings, the whole region can be more readily divided into
three rings, and has but three pairs of appendages.

16 INSECTA.

the two are firmly consolidated. The metathorax
(Pl. I., Fig. 3, 4!) is also a wing-bearing segment,
and larger than the mesothorax, but is similarly
divided.

Pl. I., Fig. 3, 22 is the scutum, Zs* the scutellum; PE.
Fig. 7, 4° the episternum, /s? the epimerum; PI. I., Fig.
5,2” the sternum.

Both teachers and scholars will probably be more or
less confused by the presence of secondary sutures and
the complex character of the segments. Some entomolo-
gists consider that each of the thoracic rings is composed
of several segments; but the majority hold the opinion
here given, and strong confirmation of this view is found in
the fact that in the youngest stages there are only three
simple rings in the thoracic region. The sutures which
subdivide the rings of the thorax arise subsequently during
growth, and must, therefore, be regarded as of secondary
origin. In primitive insects segmentation was probably
due to the mechanical effect of the motions of a cylindrical
body upon a crust-producing skin. This tendency became
fixed and hereditary in the type, and now these primitive
constrictions appear in the young, and show us the num-
ber of rings which may be considered as primitive rings.
The concentration of the terminal rings to form the head
can be explained as in the Crustacea.! The similar con-
centration of the thorax may be referred to the reactions
due to the use of the wings and legs in balancing and
transporting the body in the air and upon the earth. The
exercise of these functions would naturally tend to bring
those segments which bore both legs and wings into closer
connection, to solder them together, and increase their
diameter, on account of the necessary increase in size of
the muscles used in moving the wings and legs. The

1 Guide No. VIL, p. 41.

INSECTA. 17

prothorax, having no wings and only a pair of legs more
or less used in walking, would be proportionately less de-
veloped than the metathorax and mesothorax, and also be
more independent or less likely to become consolidated
with the mesothorax. The cape of the prothorax masks
the small size of this ring in the locust, and it is doubtless
a special adaptation of the outer folds of the skin for the
purposes of protection. How effectively it covers up and
defends the vulnerable sutures may be readily observed.
The ring inside of this cape is really very small, and it
is to this part that we refer, and not to the cape, in
the remarks above. The abdomen retains the original
conditions of free motion in every direction; and being
without special organs of flight or locomotion, has required
no special modifications of importance, and retained prob-
ably with very little change the primitive mode of segmen-
tation or division into simple, unconsolidated rings, except
in the terminal segments where the organs of reproduction
are developed.

The junction between the thorax and abdomen
should be carefully observed. It is broad and without
vertical or lateral constriction. ‘This peculiarity is
characteristic of the more generalized insects, and the
abdomen has been aptly termed “sessile”’ to distin-
guish it from the pedunculated abdomen of the more
specialized Hymenoptera Aculeata (see p. 238). The
most obvious characteristic of the abdominal region
(Pl. I., Fig. 3, C) is its division into simple, primitive
rings (c'-c'”). When separated from the metathorax,
the first ring (Pl. I., Figs. 3, 7, ¢') must be closely
examined. Its dorsal portion resembles that of the
succeeding abdominal rings. It is immovably con-
nected with the thorax in front, although behind it

18 INSECTA.

moves freely upon the second abdominal ring. On
the ventral side there is no corresponding part to
represent the sternum. On each side of the abdomen
the skin is turned inward, forming a longitudinal fold
(Pl. I., Fig. 7, 7) which separates the upper part of
each ring from the lower. Just above this fold, on
either side, is a row of breathing-holes, or spiracles
(Fig. 7, s*-s). Each spiracle is a slit-like opening
surrounded by a horny ring, and is situated on the
anterior portion of the segment: these will be referred
to again under the respiratory system (see p. 38).

The abdomen of the male (Pl. I., Fig. 7, C) is simpler
in structure than that of the female. The first eight rings
(Fig. 7, c-c®) can be readily counted, while the ninth and
tenth (Pl. I., Fig. 8, c°, c!°) are fused together, the suture
showing on the median line, but not extending on either
side so far as the fold (Fig. 7, suf). The corresponding
space on the ventral side is occupied by the sternum of
the ninth ring (Fig. 7, 4°), which is broader than the sterna
of the other segments and without any visible suture. Be-
hind the ninth abdominal sternum is the subgenital plate
(Fig. 7, #7). In the female the sternum of the eighth
ring (PI. L., Fig. 9, £*) extends backward to form the sub-
genital plate, which terminates in the egg-guide (eg.; see
also Fig. 14, egg-guide). Attached to the tenth ring is the
shield-shaped piece (Pl. I., Figs. 8, 9, 7), which embry-
ology proves to be the tergum of an eleventh segment:
Fig. 9, 7’ is the tip of the tergum. On either side of the
tergum are the podical plates (Figs. 8, 9, a), and between
these is the anus. Lying upon the podical plates, and
fastened to the tenth segment, are the movable cerci
(Figs. 8, 9, #), which are not true appendages. At the
extreme end of the abdomen are parts connected with the
genitalia, which will be described in their proper place

(see p. 33).

INSECTA. 19

The organs of sense are directly connected with the
head or its appendages, except the ‘“‘ tympanal organs,”
and these may be taken up in connection with the ab-
domen. They are light-colored, oval membranes, one
on either side of the first abdominal ring, and are sup-
posed by many to be organs of hearing. They are
modified portions of the two layers of the skin. On
the inner side they are connected with rod-bearing
organs, which in turn lead to a ganglion, and from the
latter a nerve passes to the third thoracic ganglion,’
and thence to the brain. It is supposed by those
who hold that these organs are ears that when a wave
of sound strikes the tympanum, the vibrations affect
the rod-bearing organs, and are transmitted to the
thoracic ganglion, and thence forward to the brain.

Before taking up the appendages, the compound
eyes (Pl. I., Fig. 4, ev) must be considered. It may
seem more natural to describe these organs when
observing the structure of the head (see p.13). They
are considered here in order to treat of the sense
organs together, and also because there seems to be a
connection, not yet well understood, between the eyes
and antennz, those insects with small eyes having
very often well-developed antennz, and vice versa.
There are, however, numerous striking exceptions to
this rule. The eyes project on either side, and are
fixed or sessile. In some insects, like Stylops (Fig.

1 See Minot, “ Comparative Morphology of the Ear,” Amer-
ican Fournal of Otology, Vol. 1V., April, 1882. The author
considers that the “tympanal organs” are unquestionable sense
organs, although in his opinion the evidence is decisive against
the supposition that they are ears.

20 INSECLIA:

115), Xenos, and others, the eyes are borne upon
fixed stalks; but these are simply extensions of the
head, and are not movable like the eye-stalks of the
lobster, so that they cannot be regarded as append-
ages. In the median line of the face is a simple eye,
or ocellus (Pl. L, Fig. 4, oc), and above it, on either
side, two lateral ocelli (Fig. 4, oc'!). The young locust
does not possess compound eyes, but in their place
are groups of simple eyes, which during the growth of
the embryo increase in number, and finally unite to
form the large many-faceted visual organs." Some in-
sects like Xenos have groups of simple eyes in the
adults, showing the transition state.

Very different views have been advanced in regard to
- the structure and physiology of the organs of sight. In
1826 Miiller advanced the theory of ‘‘ mosaic vision,”
according to which each fatet of the eye sees only a por-
tion of the object, so that but one image is produced. He
also maintained that the simple eyes were used for near
objects, and the compound eyes for distant views. Grena-
cher? in 1879 published a valuable work but unfortunately
there is no English translation. In 1885 Hickson ® figured
and described the structure of the compound eye. This
author maintains that the retinule (which correspond to

1 According to Patten the simple eye becomes differentiated
to form the compound eye, so that the latter he considers not
many simple eyes joined together, but “a modified ocellus”
(see “ Eyes of Molluscs and Arthropods.” Naples: abstract in
Fournal of Morphology, 1887, Vol. 1., No. 1, p. 67).

2 See Untersuchungen iiber das Sehorgan der Arthropoden.
Géttingen, 1879.

3 See the ‘‘Eye and Optic Tract of Insects,’ Quarterly
Fournal of Microscopical Science, April, 1885; also “The
Retina of Insects,” ature, Vol. XXXI.

INSECTA. 21

the rods and cones of the vertebrate eye) are the nerve-
end cells, because the ultimate fibrils of the optic nerve
terminate in them, and because the cells are always pig-
mented, either by a diffuse fluid — retinal purple —or by
pigment in granules, or both. The discovery that the
retinula contain a true retinal purple was made by Leydig
in 1864. The retinule with portions lying back of them
constitute, according to Hickson, the retina of insects.
The experiments of Plateau,) however, point to the
conclusion that insects cannot distinguish the forms of
objects, or, at best, can distinguish them very poorly.
The conclusions reached in this paper are extremely
interesting. The experiments were made with certain
Diptera, Hymenoptera, Lepidoptera, Odonata (Dragon-
flies), and Coleoptera, in a room which only admitted
light through two orifices. One of these orifices was
large enough for the insect to pass through, while the
other consisted of many small openings, no one of which
would allow the passage of the insect. In each experiment
the intensity of the light of the two orifices was deter-
mined. If the insects could distinguish the form of the
two openings, it was assumed that they would fly to the
one which was large enough to allow them to escape. Re-
peated experiments proved that they did not take into
account this difference in form, but flew to the orifice
which was most luminous. These experiments also tended
to prove that the ocelli of the Odonata, Hymenoptera, and
of many Diptera are only rudimentary organs, and of
almost no use to their possessors. In these experiments
the animals were placed under such conditions that they
could use no sense excepting that of vision, and could not
be guided either by the color or odor of bodies. Certain

1 Recherches expérimentales sur la Vision chez les In-
sectes,” Bulletins de L’ Académie Royale de Belgique, 3me série,
t. X., No. 8, 1885.

22 INSECTA.

objections, however, were raised against the method em-
ployed by Plateau, and he afterward devised a new method
carrying on extensive and more conclusive researches.1
At the same time he made comparative investigations with
the vision of vertebrates, and as a result proved that while
the latter had clear vision, easily and skilfully directing
their movements, the insects “acted in all cases as if they
had a veil before their eyes,” ? and could not perceive sharp
images of any immovable object.

Notthaft? gives a number of figures showing how im-
perfectly these animals distinguish the forms of objects.

Between the compound eyes is the first pair of ap-
pendages, the jointed antennz (PI. I., Fig. 3, a¢; Figs.
1,2). These are articulated to the head in such a way
that they move freely in any direction. The observa-
tions heretofore made upon these organs indicate that
they have very important functions, and a direct con-
nection with the brain, which ‘cannot be severed in
most insects without serious injury to the animal. The
exact nature of these functions, however, has not been
satisfactorily determined. In some a special sense
seems to reside in the antennz, which is neither ex-
clusively a sense of touch, hearing, taste, nor smell.

The experiments of Trouvelot* on Zzmenitis Disippus,
Godt., and of Packard® on Colzas, Pieris, and others, show

1 Recherches expérimentales sur la Vision chez les Arthro-
podes. Parties I—V., Bruxelles, 1887-88.

2 See Butterflies of the Eastern U.S. and Canada, Scudder,
pp- 1670-71.

3 Abhandlungen senckenberg. naturforsch. Gesellschaft.
Frankfurt, XIJ., 1881. For a further discussion of the subject,
see The Cockroach, Miall and Denny, pp. 98-109.

4 American Naturalist, Vol. X1., April, 1877.

5° American Naturalist, Vol. XI., July, 1877.

INSECTA. Za

that when the antennz of these butterflies are cut off, the
insects cannot fly with the same degree of accuracy.
When Limenitis was deprived of sight by covering the
eyes with Indian ink, it could fly; but when, in addition,
the antennz were cut off, it was wholly unable to direct its
course or find its food. When the stumps of the antenne
were touched with a solution of sugar, they received an
impression, and the proboscis unrolled. The intimate con-
nection between the antennz and brain is shown by Pack-
ard (/oc. cit.), who found that many insects, notably the
honey-bee, were more or less paralyzed when the antenne
were taken away, their motions resembling those of a bird
from which the cerebral hemispheres have been removed.
The observations of Lubbock! tend to show that the
antennz of ants are organs of smell.

The admirable experiments of Meyer ? on the mosquito
(Culex) prove conclusively that the antennz of these
insects are organs of hearing. This author, shows that a
tympanic membrane is not necessary to receive aerial vibra-
tions ; for the delicate fibrillz or hairs on the antennz of
the male mosquito vibrate to the notes of the female, and
are ‘‘tuned to sounds extending through the middle and
next higher octave of the piano.”

The recent experiments of Plateau? on cockroaches tend
to prove that faint odors can only be perceived by means
of the antenne, and not by the palpi or cerci.

The labrum, or upper lip (Pl. L., Figs. 3, 4, /z), is
attached to the clypeus (Fig. 4, c/), and can be turned
back with the pick. It is generally regarded as form-
ing with the clypeus a part of the first cephalic ring

1 Ants, Bees, and Wasps, pp. 234, 235.

* Ann. Nat. Hist., 4th Ser., Vol. XV., 1875.

3 Compt. rend. de la Soc. Entom. de Belgique, 1886. See
also Zhe Cockroach, Miall and Denny, pp. 223, 224.

24 INSECTA.

which bears the antennz.' When the labrum is
raised, the two hard, dark mandibles (Fig. 3, md;
Pl. I., ‘Fig. ro) are exposed. ‘These have eupam=
edges, which prove that the locust bites its food.
They move sideways, as do the jaws of most Arthro-
pods.”. When one mandible is cut away, the mouth
(Fig. 14,.m, p. 36) 1s.seen. :

The mouth parts of locusts are strong and well fit-
ted to masticate the tough fibres of vegetable tissues.
The destruction of crops caused by the Rocky Moun-
tain locust, Caloptenus spretus, 1s a familiar fact.
One of our common species of locusts, Calopienus
atlanis, has been known to migrate and to extend its
ravages over New England. In 1749 and 1754 “‘no
vegetables escaped these greedy troops; they even
devoured the potato-tops.”’ Days of fasting and prayer
were appointed by the colonists to avert the dread
calamity.®

Behind the mandibles is the first pair of maxillze
(El. bs: itis. <9, yee 3 NG ts ae).

Each maxilla consists of the cardo (Fig. 11, ca), stipes,
(tp), lacinia (/c), the spoon-shaped galea (g7), and the
five-jointed maxillary palpus (2”).

Between the bases of this pair of maxillz on the
median line is the tongue (Pl. I., Fig. 3, 7), a stout,
reddish organ with a chitinous upper surface rough-
ened by papille.

1 Third Report U. S. Entomological Commission, p. 279.

* An exception to this rule is found in Balantnus (weevil), in
which the jaws move vertically (see p. 165).

3S. H. Scudder in U. S. Geological Survey of Nebraska,
Final Report, 1872, pp. 249-261.

INSECTA. 25

The tongue may be regarded as the sternal plate of the
ring bearing the first pair of maxilla, which has become
greatly modified to form an organ of taste. It is homol-
ogous in position with the small sternal plate which bears
the metastoma in the lobster. (See Guide No. VII., p. 30,
Fig. 9A, /ém, sternal plate, mt, mti, metastoma.) The
second pair of maxillz (Pl. I., Fig. 3, wa’; Fig. 12) forms
the floor of the mouth and consists of two pieces which
have become united. Fig. 12, gu is the gula, zd¢ submen-
tum, d¢ mentum, /g ligula, and 2’ the three-jointed palpus.
For a detailed description of the mouth parts, see Com-
stock, Latroduction to Entomology,1888, pp. 12-16.

The palpi of insects have been regarded by the
majority of entomologists as organs of touch, though
some have maintained that they were organs of taste
and others of smell. The recent experiments of
Plateau’ tend to overthrow these views completely
and to demonstrate that the palpi of the Orthoptera
and Coleoptera do not possess either one of these
three senses. The experiments were made upon fifty
individuals, species of Carabus, Dytiscus, Staphylinus,
Blatta, Acridium, and other genera. These experiments
led to the following conclusions. First, that in the
act of eating, the two pairs of palpi remained inactive,
For example, meat was placed before a beetle (Cara-
bus) ; the insect ate it; but the palpi during the time
were directed backward on each side of the head and
not used.

Second, the suppression of both pairs did not pre-
vent the mandibulate insects from eating in a normal

1“ Palpes des Insectes Broyeurs,” Audlletin de la Société
Zoologique de France, t. X., 1885.

26 INSECTA.

way, nor did the amputation of these parts deprive the
insect of the sense of smell. The palpi of one species
of Staphylinus were cut off, and it ate. This same
insect was afterward set free in the garden, and sixty-
four days from the time of its liberation it was very
agile, and the palpi had begun to grow again, showing
that it had not materially suffered from the loss of
these organs.

In a later article’ Plateau concludes after many ex-
periments upon the air-breathing Articulates that the
palpi are not special organs of sense nor even indis-
pensable for introducing food into the mouth, but that
these appendages in the biting insects, female spiders,
and in the Myriopods belong to the category of organs
that are useless in the animals now possessing them.
In primitive ancestral forms they were doubtless use-
ful, but in the existing insects, according to Plateau,
they no longer perform important functions. While
this’ may be true of adult insects in a general way, it
is a sweeping statement, and should be received with
caution. In some larve, like those of the dragon-fly
for example, the palpi have become highly specialized
and very useful as organs for procuring food, and it is
also very difficult to account for the almost universal
presence of these mouth parts in insects which take
food, if they are wholly useless appendages to the
mouth.

Four pairs of appendages have been found attached

1 See “ Expériences sur le role des palpes chez les Arthro-
podes Maxillés. Palpes des Myriopodes et des Aranéides,”
Plateau, Audlletin de la Société Zoologigue de France, t. XI,
1886, —

- INSECTA. 27

to the head, and the inference is that this region is
composed of at least-as many rings which have be-
come so firmly consolidated that the sutures are not
easily traced. It is seen that most of the sense organs
are placed at the forward end of the body, where they
are most useful in the search for food, and where
their concentration correlates with the concentration
of the nervous system into a brain."

The three rings of the thorax each bear a pair of
legs. The first pair (Pl. I., Fig. 3, 7) is the shortest.

The leg consists of five well-marked sections; the coxa
(Fig. 3, 7, cx), trochanter (¢c), femur (/7), tibia (#6), and
tarsus or foot (¢7). The tarsus is made of three sections ;
the first two have soft cushions (cs) on the lower side,
while the third is slender, and bears at its end the pulvillus
(£2), and two claws (cw).

The second pair of legs (Fig. 3, 7’) is similar to the
first pair. The third pair (Fig. 3, 7’) is more than
twice the length. of the others. The femur (2, fr)
is club-shaped, and is greatly developed. The strong
leaping muscles contained in this section of the leg
are attached to the inner side of the skeleton, the
points of attachment being plainly marked by lines
which form a pretty pattern on the exterior. The
three pairs of legs are attached to the body at a dif-
ferent angle. ‘The first pair (see Pl. I., Fig. 2, which
represents the locust ready to leap) extends forward,
while the second passes outward and backward, and
the third upward and backward: when the insect is
flying (Pl. I., Fig. 1), the leaping-legs are straightened.

1 Worms and Crustacea, No, VIL., p. 39.

28 INSECTA.

The habits of the locust give the best explanation of the
great size and peculiar form of the hind legs. ‘Though
good fliers, these insects are pre-eminently jumpers,
and this habit has enlarged and lengthened their legs,
as in the parallel cases of animals which use their legs
in the same way, like leaping mice or kangaroos.
Bipeds also have enlarged limbs from the same causes,
like the great reptiles of the Trias, the existivg types
of birds and man.

Encourage children to watch living locusts. Note
how one alights; the short, strong claws take firm
hold of the grass blade, and the cushions of the feet
adhere to it, so that the little creature is poised
securely. When it wishes to change position, the
adhesion of the cushions to the grass serves as a point
of resistance, while the powerful muscles of the tong
hind legs are brought into actior, and the body is
shot forward to many times the insect’s height.

The invariable adaptation of an animal to the life it
leads is one of nature’s most instructive lessons, and
can be discovered and appreciated by every pupil, but
never through oral teaching or from the reading of
books. Better a child should learn to handle one
animal, to see and know its, structure and how it lives
and moves, than tc go through the whole animal king-
dom with the best text-book, under the best teacher,
aided by the best charts ever made. ‘The former
would have learned what real knowledge is, and how
to get it, while the latter would have simply learned
how to pass at his school examination.

The organs of locomotion studied in the preceding
Guides on Invertebrates were found to be adapted for

INSECTA. 29

»
swimming in a dense medium like water, or for walk-
ing upon the solid, resisting bottom or the dry land.
The appendages were modified to meet all the require-
ments of locomotion under such conditions ; but the
more difficult problem must now be considered, of
motion in a medium like air, which is itself lighter
than the body of any of the higher organisms.’ This
motion is effected, in the locust and many other in-
sects, by means of two pairs of wings. The first pair
(Pl. 1. Fig. 3, w'; Fig. 1) are long, narrow, and of
a parchment-like texture. They completely cover the
second pair when at rest, and are, therefore, frequently
called wing-covers. ‘The more flexible second pair of
wings (Fig. 3, w'’; Fig. 1) are much larger and of more
delicate texture than the wing-covers. When at rest
they lie folded like a fan. The longitudinal folding
and the position of the wings when closed has given the
name Orthoptera, meaning “ straight-winged,” to the
order to which the locust belongs (see p.102). The
thickened portions extending through the wings are
called veins and veinlets; the thinner parts between
these thickened supports are the cells. The disposition
of the veins and veinlets or general plan of each wing
should be studied, since these are more or less charac-
teristic in each order of insects.” The locust’s wing
is more or less triangular in form, with three margins, —

1 Many lower organisms, plants as well as animals, and es-
pecially spores and germs, are so minute or lightened by dry-
ing, that they float in air in vast numbers, forming a large part
of the dust of the atmosphere in many places; but these, of
course, are not considered in the above statement.

2 See Comstock’s Jntroduction to Entomology.

30 INSECTA.
$

the front or costal margin, the outer or apical, and
the inner or anal. The important veins divide the
wing into the three areas, costal, median, and anal.
When the wings are expanded as in the act of flying
(Pl. I., Fig. 1), the forward part is rigid, owing to the
larger veins which radiate from the base, while the
posterior portion is flexible. The wings are attached
to the tergal portions of their respective rings, which
are loosely connected with the lateral parts. The
movements of each tergum, which are accomplished
in the living locust by strong internal muscles, may
be imitated by gently pressing the tergum downward,
when the wings will be seen to rise. It is instructive
to observe the correspondence existing between the
size of the wings, and that of the rings upon which
they are borne. In the locust and most Orthoptera,
whose posterior wings do the larger part of the work
of flying, the metathorax is larger than the meso-
thorax ; but in other insects, like the butterfly and fly,
which use their first pair of wings more than the
second pair, the reverse will be seen to occur. The
greater amount of work done by the muscles within
these rings in moving the wings causes their own en-
largement, and the segment necessarily grows more
capacious to make room for the accommodation of
the muscles.

The wings are membranous expansions quite dif-
ferent in aspect from the body wall, but are con-
sidered to be folds of the skin which have grown out
from the tergal portions of their respective rings.
They are mere pads in the young, and their veins are
hollow, some of which contain trachez. This has led

INSECTA. 31

to the opinion that they must be regarded as out-
growths of the system of air-vessels, and of the
outer wall of the body, which have together formed
organs, varying from the sac-like pads to the fully
formed wings. Some authors, however, consider them
to be modified limbs which have been shifted in posi-
tion and altered in form and function. Whether this
be true or not, the teacher need not consider; in
either case, they are membranous expansions of the
body wall, are developed from the thick pads of the
young, and their veins are hollow tubes (see p. 39).
An artificial wing is needed to show the effects of
the resistance of the air upon the flight of insects.
One can be made of a bamboo rod and Holland cloth
which will answer the purpose fairly well. Select a
rod about forty-nine inches long, split the flexible tip
of the rod by sawing it through thirty inches, leaving
the remaining portion whole, to furnish a handle. The
spokes of a dismembered fan made of split bamboo
can then be placed in parallel lines about an inch
apart and glued to a long piece of cloth, and the top
side covered by a layer of thin cloth or tissue paper.
A wing similar in shape to that of a dragon-fly, but
straight on the forward side, can then be cut out of
this, but it should be not less than ten inches at the
broadest part. This cloth wing can be sewed or tied
into the sawed-out split of the bamboo rod with twine,
and is then ready for use. A wing might be made by
using a socket and longer strips of split bamboo, which
would more closely represent a wing with its network
of veins, but it is not essential to imitate nature very
closely in this instrument. The bamboo represents suf-

32 INSECTA.

ficiently well the functions of the large anterior veins,
and gives rigidity to the forward part of the wing, while
the flexible cloth membrane is essentially similar to a
membranous wing, if made stiff enough to maintain a
horizontal position when not in motion. If, now, this
artificial wing is carried slowly downward through the
air, it descends vertically, and the membrane remains
horizontal ; but increase the speed, and the wing, acted
upon by the resisting air, is driven downward and
forward, its vertical descent being changed to an in-
clined plane. When the wing is raised, on the other
hand, it is carried by the resistance of the air upward
and forward. Thus, by moving the rod vertically
with rapidity, the motions of insects’ wings may be
imitated, and it will be found, even though the elbow
be held stiffly against the side and the hand simply
moved up and down, lateral motion being resisted,
that the hand and forearm are propelled forward with
a speed proportionate to the rapidity of the vertical
vibrations. In this way the action of the pliable
membrane of the wings in lifting and moving a body
through the air may be roughly demonstrated.t At
times the wings are motionless, when the insect seems
to float through the air. This is owing, in part, to the
sustaining power of the wing surfaces, and also to the
fact that the weight of the body is lessened by
the prevalence and large size of air-vessels in the in-
terior. ‘These, when inflated, increase the lightness of

1 When the plane of the wing is changed, very different
effects are produced, as shown by an ingenious flying-machine
invented by Marey. (Azzmal Mechanism. International Sci-
entific Series, Appleton & Co., New York, 1879.)

INSECTA, - 33

the body through the buoyancy of heated air which
they contain. ‘The bodies of all insects are also not
burdened by heavy internal supports like the bones of
Vertebrates.

The wings, when acted upon by the leaping-legs,
produce the musical notes or strigillations peculiar to
locusts. As a rule with insects the males strigillate,
and the females are mute. ‘The genus Ephippiger of
the family Locustidz, however, is an exception to
this rule, as both sexes are provided with a musical
apparatus.' The teeth on the inner side of the femur
CPE TL, Fig. 13, p. 385.7"; a, 6, different’ views of the
same magnified) are rubbed up and down against the
outer veins of the wing-covers.” Mr. S. H. Scudder
found that certain insects would respond to the “ mock
chirping” produced by playing upon a common steel
file with a quill, and by determining the pitch of the
note of the different species and their rate at different
parts of the ‘‘song,” he was able to apply musical no-
tation, and give musical expression to the “Songs of
the Grasshoppers.” ®

The appendages of the abdomen are the three pairs
of organs which form the ovipositor (Pl. I., Fig. 3, os ;
Fig. 9, o5', os", os", p. 10). The ends of the upper pair
(Fig. 9, os') curve upward, and those of the lower pair
(os"') downward ; between these is a smaller pair (0s'"’).
Pl. II., Figs. 24, 25, 26, p. 38, represent two stages
(Fig. 26 side view of second stage) in the develop-

1See Westwood, /rtroduction to Modern Classification of
Wesects, Vol. 1., p. 453.

2 See for description of other modes of strigillation pp. 107, 132.

3 American Naturalist, Vol. I1., p. 113.

34 INSECTA.

ment of the abdomen of a young grasshopper, Locusta
viridisstma, and they show that these organs are really
modified appendages and are developed from the
eighth and ninth abdominal segments. ‘The letters
are the same as in Pl. I., Fig. 9, p. 10; &* is distinctly
seen as the sternum of the eighth ring (c*), and it
becomes the subgenital plate (Fig. 9, &”).’

1See Zeit. fiir Wiss. Zool., Vol. XXV., p. 174, 1875.

INTERNAL ANATOMY.

THE internal structure of the locust is somewhat
difficult to make out, owing to the small size of the
animal. Fig. 14, p. 36, from Edward Burgess’s origi-
nal drawings, gives the anatomy of our common red-
legged species, Caloptenus femur-rubrum.

mis the mouth; sai, the salivary glands. These glands
empty their alkaline secretion into the mouth near its base.
The cesophagus (@) leads from the mouth to the crop (Fig.
I4, crop). It is in the crop that the ‘‘ molasses,” or un-
digested food, originates. The crop passes into the small
gizzard, which is between the crop and true or chyle-
stomach (Fig. 14, stomach); from the forward end of the
latter arise six gastric caca (Fig. 14, cecum). These are
dilatations of the chyle-stomach, and ‘‘ probably serve to
present a larger surface from which the chyle may escape
into the body cavity and mix with the blood, there being
in insects no lacteal vessels or lymphatic system.” The
stomach passes into the intestine (ileum) and colon (Fig.
14, colon) ; the latter suddenly expands into the rectum
(Fig. 14, rectum), which is supplied with six rectal glands
(see Figure). At the posterior end of the stomach arises
the urinary tubes (ur, cut off, leaving the stumps); these
correspond in function to the kidneys of vertebrates. The
heart (Fig. 14; Pl. II., Fig. 16, heart, p. 38) is the en-
largement of a blood-vessel which extends along the dor-
sal side of the body. The “brain,” or supra-cesophageal
ganglion (Fig. 14, sf), gives off nerves to the antenne (a7)

35

INTERNAL ANATOMY.

a

INTERNAL ANATOMY. EY

and ocelli (0c, oc’). The infra-cesophageal ganglion has
three pairs of nerves leading to the mandibles and first
and second pairs of maxilla, respectively. The sympa-
thetic, or vagus nerve (sz), starts from a ganglion resting
above the cesophagus, and connects with another ganglion
(sg) near the hinder end of the crop. zv is the nervous
cord and ganglia which extends along the ventral side of
the body; ov, the ovary; ov.t, the oviduct; ov./’, site of
opening of the oviduct (the left oviduct is cut away) ; dc,
the bursa copulatrix; and sé, the sebaceous gland which
secretes the sticky fluid that fastens the eggs together.!

We have already alluded to the muscular power of
locusts. This is so great in some insects that they
are able to leap forty times their own height ; and the
flea leaps, it is said, two hundred times its height.
They have also been known to lift ten times their own
weight, and one kind of beetle (Geotrupes stercora-
vius), according to Newport, is able to sustain and
escape beneath a pressure of nearly five hundred times
its weight. Such facts are readily demonstrated in
the schoolroom. ‘The secret of the insect’s muscular
power lies in the extreme lightness and immense
strength of its tubular skeleton, its elastic power of
resistance to pressure, and the large surfaces afforded
for the muscles. Whatever difference, if any, there
may be in the quality of the muscles, it is only neces-
sary to examine the internal structure of an insect,
and see their disposition, and the way in which they
are attached to the skeleton, to understand that they
possess an enormous advantage over the muscles of
vertebrates. The greater comparative extent of the

1 See First An. Rep. U. S, Ent, Com., 1877, p. 261.

38 INTERNAL ANATOMY.

surfaces to which they are attached give room for the
growth of muscles of any desirable number and of
greater comparative size, increased freedom of mo-
tion and so on. ‘This point can be roughly illustrated
by putting the arm into a stiff paper cylinder, and
supposing the muscles to be attached to it, instead of
having their attachments crowded together centrally
upon a small axis of internal bones.

An instructive feature in the anatomy of insects is the
system of trachee and air-sacs. On either side of the
prothorax (PI. Il., Fig. 15, p. 33; Pl..1., Fig. Ops ages
mesothorax (PI. II., Fig. 15, Pl. I., Fig. 7, s*), and first eight
abdominal rings (PI. II., Fig. 15, Pl. I., Fig. 7, s3-s?) isa
pair of spiracles. These are openings of trachea, as al-
ready stated. According to Packard! the main system
of tracheze in the abdomen consists of six tubes, two
dorsal (Pl. IIl., Figs. 15, 16, df), two ventral (Fig. 15,
vt), and one at either side (Figs. 15, 16, s¢#). From the
latter branch small tubes whose external openings are the
spiracles. Besides these main tubes there are three pairs
of dilated trachez (Fig. 16, abt}, abt?, abt?) near the end
of the abdomen. The air-tubes are found in the thorax
and head (Figs. 15, 16, ct, cephalic trachea, of, ocular
trachez) ; they also extend into the wings and legs. The
colorless blood flows from the heart into great lacune
or *cavities without proper walls. From thence a por-
tion of it, at least, passes to the wings, where it has been
seen flowing in a network of definite channels.?, While in
the wings, according to some authors, the blood absorbs
oxygen from the air in the trachee of these organs and
becomes purified, so that the wings are not only locomo-
tive, but also in part respiratory organs.

1 See First An. Rep. U.S. Ent. Com., 1877, Chap. 1X;
2See Zhe Cockroach, Miall and Denny, 1886, Chap. VIII.

PLATE Ii.

PEP Pi

el,

4 9)

(Facing page 38.)

INTERNAL ANATOMY. 39

Moseley has figured and described the structure of the
veins and the circulation of the blood in the hind wing of
Blatta ortentalis. The latter can be observed in the wing
of this insect more clearly than in many others, owing to
the large size of the corpuscles and the absence of dark
pigment in the vessels. The so-called veins are blood-
vessels which have a thick lining of cells closely packed
together. After injecting these vessels with silver solu-
tion Moseley was unable to find any other lining than this
thick stratum of cells. The principal blood-vessels, but
not the smaller transverse vessels, have trachez running
through the middle like delicate filaments, and accompany-
ing each trachea is a nerve-fibre. The corpuscles change
their form readily, like those in the capillaries of a frog, and
in some amceboid movements were observed. As the cor-
puscles have been seen to pass above and under the tra-
chez, the latter must lie free in the vessels.

When a piece of the trachea of a locust is examined
microscopically, many short, spiral threads are seen imbed-
ded in the inner layer. Each thread passes around the
trachea a few times and then ends. These filaments are
elastic, and serve to keep the air-passages open like the
bands of cartilage in the trachea of man. Connected with
the trachez are the air-sacs. Of these there are five pairs
on the dorsal surface of the abdomen (Fig. 16, g*-g")
underlying the inner layer of the skin. Two very large
ones are figured in the prothorax (g’), and a smaller pair
in the mesothorax (g?). No less than fifty-three sacs
were counted by Packard in the head. Besides these,
many small sacs are buried among the muscles.

When a living locust is held in the hand, the process
of breathing may be watched. The pliable connec-
tions between the rings and the more or less elastic

1 Quart. Journ. Micro, Sci., Vol, XI., 1871.

40 INTERNAL ANATOMY.

nature of the external skeleton enable the insect to
enlarge the abdomen both vertically and laterally. It
contracts and dilates very regularly. When contract-
ing, the air is driven out of the trachez, much as it is
from a pierced rubber ball when a boy squeezes it.
As the muscles cease to operate, and the walls resume
their former shape, the air rushes into the interior of
the air-vessels just as it does into the boy’s ball when
the pressure of the hand is relaxed.

Plateau, in an article on the Respiratory Movements
of Insects,’ gives figures showing the size of the body
of several insects after inspiration and expiration. In
the locust and other Acridian Orthoptera the dorsal
and ventral parts of the terga and sterna approach and
recede alternately, the sterna being usually the more
yielding. This is not always the case, however, as
will be seen by the description of the mode of breath-
ing of the cockroach (see p. 102).

It is evident the system of tubes and sacs must
make the body lighter than if the same spaces were
occupied by solid matter ; and when the air contained
in them is heated by the normal warmth of the ani-
mal, they add, probably, still more to the buoyancy of
the body.

The habit of using an organ is known to possess the
power of producing modifications or variations. This
law of use may be applied to the explanation of the
changes that have taken place in the primitive appen-
dages of the vertebrate which have become the arms
and legs of the mammal suitable for walking, wings

1 See Zhe Cockroach, Miall and Denny, p. 159,

INTERNAL ANATOMY. 41

for flying in the bird, and fins for swimming in the fish.
It is not at all likely that the wings of insects were at
first the perfect organs we are acquainted with, and
they probably had a similar history. In the course of
their descent from wingless animals the laws of evolu-
tion show us that insects must have passed through a
period in which the wings gradually arose, first as pads
similar to the sac-like pads of the young of existing
insects, and then through many generations, and by
the introduction of progressive modifications, these
awkward-looking, stiff appendages became efficient
aerial supports similar to those we admire for their
lightness, complicated structure, and graceful outlines
in the living animals.'. We can understand upon this
theory that leaping insects, in striving to use every
means in their possession for levitation, may, by effort
through many generations to use their pads, have de-
veloped them into wings and also enlarged and modi-
fied parts of the tracheal system and brought it into
use in producing a more perfect wing than could other-
wise have been practicable. It is possible to account
for the way in which insects expand the crumpled
and thickened wings with which they enter upon the
imago state, by this theory, and to explain their habits
at this period, especially the deliberate and prolonged
efforts to pump air into the wings and expand them into
form before they can become dry and hard. We can
also understand how the reversal of this process could
have made the Lubber locust the heavy, unwieldly
thing it now is, through its habit of feeding vora-

+ See p79.

42 INTERNAL ANATOMY.

ciously and the neglect of its powers of flight. Cer-
tainly its wings are in transition and comparatively
small through disuse, and its descendants, if it should
have any, might become like some females of the
cockroach tribe, the possessors of very inferior and
unlovely pads.

We strongly advise teachers not to use this or any
theory in teaching immature minds. We give it be-
cause we are addressing mature minds, and know
that many of them will ask such questions and get no
reply. The use of a theory in teaching demands a
large knowledge of facts and a capacity to understand
and explain numerous exceptions, which bright pupils
are very apt to find. Immature minds ought to em-
ploy the time wholly in observing, the handling of
theory being not only beyond their grasp but injurious,
because it leads them to neglect the work which they
can do well for a game at speculative guessing.

In the locust, as in most insects, the sexes are dis-
tinct. The male (PI. I., Figs. 1, 2, 7, p. ro) is smaller
than the female (Pli1.,\Fig. 3, Pl. I1., Figs r7,7p.iga9
and is less abundant. In the autumn specimens of both
sexes can be easily collected, for they are found in con-
siderable numbers as late as November. The develop-
ment of the Rocky Mountain locust has been carefully
worked out and probably does not differ in essential
points from that of our yellow-striped locust, so that
we give it here.’ When the time of oviposition arrives,
the female makes a deep hole or burrow in the ground

1 See Third An. Rep. U. S. Ent. Com., 1880-82, Chap. X.;

First An. Rep. U.S. Ent. Com., 1877; The Locust Plague in
the United States, Riley, 1877.

INTERNAL ANATOMY. 43

by means of the strong, horny ovipositor. Pl. IL.,
Fig. 17 represents three females in the act of oviposit-
ing. When the burrow is excavated, the eggs are laid, ~
and a quantity of mucous matter discharged which
binds the eggs together and fills all the space not.
occupied by them. Finally the neck is filled by the
same mucous material, and the whole forms an egg-
mass or egg-pod. On the left of Fig. 17 the earth
has been removed, exposing one egg-pod in place and
another being placed: @ is an egg-pod taken from the
_ ground and broken open at one end; a few eggs are
lying loosely on the surface at a’, and a'! shows where
the eggs have been covered. Pl. II., Fig. 18 is a side
view of the egg-pod within the burrow. The dark
outer line represents the earth; 7 is the neck. The
eggs, averaging twenty-eight in number, are usually
laid in four rows, as seen in Pl. II., Fig. 19, which is
a view from below of the egg-pod removed from the
burrow. PI. II., Fig. 20 is a view of the same from
above. In Figs. 19 and 20 a portion of the mucus
filling the neck is seen. Along the top of Fig. 20 is
an irregular channel which is the pathway of the young
locust out of the burrow: this is indicated by arrows
in Fig. 18.

The female exhibits care in selecting the ground for
the reception of the eggs, preferring hard, compact
soil;' yet after the eggs are laid and covered with
earth, she apparently concerns herself no more about
them, so that when the young locusts come out of the

1 See Scudder, U.S. Geol. Survey of Nebraska, Final Report,
p- 258; also Riley, Zhe Locust Plague in the United States,

PP: 71; 77:

44 INTERNAL ANATOMY.

ground they are left wholly to their own resources for
self-protection. The metamorphosis of the locust is
direct, and by this we mean that the insect never passes
through a quiescent state, but remains active from the
time of its birth. Its development is a straightfor-
ward growth from the egg to the adult condition,
and is readily understood by pupils. In the books
the metamorphosis is said to be ‘‘ incomplete” and
is contrasted with the “complete” or, as we prefer
to call it, the indirect metamorphosis of the more
specialized insects. In teaching, it is obviously much
less confusing to use the terms “ direct” and “ indi-
rect,” unless the teacher begins with the “higher”
insects like bees and butterflies and makes the ‘‘ com-
plete’? metamorphosis peculiar to these forms his
point of departure. In this case he has, it is true, a
standard of comparison, though a purely artificial one,
which may make the “incomplete” metamorphosis
of the more generalized. insects intelligible to young
minds. :

The idea, however, that one set of metamorphoses
can be more *‘ complete’ than another when both be-
gin with the egg and end with the imago, is an absurd
survival of the old nomenclature, but has held its
place tenaciously in spite of changes in methods and
opinions. In the study of living forms far more satis-
factory results are obtained by following nature’s
order ; that is, by beginning the study of. types with
the simple and passing to the complex, and when
this is done with insects, the old descriptive terms of
“complete ’”’ and “incomplete” cannot be retained.

In general structure, the young or larval locust (Fig.

INTERNAL ANATOMY. 45

21, larva of one of our New England species, en-
larged) resembles its parent, though differing in minor
details. The wings have not yet grown,
and therefore the thoracic rings (Fig.
21, 5', 5", 5") have not wholly as-
sumed the modified structure of the
adult. The antennz (a/) are shorter ..
and stouter than those of the full-
grown locust. Hundreds of these
larvee can be collected by sweeping
the grass in a sunny field with a net
during the latter part of June. In
July the pupze are abundant.. The
pupa (PI. IL, Fig. 22 3, Fig. 23 9, of
Calopienus* Dodgei, p. 38) has the wings in the form of
sacs. These increase in size till the last skin is shed,
when they are fully developed. Contemporaneously
with the development of the wings the thoracic rings
become more complex in structure. The changes in
the ovipositor, illustrated by Pl. II., Figs. 24, 25, 26,
have already been described (sde “ppr 34! 4 yoVPhe
three larval skins are usually shed on or near the
ground, in sheltered places protected by grass or
other vegetation. The two pupal moults generally
occur at a higher altitude, and the exuvie may be
found attached to tall weeds or posts. When the last
skin is shed, the locust has attained its full size.

Fig. 21.

1 This genus is now referred to Pezotettix.

CLASSIFICATION OF INSEGEE

SINCE insects! are so important to teachers and
every text-book deals with them from a systematic
point of view, we have been obliged to a certain ex-
tent to do the same in order to justify the classifica-
tion here adopted, and to place before more advanced
students and readers. the principles underlying our
arrangement. Dr. A. S. Packard in his Hxzomology
jor Beginners has wisely opened the way for the
adoption of Friederich Brauer’s classification. We
have not been able to follow precisely in the footsteps
of any one author, but have quoted freely from
Packard’s books, from Comstock’s Jntroducthon to
Entomology, and Brauer’s Systematische soologische
Studien.” Although the introduction of sixteen orders
of insects seems to make the study more complicated,
it is, in reality, a very marked advance towards sim-
plicity. Teachers need not use all the types; but
whether they make a selection or not, they will find,

1 Before reading this part, teachers will do well to consult the
Origin and Metamorphoses of Insects, by Sir John Lubbock,
Macmillan & Co., New York; and Packard, “ Genealogy of In-
sects,” in Third Report U. S. Entomol. Com., 1883; or Chapters
XII. and XIII. of Our Common Insects.

2 Sitzungsberichte d. K. Akademie der Wissenschaften, Wien»
Vol. XCL., 1885.

46

CLASSIFICATION OF INSECTS. 47

we think, that they can obtain clearer ideas of the re-
lations of the different orders than by following older
although apparently less complicated classifications.

The Insects when compared with the Worms, Crus-
tacea, Myriopods (Centipedes and Millepedes), and
Arachnids (Spiders, Scorpions, etc.) possess a body
in which the three regions are strongly accented or
differentiated. The head, the thorax, or middle
region, and the abdomen are, with rare exceptions,
distinct from each other in all adult forms. The
head is especially well furnished with organs, has only
one pair of antennze, and is defined by a constric-
tion, forming, as a rule, a functional neck. The
differentiation of the thorax from the abdomen is,
however, not so complete. One finds, for example, in
the locust that the first segment of the abdomen may
be, and has been by some authors, considered to be a
part of the thorax, and a transferrence of this first ring
of the abdomen to the thorax actually does take place
in the Hymenoptera.

It is now admitted by many entomologists that
Campodea, a genus of Thysanura, more nearly repre-
sents the primitive wingless form from which all
insects may be supposed to have been derived, than
any other now living. Geologic evidence, which
would confirm this important conclusion, is as yet
wanting ;' but, on the other hand, as has been pointed

1 Brongniart has chronicled the discovery of a fossil in the
Carboniferous supposed to be a Thysanuran allied to Lepisma
or Machilis. Unfortunately the information is as yet too meagre
to be convincing. Bull. Entom. Soc. de France, 1885, p. 101.

48 CLASSIFICATION OF INSECTS.

out by Brauer,’ Packard,? and Lubbock,’ the general
prevalence of a form similar to that of this genus, or
its allies, in the larve of eleven out of the sixteen
orders of insects, cannot be accounted for on any
other hypothesis.*

1 Verhanal. d. zool. bot. Gesel., 1869, Vol. XIX., p. 299.

2 Packard sustains this view in his Embryological Studies.
Memoirs of Peabody Acad. Sct., Vol. 1., No. 2, Salem, Mass., and
in Our Common Insects, Chaps. XII. and XIII., especially p.
154. The last is a popular and highly instructive account of the
problem, showing not only the relations to Thysanura in more
detail than above, but also the common type exhibited by the
six-legged young of the Myriopods and some members of this
order, thus carrying back the origin of insects to the same com-
mon type with the Centipedes and Millepedes.

3 Origin and Metamorphoses of Insects.

4 Teachers wishing for information on the subject of the an-
cestry of insects and the more specific characters of the Thysa-
nura will be helped by the following bibliography : —

MULLER, F. fiir Darwin, Eng. trans., pp. 119-121.

BRAvUER, F. “ Betrachtungen iiber die Verwandlung der Insek-
ten im Sinne der Descendenz-Theorie.” Verhandlungen
Loologisch-botanischen Gesellschaft, Wien, Vol. XIX., 1869.

PACKARD, A. S. Amer. Nat., Vol. I1I., March, 1869.

Proc. Bost. Soc. Nat. Hist., Nov., 1870.

—— Amer. Nat., Feb., 1871.

—— Amer. Nat., Vol. V., March and Sept., 1871.

— Embryological Studies, Peabody Acad. Sci., Salem, 1871-72.

—— Our Common Insects, 1873, Chaps. XII., XIII.

—— “Scolopendrella and its Position in Nature,” Amer. Nat.,
Sept., 1881.

—— Third Rep. U. S. Ent. Com., 1883, p. 295.

Luspock. “Notes on the Thysanura.” TZvans. Linn. Soc.,
Vols. XXIII., XXVI., XXVII., 1862, 1870, 1871.

—— “On Pauropus, a New Type of Centipede.” Zvrans. Linn.
Soc., Vol. XXVI., 1870.

CLASSIFICATION OF INSECTS. 49

We have used Lepisma instead of Campodea in our
comparisons, because it is larger and easier to obtain,
and in some respects, also, it approximates perhaps
more obviously to the ordinary flattened larve of the
more generalized forms of insects. It is closer also
to the larvz of the: cockroaches, which are regarded
by Scudder and some entomologists as the most prim-
itive of existing winged forms, and are known to be
among the oldest in geologic history. This active
hexapod (Lepisma) has a thorax consisting of three
equally developed simple rings without secondary
sutures or wings, and a broad abdomen whose junc-
tion with the thorax is unconstricted. These pecul-
iarities are permanent adult characters, which are apt
to reappear during the transient stages of larval growth
in species and groups of all the orders from II. to XI.
inclusive.

The mouth parts of Lepisma and Campodea belong
to a peculiar type of generalized structures, being set
deeply in the head, and capable of being employed
both for biting and suction. They are, however, more
nearly allied in structure to the biting’ than to the
more highly specialized forms of sucking mouth parts,

— “On the Origin of Insects.” Yourn. Linn. Soc., Vol. XL,
1873.
Origin and Metamorphoses of Insects. Nature Series, 1873.
—— Monograph of the Collembola and Thysanura, Chap. IIL.,
1873.
— Origin and Metamorphoses of Insects. Book form. 1874.
Mayer, P. ‘‘ Ueber Ontogenie und Phylogenie der Insekten,”
Zetts. f. Nat., Jena, Vol. X., 1876.
1See Packard, Our Common Insects, pp. 129-132; also,
American Naturalist, Vol. V., p. 91.

50 CLASSIFICATION OF INSECTS.

and Packard and Lubbock’ have shown that both of
these modifications could have arisen from the Thy-
sanuran type.

The word ‘‘ specialization” has different applications
in different minds, and is rarely used by any one natural-
ist with the same meaning in all cases. It is necessary,
in order to fix the meaning in which it is used, to select
some standard of reference. In our opinion this standard
should be a purely structural one, and not be complicated
with physiological considerations. While it is true that
the more generalized forms as a rule have simpler modes
of living than the more specialized, the progression and
degradation of types is expressed more clearly and can be
studied more easily in the physical structure of their or-
gans and parts than in any other way. Structural modi-
fications are also probably the direct results of changes in
habits and in the physical forces of the environment, and
are therefore reliable indications of changes in the modes
of life and surroundings of the animal. Thysanura is the
standard with which all the larval and adult forms of
insects should be compared. If this be accepted, it follows
that the primitive winged insect from which most of the
orders sprang was probably an animal having two equal
pairs of membranous wings, six nearly equal thoracic legs,
head distinct with biting mouth parts, and having a mix-
ture of structural characteristics connecting it in one direc-
tion with Thysanura as the ancestral form, and in still
others with those orders of insects which have Thysanuri-
form larve. These standards of comparison enable us to
see that even the most generalized groups of existing in-
sects are highly specialized, although, like the Odonata and
Blattariz, they may represent very ancient types. Speciali-

1 Monograph of the Collembola and Thysanura, pp. 50-52;
Origin and Metamorphoses of Insects, pp. 71-73.

CLASSIFICATION OF INSECTS. 51

zation in such cases as Locustide, Perlidz, Termites, Neu-
roptera, is brought about by the addition of characteristics
to the supposed primitive winged ancestral types. The
existing animals being more complicated in structure than
their predecessors and representing progress in evolution,
the resulting structures should be considered examples of
specialization by addition. The huge third pair of legs in
Locustidz, the complicated mouth parts of Hymenoptera,
the ornamented wings of Lepidoptera, are good examples
of this kind of specialization. Such specializations may
indicate an enlargement of the field of work occupied orig-
inally by the type or a change in its habitat. Speciali-
zation may, however, take place by a different process ;
namely, through the reduction and suppression ef organs
in certain parts of the body. Thus, the existing May-flies
have mouth parts in large part obliterated and unfit for tak-
ing food, while their hinder pair of wings is smaller than the
front pair. The Coccidae have only one pair of functional
wings, etc. ; the Diptera are similarly situated ; and almost
all the adults in Lepidoptera have lost the mandibles dur-
ing the transformation of the mouth parts into a sucking-
tube. This sort of specialization, in course of which organs
are lost by reduction, leads usually to a narrower field of
work. Thus, the adult May-fly exists only to reproduce
its species ; many of the dragon-flies and Lepidoptera have
the first pair of thoracic legs so much reduced in size that
they are of no use as supports, and these insects practically
rest upon four legs; while the Lepidoptera and Diptera,
having the most complete sucking-tubes, can live only
upon fluids. Specialization by reduction gives greater
strength and efficiency to the parts which survive the
reduction, and this mode is the prevalent one among the
so-called “highest” types. These are usually the descend-
ants of types which reached a certain acme of prog-
ress through specialization by addition, and consequently
possess highly complicated organs as compared with the

52 CLASSIFICATION OF INSECTS.

ancestral primitive form. In any natural classification,
therefore, these cases of extreme specialization by reduc-
tion, although properly regarded as degraded forms, should
stand at the head or be mentioned last in their respective
groups. |

Precisely the same statement must be made with regard
to the parasites. These creatures living upon or in other
animals have attained their fitness for such habitats by
gradually losing to a greater or less extent the parts and
organs which their ancestors, who lived exclusively in the
outside world, once possessed. The wingless parasitic
insects are in most cases rightly regarded as probably the
direct descendants of allied but winged forms. It is hard
to understand the development of the fleas, for example,
in which the young in their embryonic stages and trans-
formations resemble the similar stages of some true flies
(see Packard, Entomology for Beginners, note to p. 115),
unless these animals can be considered the modified de-
scendants of winged, dipterous insects, which, on account
of their peculiar habits, have become specialized by reduc-
tion and lost their wings, and in large part their dipterous
characteristics in later stages. The position of an animal
in a table of classification should be determined by its
place in the evolution of the group, —the most generalized
or primitive first, the more specialized by addition or com-
plication next, and the still more specialized, whether by
reduction or additional complication, next, and the most
specialized last in the series. Whether the last be a para-
site reduced to an extremely degraded structural condition }
or not is a matter of no essential importance, its place in
the table or book being a matter determined, so far as
practicable, by its natural affinities.

1 Meyrick ( 7rans. Ent. Soc., Lond., 1884, p. 277) maintains
that when an organ has wholly disappeared in a genus, other
genera which originate as offshoots from this genus cannot

CLASSIFICATION OF INSECTS. 53

The existing Thysanurans are nevertheless quite
widely removed from the ancestral wingless form, with
which their own type probably came into existence,
and they possess specializations of their own which
should be taken into account. The scales and charac-
teristic mouth parts of Lepisma are probably speciali-
zations acquired by this genus, while the small pro-
thorax and very distinct head of Campodea are also
specialized characteristics. The larve of the general-
ized forms of insects also have peculiarities in their
internal structures and mouth parts which tell the
same story of acquired specializations. We mean by
the “ generalized orders of insects ’’ what we shall also
call the first series of orders, those numbered from I.
to IX., inclusive, which may be considered as a whole,
and thus more advantageously compared with the
specialized orders of insects, or the orders numbered

regain the organ, although they may develop a substitute for it.
The group of Geometrina, a number of whose larval forms have
lost two or three pairs of abdominal legs, cannot, according to
this view, give rise to a genus which will recover the lost pairs
of legs, and therefore must be regarded as a terminal develop-
ment or a group which ends in itself.

Although this view may be considered as unproven in its
general application and as difficult to demonstrate among in-
sects, it helps us to show that, as a rule, it is more natural to
place the parasites and other types that have suffered through
specialization by reduction at the head or termini of their re-
spective groups rather than to follow the prevalent fashion of
introducing them at the beginning of classifications. They repre-
sent, in other words, the finished work of evolutionary processes
acting through periods of time more or less prolonged, and not
the beginning or first steps in the evolution of their own groups
and are not in any sense primitive or generalized,

nt CLASSIFICATION OF INSECTS.

from X. to XVI., which we shall also speak of at times
as the second series of orders. These divisions are
convenient and avoid the use of the terms “ lower”
and “higher”? orders, which have seemed to us ob-
jectionable for reasons that will appear in the text.

The common ancestor of the Thysanura and all
other insects was, therefore, probably distinct from
anything now living, but, nevertheless, possessed cer-
tain common characters with the adults of Lepisma and
Campodea, and with the larvz of other orders, all of
which still continue to inherit to a greater or less
extent some of its peculiarities. If all the evidence
from these sources be brought together, the known
laws of heredity justify the naturalist in asserting that
this ancestor must have been devoid of scales, a
naked, wingless, six-footed, active insect, with only
slight differentiation between the three regions of the
body, and having three simple thoracic rings of nearly
the same size, which were not subdivided by second-
ary sutures. It was this generalized common form,
which has been inherited by the Thysanura, and by
the larvee of other insects, and not the exact form
and peculiarities of Lepisma or Campodea, a fact
clearly pointed out by Packard in Our Common In-
sects. ‘These two genera are simply the closest copies
of the ancestral form now in existence ; and we have,
therefore, following after Packard, employed the term
“ Thysanuriform,’! rather than ‘‘ Campodeaform”’ or
“‘ Lepismaform,” to designate the larvee which repeat
ancestral characteristics.

1 Third Rep. U. S. Ent. Com., 1883, “ Genealogy of Insects,”
p- 297, note.

CLASSIFICATION OF INSECTS. 55

The generalized form of Thysanura, and the man-
ner in which it reappears in the larvee of other insects,
is the natural key of the classification, and will, we
hope, enable teachers to understand more clearly the
general relations of the orders. The characteristics
of adult insects are, as we shall have frequent occasion
to remark, often similar in widely separated groups
belonging to different orders, and such parallel or
representative repetitions have been the most fruitful
cause of the mis-association of forms in the older
classifications, not only among insects, but in all sub-
divisions of the animal kingdom. Since naturalists
have learned to use the hypothesis of evolution, great
changes have taken place in their estimate of the
value of the earlier stages of development. These
have been universally recognized as giving direct evi-
dence in their characteristics of the past history of
their own type. ‘The changes of structure passed
through by the young during growth are more or less
transient, but, so far as they go, can be accurately de-
fined as abbreviated records-of the changes and modi-
fications which have been previously passed through
by the types to which they belong during their evolu-
tion in time. They have derived their principal char-
acteristics necessarily from their ancestors, and this
law of the correlation of the transient stages of the
young with the more permanent, specific, generic, or
type characters of the adults of ancestral generations,
or groups, is a necessary corollary of the law of evolu-
tion and heredity. Nevertheless, teachers must be
warned that the use of evidence of this kind requires
critical knowledge only acquired by long experience

56 CLASSIFICATION OF INSECTS.

and study ; and even then one is liable to be deceived
by appearances, and may expect to make serious errors
in spite of the most elaborate precautions.

The general acquisition of wings, through outgrowths
from the two hinder segments of the thorax, first as
mere spurs, then as articulated pads in the pupe, has
naturally led to the conclusion that these organs were
also gradually acquired by some similar gradations in
ancestral forms. Some entomologists hold that they
may have been modified legs,’ but many entomolo-
gists regard them as having arisen from organs similar
to those now found upon the abdomen of the larvee of
May-flies. ‘These larvze have gills for aérating the blood
growing out from the rings on the upper side of the
abdomen, and often some of these are modified into
protective coverings. ‘Thus the branchiz on some
rings may be transformed into articulated scales, which
resemble the wing pads of the pupz, and these appear
to explain the origin of the larval outgrowths and the
true wings, which appear upon the meso- and meta-
thorax.? Fritz Miiller and Packard, after careful and
independent investigation, have both rejected this
hypothesis. They confined themselves to closer com-
parisons of the facts afforded by the development of
wings in pupz, and recognized the difficulties attach-

1 Dr. Hagen, “On Some Insect Deformities,” AZem. Aus.
Comp. Zodl., Vol. II., No. 9, p. 22, quotes, in support of this
opinion, an extraordinary case, in which the fore pair of wings
were replaced by a pair of articulated legs in Przomus coriarius.

2 Miall and Denny (Structure and Life-Hiistory of Cockroach,
p. 63, Lovell, Reeve & Co., London) give an excellent account
of this theory with explanatory figures.

CLASSIFICATION OF INSECTS. 57

ing to any theory which would trace the origin of
aérial organs to gills. These last may spring up
sporadically upon the abdominal rings, and have usu-
ally but one tracheal tube. The wing pads, on the
other hand, always arise from similar parts of the
mesothorax and metathorax, and have several tracheal
tubes. There are also difficulties in the adoption of
‘the assumption commonly made by authors, that the
winged forms first arose from aquatic forms having
gills on the back of the abdomen. Purely terrestrial
insects develop their wings in precisely the same man-
ner as those having aquatic larve, and transitions
such as ought to be found, if this theory were true,
have not been observed. ‘This leads to the conclusion
that the wings of insects must have originated in the
same manner as organs of flight in other terrestrial
groups, according to the theory advocated by Pack-
ard. ‘Now, speculating on the primary origin of
wings, we need not suppose that they originated in any
aquatic form, but in some ancestral land insect related
to existing cockroaches and Termes. We may imag-
ine that the tergites (or notum) of the two hinder seg-
ments of the thorax grew out laterally in some leaping
and running insect ; that the expansion became of use
in aiding to support the body in its longer leaps,
somewhat as the lateral expansions of the body aid
the flying squirrel or certain lizards in supporting the
body during their leaps. Then by continued use and
attempts at flight they would grow larger, until they
would become permanent organs.” ?

1 Packard, Third Rep. U. S. Ent. Com., 1883, p. 268, in
which also are quotations from Miiller and other authorities,

ae CLASSIFICATION OF INSECIS

This argument is in our opinion very strong, espec-
ially when it is considered that the existing Thysanura
and all Thysanuriform larvee, even in the earliest larval
stages of aquatic forms, have trachez before they
acquire external gills. ‘Trachez are exclusively inter-
nal air-breathing organs, and this indicates that the
primitive Thysanuroid ancestor, if it were similar to
Thysanura and the Thysanuriform larve, must have
been unprovided with gills or any means of breathing
in the water, but was at first provided with air-breathing
organs, and consequently must have been a truly ter-
restrial and wingless air-breathing animal.

This view has also another important corollary,
namely, that existing aquatic larve are not in any
sense primitive, but that: their adaptive and peculiar
characters — gills, etc. —are secondary specializations
and that they themselves were derived from ancestors
having purely terrestrial habits and organs. In other
words, the insects of the existing faunas belong to an
exclusively terrestrial type, even those now living in
the waters, either during their larval or in their adult
stages, having been evolved from air-breathing terres-
trial forms.

The larve in May-flies respire through the skin dur-
ing their earlier stages, and do not at first have any ex-
ternal gills. In most stone-flies the larvee are destitute
of external gills throughout life or have only external
respiratory filaments: the internal trachez are, how-
ever, developed at very early stages even in embryo.
The gills have not a fixed form or position in the in-
sects, as in true aquatic types in other subdivisions of
animals. ‘The gills of Mollusca, the respiratory water-

CLASSIFICATION OF INSECTS. ao

system of Echinoderms, the gills of Crustacea, and the
aquatic respiratory organs of Vertebrates, though sub-
ject to great modifications, have typical forms which
are characteristic of large groups. ‘The tracheal sys-
tem of insects, on the other hand, is characteristic of
the class, and can be compared with the respiratory
system in other branches or classes of the animal
kingdom, which have a structure specially adapted,
like the lungs of Vertebrata or the pulmonary sacs of
the land-snails, for breathing in the air.

Mr. Samuel H. Scudder, whose acquaintance with
fossil and living forms has been as extensive and thor-
ough as that of any author, considers upon paleonto-
logical grounds that the earliest known insects were
generalized hexapods with two pairs of equal and sim-
ilarly developed wings, represented to-day by the
cockroaches. Miall and Denny entertain a similar
opinion founded upon the general characters of the
larvee as well as the geologic record, and Brauer! and
Packard notice, what we have observed above, the re-
semblances of Lepisma and their larve. The Ephem-
eroptera have, however, an ancient origin, and the
history of winged insects is so imperfectly known, the
diversity of known forms at the earliest epochs so
striking, and the differences of opinion so great, that
we cannot assert that any special forms among the
more generalized orders represent the main stock of
winged insects out of which all the others arose. We
have therefore ventured only upon the assumption that
there was probably one or more of these ancient stocks

1 See F, Brauer, Zool. Studien, op. cit.

60 CLASSIFICATION OF INSECTS.

of winged insects which sprang from the sides of the
wingless, primitive or Thysanuran stock.

The difficulty of representing satisfactorily by any
linear arrangement the relations of the orders to each
other and to Thysanura has compelled us to give dia-
grams I.-III. Diagram I., p. 60, shows by parallel bars
rising above the circular plate, which represents the
surface of the earth, the sixteen orders of insects as
they exist to-day, and below this plate the different
orders are arranged in converging bars according to
their supposed relations during geologic times. ‘This
last is purely theoretical, since the present state of
our knowledge of fossil insects is too fragmentary and
unsatisfactory to afford sufficient evidences for the
demonstration of such a classification.

Diagram II., p. 60, represents the opposite or farther
side of Diagram I., the plate having been turned around
so that the orders X.-XVI. can be more clearly seen
both above and below the earth’s surface. Diagram
III., p. 61, is a view from above the circular plate
giving in horizontal section the position of the orders.
Diagrams I., II., A represents the wingless, primitive,
or Thysanuran stock. The stems 4, 8", B'",' Dia-
gram I.; B', BY, Diagram II., represent the winged
stocks which sprang from A. These may have been
composed, so far as the facts now known are con-
cerned, of a number of separate or branching lines

1B!’ extends in the diagram to the orders Hemiptera and
Thysanoptera instead of to the stem from which these orders
sprang. It is placed here because the stem proper 1s out of
sight, being farther down and behind 2 and B",

VLIZYOIIO)

1 '
' 1

'

[SRS CO POT SS ee?

eee |
= Fi
hon ,

(Facing page 60.)

'
\ ot
Tey

Bl azyo wa Ut AH

PLIIYODI?IYUIT
Rin
~~.
TE LIYYOUDLAL
is

eae
on
Ms
NPRSMMEIMEGECCNORNOOOW oe N
T
Le

é ‘

r ‘

ie — >) V39YVouN ENE

TX aho

Javon]
[MSF NSE

PtazYyou auLay |

NGRESBINANS SORES

ALA Pray oyyAg

\_ }
Vlspjoursky fj

AX 285060} 7:0 UWEK =

Ws
rod

ent ae, A ine ee Se

*s]

#

CLASSIFICATION OF INSECTS. 61

leading up to the various orders as termini of more or
less distinct stocks.1

The line B' in Diagram II. indicates the winged
stock from which the true Neuroptera sprang, and so
far as we know, this may have been the same common

Diagram III.

stock as that from which the Ephemeroptera and
Odonata also arose (Diagram L., £). Inspite of the

1 For example, as suggested by Packard in Third Rep.
U. S. Ent. Com., p. 289, the Dermaptera may have been
derived from a form similar to Japyx, a curious Thysanuran

62 CLASSIFICATION OF INSECTS.

introduction of the quiescent pupal stage in the Neu-
roptera, their obvious resemblances to the Odonata,
and the fact that they still retain the Thysanuroid
form of larva should not be overlooked. Diagram I.
recognizes these similarities, and presents the least
modified and most ancient branches of the genealogi-
cal tree of the Insecta as near together as practicable.
The placing of Thysanura near the centre, by means of
a short vertical line,’ indicates the essentially general-
ized and larval character of the order, and does not
necessarily imply any nearer relationship to Neurop-
tera, which stands on the right, than to Coleoptera on
the extreme left. The height to which the vertical
bars have been carried above the plate is a rough
approximation to the specialization attained by the
adults, and also to the removal of the mode of de-
velopment from the primitive Thysanuroid mode.

The orders existing to-day are regarded as parallel
series differing from each other in structure, and not
as yet connected by well-known intermediate forms.
Where the probability exists that certain orders have
had a common origin, they are placed on the same
radiating line, as seen in Diagram III., orders II.-III. ;
also VI.-VII., and VIII.-IX.; and this rule has been
departed from only where the data seemed to justify

genus, and since it has characters allying it both to Orthoptera
and Coleoptera, it may be the existing descendant of some com-
mon forms from which both of these orders originated. The
Thysanura stand, according to Comstock, in a similar position
with relation to the Hemiptera.

1 See also the diagram given by Packard in 7hird Rep.
U.S. Ent. Com., 1883, p. 295.

ee
‘

CLASSIFICATION OF INSECTS. oes

a more natural interpretation, as in the case of the
orders from XII. to XVI., inclusive.

All of these graphic presentations are necessarily
extremely rough approximations to the actual facts,
and present even the authors’ views in a very imper-
fect manner. Nevertheless, if conscientiously studied,
they will, it is hoped, help to give teachers some ideas
of the principles upon which a classification is based,
and prevent them from falling into the absurd but
natural mistakes often occasioned by the linear treat-
ment of types in the text.

ORDER Ivy THYSANURA.

Tuis order is placed in the centre in our graphic
arrangement as the survivor of the main stock of
wingless forms, 4. It includes the most generalized
insects, and is represented in the Guide by Campodea
and Lepisma.

CAMPODE-.

Campodea (Fig. 27, enlarged) is only about one-
sixth of an inch in length, so that it is too small for
satisfactory class-work. It is found under stones and
indamp places. Here we have a long, cylindrical, and
hairy body, of nearly equal breadth throughout, divided
into three distinct regions, two of which, the thoracic
and abdominal, are again divided into definite and
movable rings. ‘The number of these rings — three
thoracic (4', 6", 6") and ten abdominal c'-c'® — is easily
determined, as there is little concentration of parts.
The head (A) is without eyes, but possesses a pair of
long, finely developed antennz (a7), which under the
microscope bristle with hairs. On the terminal section
there is, according to Kingsley,’a possible sense organ
which resembles a couple of beans placed side by
side, and which is supplied with the tip of the anten-
nal nerve. It may be a fact of some significance, as

1 Science Record, February 15, 1884.
64

TH VSANURA. 65

bearing upon the question of the use of the antenne,
that these organs are longer in the cave-inhabiting
species, Campodea Cookez, than in
the species that live in the light. EN g

The mouth parts consist of " j
one pair of mandibles and two N
pairs of maxille; but as these ap
are used only upon soft substances, i
they are much simpler and weaker Ko
than those of the locust, and less we. Ne
freely movable. It has already ,,,
been pointed out! that they are <i at
of generalized structure, and that ho
the more specialized mandibulate (4 X
mouth parts of locusts and suc- Pe coe
torial mouth parts of. butterflies -— Cc
may have been derived from an Ld
ancestor having mouth organs =
similar to these of Campodea. ow 54

The three pairs of legs are sim- df
ilar in structure, since they are all a
used in running. They are hairy, \S
and hooked at their ends, but are “ # A
without cushions. The simplicity ff i
of the thoracic rings indicates # *
that wings are not developed, ¥
and this is the case, the adult
Campodea never possessing flying-organs. Each of
the first seven rings of the abdomen bear a pair of
short, jointed appendages (not shown in figure ; see

Fig. 27. \

1 See’p. 49.

66 THYSANURA.

Standard Natural History, p. 137, Fig. 200). Be-
sides these there are two long, caudal setze (se) at the
end of the abdomen, which are so similar in structure
to the antennez that it seems as if they must perform
a similar function. Many of the hairs near the abdom-
inal appendages, and on the base of the sete, look
like deeply cleft leaves, and others are forked at their
ends. The appendages at the end of the abdomen
have given the name Thysanura (@vcavos, a tassel ;
ovpd, the tail) to the order, and the members of the
family Campodeze and Lepismatidze are known as
Bristle-tails, in distinction to the Poduridz or Spring-
tails. The latter are small Thysanuran insects that
are abundant in wet places. One genus (Achoreutes
nivicola) often occurs on snow, and teachers may
sometimes have a plate of snow brought in to them
covered with these tiny leapers.

According to Meinert' there are three pairs of
spiracles in the thorax of Campodea, one pair in each
ring, and none in the abdomen.

LEPISMATID.

Lepisma saccharina (Fig. 28, 2) is often found in the
attics of houses, about old window-casings, and under
loosened wall-paper. It is large enough to be studied
with a common magnifier, and can be used to better
advantage in the schoolroom than Campodea. The
body is covered with scales which resemble those of
the Lepidoptera, and give a silvery appearance to the
insect. When examined microscopically, they -are

1 Ann. Mag. Nat. Hist., 30 ser., Vol. XX., 1867.

—_—

>, =o

i pee
THYVSANURA. 67

seen to be of different shapes, being marked by parallel
longitudinal lines, and are fastened to the body by a
short stem. The body is somewhat
flattened, and the thoracic rings (3’,
6", 6'"') overlap each other slightly.
The head possesses a pair of very
small ‘eyes (ey), which are widely

_ separated, and the antennez (a7) are
long and well developed. The mouth
parts are of the biting type, and the |
insects often do much damage to
furniture when houses are closed for
the summer. Within a year we have
seen cotton window-shades badly

- eaten by these creatures. The three
pairs of legs are used in running, and
the silvery scaled insect glides so
swiftly along it is known as the “ sil-
ver fish,” “silver witch,” and “ fish-
moth.” The anterior abdominal
appendages found in Campodea are only repre-
sented in Lepisma by clusters of stiff hairs, but
the abdomen carries at its extremity three long bris-
tles, and also one pair of short, curved bristles.

The respiratory system in Lepisma is simple as
compared «with that of the locust and other flying
insects. The tracheze are present, but not the air-
sacs. The absence of these, like that of the wings,
is also characteristic of the larve of other insects,
although their adults may possess them.

Teachers will find it instructive to observe Lepisma
as a full-grown insect, and then compare it with the

Fig. 28.

68 THYSANURA.

similar but transient larval stages of many other insects,
such as the larvee of Orthoptera, of many of the Cara-
bide and Hemiptera, etc. It will be seen that, as a
member of the same order as Campodea, it never
develops beyond a generalized stage, which is repre-
sented only in the larve of more specialized insects.
It will also be seen that in the more genetalized
orders of insects, like Orthoptera, Platyptera, Hemip-
tera, Neuroptera, and in the more generalized forms
of some orders, like the Coleoptera genuina as com-
pared with the Weevils, it is oftener represented in
the larvee than among the more specialized orders or
forms, like the Lepidoptera, Hymenoptera, and Dip-
tera. In these the development has departed very
widely from the ancestral type, the larvee having secon-
dary forms, such as caterpillars, grubs, and maggots, in
the youngest stages.

ORDER II. EPHEMEROPTERA.

EPHEMERID.

THE May-fly, or “ day-fly,”” Ephemera (PI. III., Fig.
29, p- 73), is so abundant in parts of the country where
ponds and lakes occur that teachers may find it a con-
venient type. The body is long, and the three regions
are loosely connected. ‘The head is broad and short,
and the compound eyes are widely separated, stand-
ing out prominently on either side. The prothorax
(the rings of the thorax are not shown in the drawing)
is freely movable. The mesothorax is the largest
thoracic ring, and bears the large wings, while the
small metathorax carries the small, hind wings. The
antennz (Fig. 29, a7) are tiny, and the mouth parts
have become reduced in size, since the imagos exist
only for reproduction, and do not take any food.

The legs are extremely long; the first pair (Fig.
29, /') is extended forward in a straight line in the
drawing, and in this position may be mistaken for
antennee ; they are slender, and of little use as legs.
The last two pairs are attached to the sides of the
thorax, and are not crowded closely together as
in the dragon-fly, an insect which the May-fly re-
sembles. The venation of the wings is simple, and
in some species the posterior pair is wanting. The
delicate structure of these organs, together with the
ephemeral nature of the insects, has led us to sub-

69

70 EPHEMEROPTERA.

stitute Ephemeroptera (é€pypepov, short-lived insect,
mtepov, a wing) for Plectoptera as the name of the
order, and this avoids the confusion that arises from
the use of the words “ Plectoptera” and ‘ Plecoptera,”
which are not only similar in their orthography, but
the same in signification. ‘The abdomen has two or
three long, thread-like sete or stylets (se). Some
May-flies in their adult stage live only a few hours
(hence the name of “ day-fly’’), though others live
several days. The larval and pupal existence covers,
however, as is often the case, a much longer time,
lasting for a period of two or three years, and is
passed wholly in the water. Pl. III., Fig. 30, is the
larva; its respiratory organs are in the form of gills
and are attached to the sides of the abdomen.

The larvee and pupze shed their skin many times.
One genus, Chloéon, according to Lubbock, moulted
twenty-one times before reaching its full growth. The
winged insect that first appears from the pupa skin
is not the true imago, but represents a_ transitional
stage, which has been called the subimago, and it is
not till this subimago has cast its skin that the mature
May-fly is seen. This is one of the few instances
in which insects with fully developed wings continue
moulting.

One species of this family, the O@goneuria rhenana,
is white. According to Kirby, it appears in such vast
numbers on the Rhine after sunset as to resemble fall-
ing snow-flakes. In the morning nearly all, if not all,
are dead. Morse has shown how myriads of Ephem-

1 Trans. Linn. Soc., London, 1863, 1865.

EPHEMEROPTERA. 71

era are blown from the Great Lakes into the cities
on their borders, and, attracted by light, settle on the
gas-lamps.*

A Rochester Fellow,” in his amusing account of the
American Eclipse Expedition of 1860, states that the
May-flies occur in such numbers on one of the Gull
islands in Lake Winnipeg that a member of the party
on his return from a short walk was so enveloped with
them as to wholly change the color of his clothing, and
the water was covered with the exuviz of the ephem-
ere so that it was impossible to get a clean dipperful
anywhere. ‘The party found the western coast of the
lake lined with a windrow of dead May-flies nearly a
foot deep, which they traced from their canoe, for a
distance of twenty miles.®

The Ephemeroptera continue to retain in their
adult and larval stages several characters which have
led some entomologists to regard them as the most
primitive of all winged insects. ‘The simple neuration
of the wings ; slow development through many moults
of the adult, so that no lines can be drawn between
larva, pupa and imago; the stylets at the end of the
abdomen, and the paired external openings of the
organs of reproduction, are supposed to indicate a
very primitive origin. On the other hand, the imago
is farther specialized by reduction, resembling the

1 See figure in First Book of Zodlogy, P. 103.

2See The Winnipeg Country, Cupples, Upham & Co., 1886,
p- 92.

8 This book is now published by N. D. C. Hodges, 47 Lafay-
ette Place, New York, with the author’s real name, Samuel H.
Scudder, so that this story has an entirely trustworthy origin.

72 EPHEMEROPTERA.

dragon-flies but with atrophied mouth parts, The
sole function of the adult is, therefore, the reproduc-
tion of the species, and some of this group (Ccenis,
etc.) have reached an extreme stage of specialization
by reduction, being affected not only-in their mouth
parts, but also in the decrease of the number of wings
to one pair, as in the Diptera, the hinder pair having
become atrophied. ‘Thus, while this group appears to
indicate in part of its developmental history a very
ancient and primitive origin, in another part, it shows
that specialization by reduction has been at work,
probably greatly altering the original ancestral form,
and not only producing an existing adult type, whose
field of work is solely the reproduction of the species,
but also in the limited group to which Ccenis belongs,
culminating with species that imitate Diptera.

PLATE IIl. |

it
pope p

(Facing page 73.)

ORDER III. ODONATA.

LIBELLULID/.

More can be done by young persons with this order
of insects than with the Thysanura or Ephemeroptera,
and therefore we have figured and described it more
fully. Pl. IIl., Figs. 31, 32, p. 73, represent one of our
common large dragon-flies, ZzbeHula trimaculata, De
Geer, which is a good type of the order. It is found
with other species near ponds and brooks, where speci-
mens can be caught with a net, and afterward killed
with chloroform or cyanide of potassium ; they can also
be preserved in alcohol by using wide-mouthed bottles.
Strong ammonia’ or benzine can be used by young
children. Among the different species collected may
be found Lzdellula pulchella (Fig. 33, p. 74), a form
which is mistaken at first sight for Z. t77maculata,
owing to the three dark spots in the wings. Fig. 33 is
a drawing of this species made a few hours after its
transformation, which took place on the 18th of June.

The body of the dragon-fly is long and cylindrical,
and the three regions, head, thorax, and abdomen, are
loosely connected. This laxity of parts is, in fact,

1 Children should be warned against being careless or playing
tricks upon each other with ammonia. It is dangerous when
diluted and swallowed, easily producing suffocation, and may
be the cause of serious accidents when incautiously breathed
by persons with weak lungs.

73

74 ODONA TA.

one of the striking characteristics of the insects of this
order. The head (Pl. III., Fig. 32, 4; Fig. 34, p. 73)
is broad and short, convex in front, and concave be-
hind. Its shape is owing, in part, to the great com-
pound eyes (Pl. III., Fig. 34, ev), which meet on the
top of the head and extend downward on either side.

a

rpssss

y) :
aie See ea om tae
Lo AHF ih RY 1}

In some genera of the family Agrionidz the eyes are
widely separated and stand out on the sides of the
head, giving a dumb-bell-shaped appearance to this
part of the body. The neck looks like a fleshy
pivot, but is so soft and pliable that the head, in
an alcoholic specimen, can be turned twice round

i,

ODONATA. 75

without loosening its connection or the connection of
the neck with the prothorax.

The prothorax (PI. III., Figs. 32, 35, 4’) is very small,
and is not carried backward like that of the locust, but
extends like a narrow, chitinous collar around the neck.
On the dorsal side it is distinctly marked off into three
transverse portions, and the middle one is again divided
by a longitudinal suture. It is freely movable, and
by being so gives greater range of motion to the head.
If, now, the upper posterior margin of the head is
examined, it is seen to curve forward, so that the head
can be thrown back over the neck and prothorax,
meeting no considerable resistance till it is applied to
‘the convex surface of the mesothorax. When we con-
sider that the dragon-fly catches its food ‘on the
wing,” a habit which will be referred to again when
describing the mouth parts and legs, the necessity for
this free motion of the head is at once recognized."

The mesothorax (PI. III., Figs. 32, 35, 4'’) and meta-
thorax (Figs. 32, 35, 4'") are greatly developed, and
contain the powerful muscles which govern the actions
of the wings; they are also firmly consolidated, the
suture showing in Fig. 35, swf. The dorsal and ventral
portions are narrow, but the lateral parts rise like high
walls on either side (see Fig. 35). The mesothorax
extends above the head in front, and the abdomen
behind, giving a hunch-backed appearance to the
insect. Both rings incline downward and forward,
and the legs are attached to the extreme anterior por-
tion of each ring, in obedience to the law of habit, as

1 See also p. 78.

76 ODONA TA.

will be seen farther on. ‘The size and concentration
of these two rings of the thorax are correlated with
great powers of flight, the dragon-fly being one of the
swiftest fliers. Fig. 35, s°, is the mesothoracic spiracle.
The abdomen (PI. III., Fig. 32, C) is long, and in this
species somewhat flattened ; it is used by the insect in
steering its course. On either side is a fold like that
described in the locust, and the mode of breathing in
the two insects is similar (see p. 40). ¢

The abdomen consists of ten distinct rings, though in
a dorsal view there appear to be twelve, owing to the chiti-
nous ridges which extend transversely across the second

and third rings. These, however, are not continued across.

the ventral surface, and the boundaries of the true rings
are determined by sutures. The latter, though less dis-
tinct than the ridges, are seen, on careful examination,
extending entirely round the abdomen. Besides the circu-
lar ridges there is a longitudinal ridge on each side of the
abdomen, and another extending along the middle of the
back, as seen in PI. III., Figs. 31, 32. This last-mentioned
ridge is sometimes carried farther forward in the female
‘than in the male, though the former may imitate the male in
this particular (as seen in Fig. 32) as well as in the color-
ing of the abdomen. These ridges are not only hard, but
are toothed, the sharp points of the teeth extending back-
ward, so that if the nail is drawn over them towards the
head, a distinct rasping sound is produced. The circular
ridges extend to a deep channel in the ventral surface
(which is found in both the male and female), where they
curve forward, forming a_ broken, longitudinal, toothed
ridge on either side of the channel as if to protect it.
These chitinous ridges and teeth add to the strength of
the armor, and give greater rigidity to the extremely long
and otherwise weak abdomen. By reference to Fig. 33,

ODONATA. 77

Libellula pulchella, and Fig. 33, a, Libellula gquadrupla, both
natural size, it will be seen that the same useful structure
has been developed in different species as adaptations to
the similar habits of these insects.

Besides the compound eyes (PI. IIl., Fig. 34, ey,
p- 73) there are three ocelli. The largest (Fig. 34,
oc) is in the median line, below the chitinous promi-

ne
Ss

y
SS =
7 a.
P

th}

Fig. 33, a.

nence, which rises from the upper part of the head,
and in a front view cuts off the junction of the com-
pound eyes. The two small ocelli (Fig. 34, oc’) are
on each side of this prominence. The foremost ap-
pendages of the head are the short, bristle-like antennze
(Pl. III., Figs. 32, 34, af). Their minute size is in
striking contrast to the immense size of the compound
eyes. Below the clypeus (Fig. 34, c7) and Jabrum
(4a) are the deeply notched mandibles (PI. IIL,

78 ODONATA.

Figs. 32, 34, m@). The two maxille (Fig. 32, mx’)
form the first pair. The second pair of maxille (Figs.
32, 34, mx'') consists, as in the locust, of two united
lobes (one lobe is seen in Fig. 32, and both in Fig.
34). Mosquitoes and many insects have reason to
consider the dragon-fly as their enemy, but children’s
fears are groundless. Unfortunately the name “ darn-
ing-needle’’ originated with the common belief that
this insect could sew up the ears of people, and this
belief still exerts a prejudicial influence upon the minds
of young persons. In reality the dragon-fly is one of
the most harmless of insects. It has no stinging in-
strument or poison-bag in its abdomen ; and though it
defends itself when caught by threatening with its
abdomen and by using its mandibles, the former is
harmless and the latter not sufficiently strong to do
any injury.

The three rings of the thorax each bear a pair of legs
(PI. TIT., Figs. 32, 35,2', 2", 2), which diifer shigitly aa
size and structure, though they vary in length, the first
pair being the shortest and the last pair the longest.
The tarsi, or feet, are provided with hooks, but the
cushions are wanting, as the creature has no use for
them. The legs are small and slender, proving that the
dragon-fly is neither a good walker nor leaper. The
two foremost legs (Pl. III., Fig. 32,7’; Fig. 31) ex-
tend forward and these probably assist the head in
seizing the prey while the insect is flying. ‘To accom-
plish this work most successfully, it is evident the neck
must be pliable and the prothorax free, so that the
head may be capable of quick and easy motion in any
direction, conditions which we have already seen to
exist in a very remarkable degree.

ODONATA. 79

The last pair of legs (Pl. III., Fig. 35, 27'") is carried
forward, and crowded closely against the mesothoracic
pair (Fig. 35, 7’). The insect usually supports itself
on these two pairs when at rest. The explanation
for the peculiar structure of the thorax and position
of the legs is found in the dragon-fly’s habit of hang-
ing from pendent leaves or on the under side of stems
when it alights. If the insect is suspended from the
finger by the hooks of the last two pairs of legs, its
position, when resting after flight, will be imitated.
It will then be seen that this habit has resulted in
carrying the points of insertion of the legs in front of
the centre of gravity, so that the forward part of the
body inclines upward,—a more comfortable position
and giving better opportunity for vision when at rest
than if the body were on a level, or the head end
inclined downward, as it would be if the legs were
carried backward instead of forward.

The two pairs of wings (Pl. III., Fig. 32, w', w";
Fig. 35) are both used in flying, as may be inferred
from their nearly equal size and similar structure.
They are broad, transparent, and attached to the pos-
terior sloping surface of the thorax (Fig. 35, w’, w'').
Their most striking characteristic is the beautiful net-
work of veins or nervules. ‘The wings of the female
(Fig. 32) of this species have three dark spots, while
those of the male (Pl. III., Fig. 31) have only two.
The ovipositor, which is little used, is at the extremity
of the abdomen. The insect does not dig holes in
the ground for the eggs, and this organ is therefore
simpler and weaker than the ovipositor of the locust.
In the male (Fig. 31) the two terminal appendages

80 ODONATA. -

are used as claspers, while the organs at the base of
the abdomen and head of the channel before described
are connected with the genitalia.

The eggs of the dragon-fly are laid on aquatic
plants or dropped in the water. The embryological
development of Diplax with drawings illustrating dif-
ferent stages is given in Packard’s Guide to the Study
of Insects, 7th ed., pp. 54-59. Larval dragon-flies
are abundant in July and August. Fig. 36, 3, represents
one which was collected by a little girl in a slow-
running brook on the 23d of August. The terminal
portion of the abdomen is raised as it is when the

Fig. 36.

insect is breathing, the position being well shown in
the drawing. The thoracic rings are more easily
made out than in the adult. The prothorax (4') is
large and provided with hairs, and the rings of the
abdomen have long hairs in place of the toothed chit-
inous ridges.

The eyes (ev) and the antennz (a7) are prominent
and the mask (.x'') is well developed. ‘This organ
is fully described in the pupal stage because the
pupze are larger, and can easily be obtained for class
work through the autumn and spring. The legs are
hairy and not spiked. The wing-pads (z’, zw!') are

ODONATA. 81

beginning to grow out from the mesothorax and meta-
thorax, so that the larva is changing to a pupa. The
pupal dragon-fly (PI. III., Fig. 37, p. 73, pupa of one
species of Libellula) is active, but is unlike the adult
insect, owing to the watery medium in which it lives.
The body, like that of the larva, is broad and flattened
on the lower side. The head (Fig. 37, 4; Pl. IIL,
Fig. 38, front view of the same ; Pl. III., Fig. 39, side
view) is not freely movable as compared with that of
the adult, as its motion backward is limited by the ~
prothorax ; and if one attempts to turn it, not half a
revolution can be made without meeting strong resist-
ance. The prothorax (Pl. III., Fig. 37, 4’) is still
large, distinct, and ring-like. ‘The mesothorax (Fig.
37, 6) and metathorax (Fig. 37, 4'’) are less closely
consolidated than in the mature fly. The prominent
toothed ridges on the abdomen of the imago are in-
dicated in the pupa (not represented in Fig. 37, but
distinctly seen in Fig. 42, which is a dorsal view of
the pupal skin of Lzbellula trimaculata 9 , and also in
Fig. 43, a side view of the male of the same species).
The channel is entirely wanting. The compound eyes
(Pl. III., Figs. 38, 39, 40, ev) are prominent ; but in-
stead of meeting on the top of the head, they are
widely separated, as in the larva, reminding one of
the eyes of the Agrionidze. There are two minute
ocelli. The antenne (Figs. 38, 39, 40, a7) are small,
as in the adult. The most conspicuous appendage of
the head is the mask (wx''), which is the second pair
of maxillae modified for seizing food. In Fig. 40 this
mask is thrown out, while in Figs. 38, 39, it is folded
over the mouth, entirely concealing the formidable

82 ODONATA.

mandibles (Fig. 40, md) and giving an innocent ap-
pearance to a very carnivorous insect. Fig. 40 repre-
sents the lower side of the head with the mask
extended. The mandibles (md) and first pair of
maxilla (mx') have been separated, giving a better
view of the mouth (vz) and tongue (¢). The shaded
portion of the submentum (zd7) is membranous. In
some genera, as in A‘schna (for figures, see Brehms,
Thierleben, p. 519, copied by Standard Natural Fs-
tory, p. 150), the palpi («'') are modified into stout
hooks! which aid in catching and holding the prey.

The legs are attached to the extreme edge of the
thorax, and extend outward so that both the thorax
and abdomen have a flat ventral surface. The crea-
ture is often found at the bottom of the pond or brook
lying closely upon the mud, which it resembles in color.
It is also found hugging, back downward, the lower
side of leaves and water-plants. It does not hang
from objects, like the imago, but hugs them tightly
with its legs, while the flat abdomen is applied closely
to the leaf like a sucker.

A dragon-fly pupa, which was kept from the 5th of
December till the 9th of May, was not found on the
bottom of the aquarium till March 28th, but was always
hugging either the lower side of a dead opaque oak
leaf, or the stem of a growing water-plant. When
placed on the bottom, it was restless till it had fairly
established itself again in its favorite position. It evi-

1The word Odonata (ddovs, a tooth) was applied to the
dragon-flies by Fabricius, on account of the long teeth on the
second pair of maxilla. See Packard, Lxtomology for Beginners,

Pp. 346.

ODONATA. 83

dently preferred the oak leaf, for it was only found on
the water-plant a few times. When the leaf was turned
over, it always passed to the lower side before becom-
_ing quiet. In doing so it approached the edge of the
leaf, stretched out the three legs on one side of its
body, and pressed them tightly to the upper surface,
then swung its body over the edge, at the same time
extending the other three legs, and taking hold of the
leaf by the strong hooks at their ends. When this feat
was performed on a narrow portion of the leaf, one set
of legs could be seen appearing from the lower side,
just before the other set disappeared from the upper
surface.

When placed on the hand, the insect walked over it
till, nearing one side, it carefully passed under the
finger, and, embracing it, remained motionless. After
March 28th it was usually found on the mud or on
the upper side of the leaf or plant, and became more
active as the time approached for its final transforma-
tion.

The end of the intestine is used for purposes of
respiration and locomotion, while, at the same time,
it performs its proper function as an organ of excre-
tion. The rectum is a dilatable bag, having its walls
supplied with trachez, and its entrance guarded by
three stout, chitinous spikes (Pl. III., Fig. 37, v; see
Fig. 36, p. 80). When these spikes open, water passes
into the cavity of the rectum; and when they close,
they fit together tightly so that the water is prevented
from escaping. The trachez in the walls of the rec-
tum then rob the water of its air, which is distributed
throughout the body. ‘The same water is then made

84 ODONATA.

useful in the secondary capacity of a motor by being
forcibly expelled in a jet from the rectum. The
reaction of this stream against the still water behind
the abdomen gives a sudden forward impulse to the
body, and the walking pupa becomes transformed into
a darter driven by hydraulic pressure. In Agrion there
are three broad, leaf-like gills (Pl. III., Fig. 41, p. 73)
at the extremity of the abdomen, which are used as
respiratory organs, and which serve also as rudders.
Young dragon-flies can be collected in March or
April, and kept in the schoolroom, where their habits
and transformations can be observed. The pupez of
this species (Lebellula trimaculata ) stay at this season
on and in the mud at the bottom of the aquarium.
From twelve to twenty-four hours before the last pupa
skin is shed, however, they remain at or near the sur-
face. They are usually quiet, resting on a twig or
water-plant up to a short time before the final transfor-
mation begins. One which was watched by J. M.
Arms on the evening of May 16th had not appar-
ently changed its position on the following morning.
Another observed by her at the surface on the morn-
ing of May 23d was quiet till 10.27 A.M., when its
motions became quick and restless. When first
observed, a distinct longitudinal suture was seen along
the middle of the thoracic rings, and on either side,
extending obliquely downward and backward from the
median suture in front of the wing-pads, were two
other sutures. On the head were two sutures extend-
ing obliquely forward ; these are seen in Fig. 42, 32,
which is a dorsal view of the empty pupa skin drawn
after it had been in alcohol a short time. At 10.27 the

ODONATA. 85

pupa moved quickly through the water, and tried to
climb up the smooth sides of the dish. Reaching a
thick oak leaf which had purposely been placed as a
ladder, it climbed to the edge of the dish and caught
hold of the mosquito netting extending to a consider-
able height above the improvised aquarium. It now
hung, back downward, by the strong hooks on five of
its legs, while one of the forelegs was free. It would

seem as if this were a very uncomfortable position,
but the netting was chosen by the insect in preference
to a stick which had been provided for the purpose.
Afterward several twigs were supplied, but of the
eight pupze which transformed, only one chose a twig,
and this one fastened itself, back downward, upon
the lower side. At irregular intervals the abdomen
and legs were moved quickly and strongly in the effort

86 ODONATA.

to rend the skin, and the middle portion of the body
was forced outward. At 10.40 the longitudinal seam
opened, and the head and forward part of the thorax

Fig. 42, a.

were pushed out. At 10.48 the two forward legs
were drawn from their cases; at 10.49, the second
pair was pulled out; at 10.55, all three pairs were
free. From this time to 11.06 the head and thorax

Fig. 43.

were thrown backward ; the legs extended outward
and were colorless ; the wings were milk-white pads.
At times convulsive movements shook the abdomen.

ODONA TA. 87

White, tracheal threads extended from the inner side
of the pupa skin to the emerging dragon-fly. ‘These
threads are seen in the dorsal and side views of the
pupa skin (Figs. 42, 42, a2), and also in Fig. 43, 2,
which is a side view of the dry pupa skin from which
came the male dragon-fly (Pl. III., Fig. 31, p. 73).
At 11.06 the animal threw itself forward and catch-
ing hold of the head of the pupa skin, withdrew the
abdomen quickly from its case. At 11.08 it crawled
from the pupa skin to the netting. The body was
now short, light green in color, and covered with a
growth of delicate white hairs, particularly noticeable
on the thorax. ‘The legs were colorless, the wings
white and short. The body trembled, the motion
being due, probably, to the exertion of pumping air
from the tracheze into the wings in order to expand
them ; gradually both the abdomen and wings grew
longer. At 11.16 the dragon-fly walked a few steps
up the netting out of reach of the water, and re-
mained in this position till 1.51 p.m. At 11.19 yellow-
ish spots became apparent in the wings. These organs
were extended upward from the dorsal side of the
thorax, and were held together and motionless during
the whole of this stage. The channel (see p. 76) was
now only indicated by a light-colored band down the
abdomen. At 11.53 the milky white appearance of
the wings had wholly disappeared ; they had become
transparent, and the first marked indications of dark
colored spots were seen in place of the yellowish spots
mentioned above. At 12.14 the dark spots were
distinct, and the channel also was clearly defined. At
12.45 a colorless drop like water fell from the abdo-

88 ODONATA.

men, and several other drops followed at irregular
intervals. At 12.53 the dragon-fly spread its wings,
(up to this time they had been held closely together) :
after spreading they remained motionless, and were
not moved upward and downward. ‘The basal and
middle spots in the wings (see Pl. III., Fig. 32) were
well developed, but the distal spots were confined to
the anterior veins ; the color at the tips came slowly.
At 1.51 the dragon-fly, without giving any warning by
raising and lowering its wings, in other words without
any preliminary exercises, flew from the netting to the
window, a distance of about a foot. Three hours and
eleven minutes had passed since the transformation
began.

After a long larval and pupal existence covering a
period of ten or eleven months, the mature dragon-
flies usually live but a short time, though longer than
the Ephemeridz. Although the metamorphosis of
the insect is direct, the young and mature forms live
under entirely different physical conditions, one being
aquatic and the other aérial. They accordingly dif-
fer more in structure than do the larval and full-grown
locust, which are terrestrial, and which live in the same
habitat and under very similar physical conditions.
We shall see in the orders of insects, and in those
groups in which the physical surroundings, food, etc.,
differ still more widely, as they do in many cases,
that greater differences arise between the larval and
adult stages of the same insect.

After the Ephemeroptera and Odonata are studied,
it will be seen that the dragon-flies have larve which
are much wider departures from the Thysanuroid form

ODONATA. 89

than the larvee of Ephemeroptera, having more highly
specialized mouth parts and thorax. The adults are
active feeders, live longer, and have general functions
and a large field of work outside the act of reproduc-
tion. The organs of reproduction are, however, struct-
urally more specialized than in Ephemeroptera, and
resemble in general those of other insects. The
dragon-flies are eminently rapacious, like the hawks
and eagles among birds, and specialization for this
kind of life is shown in the long abdomen, thorax,
and size and power of the wings with relation to aerial
locomotion, and in the close resemblance of the adults
to the Myrmeleonidz among Neuroptera (see p. 175).
That these resemblances arose independently in the
Odonata and Myrmeleonidze is demonstrated by the
great differences in the larve and modes of develop-
ment of the similar forms, and they are, therefore, not
derived from inheritance or genetic in origin, but par-
allel or representative characteristics which have arisen
independently in two different orders.

ORDER: IV.: PLECOPTERE
PERLID.

THE stone-flies (Fig. 44, Nemoura) are also known
as Perlids. The body is long and flattened, with a
large prothorax. The
antenne equal the
body in length. The
wings lie flat. upon
the abdomen, con-
cealing it and extend-
ing some distance
beyond it. Their
plaited character
has given the name
Plecoptera (aA ékos,
plaited; mrepov, a
wing) to the order.

The larva and pupa (Fig. 45) are aquatic, and
are often found under stones. ‘They have external
gills on the under side of the thorax.

The genus Pteronarcys lives in very wet places,
and this may account for the very exceptional fact
that the tracheal gills of the larva and pupa are re-
tained in the adult.

The Plecoptera stand by themselves, but their lar-
ve present strong resemblances to those of the Ephe-

go

PLECOPTERA. 91

meridz (May-flies) and Thysanura on one side, while
the adults resemble the Platyptera. Orders II.—IV.
all have aquatic larvze possessing curious adaptive char-

Fig. 45-

acters, especially in their breathing-organs, while the
adults live in the air, being as a rule good fliers.

ORDER V. -PLATYPYERs

TERMITID.

=

THE Termites are commonly called white ants be-
cause of their resemblance to the true ants among
Hymenoptera. ‘The resemblance, however, is not .so
great as the name indicates. In structure the two are
widely different, as will be seen by comparing the Ter-
mitidze with the Formicidze (see pp. 238, 239). The
Termites have become well known in Massachusetts

of late years from their depredations in our vicinity,
notably at the State House. A colony of these insects
illustrates the fact that social habits tend to the pro-
duction of different kinds of individuals fitted to per-
form different kinds of work. The worker of our
common species Zermes flavipes (Fig. 46, hair line
represents natural size) has a light-colored body and
a brown head (A) of medium size. The color of the
92

PLAT VPTERA. 93

head shows that the insect performs the hardest work
with this part of the body. The thorax and abdomen
are broadly connected, while in the Hymenopterous
ants the abdomen has a slender stem or peduncle.
The mandibles are not large, but are strong and
horny, while in the soldier (Fig. 47, Zermes flavipes),
which performs greater labors for the protection of the
colony, the head (4) and mandibles (Figs. 47, 48, md;
Fig. 48 head of soldier enlarged) ,
are greatly developed, and the aD
latter deeply colored. The dif-
ference in structure between these
two individuals is, in fact, exactly
proportioned to the amount and
kind of work they perform. It is
also interesting to note that the Bre ,AB-
worker obliged to work below has its head turned
downward at right angles with the body, while the
soldier, using his mandibles in fighting in narrow
places, has its head extending forward or in a line
with the body. Both workers and soldiers may be of
either sex, but the reproductive organs are slightly
developed. ‘They are blind, the eyes being absent ;
and they never have wings, the name Platyptera
(rAatv, broad ; mrepov, wing) referring to the wings
of the male and female. They are in reality larvee
which never pass through the pupal stage, but are
arrested in development, and in the soldier the head
is abnormally developed to accomplish the special
work of attack and defence. The larva’ proper, or

1 Excellent figures of the larva, pupa, etc., of another species,
Termes lucifugus, can be found in Claus, 7razté de Zoologie,

94 PLAT YPTERA.

young Termite, is white ; even the tips of the mandi-
bles are only slightly tinted, while the hooks of the
feet are entirely colorless. Unlike the young locusts,
the larval Termites are nursed by the workers, who
prepare their food and tend them with great care.
The resemblance of these larve to the Thysanuran
insects is seen in the shape of the body and the dis-
tinct thoracic rings. ‘Those forms which are destined
to develop into males and females are kept longer
under the care of the workers, and pass through the
pupa stage. The pupe are colorless like the larve,
but have eyes and wing-pads fringed with hairs. They
are active, and therefore the metamorphosis of the
Termites is direct.

There are two castes of males and females. The
complemental males and females, as they are called,
are supposed never to leave the nest. They are of
a light color, like the workers. In case of need, sev-
eral of these females are substituted for a true, pro-
lific queen. They can produce but few eggs, however,
and do not enlarge as does the queen. The king
and queen caste arises in the spring. ‘They fly out in
clouds from the nests for their marriage flight. They
then alight on the ground and lose their wings. The
workers select from these a pair for each nest, and the
rest soon die. The royal pair are housed in a special
apartment. In Zermes flavipes this caste is dark chest-
nut or black, but the royal pair have never yet been
found in any nest.

The colorlessness of the Termites is interesting,

pp. 870-873. See also Packard, Entomology for Beginners,
p. 65.

PLAT YPTERA. 95

since it correlates with their habits. They are more
exclusively confined to their nests than the ants, and,
like cave animals, being protected from the action of
the atmosphere and light, they are colorless or only
slightly colored. The exceptional coloring of the per-
fect males and females, like the coloring of the jaws
in larvee before they begin to feed, is probably due to
inheritance, the vestiges of a time when they lived an
open and freer existence, and had not yet arrived at
the remarkable stage of specialization which they now
exhibit. The king, or perfect male (Fig. 49, Zermes

dirus) possesses wings, as already stated, but these
serve only the purpose of reproduction. They are
not essential either as respiratory or as locomotive
organs, and are used only for a single aérial excursion
called the “ marriage flight.” The queen (Fig. 50,
queen of Zermes bellicosus, natural size) has a small
head (4) and thorax (4', 6", 6'"'), but the abdomen (C)
at the time of egg-bearing is immensely distended ;
c'—c® are the plates of the abdominal rings, which were
close together before oviferation began. At the time
of egg-bearing a peristaltic motion of the abdomen

96 PLATYPTERA.

continues incessantly, and, according to Smeathman,
the above species produced
sixty eggs a minute, or upward
of 80,000 a day, if the eggs
were laid uninterruptedly.
a The habits and destructive
work of the Termites of Brazil,
and of our common species
( Zermes flavipes) have been de-
scribed by Dr. Hagen.” These
ants are very abundant in New
England, being found chiefly in
dead trees and rotten wood ;
fortunately, they seldom attack
living trees, but have been found
injurious to grapevines and ge-
ranium cuttings in greenhouses.’
They are also fond of wood
moistened by steam, such as
the roofs of wooden bridges
through which steam cars pass
daily. They swarm in June,
and interesting observations up-
on their habits could be made
— eat this season. A number of
Fig. 50. instances are given by Dr. Hagen

1 See Fritz Miiller. Zeitschrift fiir Medizin und Naturwis-
sensch. Jena, 1873.

2 See “Probable Danger from White Ants,” Amer. Nat,
Vol. X., 1876; also, ‘Remarks upon White Ants,” Proc. Bost.
Soc. Nat. Hist., Vol. XX., 1878-80. “Monographie der Ter-
miten,” Zzzn@a Entomolog., Vols. X., XII., XIV.

*Can. Ent. Vel. XTX, p. 219:

PLATYPTERA. 97

showing how destructive these insects are in houses,
eating away the inside of timber and leaving the
outside untouched and apparently sound, so that some-
times a building is liable to sudden and unexpected
collapse.

The African Termites have been described by
Smeathman,’ who is still an authority on this subject.
The species, Zermes bellicosus, already referred to,
differs from our American white ant by building clay
hillocks from ten to twelve feet high. In the centre
of these and near the surface of the ground is the
royal chamber occupied by the king and queen.
Extending a foot or more around this chamber on all
sides are the apartments of the workers and soldiers,
and beyond these the nurseries and storehouses. It
is a significant fact that while all the other chambers
are built of clay, the nurseries are “totally different,”
being made of wooden materials, apparently cemented
together with gum.

PSOCID.

These insects (Fig. 51, Psocus Lineatus, enlarged)
are small, reminding one of the plant-lice, or aphides
(Fig. 81). The head is large in proportion to the
size of the animal. The small prothorax separates
easily from the mesothorax, coming off readily with
the head; the abdomen is much shorter than the
wings.

The compound eyes are small though prominent,
and the antennz very long. The mouth parts are for

1See Phil. Trans. Roy. Soc., 1781; also, Romanes, Animal
Intelligence. International Scientific Series, 1882.

98 PLAT YVPTERA.

biting, the insect feeding upon lichens and dry vege-
tation. ‘The legs are long and slender. The wings
have few veins, and when the insect is not flying are

=
my

ESS
ASS

me”, :
CTY SSS

—
J

Fig. 51.

folded roof-like over the abdomen. The metamor-
phosis of the Psocideze is direct, and the larve resem-
ble the adults excepting in not possessing wings.

The book-lice are larva-like, wingless forms of this
family, with strong legs suitable for running. They
are light-colored, minute insects common in neglected
books and collections. ‘Though called lice on account
of their aspect, they do not resemble them in structure,
and are not parasites.

MALLOPHAGID.

These are minute parasites that live principally
on birds. They can be collected from chickens.
They are unlike true lice in having mouth parts for
biting, and they feed upon dandruff, feathers, etc.
Several species are found also upon mammals.

Among the Platyptera the white ants and book-
lice are terrestrial in all stages, but the members of
the subdivision of Mallophagide are parasites, as stated
above, and possess the usual specializations noticeable

PEAT YPTERA. 99

in such groups. Paiasites living upon other animals,
and subsisting upon the food provided by the host,
are usually wingless, and are generally looked upon as
having been evolved from more normal winged forms.
They are examples of specialization through reduction
of parts, and usually have lost the wings, and often
the biting mouth parts, etc., probably because of dis-
use, or some cause directly connected -with their
peculiar mode of life. We repeat that they should
be placed, therefore, after the normal forms of the
types to which they are allied, and not before them,
as is very often done in text-books. Among the
Platyptera the Termites are considered by Dr. Hagen,
the most thorough student of these singular forms, to
be allied to the Orthoptera, and Brauer considers
them to be similar, also, to the Dermaptera.

ORDER VI. DERMAPTERA.

FORFICULID/E.

THE ear-wig, Forficula (Pl. IV., Fig. 52, p. 102) has
a long body with the thorax and abdomen broadly
connected. The upper pair of wings (Fig. 52, z’) is
small and chitinous, somewhat resembling the -wing-
covers of beetles ; hence the name Dermaptera, from
the Greek (d¢pua, skin; wrepdv, wing). The lower
pair is large and rounded. ‘The greater part of the
lower wing has radiating veins, and when not in use is
folded like a fan, the pivot being at the middle of
the front margin ; the wing also is folded twice cross-
wise, so that only a small portion (Fig. 52, w"’)
extends beyond the wing-covers. ‘The name Forficula
alludes to the forcep-like appendages (PI. IV., Figs.
52, 53) at the end of the abdomen which serve to
flirt open the closed wings, and that of ear-wig to the
belief formerly held that this insect was fond of creep-
ing into the ears of sleeping persons. According to
Kirby! ear-wigs have sometimes entered the human
ear for concealment. Two or three species of Forficu-
lidze are found in New England, but these are of small
SIZE:

The larva (PI. IV., Fig. 53, Forjicula auricularia)
has distinct thoracic rings, and though the wings have
not grown, the forceps are quite strong organs.

1 Text-book of Entomology, p. 82.

100

DERMAPTERA. 101

The ear-wigs are terrestrial, very generalized in
structure, and placed by Brauer and Packard next to
the Thysanura ; but their close relations to the Orthop-
tera have been recognized by these authors, and we
have placed them next to, though not in, that order,
as has been done by several of the best authorities.
Their larval and adult characters seem to indicate the
primitive origin of the two groups Dermaptera and
Orthoptera.

ORDER Vif. -ORTHOPTER

THE distinguishing characteristics of the Orthoptera!
or straight-winged insects (dp60s, straight ; mrepov, a
wing, p. 29) are already familiar through the study of
the locust, but a few of the commonest species remain
to be noticed.

BLATTID#.

The cockroach, /eriplaneta orientalis (Pl. IV., Fig.
546; Fig. 552, p. 102), is, pre-eminently, a flattened
insect. ‘The wedge-shaped head (4) is bent under,
and nearly concealed by the large prothorax (4'). The
thoracic rings (Fig. 55, 4’, 4", 6") are simple and un-
consolidated. ‘The rings of the abdomen overlap eack
other, and are capable of great extension and com-
pression, and, indeed, the whole body seems to be
able to adapt itself to narrow quarters in crevices.
The terminal rings in the abdomen of the female are
bent downward, as shown in the drawing, and are
coarsely serrated on their edges, quite different from
the five segments that precede them. The mode of
breathing of the cockroach is somewhat different from
that of the locust. The sternal portions of the rings
are less yielding than the tergal parts, and therefore
the latter rise and fall more appreciably. Plateau® gives

1See also remarks on pp. 110-112.
2 Miall and Denny, 7he Cockroach. pp. 161, 162,

102

(Facing page 102.)

ae
.

a figure showing the difference in the size of the abdo-
men after each inspiratory and expiratory movement.

The eyes are inconspicuous and the antenne very
long. The mouth parts are for biting, and are stout
and dark-colored, suitable for such an omnivorous
creature, which lives upon both vegetable and animal
food, which in some cases destroys clothing, and in
the tropics has even been known to nibble the toe-
nails of a sleeping person. The structure of the legs
is peculiar. The coxa (not seen from above) is flat-
tened and pressed closely to the body, while the flat-
tened femur (Pl. IV., Fig. 54, jr), tibia (2), and
tarsus (¢v) are long and strong, enabling their pos-
sessor to run swiftly. The tarsus has five joints, and
at the extremity are two claws.

The wings in the male (Pl. IV., Fig. 54, w’, w'') are
shorter than the abdomen. In the female the upper
wings (Pl. IV., Fig. 55, w’) are small, and the lower
pair is wanting, although its remnant may be repre-
sented by the lateral portion of the metathorax, which
spreads outward and has the semblance of a wing.

The female does not deposit her eggs in the earth
like the locust, but carries a sac about with her
attached to the abdomen. In this sac the eggs are
placed in two rows. It can be opened with a knife,
and the enclosed young shown with a magnifier.
This habit of forming a sac and carrying the eggs
and young is very interesting. The larve, when
hatched, are white, and according to Riley are brooded
over by the mother. The larval cockroach (PI. IV.,
Fig. 56) is wingless, and by the simplicity of its struc-
ture reminds one of Thysanura. |

ORTHOPTERA. 103.

104 ORTHOPTERA.

For a description of the structure and life history of
this insect, and for theoretical considerations in re-
gard to the genealogy and causes of metamorphosis,
see Zhe Cockroach, Miall and Denny, 1886; also
consult Huxley’s /nuvertebrata, and Rolleston’s Forms
of Animal Life. ‘The geological history of the insect
is extremely instructive. “Indeed,” says Mr. Scudder,
‘“‘paleontologically considered, no insect is so inter-
esting as the cockroach. Of no other type of insects
can it be said that it occurs at every horizon where
insects have been found in any numbers ; in no group
whatever can the changes wrought by time be so care-
fully and completely studied as here; none other has
furnished more important evidence concerning the
phylogeny of insects.’’!

The common form of the same group known as the
Croton bug (£ctobia germanica) can be made very
useful to students. They can be induced to watch its
habits and report upon what they see; upon its re-
markably flattened body and appendages enabling it
to crawl into narrow crevices and escape pursuit, its
powerful limbs and consequently quick motions, its
capacity for ascending even smooth walls, and reckless
habit of leaping from any height when alarmed, the
strange fact that it uses its wings but rarely and prefers
to trust to its legs in trying to escape pursuit. Even

1 Miall and Denny, Zhe Cockroach, Chap. XI. Also consult
Scudder, “ Paleeozoic Cockroaches,” Jem. Bost. Soc. Nat. Hist.,
Vol. III., Part I., No. III., 1879; “ Mesozoic Cockroaches,” AZem.
Bost. Soc. Nat. Hist., Vol. T11., No. XIII., 1886; and “ System-
atic Review of our Present Knowledge of Fossil Insects,”
Bull. U. S. Geol. Surv., No. 31, 1886,

s iu .

ORTHOPTERA. 105

the females in this species have not yet lost the wings,
though they have apparently taken the first step in
that direction, having ceased to use them habitually,
preferring to run and leap when in danger.

Some Croton bugs are occasionally light-colored :
these have just moulted, and their new, soft skin has
not yet had time to harden and darken into its natural
shade.

The ancient cockroaches had, and the wild ones now
existing have similar forms to those which occupy our
houses, and it is evident that their curious adaptations
of structure were acquired when living under stones
and in narrow shelters before man came into being.
Their habits of life and feeding, and the shape of their
bodies having fitted them for a life of semi-domestica-
tion, they, like mice and rats, have naturally been led
by the search for food into habitations of all kinds
and thriven there on account of the remarkable fitness
of their organization. We do not as yet know to
what extent, if any, their structures have been modi-
fied by the habit of living in houses, and very inter-
esting researches might be made upon such points by
persons residing in the country, where the wild forms
could be studied and compared with those found in
houses.

PHASMID/E.

The walking-stick, Diapheromera femorata, Say,
(Pl. IV., Fig. 57) is rightly named, since the insect re-
sembles a long, slender stick. It imitates nature by
changing from a green color in the spring to gray and
brown in the autumn, making itself more secure against

106 ORTHOPTERA.

the attacks of its enemies in this way... The word
“slow” is hardly expressive enough to describe the
motions of this insect, and as slow-moving animals are
more apt to be caught by birds and other voracious
creatures the walking-stick has added to its chances
of escape by a habit it has of remaining motionless
and apparently dead for a considerable length of time.

The head (Fig. 57, 4) is bent ata slight angle of
the body. The prothorax (Fig. 57, 4') is small, and
at first sight it seems surprising that it should carry
such a pair of well-developed legs; these legs, how-
ever, are weak locomotive organs. ‘The mesothorax
(6) and metathorax (4'") are long and unconsoli-
dated, and this fact correlates with the absence of
wings. ‘The eyes are small, but the antenne are ex-
tremely long. The mouth parts are used for biting
vegetable substances. The three pairs of legs are
slender, and adapted in general for slow movements
as stated above. ‘The insects will, however, on occa-
sion, run so fast that it is hard to catch them, though
not by any means so fast as a cockroach. ‘The feet
have the pulvillus and claws of the locusts.

GRYLLID-.

The crickets have shortened, rounded, and green,
brown, or black bodies. In Gryllus (Pl. IV., Fig. 58)
the head is at right angles to the body. ‘The pro-
thorax (4') resembles that of the locust, but does not

1 The interesting subject of protective imitation, so admira-
bly illustrated by the Phasmidee, is considered under the head of
the “ Origin and Uses of Colour in Animals,” by Wallace in his
work on Darwinism, 1889, Chaps. VIII.-XI.

ORTHOPTERA. 107

extend backward so far. The small mesothorax and
larger metathorax (concealed in the drawing by the
wings) are loosely connected. In the larval cricket the
dorsal portions of these thoracic rings resemble in color
and simplicity of structure the succeeding abdominal
rings. When the wings begin to be developed, however,
the different parts of the terga become more apparent,
and the color of the metathorax is lighter. The abdo-
men has no longitudinal fold but a soft, fleshy area or
pleural zone in which the spiracles are distinctly seen.
When breathing, this pleural zone is depressed or re-
sumes its original condition as the terga and sterna
approach or recede alternately.

The eyes are small and widely separated in both
sexes. Here again the antenne are extremely long.
The biting mouth parts are strong. ‘The leaping-legs
are more slender than the locust’s, and the feet are
without a pulvillus. The wing-covers are horny and
bent downward against the sides of the body. The
“chirp” of the male is produced by rubbing the
veins in the middle of one wing-cover upon those of
the other. The second pair of wings are light-colored,
and comparatively useless as flying-organs, although
sometimes nearly twice as long as the first pair.’

The abdomen bears at its extremity a long oviposi-
tor (Pl. IV., Fig. 58, os) which consists, apparently, of
two pieces. Each of these pieces, however, is made
of two parts united so as to form a canal. The union

1 In a smaller cricket, a species of Nemobius, which has
habits similar to those of Gryllus, the wings are entirely want-
ing, and flight is impossible,

108 ORTHOPTERA.

is not strong, so that the four parts may be readily sep-
arated. The abdomen also bears two caudal setze (se).

The mole-cricket (G7yllotalpa borealis) offers a
most instructive example of the effects of the habit
of burrowing upon structure. The search for food,
such as the roots of plants, worms, and grubs, and the
habit of living in the earth, has led this animal to
excavate subterranean galleries; and in so doing it
has modified the structure of its fore limbs till they
have become stout, strong, and efficient digging im-
plements. A similar adaptation is seen among Ver-
tebrates in the foot of the common mole, the animal
whose name has been given to the insect. Living
underground, the mole-cricket has no need of leaping-
legs, and therefore the third pair of legs are not
greatly enlarged.

LOCUSTID.

The characteristics of these insects have been briefly
stated on p. 9.

After the structure and habits of the locust become
familiar to pupils, a very instructive lesson may be
given on the meadow grasshopper, Orcheliimum vul-
gare (Pl. IV., Fig. 593; Fig. 602). This grasshop-
per lives among the grass and green plants of moist
fields and meadows, and its near relatives, the katy-
dids,’ among the leaves of shrubs and trees. ‘The col-
oration of each species is admirably adapted to its
habitat, the grasshopper and katydid being surrounded
by foliage, and on green stems are a lively green;

1 For figures and descriptions of different species of katydids,
see Riley, Sixth Report Noxious and Beneficial Insects of Mis-
sourt, 1874, pp. 150-169.

ORTHOPTERA. 109

while the locusts, which stay near the dull-colored
earth, are dingy shades of brown and red.

The eyes of the grasshopper are smaller than the
locust’s, while the antennz, though not so stout, are
very much longer. The mandibles are light-colored
with the exception of the edges, which are horny,
showing the effects of work. ‘The palpi of the first
pair of maxillze are remarkably long. ‘The mesothorax
and metathorax are not consolidated, but move upon
each other, and this condition correlates with the
structure of the legs and wings, the legs being less
muscular than those of Iécusts, while the wings are
leaf-like, having no stiff, chitinous, anterior veins.

The slight concentration of the thorax; the weak
structure of the legs and wings ; the light color of the
mandibles ; in brief, the delicacy of the whole organi-
zation, show that the meadow grasshopper is not a
strong leaper, good flier, nor voracious eater, like the
more robust locust. The sword-shaped ovipositor
(Pl. IV., Fig. 60, os) is made of four plates, and the
edges near its end are horny and saw-like. The
corresponding parts in the male (Pl. IV., Fig. 59) are
used as clasping-organs.

ACRIDID#.

The genus Caloptenus, as already stated, belongs
‘to this family, and has become familiar through the
study of Calopienus femoratus. ‘The Rocky Moun-
tain locust, Caloptenus spretus, Uhler (for figures, see
Standard Natural History, p. 197), is similar to Calop-
tenus femoratus in structure, but in size it more nearly
resembles the common little red-legged locust, Ca/op-

110 ORTHOPTERA.

tenus femur-rubrum. The ravages of this insect in
the West are described in the First, Second, and Third
Reports of the United States Entomological Commis-
sion, 1877-83.

The little grouse locust, Tettix (Fig. 61, enlarged),
belonging to this family, is
very instructive. The pro-
thorax (4') has grown back-
ward, and taken upon itself
the work of the wing-covers,
and these being no longer
needed, have become reduced
to mere scales (w'). The
second pair of wings (z"’) is
seen projecting beyond the
prothoracic cover.

Most Orthoptera are ter-
restrial, both in the larval and
adult condition, and are sub-
ject to similar physical surroundings. ‘They take food
in a solid form, and the majority are vegetable eaters,
and have to hunt for a living throughout life. This
similarity in habits and habitats is correlated with a
corresponding similarity in structure and development.
The larve are, as a rule, active feeders, resembling
their own adults or imagos quite closely in this re-

Fig. 61.

spect, and do not have to go through with any very”

marked changes during their growth.

We have seen that the cockroaches have special-
ized modes of protecting the eggs and young in
sacs and are exclusively terrestrial ; nevertheless, in
these, which are the most generalized forms, the Thy-

ORTHOPTERA. 111

sanuriform stage is distinctly shown. In the still more
specialized forms, Mantidze, Phasmidze, and the Salta-
torial families, these stages are accelerated or absent,
and the young when born are more like the adults,
or have usually more specialized proportions in the
parts of the body, etc., than in the larve of cock-
roaches. Some writers, notably Balfour, have supposed
that protection of the ova produced such results, but
the ova in some genera of the Phasmidz are dropped
upon the ground and exposed through two winters
and one summer without protection of any kind. Such
types as the three groups just mentioned are commonly
brought forward as fatal objections to the derivation
of insects from a form similar to Thysanura. The
young locust when hatched has enormous leaping-legs,
a body which is short in proportion, and a large head
and thorax like the adult. There are no signs whatever
of a Thysanuran ancestry in the larve except the ab-
sence of wings. It is obvious that the large leaping-
legs, the head with its peculiar pose, and the characters
of the thorax have been formed before the animal could
have had any use for them, before, indeed, it was out
of its egg-case. No one can deny that the peculiari-
ties of the hind-legs are adaptive ; and their presence
at such early stages, before they can be used by the
animal, shows that their reproduction in the young of
existing saltatorial forms is due to inheritance. The
affinities of the saltatorial forms of Orthoptera, with
the generalized Orthoptera (Cockroaches), are shown
in obvious characteristics; and this great difference
in development is accounted for, according to our
mode of viewing the problem, by a law of heredity

112 ORTHOPTERA.

which has been stated very often in other publica-
tions. This in a few words is as follows: In any
series of forms evolving through time, new character-
istics are acquired by each species or new form.
These novel characteristics show a strong tendency, as
a rule, to reappear in the new forms subsequently
evolved at earlier stages in the development of
individuals than those in which they first appeared.
This process, long continued, finally causes the later
acquired, stronger, and more suitable characteristics
or modifications to crowd upon and replace the older,
ancestral, and useless characteristics of the younger
stages. When this process is carried to an extreme,
the later acquired adaptive characters, as in the locust,
may absolutely supplant the older ancestral stages.
The law of acceleration in development, as this has
been called, is, therefore, adequate to meet all objec-
tions arising from such cases, and amply accounts for
the absence of the Thysanuriform larva in the salta-
torial Orthoptera, and other similar cases where the
adult characters of a group appear in the larval stages
and replace the hereditary larval characters.

g
¢

al

‘

webDER Vil THYSANOPTERA.
THRIPID®.

Tuis order contains the family Thripide, represented
by Zhrips striatus (Fig. 62; hair-line represents
natural size), an insect too small for sat-
isfactory class-work. ‘This species feeds
upen onion plants, while Zips cereahum
is the little black insect which destroys
large quantities of wheat. Specimens of
other species can be obtained from daisies
and clover. The mouth parts of Thrips are
interesting organs, since they are interme-
diate in form between the true sucking and
biting mouth parts. The mandibles are
bristle-like, but both pairs of maxille, with
palpi, are developed. The feet are very curious, ending
in bulbs ; on this account these insects are often called
Physopoda. ‘The remarkable fringed wings possessed
by Thrips have given the name Thysanoptera (6vca-
vos, fringe ; wrepov, wing) to the order. These are
not without their parallels, and similar modifications
occur in some minute Lepidoptera (Pterophoridz)

- and Hymenoptera (Proctotrupide). These appear to

us to be cases of similar specializations in the same
parts.
The species of Thrips have larvee which are remark-

113

114 THYSANOPTERA.

ably similar to Thysanura; but the adults are more
widely removed from their own young than the adults
of Dermaptera. Their relations to the next order
have been generally admitted."

1See Packard, Third Rep. U. S. Ent. Com., p. 297- :

ORDER TX.” HEMIPTERA.

Tus order is divisible into two well-marked groups,
the Heteroptera and Homoptera. A type of the order
is the squash-bug of the Heteroptera. In accord-
ance with the plan adopted in this Guide the type will
be described first, and after some of the more com-
mon forms of the two groups have become familiar
the general statements will be given (see pp. 142-
144). It is hoped that teachers will follow this method
in their lessons, encouraging their pupils to find all
the characters of the type first, and not begin by giv-
ing them general statements or by telling them off-
hand what they ought to discover by their own efforts.
Teachers do not teach writing, reading, and arith-
metic by doing the work themselves ; why should they
not follow the same principle in natural history ?

The squash-bug, Anasa ¢rists (Pl. V., Fig. 63, en-
larged, p. 115) is often found abundantly on the vines
of the summer squash, and during July, August, and
September all stages from the egg to the full-grown
insect can be collected. It belongs to a large family,
the Coreidz (see p. 125), and is extensively distrib-
uted.

The head (Pl. V., Fig. 64, 4) is flattened horizon-
tally, and connected with the thorax by a short neck
which allows but little freedom of motion. The dor-

ELS

Ra. bee

116 HEMIPTERA.

sal portion of the prothorax (Pl. V., Figs. 63, 64, 4')
extends backward over the greater part of the meso-
thorax and fits it closely, while the sternal portion is
firmly soldered to the mesothorax. Pl. V., Fig. 65 is
aside view of the head and thorax. The prothorax
(4') has been raised, exposing the forward part of the
mesothorax (6", 77) below.

The triangular form of the prothorax gives proper
support to the narrow head for the work of piercing
the tissues of vegetables with the proboscis. Not
only is this form of the prothorax in direct correlation
with the sucking habits of the insect, but the broad
body behind is admirably adapted to the uses of a
type that feeds in this way, and walks and runs from
preference, not living habitually on the wing.

The mesothorax (Pl. V., Figs. 64, 65, 4'') is large,
and extends backward in the form of a pointed
triangular piece, the scutellum (Pl. V., Figs. 63, 64,
65, 4°), which nearly conceals the small, dorsal por-
tion of the metathorax (Fig. 64, 4'""). This scutellum
varies greatly in size in different genera, becoming so
large in the genus Scutellera (Fig. 74, p. 126) as to
cover the abdomen and wings. While the metathorax
is ring-like above (Pl. V., Fig. 64, 6'", p. 115); at
the sides it broadens out (Pl. V., Fig. 65, 4’) and
resembles the lateral parts of the mesothorax. The
sternum is perforated by two openings of glands which
secrete a liquid with a disagreeable odor. According
to Professors Verrill and Johnson! this odor bears the
most resemblance to that of the formate of oxide of

1 Proc. Bost. Soc. Nat. Hist., Vol. X1., p. 160.

-
t HEMIPTERA. 117

anyl, or the formate of anylic ether. The broad, flat-
tened abdomen (Pl. V., Fig. 64, C) is connected with
the thorax by a broad junction, and is concave above
and convex below. The spiracles are situated along
the lower sides. The mode of breathing of the squash-
bug is similar to that of the cockroach (see p. 102).
The squash-bug has a pair of small compound eyes
(Pl. V., Fig. 66, two-thirds view of head, ey; Pl. V.,
Fig. 67, side view of same, ey) and two ocelli (Fig.
67, oc'). ‘These are seen, but not lettered, in Pl. V.,
Fig. 64. The foremost appendages are the long, stout,
and jointed antennze (Fig. 64, a7), the first and last
sections of which are enlarged. Below these are the
labrum (Pl. V., Figs. 66, 67, Zz) and sucking-tube
(Pl. V., Fig. 64, sw), which extends from the front of
the head backward, close to the lower side of the
body (Pl. V., Fig. 65, sz). The two parts forming
the second pair of maxillz are united here as in the
locust and dragon-fly, but instead of forming an apron-
shaped organ, they make a long, jointed, and deeply
grooved tube (PI. V., Fig. 66, mx"). The other two
pairs of mouth parts are modified from biting-organs
to sharp needle-like piercers (Fig. 66, md, mx').
When the labrum is lifted these organs are raised with
it, as shown in Fig. 66. The mouth parts of this insect
are so small that scholars have much difficulty in
making them out, and are often uncertain as to their
number and homologies. In this case one of three
things must be done. The teacher must tell his pupils
some of the facts, or he must resort to a blackboard
drawing which places the organs at once before the
pupils without any effort on their part, or he must

118 HEMIPTERA.

provide larger specimens where the organs are more
clearly shown, so that the scholars can find, draw, and
describe them unaided. If he provides specimens of
the harvest-fly, or “locust,” as it is erroneously called
(Fig. 78, p. 131), the doubts of the pupils are cleared
away. ‘The tube is so well shown in this insect that
scholars often come to the conclusion it is only-another
form of the apron-shaped organ which they have de-
scribed as the second pair of maxillz of the locust.

The insect thrusts the piercer into the plant it feeds
upon, and by means of the muscles of the pharynx
draws up the sap. The process is similar to that by
which butterflies obtain their food (see pp. 189, 190).
The three: pairs of legs (Pl V., Fig. tay 75 pe
p. 115) are adapted for walking and running rather
than leaping. The upper wings (Fig. 64, w’) have
two well-marked textures, the basal portion being
chitinous, and containing a few large veins, while the
remaining portion is membranous, with many small,
parallel veins. ‘This characteristic has given the name
Hemiptera (ym half; mrepov, a wing) to this order
of insects. The lower wings (z'’) do not have these
two textures, but are membranous throughout, with few
veins. The network of nervures so conspicuous in the
wings of the Odonata is here entirely wanting. Both
pairs of wings lie flat on the back, and the membra-
nous tips overlap. The abdomen does not bear ap-
pendages, the ovipositor being within the body.

These insects spend the winter in sheltered crevices.
In the last of June and first of July the female lays her
eggs on the lower side of the leaves of squash-vines.
We have seen these leaves in August thickly covered

Ob ONG Gk ste ng tI

ie Mes PORN

PPG ia ye) Deed path S er ae f mys

HEMIPTERA. 119

with the larvee and pupe, and an instructive collection
can be made at this season, illustrating the different
stages in the development of the insect, and also the
origin and growth of the wings. The body of the
larva (Fig. 68, 2) is light brown, excepting the head,
which is dark and chi-
tinous, as shown in the
figure. The prothorax
(6') does not overlap
the ring behind it
(marked 4''). The meta-
thorax (6''') is in the
form of a narrow ring.
The first ring of the
abdomen (c’) is simple,
and smaller than the suc-
ceeding abdominal rings.

The working anten-
nz, sucking-tube, and legs are dark and horny, con-
trasting strikingly with the light color of the thorax
and abdomen. -

By examining different stages of the pupe (Fig.
69, #, one stage), it will be found that the thoracic
rings of the larva undergo a greater change than would
appear at first sight. ‘The larger portion of the dorsal
part of the ring marked 4" in Fig. 68 becomes the
mesothoracic scutellum (Fig. 69, 4°), and the question
arises, What exists in the larva that can develop into
the large, horny scutum (Fig. 65, “) of the adult?
To answer this question, one must examine a number
of pupz. It is then seen that the forward part of 6”
(Fig. 68) enlarges, while the prothorax grows back-~

Fig. 68.

120 HEMIPTERA.

ward and overlaps it. It is at this time light-colored,
The tendency oo concentration of the thorax
seems to be _ back-
ward, or in the direc-
tion of the centre
of gravity of the
body, rather than
headward. It has
already been seen
that the scutellum
(Fig. 69, 4°) ex-
tends backward in
the adult, conceal-
ing the metathorax,
‘which is distinctly
seen in the pupa
(Fig. 69, 8'"), bear-
ing the second pair
of wings (zw!’). The
thorax and abdomen of the pupa are more chitinous
than the same parts of the larva, though the head in
the specimens examined was not so dark-colored.
The antennz, sucking-tube, and legs resemble those

of the adult.

_ attention of children. They must be handled

‘since they frequently inflict severe stings with

HETEROPTERA.

THE two following families include forms of Hemip-
tera that live in the water, and show curious adap-
tations for an aquatic existence. Children can easily
collect water-bugs, which always add to the interest
of the lessons, and are instructive additions to their
own and the school cabinets.

NOTONECTID.

The back-swimming water-boatman, JVofonecta un-
dulata, Say (Fig. 70), is very common in our ponds.
Few insects are more interesting, and their
swift movements in water and oar-like use of
their legs are sure to awaken and fix the.

cautiously, and held by the thumb and fin-
gers applied to either side of their flat bodies,

their sharp beaks. Fig. 70.
The back of Notonecta resembles in shape the
bottom of a boat, and it is this part that cleaves the
water, the insect always swimming with its back down-
ward. The thoracic rings can be easily made out;
the metathorax is the largest segment and bears the
long, hairy swimming-legs which propel the animal
through the water. The insect carries air about with

I2I

122 HEMAIPT ERA.

it under its wings, which is used for respiration, and
which also helps to lighten the body, so that it rises
quickly from the bottom of the pond whenever it
loosens its hold of an object to which it may be cling-
ing and allows itself to float upward. Notonecta is
obliged to come to the surface frequently, as the
greater part of the air being under the wings comes
in contact with the water but little. Corisa, another
genus of water-boatman, has its body almost com-
pletely enveloped with air, which glistens like silver.
This air-film is constantly retained, and probably acts
as a tracheal gill, so that the insect is able to remain
under water a long time.’

BELOSTOMID.

The giant water-bug, Belostoma (Fig. 71), shows
several of the characteristic Hemipterous organs on
a large scale, and can be made very useful on this
account. The body is broad and flattened at the
edges. The head is remarkably small for such a large
insect, and the eyes take up a great part of it. At
first sight the antennz appear to be wanting, as they
are bent under and are entirely concealed by the eyes.
The position and unique structure of these organs
suggest some peculiarity in function, which can only
be ascertained with certainty by careful observations
of the habits of the animal. The sucking-tube is
short but strong, and with it the insect can inflict a
severe sting.

1 Comstock, American Naturalist, June, 1887, p. 577:

2 Children will be interested in an article on ‘ Fish-Destroy-
ing Bugs” by Dimmock in Zhe Swiss Cross for June, 1887.

a well
a
ey

HEMIPTERA. 123

The prothorax strengthens the head effectually, for it
takes the same downward curve, and moves in obedi-
ence to it and the fore-
most legs. On the lower
side it is hollowed out for
the first section of the
legs, which appear to be
attached to the neck in-
stead of the prothorax,
sO near are they to the
head. These legs are fit-
ted for catching and hold-
ing animals like small fish
and frogs. The tibia moves
upon the femur like the
blade of a penknife upon
its handle. This mode
of forming a claw for
catching and holding the
prey is characteristic of
the Insecta, and is in q
curious contrast with the Fig. 71.
very different mode of -
forming a similar weapon in the Crustacea. The
animal moving swiftly through the water seizes a
chub or other young fish, and holding it near the
neck inserts its powerful beak and sucks the blood.
It destroys great numbers of young fishes in the
breeding ponds, so that the Massachusetts Fish
Commissioners have been obliged to make extraordi-

* See Guide No. VIL, pp. 22-24.

124 HEMIPTERA.

nary efforts in order to trap and kill these destructive
insects.

The mesothorax with its chitinous scutellum and the
metathorax are similar to these parts in the squash-
bug. The upper wings are well developed, and for
class instruction a single specimen of Belostoma will
help the teacher in the way of making clear the pecu-
liarly formed Hemipterous wing.

The following families of Heteroptera are terres-
trial.

REDUVIID~.

The interesting “ wheel-bug,” Prionidus cristatus,
Linn. (Fig. 72, @), is found on the cotton plant
at the South, which it protects by destroying its ene-
mies. The prothorax has a huge cog-wheel crest
(see Fig. 72, 6). The sucking-tube is stout, and
blackened at its tip, indicating that it performs hard
work. ‘This is, in fact, true, as the animal is carnivo-
rous, thrusting the sucking-tube into the bodies of
insects, particularly of caterpillars, as shown in the

drawing, which forcibly illustrates the tragic side of —

insect life. According to Mr. Glover a young Prioni-
dus destroyed ten caterpillars in five hours.’ Fig. 72, ¢,
represents the eggs laid in a hexagonal mass and @ two
eggs magnified. A harmless-looking member of this
family, Opsicewtus personatus, is found in the Atlantic
states. It is from a half-inch to nearly an inch in length,
and black or dark brown in color. The prothorax is
strongly constricted in the middle, rounded in front,
and has a prominent groove on the middle line.

1 See Rep. on Cotton Insects, Dept. Ag. 1879.

Comstock states, on the authority of Dr. Le Conte,
that this insect stings with its beak when incautiously
handled, and the pain and swelling may last for a long
time. The Hemiptera can always be handled safely

HEMIPTERA 125

Fig. 72.

by holding them by their two sides between the thumb
and forefinger so that they cannot use their beaks.
The species, as a rule, however, are not dangerous.

COREID.

The squash-bug, already described, is a representa-
tive of the Coreide.

126 HEMIPTERA.

.PENTATOMID.

The members of this family have a large scutellum.
The soldier-bug, Podisus spinosus (Fig. 73, 6), has a
sucking-tube (@) used for piercing animals and plants.
It devours the potato-beetle and currant-worm.

SCUTELLERID:.

The scutellum in this family is remarkably devel-
oped (see Fig. 74); it has, in fact, grown out and
covered the wings and abdomen. In the drawing the
wings (z', w'’) have been drawn to one side. This
extraordinary scutellum is sometimes mistaken by the
superficial observer for the wing-covers of a beetles —
It will be observed, however, that it is the homologue
of the undivided but small scutellum of the beetle,
and like that it has no central, longitudinal suture.

The following examples cannot be considered as
complete parasites, but they are nevertheless degraded
forms, and their habits and structures present transi-
tions to true parasites like the lice. They do not lay
their eggs upon or in the bodies of other animals, but
they visit them for the purpose of obtaining food by
their own efforts. The effect of this intermediate

- HEMIPTERA. 127

condition is shown in their forms, wingless bodies, and
habit of concealing themselves in bed-clothing, etc.,
instead of flying and hunting freely.

CIMICIDE.

The bed-bug, Crmex lectularius, Linn. (Fig. 75, £),
has a flattened body. The
head is small, with com-
pound eyes, but no ocelli.
The mouth parts are well
developed.’

The fore part of the pro-
thorax (4') is scooped out
for the reception of the
head, so that its sides may
extend forward to the eyes.
The connection of the pro-
thorax with the mesothorax
is neck-like, allowing con-
siderable freedom of motion to the prothorax and
head. The portion of the small mesothorax (6!)
that is seen from above is triangular in shape, and
bears the remnants of fore-wings (Fig. 75, w!) which
are merely scales. ‘The form and position of these
scales is quite different from anything before described.
They broaden out towards the median line instead of
extending backward, and are placed close to the body,
so that at first sight they appear to be the metathorax.
They really cover the metathorax, which is crowded

1 For figures of these organs, see Graber, Die dusseren me-
chanischen Werkzeuge der Wirbeltiere, 1886,

128 HEMIPTERA.

closely against the mesothorax. In Fig. 76 (4%) the
scales have been removed, showing the extremely
small metathorax (6!)
which has lost its wings
and seems to be disap-
pearing altogether. In
hot countries some
species are found pos-
sessing wings, but in our
climate the true wings
Pie oe: are wanting, and the
wing-covers are, as we
have seen, tiny scales. The anterior portion of the
first abdominal ring (marked c’) is light-colored, being
covered by the scales (Fig. 75, zw’); the posterior por-
tion (Fig. 76, ¢c’) is unprotected, and is darker.

These disagreeable insects are found in houses where
they attack other insects as well as man, while they are
preyed upon, in their turn, by the cockroach. ‘They
are said, also, to occur in chicken-coops and pigeon-
houses, but their existence in a wild state is considered
doubtful by Comstock. This author recommends
travellers to use Pyrethrum powder strewed between
the sheets in suspicious lodgings.

PARASITICA.

The following are examples of still greater changes
in habitat. The animals find shelter and food either
partly or wholly upon the bodies of other animals,
and may properly be called parasites.

;

HEMIPTERA. 129

PEDICULID.

_ The division Pediculina, represented by the fam-
ily Pediculide, is regarded by Packard and Com-
stock as a subdivision equivalent to the sub-order of
Heteroptera or Homoptera. These insects are repre-
sented by the parasitic lice, occurring on the bodies
of mammals, including man. Fig. 77 is the human
louse (Pediculus capitis, DeGeer), in-
habiting the head. In these insects
there are two simple eyes. The tho-
racic sutures have become indistinct,
although, according to Uhler, they can
always be made out by means of stain-
ing-fluids. ‘This being the case, these
insects cannot be compared with sim-
ple adult forms like Campodea, Lepis-
ma, and the like, or with larval forms
like the larval locust, for in these the
thoracic sutures are distinct. ‘They are probably in-
sects allied to the bed-bugs, that have become special-
ized by reduction resulting from parasitic habits. They
have lost not only their distinct thoracic sutures, but
also their faceted eyes and their wings, while the feet
have taken on characters adapting them for clinging
rather than leaping or running. ©

The human-body louse (/ediculus vestiment) has
several varieties, which agree in coloration with the
different races they live upon. ‘The one which infests
the Caucasian race is yellowish, tinged with gray ; that
of the West African and Australian is nearly black ;

Fig. 77.

130 HEMIPTERA.

of the Hindoo, dark and smoky; of the Africander
and Hottentot, orange ; of the Chinese and Japanese,
yellowish brown; of the Indians of the Andes, dark
brown ; of the Digger Indians of California, dusky
olive ; of the more northern American Indians near
the Esquimaux, paler, approaching to the light color
of the parasites of the European.!

1 See Comstock, /rtrod. to Ent., p. 131, in which also other
species that infest cattle, horses, etc., are mentioned and figured.

HOMOPTERA.

CICADIDE.

AN instructive lesson can be given on the Cicada,
or harvest-fly (Fig. 78, nat. size). ‘This insect is often
erroneously called the “locust,’’ owing, probably, to
its habit of appearing in large numbers. The head
(Fig. 78, A) is broad and triangular, with the apex of
the triangle turned backward. It has two prominent,

widely separated eyes (ey) and three bright ocelli
(not clearly shown in the drawing). ‘The large, light-
colored neck is entirely concealed, the chitinous head
being set firmly against the hard prothorax, so that
the cheeks and projecting eyes form a hollow on each
side for the reception of the coxe of the first pair of

131

132 HEMIPTERA.

legs. Lateral motion is reduced, in this way, to a
minimum, as such motion would be of little service
to a sucking insect. The thoracic region is devel-
oped at the expense of the abdominal. ‘The pro-
thorax (Fig. 78, 4’) overlaps the forward part of the
mesothorax, but is not consolidated with it. The
huge mesothorax (4) bears the large, active fore-
wings, and contains the great mass of muscles that
moves these organs. ‘The posterior edge of this ring
is stiffened by chitinous bars. ‘The letter W, conspic-
uous on the mesothorax, was formerly supposed to
stand for the word War, and the appearance of the
insect was dreaded by superstitious people. These
peculiar markings are now thought to be due, very
largely, to internal causes.’ The metathorax (4'"’) is
reduced to a narrow ring, dorsally, and it bears the
small hind wings. The connection of the abdomen
with the thorax is broad.

The note of the male harvest-fly is produced by
means of the apparatus on the lower side of the
base of the abdomen. If the membranous folds that
extend backward over the first abdominal ring are
lifted, two cavities are exposed, bounded on their
posterior side by brilliant, iridescent plates. Strong
internal muscles connect with this apparatus, and by
their contraction and relaxation the sound is_pro-
duced. In the female this apparatus is not devel-
oped, and she is, consequently, voiceless.

The antenne (Fig. 78, a) are bristle-like. The

1 See “On the Color and Pattern of Insects,’ Hagen, Proc.
Amer. Acad., Vol. XVIL., p. 234, April, 1882.

a ;

HEMIPTERA. 133

sucking-tube with its piercers is a strong organ. We
have already shown (see p. 118) how helpful these
mouth parts may be in the lesson on the squash-bug.

Both pairs of wings are membranous throughout,
differing from the fore-wings of the squash-bug in this
respect. When at rest they slope roof-like at the
sides of the body.

The development of the insect is direct. The life-
history of the different species, that take respectively
seventeen and thirteen years to pass through their lar-
val stages, is familiar." There are other species in
New England which pass through their metamorphosis
in one or two years. Fig. 79 is, probably, the larva of
Cicada ftibicen, a_ species
which is found quite abun-
dantly in the pupa and imago
state in Massachusetts. The
larva is grub-like: the rings
(4', o") are large like those
of the adult; and the meta-
thorax (6'") is more distinctly
seen. ‘The peculiar thoracic
markings of the adult are not
yet developed. ‘The fore-legs
(7') are strong, claw-like implements, by means of
which the larva digs its way out of the earth. If the
young seventeen-year Cicada is examined just after
hatching from the egg, these organs are seen to be
already formed, and their tips colored. In this case

1See American Entomologist; also Riley, The Pertodical
Cicada, Bulletin, No. 8, Dept. Ag. 1885; Riley, Report a the
Entomologist, Dept. Ag. 1885.

ist HEMIPTERA.

the color must have been inherited, though it was
doubtless first produced in the ancestors by hard
work.

Fig. 80 is the imago emerging from the pupa skin.
This transformation can be easily
watched by the young, and speci-
mens illustrating different stages
in the process can be collected
by them in the summer time,
preserved in alcohol or dried, and
brought to the school in the au-
tumn for use in the Natural His-
tory lessons. ‘The prevailing
color of the wings and legs of
the emerging Cicada is at first
green, though the hooks and
spines of the legs are brown.
White tracheal threads, similar in
appearance to those of the pupal dragon-fly, extend
from the inner side of the pupa case. ‘The wings
are soft and pliable. They are extended slowly to
their full length, and in the specimens observed were
not moved upward and downward. Some time is
required for the cuticle of the insect to acquire its
normal color and rigidity. One that left its pupa
case at 1.40 P.M. had not taken on completely the
dull hues of the adult at seven o’clock in the evening.
The pupa sometimes clings to the lower side of a
twig, and goes through its transformations with the
back downward like some of the dragon-flies.

|
|
|
|
|
|
|
|

|
|
|

Fig. 80.

HEMIPTERA. — 135

APHIDID.

Specimens of Aphis can often be obtained on house-
_plants. They have bodies as green as the vegetation
upon which they feed, so that those who attempt to
destroy them soon find out that their color is a means
of protection. Fig. 81 represents a mature winged
female. The rings of the thorax are not fused to-
gether, but can be seen distinctly under the micro-

scope. The wings, as in other insects, are attached
to the mesothorax and metathorax.' Fig. 82 is a
wingless and larval female in which the thoracic re-
gion is slightly differentiated from the abdominal, hav-
ing three distinct segments.

The antenne in both forms are long. The sucking-

1 Distinguished entomologists have said that both pairs of
wings are attached to the mesothorax. This is probably an
error due to the concentration of the rings of that part of the
body in some of the smaller species. Properly prepared micro-
scopical preparations should be made if teachers wish to dem-

onstrate this fact.
ta

‘
’
. ne

136 HEMIPTERA.

tube in the wingless female, Fig. 82, is chitinous at
its extremity. The legs are similar in structure.
The abdomen in both forms bears
two tubes, from which the sweet
liquid, or “ honey-dew,” exudes. Ants
feed upon these sweet excretions, and
have also learned to keep the Aphides
and to take care of them in their nests.

The plant-lice are good illustrations of that process
of reproduction known as parthenogenesis, or the pro-
duction of living forms without the intervention of the
male. The sexually perfect males and females are
born usually in the autumn. After pairing, the males
die, but the females do not die until they have laid
their eggs. In the spring these eggs, which are often
spoken of as true ova because they are fertilized,
hatch ; but the offspring are usually wingless females
which are able to feed immediately after birth. These
females are not sexually perfect in structure, and have
therefore been called “ agamic.”’ They do not pro-
duce true eggs, but in many cases they are vivipa-
rous, or, in other words, bring forth living young, which
feed on the milk excreted by the parent until strong
enough to pierce the bark or leaves and suck the
juices of the plant on which they live. ‘This genera-
tion is either wingless or winged or both, but the
number of winged forms is limited ; they are agamic
individuals which can migrate and found other colo-
nies. Besides these viviparous forms, there may be
agamic individuals in the same colony which pro-
duce egg-like bodies (pseudova), from which the

Fig. 82.

1 For fyrther remarks, see p. 240 of this Guide.

a

HEMIPTERA. 137

young are afterward hatched, or in place of these
pseudova, the young may be enveloped at birth only
by a thin pellicle, which they immediately burst.

Many broods are produced during the warm weather.

The last brood is brought forth at the approach of
cold weather, and differs from the preceding in being
largely made up of perfect males and females." Some
of the agamic individuals may survive through the win-
ter and reappear in the spring.

It has been proved by experimentation that Aphides
can be kept ina room maintained at a proper heat for
four years, and in the case of the two species tried,
no sexually perfect males and females were hatched.
The failure of proper nourishment, even in warm
weather, may be the cause of the premature produc-
tion of a sexually perfect generation. Thus the per-
petuation of the species is secured not only by the
winged agamic members of the community, but, in the
event of a failure of food through any cause, drought,
etc., even in warm weather, or in case of danger aris-
ing from the approach of cold weather, still further
security is provided in the generation of sexually per-
fect males and females, the latter of which produce
true ova. The Aphides can be easily kept in the
schoolroom and studied. They are found on neg-
lected house-plants, and are often crowded together in
great numbers upon the leaves and stems. Their hab-
its and characteristics are not difficult to observe, and
a little care and patience will produce results which
will amply repay both teachers and pupils.

1 For drawings illustrating the development of Aphis, see

Huxley, 7rans. Linn. Soc., London, Vol. XXII.; also Com-
stock, Jntrod. to Entomology, p. 155.

138 HEMIPTERA.

Phylloxera, an interesting genus, has been studied,
and the life-history of several species admirably worked
out by Dr. C. V. Riley.’ These are pests of the grape-
vine, and for those living in favorable localities this
form might be advantageously studied.

The tree-hoppers are very curious little insects,
frequently brought in by children. ‘The body is com-
pressed and thin, having sometimes a triangular appear-
ance, due to the very broad prothorax, which extends
backward in an extraordinary way, often covering a
large part of the body, and sometimes forming horns
or humps. )

COCCIDE.

The female of the scale insect is an instructive
example of specialization by reduction, while the male
imitates the flies in some characters. The process of
reduction is carried so far in the female of some spe-
cies that all trace of segmentation is lost. Fig. 83, a,
is the scale or female of Lecanium found on the
maple; Fig. 83, 4, the same species, occurs on the
Osage-Orange. In the Report of the Entomologist
for 1884 (see also American Naturatst, June, 1885,
pl. xvii.), Riley has figured the egg, larva, female
scales, and adult male and female of this species,
under the name of Pulvinaria innumerabilis. This
entomologist has also observed the development of
Aspidiotus conchiformis?

1 Sixth and Seventh Reports Noxious and Beneficial Insects
of Missouri, 1874-75.

* For figures, see Packard’s Guede to the Study of Insects, p.
529:

HEMIPTERA. 159

The larva is active; its body is ringed, and bears
a pair of antenne, three pairs of thoracic legs, and
caudal appendages. In about three days the larva
becomes fixed, and eleven days afterward has lost all

‘
i

AS
| 4
4 \ \ ;
J

Fig. 83.

power of locomotion, the thoracic legs, together with
the antennz having disappeared. ‘The scale is con-
structed in its outer part of the moulted skins of the
animal which are not cast off, but are retained in place
and held together by a gummy excretion, The eggs

140 HEMIPTERA.

are laid under this scale, the body of the mother
diminishing in size to make room for them. Finally
the dried and shrunken remains of the body are added
to the scale in the interior, which, thus completed,
becomes an efficient shelter for the eggs and young
larvee when hatched. ‘These facts are as impressive
and remarkable as any that have ever come within the
observation of naturalists. Nevertheless they can be
observed, and the different stages collected by chil-
dren. It is not difficult to see on the under sides of
the scales the remnants of the abdomen of the mother,
whose body has thus been transformed into a house
for the protection of her children.

The early larval life of the male is similar to that of
the female, according to Comstock.’ Both lose their
antenne and legs with the first moult, and the second
(the last in the female) occurs at the same time. The
metamorphosis of the male, however, is indirect.
After remaining quiescent for a time, it casts its skin,
and the adult that appears after this last moult posses-
ses antenne and legs, and is a perfect form. It, how-
ever, has one peculiarity which may mislead the young
observer, and cause him to think it a member of
another order, the Diptera. It has but one pair of
wings, and, like the flies, the hinder pair have become
reduced to a pair of minute, elongated appendages.
These consist of two club-shaped organs called “ hal-
teres,” each furnished with a club-shaped bristle
which fits into a pocket on the anterior wing of the

1See An. Rep. Dept. Ag., 1880; also, Second Rep. Cornell
University Experiment Station, 1883; Introduction to Ento-

mology, pp. 134-155.

HEMIPTERA. 141

same side. The aspect of the head and body and of
the fore pair of wings and the halteres is quite distinct
from those of the Diptera, and the more careful
observer readily recognizes that the insect belongs to
the Homoptera. Such resemblances in the form of
the body and its organs are not infrequent in the
animal kingdom between animals belonging to widely
different stocks, and are spoken of as representative,
parallel, or homoplastic forms.

The only function of the male is reproduction ; he
does not, therefore, eat anything, and the useless
mouth parts are lost. This singular creature has also
another remarkable peculiarity, the lost mouth parts
are replaced by an additional pair of eyes.

The mealy bugs, Dactylopius, so common on green-
house plants, do not lose the power of locomotion, and
in place of the scale the body is often covered with a
cottony excretion. The cochineal bug, Coccus cach,
is anative of Mexico. The well-known dye is made
of the female insects which are killed and dried.
Lake and carmine are also prepared from cochineal.

The lac-insect, Carteria acca, is obtainable in
what is called stick-lac. This substance is composed
of the twig and incrustation made up of the gummy
resin of the plant, the scales of females, and the bodies
of their young. The females pierce the plant and the
resins that exude make the scale more effectual as,
a protection for the eggs, and also answer as food for
the larvee. Shellac, the well-known varnish, is made
from the incrustations of stick-lac.

1 Comstock, Jtrod. to Entomology, p. 138, and Report for
1880.

142 HEMIPTERA.

The Hemiptera include all the true bugs. They
live, as we have already seen, both in the water and
on the land, and, therefore, present a greater diver-
sity of structures than is observable among the Or-
thoptera. They feed upon the juices of plants or
animals, and are provided with a sucking-tube. In
the Hemiptera the connection of the abdomen and
thorax is not constricted, and no waist is formed.

The less specialized group, Heteroptera, have flat-
tened bodies with two pairs of wings. The first pair
is coriaceous or horny at the base, and the lower por-
tions membranous. They lie flat on the back when
folded, and the lower parts overlap. The head is
usually more or less acute except in Notonectidz
and Coriside, and the beak arises from the forward
part.

The more specialized group, Homoptera, have two
pairs of membranous wings (except the males of the
Coccidz) which are of uniform thickness. ‘They lie
in a sloping position, like the sides of a roof. The
head is usually more or less obtuse or blunt, and the
beak arises from the hinder part of the lower side.

The Heteroptera have more direct development
than the Homoptera, but the larvz are very distinct
from the Thysanuroid type in both of these divisions,
on account of the early development of the sucking-
tube, and the prevalence of a broad, oval body.
Nevertheless, in many species the larvee have very
generalized proportions in the development of the
thorax and abdomen, reminding one of the larve of
cockroaches. Brauer, Packard, and Lubbock have
shown that the sucking-tube could have been derived

HEMIPTERA. 143

from biting mouth parts. This form of the larva,
therefore, probably arose from Thysanuroid-like an-
cestors having the usual form of mouth parts, but the
excessive acceleration of development in forms of
later occurrence has brought about the loss of all the
transitional characteristics, and all traces of this origin
are now skipped or left out of the stages of growth
in the development of the mouth parts of existing
species.

There are several groups of the Heteroptera in
which the development is more or less accelerated
in other respects, the Thysanuriform stage of larval
growth being abbreviated or perhaps absent, so far as
relates to the equal proportions of the thoracic rings.
The larvz,in other words, like those of the more
specialized groups of Orthoptera, mentioned above,
resemble their own adults, the ancestral Thysanuriform
stage being either wholly or in large part skipped.

The larval forms and adults of Homoptera present
greater departures from the generalized type of Thy-
sanura than those of the normal Heteroptera. The
curious similarity between the wings and halteres of
the adult males of some of the Coccidz (scale in-
sects) and the same organs of Diptera is a notable
example of this divergence, and is also one of the
most remarkable examples among insects of the in-
dependent origin of similar characteristics in different
orders, as has been stated above.

The extraordinary larve of the Cicadas, which Dr.
Packard regards as the most highly specialized of the
Hemiptera, are certainly in many respects very wide
departures from the Thysanuroid standard. They are

at HEMIPTERA.

also very interesting on account of the length of time
spent in the ground by some species while passing
through the larval stages, and also because there is a
certain resemblance between the aspect of their larvee,
which are really hexapod grubs, and the grubs of
some Coleoptera having similar burrowing habits. In
consequence of this habit the development is highly
accelerated and there is no Thysanuriform larval stage,
this last having been replaced in the development by
adaptive, grub-like stages similar to those common
among beetles.

('Gp] eded Suioe4)

Sonu. LOLROPTERA:

THE reasons for giving the order Coleoptera ics
position in the classification, as shown in Diagrams
I-III., are stated on pp. 165-169. ‘The group of
Coleoptera genuina shows the relationship of the
order to the Thysanuran insects more plainly than the
more specialized group of weevils.

The Coleoptera are so abundant throughout the
United States that teachers will find but little diffi-
culty in obtaining specimens. We have chosen as a
type the common May-beetle, Lachnosterna fusca,
Frohl (Pl. VI., Figs. 84, 85, enlarged, p. 145), usually
called the May-bug, June-bug or Dorbug, though there
are others equally good. Even the potato-beetle (Fig.
gI, p. 150) can be used when larger species are not
at hand. In the last of May or first of June scholars
should be encouraged to collect specimens of May-
beetles. The insects are attracted by lights in the
evening, and in seasons when they are very abundant
a large number may sometimes be obtained under
electric lights, and in this way a class can be pro-
vided with the necessary material. ‘The mature pupz
are often found by spading and by following the plough
in the spring of the year.

The insect is dark brown in color, with many little
pits or depressions on its back. The head (Pl. VL,

145

146 COLEOPTERA.

Fig. 86, A, p. 145) is the smallest region of the body,
apd can be withdrawn beneath the prothorax so far as
the eyes (see Pl. VI., Figs. 84, 85). It is noticeable
that many insects which are not provided with large,
claw-like implements for digging, often have the head
small, and the posterior part of the body broad, givy-
ing a more or less wedge-shaped form which serves
the creatures well when burrowing in the earth. The
prominent clypeus (Fig. 85, cZ) projects like a visor
over the face. The compound eyes (Fig. 84, ey) are
small, and there are no ocelli. The prothorax (PI.
VI., Fig. 86, 6’) is large and movable. The small
mesothorax (Fig. 86, 6’), with its short scutellum
(4s”), and the large metathorax (Fig. 86, 6’) are
firmly consolidated. The metathorax is complex in
structure, being made up of chitinous and membra-
nous portions. Pl. VI., Fig. 87, is a front view of the
ring; 7 is the scutum; 4°, the scutellum; e, the
fleshy membrane. ‘The tiny plates (y) are horny, and
are seen in the dorsal view (Pl. VI., Fig. 86, 4’, y).
The abdomen (Fig. 86, C) is shortened and pressed
forward, as it were, to make a close and broad con-
nection with the thorax. Compactness or concentra-
tion of parts, as compared with the more generalized
insects, is an important characteristic of the beetle’s
body, and it is most marked in the thoracic region,
which bears the locomotive organs. The upper mem-
brane of the abdomen, like that of the squash-bug,
is protected by the thick wings, and not being con-
tinually exposed to external forces is, therefore, soft
and flexible. This flexibility aids greatly in respira-
tory movements, the terga rising and falling, while the

COLEOPTERA. 147

- chitinous sterna move but slightly. On the sides of
the abdomen the spiracles are distinctly seen.

The jointed antennz (PI. VI., Fig. 86, a7) are ter-
minated by three leaf-like plates, and this peculiar form
has given the name of Lamellicorns to all the beetles
belonging to the family Scarabeeide. ‘These appen-
dages assume many remarkable and unique forms
among beetles, as will be seen by reference to any
illustrated work on Coleoptera. The mouth parts are
formed according to the Orthopterous type, consisting
of a pair of mandibles (Fig. 86, md), and two pairs
of maxille (Fig. 86, mx', mx''). They are strong
organs, although much smaller than those of the
locust. The three pairs of legs (Fig. 86, 7’, 2", 7") are
stout, and so well fitted for running that the beetle
takes the same position among runners that the locust
holds among leapers, or the dragon-fly among fliers.
The two legs of the last pair are placed far back on
the thorax, and at some distance from each other.
Scholars should be encouraged to find out how these
insects use their legs in running. A figure by Graber?’
shows one in the act; the fore and hind legs on one
side of the body, and the middle leg on the other, are
put out first, and afterward the other three legs, so
that the two sets act alternately.

The hard wing-covers, or elytra (Pl. VI. Fig. 86,
w'; Figs. 84, 85, w'), stiffened by chitine, bend down-
ward at the sides and back so as to enclose the true
wings (Fig. 86, zw''). This peculiar structure is used
to distinguish the order, Coleoptera (xodéos, sheath ;

1 Die Insekten, Part I., p. 161; copied by Packard, Manual
of Zodlogy, fifth ed., 1886, p. 327.

148 COLEOPTERA.

mrTepov, Wing) or sheath-winged insects. These elytra
are but little used, and the mesothorax is correspond-
ingly small and narrow. ‘They extend outward on
either side, at right angles to the body when the in-
sect is flying, and their form and weight is one cause
of the beetle’s clumsy motions in the air. The chiti-
nous character of the wing-covers is constant, and en-
ables scholars to recognize quickly the members of
this order of insects. The true or hind pair of wings
(Fig. 86, zw") are active in flight, and are well devel-
oped like the metathorax that bears them. When not
in use they are neatly folded over the abdomen by
means of a joint in the large anterior vein. The abdo-
men does not bear an external ovipositor. The meta-
morphosis of this insect is indirect. Lintner’ has
shown that our knowledge of its life-history is far from
satisfactory. ‘The eggs are probably laid in the earth,
the female burrowing by means of the wedge-shaped
head and first pair of legs.

The larva or grub (Pl. VI., Fig. 88) leaves the egg in
avery immature condition. Its body is white in color,
cylindrical in form, and the thoracic and abdominal
rings resemble each other. ‘These are creased in such
a way that the apparent number of rings is much
greater than the real number. ‘The posterior part of
the abdomen is curved under the body, which indi-
cates that the insect does not crawl on a level surface
like the caterpillar, but moves about surrounded by
earth, or lies quietly upon its side. So strongly fixed
is this habit of lying upon its side, that when the grub

1 See “The White Grub of the May-Beetle,” Bull. N. Y.
Mus. Nat. Hist., No. 5, 1888.

COLEOPTERA. 149

is taken from its habitat and placed on some earth in
a pan it still keeps this position.

The mandibles and maxille are fitted for biting, and
the three pairs of legs are short and stout. The larva
lives in the soil for two or three years, feeding upon
the roots of grass, strawberry vines, corn, grain, etc.
(see Fig. 88), sometimes doing great injury to these
plants. It then makes an oval cavity in the earth, by
moving from side to side, and lines it with a secretion
from the body. ‘This answers for a cocoon (PI. VI.,
Fig. 89) in which the pupa (Fig. 89; Fig. 90, pupa
taken out of the cocoon) remains quiescent. In this
condition the legs are free, and the antennze and wing-
pads are distinctly seen. The insect in this period
of repose becomes fitted for the very different life of
a winged animal. Its body shortens, the thoracic rings
become differentiated from the abdominal, and the
antennz, mouth parts, legs, and wings assume their
adult proportions. In May the imago appears, and
at once begins to feed upon the leaves of trees and
shrubs, particularly of the cherry.

CHRYSOMELID.

The Colorado potato-beetle, Doryphora decem-
lineata (Fig. 91, d, @), is similar in structure to the
May-beetle. Within twenty-five years this insect has
spread over an area of 1,500,000 square miles. Spec-
imens can be obtained in great numbers from the
potato-vine. Fig. gt, f, is the leg of the beetle ; and
Fig. gt, e, the wing-cover. ‘The latter has alternating
stripes of brown and yellow, while the true wings be-

150 COLEOPTERA.

neath are a beautiful rose color. The eggs (Fig. 91, a)
are laid on the lower side of the leaves of the potato
plant. The larva (Fig. 91, 4, 4) is a short, thick-set
grub, with a dark-brown head, and a prothorax some-
what stiffened by chitine. The remaining thoracic and
abdominal rings are fleshy. This larva burrows into
the ground and there changes to the pupa (c). In less

than a month from the time the eggs are hatched the
beetle has passed through its indirect metamorphosis.
Two or three broods are produced in a season, and
the last brood remains underground during the winter.
The home of this beetle was originally among the
Rocky Mountains, where it fed upon a wild species of
potato. Afterward it acquired a taste for the culti-

COLEOPTERA. 151

vated species, and followed the crop easterly. It is
interesting to note that a very closely allied beetle,
Doryphora juncta, refuses to feed upon the cultivated
potato.

SCARABAEID/.

This family includes besides the May-beetle, which
we have used as a type, the goldsmith beetle, Coza/pa
fanigera, Linn., the familiar ‘‘ rose-bug,” MWacrodactylus
subspinosus, Fabr., and the Scarabeus, sacred to the
ancient Egyptians. Some of the largest beetles be-
long here, as the Dynastes hercules from South Amer-
ica. ‘The male of this species measures about six
inches in length, and it has an immense horn extend-
ing forward from the prothorax, and another from the
head, so that it has a really formidable aspect. Many
of the males of the Lamellicorns have stag-like horns,
which are greatly reduced in size in the female.
Darwin' has given figures of several genera showing
the difference in the size of these organs in the two
SEXES.

LAMPYRID.

Fig. 92, a, is one of our common fire-flies, Photuris
Pennsylvanica; Fig. 92, 6, the larva of another species
of Photuris. ‘The luminous organs are situated in the
abdomen. According to Westwood, the egg, larva,
and pupa are all luminous, though the light is brightest
in the mature insect. There are various views in
regard to the cause of phosphorescence, but it seems
probable that the light-giving organs have the power

1 The Descent of Man, Vol. I., p. 358.

152 COLEOPTERA.

of secreting a substance which becomes luminous
when acted upon by oxygen. ‘The supply of this gas
is probably provided by the trachez, if this theory is

Fig. 92.

correct. Dimmock has observed that when one sex of
any species of Lampyridz is more luminous than the
other, the less luminous sex has, as a rule, the best
developed eyes. This fact may throw some light on
the origin of the phenomenon of phosphorescence.
The male and female of the species mentioned above
have wings and elytra, but the females of some genera
in this family do not possess these organs, and they
are commonly called “ glow-worms.” Fig. 92, ¢, rep-
resents a glow-worm of the genus Lampyris.. The
females of such species do not develop beyond a
modified larval stage. While the reproductive system
fills out its cycle of growth and development, the

COLEOPTERA. 153

form and some of the parts of the body of the in-
sect remain fixed, retaining more or less of the con-
dition and aspect which characterized the caterpillar-
like larva.

DERMESTID.

The Buffalo-beetle or “ carpet-beetle,” Anthrenus
scrophularie (Fig. 93, 2), appeared in New England

Fig. 93.

in 1872. The beetle is about one-twelfth of an inch
long, and is black with white and brick-red markings.
The distinct thoracic and abdominal rings of the larva
(Fig. 93, @) are supplied with tufts of hair, and from
the posterior part of the abdomen there extends back-
ward a long brush of delicate hairs. This hairy appear-
ance, together with the fact that the insect was first
found injuring carpets in Buffalo, N. Y., suggested the
name of Buffalo-beetle. The short legs are beneath,

Lo COLEOPTERA:

though not seen in the drawing. This larva attacks
many household articles, but is especially fond of
carpets and woollen garments. No preventive is more
effectual than repeatedly shaking these garments. The
larve, unlike those of the clothes moth, do not cling
to the goods, but fall and can then be killed. Benzine,
kerosene, naphtha, boiling water, and corrosive subli-
mate’ can be used for killing the larvee.

The metamorphosis is indirect. Fig. 93, 4, is a
dorsal view of the pupa with the split larval skin sur-
rounding it; Fig. 93, ¢, a ventral view of the same
removed from the skin. After casting the pupa skin
the beetles leave our houses and feed upon the pollen
of plants, notably of Spireeas, after which the females
return and lay their eggs. The beetles do some dam-
age, although but very little as compared with the
larvee.

The family Dermestidze includes many insects
destructive to entomological collections. Teachers
sometimes find their specimens badly eaten, and the
bottom of the insect boxes covered with a fine dust.
To prevent such attacks, camphor gum, benzine, tur-
pentine, or, better than these, disinfecting cones, made
chiefly of naphthaline, should be used. ‘These cones
are manufactured in Philadelphia and sold among tax-
idermists’ supplies. Small, uncorked bottles of bisul-
phide of carbon can be placed in the collections, and
the liquid allowed to evaporate. This will kill every
living thing, whether in the form of an egg, larva, pupa,

1 This is a dangerous poison and can be used effectively and
safely only by persons of experience,

COLEOPTERA. 155

or imago. Care, however, must be taken in using
this liquid, as it is explosive when mixed. with air,
while being evaporated, and also poisonous. It is,
however, extensively used, and with proper precau-
tions it can be employed more effectively than any-
thing else, especially in large collections.

COCCINELLID~..

The “lady-birds,” or ‘lady-bugs” (Fig. 94), are
common, and are great favorites with young
children. ‘Their small round bodies with
little, short legs, their brilliant spots and
pretty patterns, make them attractive insects
in spite of the disagreeable odor which they
sometimes give out as a means of protec-
tion. They pass through an indirect metamorphosis
like other beetles. The larva is provided with three
pairs of legs, and when ready to transform, fastens
itself by its abdomen to a branch, leaf, or some other
object.

GYRINID.

If these water-beetles are kept in the schoolroom,
their rapid circular movements on the surface of the
water, which have given them the name of whirligigs,
their motionless resting-periods, and their power of
diving to escape from danger, can all be observed.
When seen from above they do not appear at times
to’ have locomotive organs, yet, when looked at from
below, the legs are broad and paddle-like. These
insects can look downward into the water and upward

156 COLEOPTERA.

into the air ; for their eyes are divided in such a way as
to make them appear to have one pair on the lower
and another pair on the upper side of the head. ‘They
breathe air, carrying it with them into the water in a
curious way. ‘They take it, as they dive down, in the
shape of a bubble on the end of the abdomen, and
usually remain at the bottom only a short time. In
the Hydrophilidz the air is attached to the hairs on
the lower side of the body, and looks like a film of
silver. This is a purely mechanical effect and may be
successfully imitated by plunging into water a piece
of cloth with a long nap.

Fig. 95 is the larva of a European species of the
genus Gyrinus. Each segment of the ab-
domen bears a pair of respiratory organs.
When ready to pupate, the larva leaves the
water and spins a cocoon. Dineutus con-
tains larger species than Gyrinus, and can
easily be obtained for class work. In the
family of diving-beetles, or Dytiscidz, the
larvee have mouth parts quite different from
those of most beetles. The mandibles are
hollow, and liquids are sucked up through
them. By this remarkable modification a
mandibulate insect has rendered its biting-organs suit-
able for a diet of liquid food.

CARABID.

One of the best places for collecting ground-beetles
and their larvze is under stones on the banks of rivers.
The family is a very large one. Harpalus caliginosus,

COLEOPTERA. 157

Fig. 96, is acommon form. This beetle, like most of
the Carabide, is carnivorous, although not exclusively
so, as it has been seen eating the
seeds and pollen of plants. The
legs are long, and the insect is a
good runner.

The Cicindelide, or tiger-beetles,
resemble the Carabidz, though the
family is not so large. They are
found in sandy places. The man-
dibles are strong and armed with
teeth, unlike those of the ground-
beetles. These insects are faster
runners and swifter fliers than most other beetles.

Fig. 96.

PARASITIC .COLEOPTERA:

The two following families of Coleoptera show the
effects of specialization by reduction, resulting from
the parasitic habits of the larva or adult.

MELOIDE.

The Meloidz are often described as “oil” or
“blister ’’ beetles, owing to the cantharidine contained
in their bodies, which formerly was largely used in the
preparation of blister plasters. The life-history of
these beetles is instructive, as many of their larve are
parasitic and undergo important structural changes.
Pl. VIL., Figs. 97-113, p. 158, illustrating the life-his-
tory of Epicauta, are taken from the First Annual
Report of the U. S. Entomological Commission, 1877.
The beetle, Epzcauza vittata, Fabr. (Pl. VIL., Fig. 113),

158 COLTRUTIE KA,

is a long, narrow insect with the prothorax rounded and
freely movable. It does not look very unlike other
beetles, but its development is remarkable. Accord-
ing to Riley it lays its eggs (Pl. VII., Fig. 97) in the
ground, usually near the egg-pods of locusts. In about
ten days the larva, known as the triungulin (PI. VIL.,
Fig. 98), hatches, and is at first weak and colorless,
but soon becomes light brown in color and very ac-
tive. The head (Pl. VII., Fig. 99) is provided with
antenne (a7), mandibles (md), and palpi (+, x"’).
The legs (Pl. VII., Fig. roo) are long and well armed
with spines. This larva burrows through the mucous
neck of a locust’s egg-pod (Pl. VII., Fig. ror ; /, the
larva), and sucks out the contents of one of the eggs.
In time the skin splits along the back, and the second
larva (Pl. VII., Fig. 102) appears with the legs much
reduced in size. Pl. VII., Fig. 103, is the antenna;
Fig. 104, the maxilla ; and Fig. 105, the leg. The dif-
ference between this leg and that of the first larva
(Fig. 100) is striking. ‘Pl. VII., Fig. 106,16 4 aige
view of the larva, showing its natural position within
the egg-pod. The last stage of the second larva is
represented in Pl. VII., Fig. 107. It now leaves the
pod and forms a cavity in the earth, in which it lies
motionless, and is known as the coarctate larva or
pseudo-pupa (Pl. VIL, Fig. 108, with the skin adher-
ing behind; Fig. 109, dorsal view of the same; Fig.
110, head, from the front). The legs (Pl. VII., Fig.
T11) in this stage are little more than tubercles. The
insect usually hibernates in this condition. In spring
the third larva appears, which is very similar to the
coarctate state of the second larva. It is somewhat

("gS] eBed Sujoe4)

TIA GALVWId

ao es, ee

COLEOPTERA. 159

smaller and lighter colored. It is active, and burrows
in the ground, but seems to take little nourishment.
In a few days the larva transforms to a pupa (PI. VIL.,
Fig. 112, pupa of Lpicaufa cinerea, Forst.), and in
five or six days the imago (Pl. VII., Fig. 113) is fully
formed. This peculiar mode of development is known
as hypermetamorphosis. It is instructive because,
although beginning its existence as a Campodea-like
form with well-developed legs, the Epicauta becomes,
by the laws of variation and adaptation governing ani-
mals, a creature with small, weak, tuberculous legs and
a grub-like form. This process of reduction is not
carried so far as in the Stylopidz, and the young Epi-
cauta never becomes entirely legless.

The genus Meloé of this family is not uncommon
in Massachusetts. It is a dark-blue beetle, with small,
short, and quite soft elytra and no wings. This re-
duction in the size and number of the wing-covers
and wings is carried still farther in Hornza minutipen-
nis, Riley, where both males and females are without
wings, and, practically, without elytra, as these are
extremely small.

The larve of Meloé, instead of feeding upon the
eggs of the locust, devour those of the bee (Antho-
phora), to which they are transported by clinging to
the hairy body of the mother. The second larva
feeds upon the honey in the cell intended for the
young bee. ‘The coarctate stage or pseudo-pupa is
then passed through, giving rise to an active fourth
(usually called third) larval form, which eats its way
out of the cell and goes into the true pupa stage, from
which the beetle emerges. In Sitaris, the same his-

160 COLEOPTERA.

tory is followed, but the pseudo-pupa is still more like
a true pupa, the skin not being cast off, but retained,
and all changes preparatory to the appearance of the
fourth form taking place inside of this covering. In
these cases, as in all the forms which have a true quies-
cent pupa, this follows after a period during which the
insect has eaten a large quantity of food, while not
doing any correspondingly large amount of work,
hunting, fighting, nest-making, reproduction, etc. The
nutriment, not being used or burned up in the body
to supply the waste of the tissues occasioned by such
labors, accumulates. ‘Then a period of rest comes, as
a natural consequence of the gorged condition of the
tissues, and the creature takes an after-dinner nap,
while the body keeps on in the natural course of its
development into the next stage. That it is develop-
ment and not growth that takes place is shown by the
actual shrinkage of the adult, so that the next stage of
the development is readily contained inside of the old
skin of the last active form, and is not uncomfortably
accommodated, although it may have acquired longer
legs and other modifications of parts, requiring con-
siderable room for their proper storage. The habits
leading to the quiescent larval or pseudo-pupal stage
in these remarkable forms are, therefore, precisely
comparable to those which usually precede the true
pupal stage in other groups. It is also to be noted
that the fourth larval form in the Meloidze does not
do much feeding, if any, and seems to be merely a |
provision for removing the animal from its feeding
grounds to some more appropriate place, where the
pupa can be safe while going through the necessary
changes in its development.

COLEOPTERA. 161

Among the Meloide there are forms of especial
interest, owing to the fact that their mouth parts are
similar to those of the Lepidoptera. These are certain
species of the genus Nemognatha, one of which is
found in South America, and has been described by
H. Miiller.' In this beetle the two maxille are greatly
prolonged and hollowed out on the inner side, so
that when they are pressed closely together they form
a proboscis for sucking the sweet juices of flowers,
similar to the trunk of the Lepidoptera.

STYL@PIDA:.

In these parasites specialization by reduction has
been carried so far that the adults, especially the fe-
males, have lost many of their organs, while the larvee
are at first hexapod and afterward footless. Fig. 114,
a, represents the abdo- :
men of a bee with the
head of the female Sty-
lops extending from be-
tween the rings. The
dotted line shows the
body in natural position ;
Fig. 114, 3, is the para-
siteremoved. The head
is large and _ without
eyes; the thorax and
abdomen are _ bag-like.
The mandibles are small,
and the feet and wings
wanting. Figs. 115, 116, Fig. 114.

1 See Kosmos, January, 1880, p. 302.

162 COLEOPT LAA:

represent a male Stylops, probably of the same species.
It is about a fourth of an inch long. The eyes are
prominent and mounted on pedicels which, as stated

Fig. 115.

on p. 20, are not jointed stalks, but simply prolonga-
tions of the sides of the head. ‘The small mesothorax
bears the modified wing-covers, which at first sight
remind one of the halteres
of the Diptera, and the
metathorax, the largest por-
tion of the body, carries
the broad, fan-shaped
wings. The larve are born alive, as the female Sty-
lops is viviparous. ‘They have three pairs of legs, and
are very active. On leaving the parent, they find
their way to the abdomens of other bees, where they
moult their skin and appear as footless grubs.

Fig. 116.

The two following families are not parasitic, but
most of their larve live surrounded by their food, as in

COLLOPTERA. 163

wood, nuts, etc., and are well adapted to their environ-
ment by having very small, weak legs, or by being
absolutely footless. In most of the members of the
family of Weevils (Curculionidz) the active, six-legged
stage of the larva, represented in the life-history of
Epicauta and Stylops, is not passed through, as the
larva is apodous from the start. This is another illus-
tration of the law of accelerated development, by
which certain stages are either passed over quickly or
entirely skipped (see pp. 112, 283, 284).

CERAMBYCID.

This family includes a large number of borers, among
which is the common apple-tree borer, Saferda can-
dida, Fabr., and the hickory-tree borer, Clytus pictus
(Fig. 117). This is a black beetle marked by spots of

Fig. 117.

beautiful yellow hairs. The prothorax and metathorax
are large, especially the latter, while the mesothorax
is small. The eyes are of medium size and the
antenne are long, giving the name of Longicorns to
the family. The legs are situated at the extreme pos-
terior edge of their respective segments. Fig. 117, a,
is the larva. The grubs of the Cerambycide have

164 COLEOPTERA.

feet that are scarcely perceptible or are entirely foot-
less, and most have sharp teeth admirably fitted for
boring into hard wood. They live from one to three or
more years in the trunks of trees, then make cocoons
of chips and pass into the pupa state. Fig. 117, 4, is
the pupa of Clytus.

CURCULIONID©.

The weevils (Fig. 118, ¢, /thycerus noveboracensis,
Forster) have the head extended
into a stiff proboscis, which is
used in feeding, and which in
the female takes upon itself the
additional work of an ovipositor,
boring holes in wood, nuts,
grain, etc., for the reception of
egos (Fig: 118, @). On oae
sides of the proboscis are the
antennz, and at its end are
the small, biting mouth parts.
Examples of this kind, where
one organ performs the function
of another, are by no means un-
common. It is usually an error
to assume that any organ has
always had the same kind of
work to do, or even that it performs the same common
function in the same way in all of the living represent-
atives of any large group of animals, because we find
it doing this work in the same way in all the species
that we may happen to know. The vertical motion of

COLEOPTERA. 165

the jaws of the chestnut borer (Lalaninus caryatrypes),
described below, is one of the most curious examples
of the unexpected modifications which sometimes
appear. Asa rule, not only insects but almost, if not
all Crustacea, Myriopods, and Arachnids ; that is, most
of the Articulata, have jaws formed from modified
limbs, and these organs almost invariably, as might be
expected with such an origin, move inwards from the
sides, or are opposite to each other like the bases of
the legs and appendages from which they have sprung.
The power of adaptation possessed by animals is, in
fact, so great that organs as a rule seem to have be-
come adapted to the performance of the most useful
functions, whatever these may be, regardless of what
their original duties may have been.

The grubs (Fig. 118, 4) are soft and footless, fleshy
tubercles extending down the sides of the body, and
performing the function of locomotion when neces-
sary. These larvae resemble those of Hymenopterous
insects, to be described hereafter. When ready to
pupate, they spin silken cocoons. There are many
species of weevils, some of which pass their larval life
in nuts and grain, while others live in fruits like the
plum, grape, and peach. One species, Balaninus
caryatrypes, bores into chestnuts and lays its eggs. In
these weevils the mandibles move vertically, as stated
above. ‘The footless grubs are often found in the nuts.
When full grown, the larva finds its way out of the nut
and passes the pupa state in the ground.

The position given to the beetles on the extreme
left of the table requires explanation. Notwithstand-

166 COLEOPTERA.

ing their indirect mode of development, this order is
in many respects nearer to the Orthoptera and Hem-
iptera than to Hymenoptera or Lepidoptera. This is
shown primarily in the retention in many groups of a
Thysanuriform larva, and secondarily in the similar
retention of generalized characters in the aspect of
the adults.

Among the orders I.-IX., the May-flies, dragon-flies,
stone-flies, and termites do not present any marked
tendency to the production of wing-covers in the first
pair of wings, but in the large and representative
orders, the Orthoptera, and Hemiptera (Heteroptera),
and in Dermaptera there is a decided tendency in this
direction, shown in the general thickening or partly
thickened character of the first pair of wings, and
their differences of color and use. There is also in
the same orders a marked tendency to differentiate
the prothorax, and this is frequently very large.
The Coleoptera carry similar tendencies to their
highest possible development; the first pair of
wings are transmuted into true wing-covers, are
distinct in color, comparatively useless as organs
of flight, and entirely coriaceous. The abdomen is
like that of the more generalized orders, sessile or
continuous with the thorax, no true waist being devel-
oped, and the prothorax assumes great prominence.

In most families, such as the Coccinellide (lady-
birds), Carabidze (ground-beetles), Dytiscidz (water-
beetles), Silphidee (burying-beetles), Staphylinidee
(rove-beetles), etc., the larvee have more or less of a
flattened, active —Thysanuran form and _ proportions,
and are, on account of their biting mouth parts, even

COLEOPTERA. 167

less widely removed from the standard than the larvee
of Hemiptera. Other families, however, of normal
form, such as the May-beetles and others among La-
mellicorn beetles, have soft-bodied, cylindrical grubs,
which retain only the active habits and legs and the
immature proportions of the thoracic rings in the
Thysanuriform larvee, while some of the Chrysomelidz
(leaf-beetles), Lampyridz (fire-flies, glow-worms,
etc.), and others may have larvee of cylindrical type,
similar to caterpillars in their shape and aspect,
though quite different in not having legs on the
abdomen, and in their internal structures. Others,
again (Cerambycide), even among normal forms,
may have larvz, in whose soft, cylindrical bodies
only traces of the legs remain, the biting-jaws, how-
ever, being well developed. Finally, in the weevils,
the most highly specialized representatives of this
order, with curious abnormal head and prothorax, a
footless grub form becomes common, and the Thy-
sanuroid ancestor is not represented. That the active,
hexapod grub is a derivative from the more primitive
Thysanuriform larva is settled by the development of
such genera as Meloé and Sitaris, in both of which
the primitive larval stages appear before the grub
stage is reached. That the footless grubs are, as a
rule, derived from the active hexapod grubs is also
probable, since the footless grub follows after the six-
footed form, and is developed from it, whenever these
stages occur in the same individual. It would, there-
fore, seem to be highly probable that the footless
larvee of the weevils were derived from an ancient
type which possessed an active hexapod larva like the

168 COLEOPTERA.

normal members of the Coleoptera. Either this is.
the true history of their evolution, or we must adopt
the improbable supposition that the Rhynchophora
(weevils) have had a mode of evolution which is not
recorded and epitomized in the development of the
most highly modified existing forms of this order, and
the modifications exhibited by them have not been
affected by the past history of their own group.

The extraordinary specialization shown in the males
of Stylopide should be noticed in this connection.
They have slender, curiously crooked appendages,
which resemble the halteres of the Dipteraand Coccide,
but which occur by the reduction and deformation of
the fore-wings and not of the hind-wings. The small
prothorax and mesothorax, the huge metathorax and
comparatively small abdomen, form a strange contrast
with the usual outlines of beetles, and the arrested
development and degraded structure of the parasitic
female remind one also of the condition of the same
sex in the Coccide. The extraordinary parasitic
genus, Sitaris, passes through four larval stages, includ-
ing a quiescent larval stage, called by M. Fabre a
pseudo-chrysalis, and this, as stated by Lubbock, re-
minds one of the pupa of Diptera. ‘The forms of the
adults are, however, more normal than in Stylops, the
elytra and prothorax being also less reduced.

The equally interesting researches of Riley upon
the development of blister-beetles, and the remark-
able series of hypermetamorphoses through which
Epicauta vittata passes have been described upon
pages 157-159 of this Guide and illustrated in Figs.
97-111, 113. This is an exceedingly valuable series

COLEOPTERA. 169

for the illustration of the effects of habit in producing
the various complications of developmental history ob-
servable in the life-histories of insects, and especially
the modifications by reduction occurring in parasites.’

1 “ Tarval Habits of Blister-Beetles,” 7rans. St. Louis Acad.
Sctences, Vol. III., p. 552.

ORDER XI NEUROPDERZ

Tue Neuroptera is a small order, including Cory-
dalus, the lace-winged flies, ant-lions, and Mantispa.

SIALID/.

The crawler, Corydalus cornutus, Linn. (Pl. VIIL.,
Fig. 119, ¢, 6 , p. 170), 18 one of our largest Mimeem
The head and prothorax are flattened and movable.
In the male, the mesothorax and metathorax are not
consolidated, but are separated by a groove, which is
deeper on the ventral than dorsal side. Both rings
are capable of vertical motion, though the downward
motion is freer than the upward: they also move
laterally.

The eyes are small, but compensated for by the
antennz, which are long and stout. The mandibles
of the female (Fig. 119, 7) are strong and toothed,
and are in a line with the body as the insect darts
forward for its food; those of the male (Fig. 119, ¢)
are extremely long, toothless, and their ends cross:
they are used as clasping-organs rather than for
obtaining food. The three pairs of legs are similar
in structure. As the wing-bearing segments -are not
consolidated, we should expect to find Corydalus a
slow rather than a swift flier, notwithstanding the
unusual spread of the wings, which are from 100-

170

PLATE VILE

(Facing page 170.)

Fig. 11g.

a Rear
Rat jk ere ak Tes Hi

NEUROPTERA. 171

135"™ (4-5.4 inches) from tip to tip, and, as a matter
of fact, the movements of this insect are slow and
uncertain as compared with the rapid motions of the
dragon-fly. Great powers of flight are not wholly
dependent upon the comparative size of the wings,
as will be seen in the case of the Lepidoptera (see
p- 187). In structure, both pairs of wings are trans-
lucent, with an open network of veins, the term Neu-
roptera being from the Greek (vetpov, nerve ; rrepov,
a wing), and signifying nerve-winged.

The egg-mass of Corydalus is peculiar and inter-
esting. It averages 21™™ in length, and contains from
two to three thousand eggs, each of which is 1.3™™
long, about one-third as wide, and covered with a
delicate shell. The young hatch simultaneously and
in the night.’

The larva, or “ Dobson,” as anglers call it (Fig. 119,
a), is aquatic. The body is larger and stouter than
that of the adult, as is often the case with larve, and
the head is similar in shape, but of a deeper color.
The thoracic rings are distinct and movable. The
abdomen has nine pairs of long appendages extending
from the sides (see Fig. 119, a, which represents the
first eight pairs) ; at the base of the first seven pairs
are tufts of tracheal gills (not distinctly seen in the
drawing ; see Comstock, /utroduction to Entomology,
Fig. 191). Besides these organs there are eight pairs
of abdominal and one pair of thoracic spiracles ; these

1 See Proc. Amer. Assoc. Adv. Sci., Vol. XXV., p. 275.
See also Zittel, Handbuch der Paleontologie, Bd. II., Fig. 981,
for figure of the egg-mass of Corydalites, a fossil form.

172 NEUROPTERA.

are used by the mature larva for breathing air when it
leaves the water, before making a cavity or cell in the
earth in which to pupate. The pupa (Fig. 119, 4)
remains inactive for about a month, and has neither
mouth nor anus. During this period of immobility
very great structural changes go on, which fit the
water-insect for an aerial life in much less time than
would be possible were the insect active.

HEMEROBID.

The lace-winged fly, Chrvsopa (Fig. 120, @), is a
beautiful insect, though its odor is disagreeable. The
head is dumb-bell-shaped, with brilliant golden-col-

Ze PAN 2 iter
AS
ry

on

+94,

a

a8

Fig. 120.

ored eyes projecting on either side. The plan of
structure observable in the thorax is exactly reversed
from that of the dragon-fly. The markings ‘in the last
two thoracic rings extend downward and backward,
and the legs are carried backward instead of forward.
The wings, though large, are extremely delicate, and
the flight is weak.

According to Comstock, the female before laying

NEUROPTERA. 173

an egg emits from the end of her body a small drop
of a tenacious substance: this is drawn into a thread
by lifting the abdomen ; then an egg is placed on the
tip end of the thread. These threads or stalks (Fig.
120, 6) are often attached to plants infested with
aphides. The larve (Fig. 120, c) feed on the plant-
lice, and are called aphis-lions. The mouth parts of
these larve are peculiar. On the lower side of each
mandible is a groove into which fits the maxilla,
forming a tube through which the blood of animals
is sucked. Fig. 120, @, is the small, round, silken
cocoon in which the larva transforms to a pupa, and
in ¢ of the same figure the lid of the cocoon is seen
with the small opening, out of which comes the mature
fly. To the same family belongs the ant-hon, JZy7-
meleon obsoletus (Fig. 121), common at the South.

WEEE:

Fig. 121.

Specimens of this insect can be sent to Northern
teachers through the mail, and they can also be found
in limited areas in New England. The mandibles of
the adult are small, but those of the larva (Fig. 122)
are large and stout. ‘The larva has the curious habit
of making a funnel in loose sand, by using its head and

174 NEUROPTERA.

mandibles as digging-implements. It buries itself at
the bottom of this funnel, with the exception of its
mandibles, which are extended and ready
to seize any unfortunate insect that falls into
the trap. Large insects of course readily
escape, but the small ones, ants and so on,
are carried back to the bottom of the funnel
not only by the yielding of the sand under
their feet at every attempt to escape by
climbing the sides, but also by the efforts of the ant-
lion, which throws up sand from the bottom, and thus
deepens the pit and causes the sand to slip down
from the sides and the insects with it.' The pitfalls
are usually made near ant-hills, and many an ant in
travelling to or from its home falls a victim to the hid-
den and voracious ant-lion.

The family Hemerobide includes one form, Man-
tispa, which is of special interest. Brauer has studied
its life-history, and found that it is very complicated.
The female lays its eggs on stalks; these hatch, and
the larvz are six-legged and active. In the spring
these larvee become parasitic in the egg-sacs of spi-
ders of the genera Lycosa and Dolomedes. ‘This larva
moults, and the second larva resembles a caterpillar,
with thick body, small head, partially obsolete anten-
nee, and legs much reduced in size. ‘This larva spins
a cocoon, and the pupa remains quiescent. In about
a month the imago appears.

The position of the Neuroptera in the classification
will be seen by reference to Diagrams I., II., p. 60.

Fig. 122.

1 See Emerton, Amer. Nat., Vol. IV., pp. 705-708.

NEUROPTERA. 175

The. lace-winged flies, ant-lions, etc., differ in impor-
tant characters from their parallel or representative
forms among the Odonata and Ephemeroptera, and
Packard has given an excellent summary of these dif-
ferences in his Hufomology for Beginners (see pp.
84-87), accompanied by figures which illustrate the
facts. He speaks also of the primitive form of the
larva when compared with those of the remaining
orders. Though the mouth parts are much modified
as compared with the primitive biting type, especially
in the aphis-lions and ant-lions, there is an unques-
tionable resemblance to Thysanura in their larve.
This indicates derivation from a primitive Thysanuroid
ancestor, through some intermediate winged insect.
What this intermediate winged insect may have been
it is difficult to determine with certainty. We have
for the present assumed that it may have been similar
to the winged ancestors of the orders X. to XVI., and
have designated it in Diagram IT. as B’.

ORDER XII. MECOPTERA.

PANORPID~.

Tue Mecoptera (often written incorrectly Mecap-
tera) form a small order and is represented by
Panorpa, or scorpion-fly (Fig. 123). The prothorax
of this insect is small,
like that of the Le-
pidoptera; the meso-
thorax and metatho-
rax are much larger
and bear the two pairs
of similarly developed
wings, which are long,
narrow, and with few
cross-veins. These char-
acteristics have given the name Mecoptera, from the
Greek (yjxos, length; arepdv, wing) to the order.
The abdomen of the male is long, and near its pos-
terior end it is constricted; but the last ring is
enlarged, and bears the long, forcep-like clasping-
organs which have given the name of scorpion-fly to
the insect. In the female the posterior rings are small
and tapering, and bear a pair of short, thread-like
organs.

The small, biting mouth parts are at the end of a
kind of beak, or rostrum, which reminds one of the
rostrum of the weevils.

176

MECOPTERA. 177

The larva resembles a caterpillar in form, and in the
possession of three pairs of thoracic legs and abdomi-
nal prop-legs. In the caterpillar, however, there are
never more than five pairs of prop-legs, while Panorpa
has eight pairs. Besides the feet, there are warts on
the body provided with bristles.

The snow-insect, Boreus,' also belongs to this order.
Here the prothorax is larger than in Panorpa. The
male of this genus has short wings covering only
about half of the abdomen, and so stiff as to be use-
less flying-organs, while in the female the wings have
wholly disappeared.

The scorpion-flies have been described by Packard
in the volume so often quoted. He shows that while
the adult is more lke the Neuroptera, the larvee, as
we have stated, are very similar to caterpillars, having
two-jointed abdominal legs, and four-jointed thoracic
legs, and suggests that the Mecoptera and Lepidop-
tera arose from the same stem-form.

The general absence of a true Thysanuriform larva
in the development of Mecoptera and remaining
orders is a great and probably significant change.
It may indicate that these orders have not passed
through any Thysanuroid ancestral epoch, during
which their immediate ancestors were wingless and
similar to Thysanura. It is possible that they may
have been derived from some winged form similar to
Neuroptera, since this is older and more primitive
in its mode of development and presents transitional
characters in this respect as well as in the larve of
some forms like Mantispa.

1 For colored figure, see Westwood, Jnxtrod. Mod. Class. Ins.,
frontispiece, Fig. 3.

ORDER XIII. TRICHOPTER
PHRYGANEID&.

THE caddis-flies and their larve, the caddis- or case-
worms, are very instructive. The latter can be kept
in aquaria, and their habits afford much enjoyment
to young people. Anabolia (Fig. 124) is a common

ZA RI
ENS SS
=\N

i

genus. In its general characteristics it resembles the
more generalized Lepidoptera, so that it is often called
a moth. The body is long and hairy ; the head small,
with widely separated eyes. The three thoracic rings

(Fig. 124, 6’, 4", 4') are distinct, the mesothorax
178

TRICHOPTERA. 179

being the largest. The mouth parts are very small
and weak, and are used for sucking rather than biting.
Burmeister and Westwood state that caddis-flies do
not take any food, and according to Dr. Hagen the
larger part of Phryganeidze take no nourishment ex-
cept, perhaps, some fluid. The wings are hairy, —
hence the name Trichoptera (Opi€, a hair; wrepdv, a

Fig. 126. Fig. 125. Fig. 127.

wing) given to these insects, — and have but few cross-
veins, resembling in this respect the wings of moths.
The larva of Anabolia (Fig. 125) is like a cater-
pillar in shape. The head and thorax are brown and
more or less chitinous, but the abdomen is light-
colored, soft, and defenceless. At first the insect is
white ; but when exposed to attrition and the action
of the atmosphere the forward parts of the body

180 PRICHOPTE RA

become colored. The larvz live in cases somewhat
after the manner of the hermit crab, but unlike that
unprincipled animal they set themselves honorably at
work and make an artificial covering or case by fast-
ening small stones and sticks together, as seen in Fig.
126.

The eyes are small, and here there is an exception
to the general statement of the relation of these parts,
since the usual compensation in other sense organs is
not provided, the antennz being wanting. ‘The man-
dibles are strong because they perform the double
work of mastication and locomotion. If the caddis-
worm is placed on the hand, it fastens its mandibles
in the cuticle of the skin and pulls itself and its case
along, oftentimes with such strong, quick motions that
it turns half a somersault, coming down upon its back.

The first abdominal ring, or the one behind the
metathorax, belongs apparently with the thorax, and
bears three round, blunt organs (not clearly shown
in the drawing), one on either side, and one in the
middle of the dorsal surface. These enlarge and
contract as the animal moves. ‘The rings of the
abdomen, with the exception of the first, bear on
both sides rows of white filaments which are respira-
tory organs. -These come off from either side of the
sutures that separate the rings, and on the last ring
there is a pair of jointed appendages with stout, horny
hooks at their ends, the points of which are directed
forward. It is by means of these hooks that the animal
is held securely in its case when attempts are made to
pull it out. When the larva is ready to change into
the pupa (Fig. 127), it closes the tube and remains

TRICHOPTERA. 181

quiescent. It then resembles the pupz of moths, and
while in this state very great changes take place; as
has been already mentioned, the mouth parts become
reduced in size, the antennz and wings develop, and
the respiratory organs disappear.

Two instructive species of caddis-flies have been
found in streams near Boston.’ One of these makes
apparently a tunnel (Fig. 128, enlarged) and attaches it
to a stone. The insect, however, economizes material
by allowing the stone to serve as the lower part of the
tunnel. Close to the opening which is towards the
current the larva erects a vertical framework and
across it stretches a net (see Fig. 128). The food

brought down by the current is caught in the meshes
of the net, and the insect, without wholly leaving the
protection of its house, is able to enjoy the meal its
ingenuity has secured. Fig. 129 is the case ofethe
pupa. The other species, belonging to the genus
Plectrocnemia, makes its case of mud. It consists of
one or more lateral chambers (Fig. 130), with a tall

1 See “ Description of Two Interesting Houses made by Na-
tive Caddis-fly Larve,’ Cora H. Clarke, Proc, Bost. Soc. Nat.
/iist., Vol. XXII., 1882-83.

182 TRICHOPTERA.

chimney which rises above the surface of the mud,
and appears like a twig with a hole at its apex.
Fig. 131 is the case of a young larva, and in Fig. 132
the. pup: are: seen;
Sometimes the chimneys
have two openings, as
shown in Fig. 133.

The caddis-flies re-
verse the order of rela-

Fig. 130.

tions as found in the Mecoptera. Their larve do not so
closely resemble those of the moths, while, on the other
hand, the adults are very much more like the latter than
are the adults of Mecoptera.
The habits of the larvee liv-
ing in tubes or cases would
have led to the suppression
of the useless abdominal
legs, if these ever existed.

Fig. 131. Fig. 132.

TRICHOPTERA. 183

The absence of these appendages is not an important
characteristic, since even among Lepidoptera, when-
ever the habits of the larva render certain
pairs useless, they are apt to disappear, and
even the thoracic legs, which are much
more essential and persistent, may also in
extreme cases become useless and be ob-
literated. The Geometridz, which do not
walk, but have a looping gait, and therefore
do not need the central pairs of prop-legs,
have lost all but the last two pairs of these
organs (see Fig. 157), and some Noctuide,
which are partial loopers, have, according
to Packard, lost the first pair. In some ~~
of the Lyczenidz, according to Scudder,!
the gait of the larve is a gliding mo-
tion, and thé prop-legs are accordingly very minute.
Among the smaller moths, according to Stainton, the
larvee of the genera which bore in leaves, like Antispila
and others, have no prop-legs, and even the typical
thoracic legs have suffered reduction, having become
very short and minute. These tendencies reach their
natural culmination in Phyllocnistis, the larva of which,
according to Clemens, has no legs at all.’

Packard states that the thorax in the adult caddis- |
fly is like that of the smaller moths, Microlepidoptera,
“the prothorax being small and collar-like ; the me-
tanotum formed on the lepidopterous type, as is the
rest of the thorax, especially the coxze and side-pieces

Fig. 133.

1 Butterflies. Henry Holt & Co., New York, 1881.
See p. 202: ee

A

184 TRICHOPTERA.

(pleurites) ; while the long, slender abdomen recalls
the shape of that of moths. Moreover, the body and
wings, usually hairy, are sometimes covered with scales,
and the venation is somewhat as in moths.” It is also.
to be observed that the abdomen is sessile, as in the
Lepidoptera. It is very difficult, in view of these
affinities of the adult caddis-flies with the moths, to
escape forming the conclusion that the Trichoptera
had a common origin with the Lepidoptera.

DRDERAIV, - LEPIDOPTERA,

BuTTERFLIES Offer the best illustrations for the school-
room of the complex phenomenon of indirect meta-
morphosis. ‘They are preferable to the Coleoptera,
because the larval stage in the latter group is usually
passed underground. ‘They afford better examples
than can be found among Hymenoptera and Diptera,
because, as a rule, they are larger, and scholars can
observe more easily the different stages, — egg,
larva, pupa, and imago. ‘They can also see some of
those processes by which the crawling and biting
caterpillar adapts itself to the life of a flying and suck-
ing insect. These lessons are always interesting, but
they might be made far more instructive than they
often are if they were taken in a rational and natural
order after the lessons on simple insects. ‘These pass
through a simple or direct metamorphosis, and when
this has been comprehended by the class, the mean-
ing of such complex life-histories as are presented in
Lepidoptera become more intelligible. Happily the
time is not distant when the sublime order in the evo-
lution of all things in the universe will be recognized
and adopted by teachers in planning their courses
of study. When this time comes, lessons in natural
history will not only be more interesting, but more
valuable as means of mental training, since the mind

185

186 LEPIDPORT ia.

comprehends natural processes better when taught by»
natural methods.

The monarch or milk-weed butterfly, Danazs A7-
chippus, Fabr. (Pl. IX., Fig. 134, ¢, p. 186), is abun-
dant during July and August wherever the milk-weed
grows, and is often seen flying among our cultivated
flowers. If for any reason specimens of this genus can-
not be obtained, the white cabbage butterfly, Areris
rapae, Linn. (Figs. 168, 169, p. 215), can be easily
caught in our gardens. The specimens can be chloro-
formed, and the wings spread on simple wooden set-
ting-boards. ‘These the children who have taken les-
sons in carpentry will like to make for themselves. It
is often convenient for teachers to preserve the butter-
flies in envelopes immediately after they are killed.
As the dried specimens are extremely brittle, it is
better to soften them before handling. Forty-eight
hours before the lesson is to be given cover the
bottom of a dish with wet sand, and over this place
tissue paper, then lay the butterflies upon the paper,
and cover the dish. The body, wings, and legs will
become pliable, and the observational work can be
done much more satisfactorily.

The obvious characteristic of the butterfly’s body
is its coating of hairs and scales. After this has
been observed, it must be scraped away in order to
expose the chitinous parts beneath. The three re-
gions are then distinctly seen. The broad, short head
(Pl. IX., Fig. 135, 4; Fig. 136) is freely movable, and
the compound eyes (Fig. 136, ev) stand out promi-
nently on either side. The prothorax (Pl. IX., Fig.
135, 4') is reduced to a little, narrow ring, which ap-

PLATE IX.

(Facing page |86.}

LEPIDOPTERA. @ 187

pears like a part of the neck, and is free from the
mesothorax. ‘The small size of this ring is one of the
important characters of the Lepidoptera, distinguishing
this order from the Thysanura, Orthoptera, Hemip-
tera, Coleoptera, and Neuroptera. On the upper side
of the prothorax are two knob-like prominences, which
in the living butterfly are tipped with white hairs. The
mesothorax (Fig. 135, 4’) is large and strong. It is
convex above, and bears on its forward part a pair of
patagia or shoulder lappets (74), which are also pos-
sessed by the wasps among the Hymenoptera (see
p. 242). The metathorax (Fig. 135, 4’), though
smaller, is nevertheless stout and chitinous. It is
separated from the mesothorax by a deep groove, and
the two rings move upon each other. In most of the
flying insects already observed, such as dragon-flies,
harvest-flies, etc., the power of flight has been cor-
related with a marked tendency to consolidation of
the thoracic region. Most butterflies offer apparently
an exception to this rule; for while they are pre-
eminently fliers, the mesothorax and metathorax are
each capable of considerable freedom of motion. An
explanation of these facts is found in the peculiar
flight of this insect and the unique structure of the
hind-wings. The movement is slow and wave-like
as compared with the swift, arrow-like flight of the
dragon-fly. The long veins in the posterior part of
the hind-wings (see Fig. 134), not found of such
length in any of the insects before described, aid in
producing the slow, fluttering motion. If, now, we
could find a butterfly or moth whose flight was swift
and sustained, and whose hind-wings, therefore, were

188 e@ LEPIDOPTERA.

without long, posterior veins, then we should expect
that this form would have its thoracic rings more
clésely consolidated. Just such a condition of things
is found to exist in the hawk-moth (see p. 208), where
the more rapid flight is correlated with greater con-
solidation of the thorax, so that the general law ob-
served in other insects holds good.'

Pl. [X., Fig. 137, is a-view of the thorax of Danats
Archippus taken from Edward Burgess’s paper on
“Contributions to the Anatomy of the Milk-weed
Butterfly.”” The prothorax (4') has its scutum (7)
and scutellum (¢s'), episternum (4'), and prothoracic
spiracle (s’). The mesothorax (4) and metathorax
('") are each composed of a scutum (Z’, 7°) and scu-
tellum (4°, 4°), of episterna (47, 2°) and epimera
(As’, hs*). The point of insertion of the wings is
marked by w’, w''; is the shoulder lappet, and cx
the coxa of each leg. The abdomen (PI. IX., Fig.
135, C) is long and slender. It is composed of eight
similar rings which are covered with tiny scales. The
scent organ of the male is probably situated near the
posterior end.

The compound eyes (Pl. IX., Figs. 136, 140, ey;
Fig. 140, ey', cornea of eye) have many facets. The
number of these facets varies greatly in the different
genera, ranging, according to Mr. Scudder, from about
fifteen hundred to four thousand in a square milli-
metre. The ocelli are wanting. The antenne (PI. IX.,
Fig. 135, a¢; Fig. 134) are thread-like, and knobbed

1 See also p. 16 for other remarks on the effects of use of the

legs and wings; also p. 30.
2 Annis. Memoirs Bost, Soc. Nat, Hist., 1880.

LEPIDOPTERA. ; 189

at their ends, often appearing like clubs. The shape
of these organs is so constant that it usually, though
not always, serves as a distinguishing characteristic
between butterflies and moths (see p. 196), and has
been used to justify the name of Rhopalocera (see p.
212) as applicable to this group of Lepidoptera. The
mouth parts first observed are the sucking-tube or
trunk (Pl. IX., Figs. 135, 136, #«'), which is usually
coiled like a watch-spring, and the hairy palpi (Fig.
135, x"). Looking more closely, two small, immoy-
able, horny pieces (Fig. 136, mad) are seen on either
side of the sucking-tube: these are the remnants of
mandibles. The trunk represents the first pair of
maxille, whose palpi are small (Fig. 136, x’). A
cross-section of the trunk is shown in PI. IX., Fig. 138.
According to Mr. Burgess,’ it consists of two lateral
parts, each representing one maxilla. These parts
are convex on the outer side and concave on the
inner. By the union of the two concavities a com-
plete central tube (cz) is formed. ‘The lateral parts
are filled with muscles (z), tracheze (4), and nerves
(ur'), while the central tube is hollow and opens
into the pharyngeal sac, the floor of which is seen in
Pl. IX., Fig. 139, Af. When the sucking-tube is
thrust into the corolla of a flower, the sweet fluid is
drawn upward by the alternate contraction and dila-
tation of the pharyngeal sac. Pl. IX., Figs. 139, 140,
make this subject clearer. Fig. 139 is a longitudinal
section of the head, giving a view of the interior of

1 Zoc. cit. See also “The Structure and Action of a Butter-
fly’s Trunk,” Amer. Nat, Vol. XIV., p. 313, 1880.

190 LEPIDOPTERA

the left side; mx! is the sucking-tube ; Aff, floor of
pharyngeal sac; fv, pharyngeal valve; sd, salivary
duct ; ve, cesophagus ; /s, @, frontal and dorsal mus-
cles, which hold the sac in position. Fig. 140 shows
the sac hung by the five muscles, — dorsal (dz), frontal
(72), and lateral (4) ; ve is the cesophagus, which ex-
tends backward. When the muscles just mentioned
contract, the pharyngeal sac enlarges: this causes a
vacuum, which is at once filled by the nectar that
flows upward through the sucking-tube ; the muscular
sac then contracts, and the liquid food is forced back-
ward into the cesophagus, the pharyngeal valve pre-
venting it from passing downward into the trunk. The
second pair of maxillz are reduced in size, but the
palpi (Pl. IX., Fig. 135, x’) are large and hairy. The
muscle which moves one of. these palpi is seen in
PLEX, His. THekor Lie.

The legs are very small and weak, being used for
supporting the insect, and not much for locomotion.
The species Papilio (Ageronia) feronia is an exception
to this rule, since, according to Darwin, it uses its legs
for running, notwithstanding it is a high flier. The
first pair (Pl. IX., Fig. 135, 7’), borne on the weak
prothorax, is useless even for supporting the butterfly.
The section nearest the body is thickly covered with
hairs, for which reason this insect is placed among
the brush-footed butterflies, or Nymphalidze (p. 219).
Both pairs of wings are well developed, though the first
pair is the larger. The distinguishing characteristic
of these organs is the thick coating of scales or modi-
fied hairs which has given the name of Lepidoptera,
(Aerts, scale; mrepov, wing), signifying scaly wings,

LEPIDOPTERA. 191

to this order. These scales overlap each other as seen
in Fig. 141. In size, color, and markings, they vary
in different genera, and are attractive microscopic
objects. Mr. S. H. Scud- :

der, in his smaller work __ jij
on Butterflies, considers
the subject of the color
and patterns of the wings
(see Chaps. IX., X., XI.).
This book should be in
the hands of every
teacher, as it contains a
trustworthy account of
the structure, habits, and
life-histories of butterflies, especially of our Ameri-
can forms.’ When the insect is resting, the wings are
raised so that they meet over the back. The male
_ (PL IX., Fig. 134, p. 186) of this species can be readily
distinguished from the female by the little patch of
black scales on one of the lower median veins of the
posterior wings. ‘This insect has the habit of migrat-
ing in large flocks on the approach of cold weather,
and an interesting account of their movements south-
ward is given by Riley in the American Entomologist?

\ t

Fig. 141.

‘ 1See also Scudder, 7he Butterflies of the Eastern United
States and Canada, with Special Reference to New England,
1888-. This is one of the most remarkable memoirs ever
published on a scientific subject, and every library should have
a copy for the use of teachers. It is illustrated with plates and
figures of the highest excellence, and the butterfly is considered
from ninety-five different points of view, the style being a happy
mixture of the popular and scientific.

2 2d series, Vol. I., pp. 100-102, 1880.

192 LEPIDOPTERA.

When more observations are made, it may be proved
that their migratory movements are periodic, and as
regular as the annual migrations of birds. Besides
the legs and wings there is the pair of small, hairy
shoulder lappets (Pl. IX., Fig. 135, 2), already re-
ferred to, attached to the mesothorax, which protect
the hinge of the wing from injury.

The metamorphosis of butterflies is indirect. The
egg (Pl. IX., Fig. 142, much enlarged) of Danazs
Archippus is dome-shaped, and with its delicate mark-
ings is a little gem in itself: it is attached to the under
side of a leaf. The eggs are laid from the time the
insect appears in June until as late as July and August ;
in four or five days they hatch, and the larve, or
caterpillars, are so voracious they begin at once to
devour their egg-shells, and afterward the leaves upon
which the eggs are placed. In two or three weeks
the caterpillar (Pl. IX., Fig. 143) has attained its full
size. It has a plump, cylindrical body consisting of
a head and thirteen similar rings, and is marked by
well-defined bands of a brown color. ‘The rings are
fleshy and, therefore, more easily creased than if they
were chitinous : these creases make the apparent num-
ber of rings greater than the real number. ‘There are
no compound eyes, but a number of ocelli (Pl. IX.,
Fig. 144, 0c!) on the sides of the head. The appen-
dages of the small but distinct and chitinous head are
somewhat difficult to make out. The antenne (Fig.
144, af) are short. The strong mandibles (md) are
useful, and are, therefore, movable, unlike those of
the mature insect. The first pair of maxille (sz')
has two pairs of palpi, while the second pair (m.x"’)

LEPIDOPTERA. 193

has only one. Attached to the second pair of maxille
is a little horny tube, the spinneret (sz), by means of
which the caterpillar spins the web on which it walks.
Following the mouth parts are three pairs of appen-
dages in the form of true, jointed legs (Pl. IX., Fig.
143, /'-/'"), the first pair, like the first ring, being
the smallest. Each of these legs is terminated by a,
horny claw. The second ring also bears a pair of
thread-like organs on its upper side. ‘Two rings with-
out appendages succeed the leg-bearing segments.
Following these are four rings with four pairs of ap-
pendages in the form of fleshy, unjointed false legs, or
prop-legs, also called pro-legs (4s'—2s*), which serve
to prop up the long body, and are capable of exten-
sion and retraction. Of the four remaining segments,
only the last, or thirteenth, bears a pair of prop-legs
(és°). All these stumpy prop-legs are provided with
tiny hooks which help the animal in clinging to an
object when one attempts to lift it. From the upper
side of the eleventh ring a pair of thread-like organs
is given off, similar to the pair from the second ring
behind the head.

The caterpillar feeds voraciously so that it may store
up sufficient food for use during the changes that take
place in its quiescent or pupal stage. When ready to
become a pupa or chrysalis (the pupz of butterflies
are usually called chrysalids, because those of many
species are marked with brilliant golden spots), it spins
a mass of silk, fastening it to some object, and then
attaches itself to the silk by means of the last pair
of hooked prop-legs (see Pl. IX., Fig. 145) and the
spines of the anal plate. While hanging in this posi-

194 LEPIDOPTERA.

tion, with the head curving upward, its skin splits.
Gradually this larval skin shrinks, and works its way
upward towards the silken attachment (see Pl. IX.,
Fig. 146). The chrysalis is kept meantime from fall-
ing to the ground by elastic ligaments at the end of
its body, by which it is fastened to the larval skin. In
time, the long, horny piece at the extremity of the
chrysalis, called the cremaster, which is the homo-
logue of the anal plate of the larva, is withdrawn, as
seen in Pl. IX., Fig. 147, which, though slightly in-
accurate, illustrates the process. Before the larval skin
has become disconnected with the chrysalis, the latter
has taken hold of the mass of silk by the hooks of
its cremaster and hangs securely."

The chrysalis finally assumes the form shown in Pl.
IX., Fig. 148. It is one of our most beautiful chrysalids,
of a pale green color marked with characteristic golden
spots, which do not lose their color in alcohol. Within
the chrysalis case the insect remains motionless, and
the changes which transform the caterpillar into the
butterfly take place in from nine to fifteen days. As
it is quiet, organs of locomotion are not needed, and
these are encased in sheaths and fastened tightly to
the body. At the end of this time the chrysalis ex-
hibits great muscular strength, and in twenty-four or
forty-eight hours succeeds in splitting its case, and
the imprisoned butterfly is liberated. At first its body
and legs are weak, and the soft, moist wings are folded.
In this condition the insect will stand or seemingly sit

1 For figures and detailed description, see American Ento-
mologist, 2d series, Vol. I., p. 162, 1880.

- LEPIDOPTERA. 195

on your hand, not attempting to walk unless gently
pushed, when, probably through fear of losing its equi-
librium, it will take a few steps. The body and wings
tremble, while the latter are moved upward and down-
ward in the effort to expand them. When fully ex-
panded and dried, the insect is ready to begin its
aérial life. :

The earliest butterflies of this species which have
not hibernated are found in New England in June
and July, and are emigrants from the south. Far-
ther south they winter in the imago state, and make
their appearance early in the following year, and have
several broods in a season. In New England the
progeny of the colonists fly to the southward in the
autumn.

HETEROCERA (MOTHS).

THE moths are the most generalized forms of the
Lepidoptera. The American silkworm, Zelea Poly-
phemus (Fig. 149, 8, p. 197), may be taken as a type.
Sometimes the clothes-moth, Tinea (Fig. 153, +, p. 201),
can be more easily obtained. The body of Telea is
large, stout, and hairy. When these hairs are scraped
away, the three rings of the thorax are seen to be
separated by well-marked sutures. In Tinea, Fig. 153,
the mesothorax and metathorax are distinctly seen, and
are simpler than in Telea. In the moths, the connec-
tion between the thorax and abdomen is broader, as a
rule, than in butterflies.

The antenne of Telea (see Fig. 149) are feather-
like — one characteristic form among moths. Those
of the male are much broader, larger, and more
beautiful than those of the female. The mouth parts
are extremely small and weak, and the insect laps
up its food, such an eating-apparatus indicating that
the moth is not long-lived. The fore-legs are devel-
oped, and like the second and third pairs are useful
for supporting the insect. The wings are very large,
and when at rest are held in a drooping instead of an
erect position. These moths fly chiefly at night.

The eggs are usually laid on the lower side of oak
leaves. While it is true that most butterflies and

196

197

198 LEPIDOPT EKA.

moths select the leaves that their young, the cater-
pillars, love best, yet, according to L ‘Trouvelot,!
Telea Polyphemus sometimes lays its eggs on plants
which the larve do not eat ; and when, as occasionally
happens, there are no other plants for a considerable
distance, the caterpillars die, being unable to adapt
themselves to their new diet.? The caterpillar (Fig.
150) is one of our largest, and is bright green in color.

Fig. 150.

1 American Naturalist, Vol. 1., pp. 30, 85, 145.

2See also Poulton, “ Notes in 1886 upon lepidopterous
larvee:” Trans. nt. Soc. Lond., 1887, p. 281. The writer
maintains that the young lepidopterous larva, on hatching, is in
a far less specialized condition, as regards its food plants, than
that which it will subsequently reach, and this condition is sup-
ported by the fact that young larvee will nibble leaves of plants
upon which the species has never been found, and may some-
times grow for a considerable time upon such food. The ob-
servation that the newly-hatched larva is free to form new

LEATDOPLTERA: 199

Rows of hairy tubercles extend down the body. The
head is small, and the mouth parts are for biting.
The amount of food consumed by this animal is in-
credible. It is, in fact, one of the greatest eaters and
fastest growers. By experimentation, Trouvelot found
that when the young silkworm hatches, it weighs ay
of a grain ; when 10 days old, it is 10 times its original
weight ; when 30 days old, 620 times; and when 56
days old, 4140 times its original weight. The food
taken by a single silkworm in 56 days equals in weight
86,000 times the primitive weight of the worm ; of this
about + of a pound becomes excrement,-207 grains
are assimilated, and over 5 ounces have evaporated.
The three pairs of legs are short and weak, while
the prop-legs, especially the last pair, are stout and
horny, being useful locomotive organs. Before the
last skin is shed, the larva makes a silken cocoon
(Fig. 151, natural size) protected on the outside by
leaves. During the win-
ter months the leaves
often get broken and
partly worn off, as seen
in Fig. 151. The pupa
(Fig. 152) remains
motionless for about
nine months; then
during May, in the
vicinity of Boston, it changes to a moth. If the pupz

Fig. ISI.

relations with occasional or rare food plants, which could not be
used as food successfully by the more mature larva, goes a long
way towards the explanation of changes both in habits and
structure which must have occurred in the past.

200 LEPIDOPTERA.

are kept in cold, dark places, the development is
retarded, and when kept in a warm schoolroom, it is
quickened, so that the
pupz will often trans-
form as early as the sec-
ond weekin April. When
the pupa is ready to
e come out of the cocoon,
——— it secretes a liquid con-
Fig. 152. taining bombycic acid,
which dissolves the gum
uniting the silken threads: it then escapes without
breaking a fibre. On the right of Fig. 151 is the open-
ing where the moth came out, and on the edges the
silken fibres are distinctly seen. The silk is valued
highly for its strength and glossy lustre. After the
moth is free, let the pupils examine the empty co-
coon. It is moist inside, and the cast-off pupa-skin
is found within, attached to the end opposite the
opening.

TINEID~.

The clothes-moth, Zizea pellionella, Linn. (Fig.
153, +) is a small buff-colored insect which is some-
times seen flying about our rooms in April and May,
but seldom in the vicinity of bright lights. When the
wings are spread, these moths do not measure more
than half an inch in breadth, and are, therefore, much
smaller than the “ millers” that fly around lights, and
are erroneously supposed, by some, to eat woollen
garments. The head of Tinea looks like a small
cushion of hairs ; the eyes are small, but the antennee

EF PIDOPTERA: 201

are extremely long.
delicate fringe of hairs,

The narrow wings have a long,
a characteristic of the more

Fig. 153.

generalized moths. The resemblances existing between
this insect and the caddis-fly of the Trichoptera have

already been men-
Goned. >> Pio. 15 3.
a; a represents the
caterpillar; 4, its
case made of wool
or hair, and often
times of cotton, the
color of the case
differing with that
of the material

Fig. 153, a.

i See pero.

202 LEPIDOPTERA.

used; ¢, the pupa.’ This family is of especial in-
terest because it contains a few genera (Antispila,
Heliozela, Nepticula) whose larvae have very minute
thoracic and no abdominal legs. The habit of mining
leaves and living within the burrows has probably
brought about these changes in structure. The larva
of Phyllocnistis has not only lost the abdominal and
thoracic legs, but, according to Clemens, to a great
degree the power of motion, and, as stated by that
author,” it makes “little or no voluntary movement
when removed from the mine, and does not retreat
in its mine when touched.” Other allied genera have
also been described by the same author as having
similar habits and being similarly modified.’

In the Catalogue of Tineina by Chambers,* Clemens
is also cited as mentioning the resemblance of the
larva of one species of Nepticula to the larva of a
Dipteron. Drawings of this’ genus and of Antispila
are given in the Wat. Hist. of the Tineina, Stainton,
Vols. T.; XI.

Among butterflies no absolutely footless larve have
been found. The caterpillars of Thecla, which glide
rather than walk, approximate to this condition in so
far as they possess only the three pairs of jointed

1 For further information, see “ Insect Life,” Budd. U. S. Dept.
Ag., Vol. II., Nos. 7, 8, 1890.

2 Proc. Phil. Acad. Sct., 1856, p: 327-

8 See Zineina of North America, Clemens, pp. 25, 26. Also
compare the description of the larva of Lithocolletis (p. 63)
with that of Leucanthiza (p. 85), Tischeria (p. 80), and finally
Aspidisca (p. 26), and Phyllocnistis (p. 83).

4 Bull. U. S. Geol. and Geog. Survey, Vol. IV., No. 1, 1878.

LEPIDOPTERA. 203

thoracic legs, and these are very minute and not visi-
ble from above. It is interesting to note that several
species of Thecla also have the habit of boring, select-
ing fruits of different kinds, and among the Lyce-
nidz the caterpillars of the species /uctsalia irus bore
into the plum.’ Figures of species of Thecla are given
in Lépidoptéeres et Chenilles de f Amerique Septentri-
onale, Boisduval et Leconte.

PHALAINIDZE.

The “ fall canker-worm” moth, Anzsopteryx pome-
taria (Fig. 154, @), is better known as a caterpillar,

and this is improperly called a “worm.” The body is
covered with scales (Fig. 154, @) ; Fig. 154, ¢, repre-
sents the joints of the antennz, which are uniform in
size. ‘The wings of the male (Fig. 154, a) are held
horizontally when in repose ; the female (Fig. 154, 4)
is without wings. The moths arise from the ground
the middle or last of October and lay their eggs (Fig.
155, a, 5, side and top views; e, mass of eggs) on
both fruit and shade trees, particularly the apple

1See Scudder, The Butterflies of the Eastern United States
and Canada, pp. 800, 840, 1930.

204 LEPIDOPTERA.

and elm. ‘These eggs hatch about the same time as
those of the spring canker-worm moth.’ The larva
(Fig. 155, 7; ¢, an enlarged ring of larva, side view ;
@, dorsal view showing markings) has six thoracic
legs, but only three pairs of abdominal prop-legs ; and
the spring canker-worm (Fig. 157, @) has only two
pairs of prop-legs. The larve (Fig. 155, 7) are called

“loopers,” “‘measuring-worms,” and “ geometricians,”
as they loop the body when walking. ‘This is done

by taking firm hold of an ob-
9 ject with the prop-legs, then
extending the body and grasp-
ing another object with the
thoracic legs, after which the
body is drawn upward and for-
ward in the form of a loop.
The larva also extends its body
as seen in the drawing and
holds it in this position a long time. In so doing, it
resembles a twig, and as these larve are eaten by

1See Third Rep. U. S. Ent. Com., Chap. VII.

LEPIDOPTERA. 205

insectivorous birds, this position may serve as a means
of protection. They transform in silken cocoons, in
the earth or under leaves or stones. Fig. 156, a,
is the pupa of the male ;
6, that of the female, also
seen in Fig. 155, g. 2, top
view of anal tubercle of
pupa, enlarged. The
“spring canker-worm,”
Paleacrita vernata (Fig.
i 7,@; Wego, enlarged,
natural size shown in the small mass at side; c, one
ring of larva, side view; @, the same, dorsal view),
is more abundant than the “fall canker-worm,” and
may be distinguished from it by not having prop-legs
on the eighth ring. ‘These moths come out of the
ground in the early spring.’

Fig. 157.

NOCTUIDE.

The “northern army-worm” moth, Zeucania unt-
puncta, Haw. (Fig. 158), is so cailed because the
larve (Fig. 159) often march in vast numbers. This
manner of travelling, however, is abnormal, as stated
by Riley,” the insects being usually sedentary in habit,
and not marching unless their numbers are large, and
the food supply of the region too small. Genera-
tion after generation of these caterpillars may live
in a given district, feeding upon grass until one or

1 For further information on the Phalzenide, see “ Packard,
Monograph of Geometrid Moths,” Hayden’s U. S. Geol. Sur-
vey, Vol. X., 1876.

2 Third Rep, U. S. Ent, Com., 1880-82, Chap. VI., p. 109.

206 LEPIDOPTERA.

more seasons of drought, which are favorable for their
increase. ‘They then begin to multiply, large numbers
hibernate, and the
following spring mul-
titudes of moths ap-
pear, lay their thou-
sands of eggs, from.
which the caterpil-
lars are hatched. As
soon as the surround-
ing vegetation is
eaten by these caterpillars, they are obliged to starve
or go elsewhere, and this explains their sudden appear-
ance in vast numbers in new regions. ‘They devour
grass and grain. In 1770 they spread over New

England. “They went up the sides of the houses
and over them in such compact columns that nothing
of the boards and shingles could be seen. Pumpkin
vines, peas, potatoes, and flax escaped their ravages.
But wheat and corn disappeared before them as by
magic. Fields of corn in the Haverhill and New-
bury meadows, so thick that a man could hardly be
seen a rod distant, were in ten days entirely defo-

LEPIDOPTERA. 207

liated by the ‘ Northern Army.’”’' During recent years
they have appeared several times in New England,
notably in 1861 and 1875.

The life of the larva varies greatly in length, depend-
ing upon temperature. In St. Louis, at an average
temperature of 80° F., it covers a period of fifteen
or sixteen days. In Northern Illinois, Walsh gives the
period at “from four to five weeks.” The last brood
usually hibernates in the caterpillar stage, so that in
this case the larval life covers four months or more.
The caterpillars suddenly disappear, as they usually
burrow in the ground and become pupe (Fig. 160).
In warm climates there may be sev-
eral broods, but in New England there
are probably only two.

The common name of “ cutworm”’
is given to the larvz of the Noctuid moths, particu-
larly to those of the genera Agrotis, Hadena, and
Mamestra.

BOMBYCIDE.

This family includes the American silkworm, already
described (see pp. 196-200), and the mulberry silk-
worm, Lombyx mori, which has been reared in China
for many centuries, and with varying success in our
own country for three hundred years. Teachers liv-
ing in the vicinity of Florence, Mass., also of Phila-
delphia and farther south, are favorably situated for
obtaining the eggs of the silkworm and watching
them develop. The larva will live for a time upon
lettuce, although it much prefers mulberry leaves.

1 See Riley, Eighth Mo. Ent. Rep., pp. 25-29.

208 LEPIDOPTERA.

It is nearly black when young. Jn about a month
it changes to a pupa, spinning its remarkable white
cocoon of silk. The pupa stage covers about three
weeks. The effects of domestication can be clearly
seen in this species of moth ; for although the individ-
uals still possess wings they do not use them. The
common Cecropia moth, Matysamia Cecropia, also
belongs in the group of silk-makers. Cocoons of this
moth can be obtained in the autumn, and if hung in
a cool place, the scholars can watch the transforma-
tion the following March, April, or May. ‘The beauti-
ful green Luna moth, Actas Luna, and the common
Attacus Promethea are included in this family.

SPHINGIDZ.

These “hawk” or ‘ humming-bird” moths always
interest the young. They are stout, strong insects, with
large, hairy bodies (see Fig. 161, AZacrosila quingue-
maculata, Haw.). The rings of the thorax, as already
stated (see p. 188), are not so loosely connected as
in the slower flying butterflies and moths.

The sucking-tube is extended to great length, that
it may reach the sweet fluids at the base of the deep
corollas of flowers. The legs are strongly spiked, and
well fitted to support the weighty body. By means
of the neat and most ingenious contrivance found in
many moths, the fore and hind wing on each side are
fastened together, so that the power of flight is greatly
increased. When the two wings are separated, the
little horny hook at the base of the hind-wing, and

—

209

LEPIDOPTERA.

Fig. 161.

210 LEPIDOPTERA.

the manner in which it catches hold of the fore-wing,
as they are both expanded, can be observed. ‘These
moths fly in the twilight and dpring the day. Chil-
dren living in the southern states can often see the
common ruby-throated humming-bird and this moth
in the twilight, both supporting themselves upon their
rapidly vibrating wings, while their long sucking-tubes
(in one a bird’s beak and in the other the unrolled
tube of a moth) are thrust into the depths of flowers
on the saine stem. ‘They are not so abundant in the .
middle and northern States, but may nevertheless be
observed when in motion, and when it is so dark that
the differences in coloration are not clearly distinguish-
able. The resemblance of the moth to the humming-
bird can then be seen to consist in its quick, darting
flight, and its habit of sucking the nectar of flowers
while supporting itself in the air.

The larva known as the “ potato-worm”’ (Fig. 161, a)

award Gaal

Fig. 161, a.

is found on both the potato and tomato plant. It also
feeds upon the tobacco plant in the northern States.
Near the end of its body there is a single “ horn” or
projecting spike.

The caterpillar has the habit of raising the forward
part of the body, and remaining motionless in this

LEPIDOPTERA. 211

position for some time; hence the name Sphingide,
or sphinx-like, given to this family.

Fig. 161, b.

The larva transforms in the earth. The pupa (Fig.
161, 4) has a long, jug-like handle, which is really the
case of the sucking-tube.

RHOPALOCERA (BUTTERFLIES).

THE classification of butterflies which we have
adopted is illustrated by a genealogical tree in Mr.
Scudder’s smaller work on Lutterfiies (see p.246). Ac-
cording to this classification the group is divided into
four families and many sub-families. Most entomolo-
gists agree in regard to the position of the Hesperide,
as these insects have many characters in common
with moths. ‘The chief difference of opinion is in
the position accorded the Papilionidee and Nymphali-
dee, many naturalists placing the former at the head
of the Lepidoptera. The Papilionidz, however, have
many features resembling those of the Hesperidee, as
pointed out by Scudder, and in the partial atrophy
of the fore-legs and the mode of transformation, the
Nymphalidz are farthest removed from the moths,
and therefore the most specialized of butterflies.

HESPERID~.

These butterflies resemble moths by having stout
bodies and the three pairs of legs developed as organs
of support. The antennz instead of being distinctly
club-shaped as in most butterflies are hooked at their
ends. Owing to their short, jerking motions, these
insects are known as skippers. When at rest, many

232

LEPIDOPTERA. 213

hold the hind-wings horizontally, and the fore-wings
erect. Fig. 162 represents the white-spotted skipper,
Epargyreus Tityrus, Fabr. (under surface of the wing

Fig. 162.

shown on the left). The caterpillar (Fig. 163, one-
half natural size) lives in a house or nest (Fig. 164,
one-half natural size), which it makes by fastening
several leaves together with silk. If a leaf is given
the little caterpillar at birth, it will try to build its

Fig. 163. Fig. 164.

house as soon as it has eaten its egg-shell. The
chrysalis (Fig. 165, natural size) transforms in a
cocoon (Fig. 166, natural size) like the pup of

214 LEPIDOPTERA.

moths. This cocoon, however, poorly represents the
strong, safe cocoons of many moths; and as if to
make up for its deficiencies, the chrysalis fastetis itself

to the inner wall by two silken threads, as seen in

Fig. 166. Fig. 167, enlarged, represents the last ring

of the body with the cremaster. Fig. 167, a, is one
hook of the cremaster.

The skippers are well represented
in America, and have received
many popular names, such as
“ dusky wings,” “sooty skippers,”

Fig. 167. a. . “ clouded skippers,” etc: Siepeme
generally small and of dull colors.

PAPILIONIDE.

The cabbage butterfly, Pieris rape, Linn. (Fig.
168, 2; Fig. 169, ¢ ), belongs to this family ; also the
common sulphur-yellow butterfly, Cohas philodice,
and the large, beautiful swallow-tails (Papilio). The
Papilionide, like the skippers, have the first pair of
legs well-developed, but with few exceptions they do
not transform within cocoons. The silken attachments
are spun, however, and the chrysalis hangs from some

LEPIDOPTERA. 215

solid object by the posterior and middle portions of its
body, as seen in Fig. 170, which represents the chrysa-
lis (4) and also the caterpillar (@) of the cabbage-butter-

Fig. 168, 2

fly (P. rape). This is seen more plainly in Fig. 171,
which is the chrysalis of another species of Pieris
' (~. oleracea, Harris). The Papilionide hold the
wings erect when at rest, and fly in the daytime.

The cabbage-butterfly offers one of the most re-

markable and completely recorded examples of insect
migrations. It was imported from Europe about the
year 1860, and finding such favorable conditions here

216 LEPIDOPTERA

for its growth and increase, it extended its habitat till,
in 1883, it had reached the Rocky Mountains, and by
this time it probably holds possession of the whole
United States.’

The family Papilionidz includes
the species Lucheira socials, found
in Mexico. These butterflies live
together in large numbers ina parch-

ment-like nest reminding one of the
social Hymenoptera.

Another species of the same
family, Papilio ajax, illustrates in a
most remarkable manner the effects of temperature
upon structure. This species is distributed widely from
Southern Canada all through the Southern Atlantic
States to Florida, and the Gulf States westward in
Missouri.

There are three distinct varieties of the species,
comprising in each variety both males and females,
originally described under the names of Walshu, Tela- —
monides, and Marcellus. Walshii and Telamonides are
not found in the extreme northern range of the species,
where Marcellus alone survives.

Starting in the springtime in West Virginia, we find

Fig. 170.

1 See Scudder, “The Introduction and Spread of Preris rape
in. North America,” 1860-1885, JZem. Bost. Soc. Nat. Hist.,
Vol“lV, Nos 3;°1887-

LEPIDOPTERA. 217

Walshii appearing from a proportion of chrysalids
which have passed through the preceding winter, and
which are opened by the pupz before the 15th of
April ; the remainder, which are opened by or before
the last of May or first of June, give out only the
second form, the Telamonides. These two varieties,
Walshii and Telamonides, lay eggs which pass through
the usual caterpillar and chrysalis stages and are
hatched after the first of June, but instead of coming
out as either Walshii or Telamonides, they are the dis-
tinct variety Marcellus. How purely this is a matter
of the seasons is shown by the following additional
facts. Of all the eggs laid by Walshii or by Walshii
and Telamonides before the last of April, there are
ten per cent which remain for some cause or other
undeveloped and pass the summer and winter as chrys-
alids. Of all the eggs laid by Telamonides or Walshii
in May, thirty-five per cent pass over to the next
spring. About the rst of June Walshii dies out. Of
all the eggs laid by either of the two forms which are
still surviving, Telamonides and Marcellus, in June,
fifty to sixty per cent are retarded and pass over the
winter. Before the end of June Telamonides dies
out, leaving only Marcellus surviving.

Of all the eggs laid by this form in July, about
seventy per cent are retarded in development and
pass the winter as chrysalids. Marcellus may have
several successive broods, but the eggs of each brood
either pass over the winter or develop the same season
in from twenty-seven to thirty-eight days into perfect
butterflies. Thus in the spring we have a grand mix-
ture of the chrysalids of the three forms Walshii,

218 LEPIDOPTERA.

Telamonides, and Marcellus, but from these only two
forms are reproduced in succession, Walshii before
the 15th of April, and Telamonides between the 15th
of April and the ist of June, and Marcellus is born
from these alone by the new eggs they produce after
this date.

According to Weismann, this polymorphism is due
to the direct influence of the physical surroundings
acting upon the chrysalis through certain fixed periods
of time.

LYCAENID®.

The Lyczenidz, or gossamer-winged butterflies, in-
clude small but beautiful insects known under the
popular names of the “ blues,’’ “ coppers,” and “ hair-
streaks.” Our American copper, Heodes Hypophleas,
Boisd. (Fig. 172, natural
size), is an example of
this family. The fore-legs
of the female are like
the other two pairs, but
those of the male have <
undergone changes ren-
dering them less useful

Fig. 173-

for supporting the insect. ‘The caterpillar when first
hatched has long hairs, but when older (Fig. 173, nat-

LEPIDOPTERA. 21S

ural size), its hairs are so short it appears to be
naked. The chrysalis (Fig. 174, natural size) is at-
tached in much the same way as the chrysalids of the
last family, with the exception that the silken thread
around the middle of the body is drawn
much more tightly. This butterfly win-
ters in both the caterpillar and chrysa-
lis state. Several broods are hatched
during the summer, and the spring butterflies are more
brightly colored than the later broods. The genus
Thecla belongs in this family. Its larvee are slug-like,
having very small thoracic feet, see pp. 183, 202.

Fig. 174.

NYMPHALID.

Our typical form, Danats Archippus, is included in
- this family.

Vanessa Antiopa, or the “mourning cloak,” is an-
other common species. The larve live together in
large numbers, and can be obtained from the willow
and poplar in June andalsoin August. ‘They are satis-
factory specimens for the schoolroom. ‘The contrac-
tion of the body of the caterpillar, the hardening of
the skin to form the chrysalis, and the final transfor-
mation after eleven or twelve days of pupal life can
all be observed by the young.

The family Nymphalidz offers a greater variety of
structure than the other three families, and the largest
number of cases of protective coloring and mimicry.
One of the best examples of mimicry is that of Basz/-
archia Disippus (Limenitis), imitating the colors of
. Danais Archippus. The disagreeable odor and taste

220 LEPIDOPTERA.

of Danais prevents it from being attacked by birds,
tree-toads, lizards, dragon-flies, and the like. Now,
Basilarchia has no disagreeable odor, and therefore
it is in great danger of being devoured. It has, how-
ever, mimicked the colors of Danais so perfectly that
it might be easily mistaken for it by insectivorous
animals.

In the Nymphalidz, generally speaking, the two
fore-legs are useless as organs of support, and the
chrysalis is not attached by the middle, but hangs by
the tail. These are known as the Suspensi, in distinc-
tion to the Succincti. The straight ventral surface of
the abdomen of the chrysalis of the Suspensi (more
plainly seen in Fig. 175 than in Fig. 148) is explained
theoretically by supposing that the Sus-
pensi have passed through the stage rep-
resented by the Succincti. In the latter
this straight ventral surface would have
been produced necessarily when the larvze
fastened themselves to hard, flat surfaces
with the back downward.

Teachers who take up this order will
soon become familiar with many species

Fig. 175. Of moths and butterflies that have not

been mentioned here, but these are fully
described in the numerous works on Lepidoptera.’

Sufficient has been said to show that much can be
done with this order in the schoolroom. ‘The accu-

1 Polygonia interrogationis.

2See The Butterflies of North America, W. H. Edwards,
I.-III., 1868-1890, which gives the life-history of many species
with full and excellent illustrations,

LEPIDOPTERA. 221

rate observation of the structure and metamorphosis
of a few forms will lead scholars, it is to be hoped, to
make really interesting collections illustrating not only
the full-grown moths and butterflies in their vicinity,
but also all their larval and pupal stages of growth.
These different stages of development cannot fail to
impress most profoundly the maturer mind of the
teacher ; for “it is the growth rather than the perfec-
tion of any organism which is of supreme interest,”
and the study of the life-histories of Lepidoptera will
lead teachers and pupils to a more intimate knowl-
edge of the habits of these insects, and to. the acquisi-
tion of habits of observation in the field and at home,
which cannot fail to give them mental occupation and
discipline of great value to their future progress.

A few words must be added in regard to the syste-
matic position of the Lepidoptera. The great diffi-
culty in placing this and the following orders consists
in the fact that the secondary larval stages have com-
plete possession of the younger periods, and no form
is known which has a Thysanuriform or primitive
larva. ‘The caterpillar, the secondary larval form, is
peculiar to the order, and its general prevalence and
the constancy of its characteristics are strong evi-
dences that it is now fixed in the organization and
hereditary.

The obvious affinities of the Trichoptera and Me-
coptera enable one to bring the Lepidoptera into close
proximity with these two orders, and in the absence
of other positive evidence to provisionally consider
the three as having had a common origin.

Scudder in his little book on Axzéterflies, and again

222 LEPIDOPTERA.

in his Butterfites of the Eastern United States and
Canada, with Special Reference to New England, de-
scribes the curious, transparent, crescent-shaped bands
at the base of the antennze in the chrysalis, which
have facets like the outer covering of the faceted eyes
of the adults, but have no corresponding internal
structures. This eminent entomologist points out
that such structures indicate the former presence in
the pupa of faceted eyes of which these cuticular
organs are the surviving remnants. ‘This would lead
to the supposition that the pupal stage in the ances-
tors of these existing forms must have led an active
existence, and that.one of the results of the incoming
of the quiescent pupal habit made their eyes useless,
and they were lost except in so far as the crescent-
shaped bands are concerned. ‘The archaic butterflies,
therefore, probably had direct metamorphosis like the
first series of orders.

ORDER XV. HYMENOPTERA.

A coop type of this order is the honey-bee, Afzs
mellifica (Pl. X., Fig. 176,.9, p. 224). We have fig?
ured the worker-bee in preference to the male or queen,
as it is most abundant. Bees can be obtained by the
quantity from apiarians, and single specimens can be
collected with little danger. If the flower in which
the bee is sipping nectar is quickly secured over a
wide-mouthed bottle containing alcohol, by means of
the stopper, and then gently shaken, the bee falls down
and cannot escape.

The body of the honey-bee is short and hairy.
#he-head (Pl: X.;. Fig. 177; 4 ; Fig. 176) .is large tin
_ proportion to the size of the body, and triangular in
shape. The prothorax (Fig. 177, 4’) is very small, and,
like that of the Lepidoptera, is not consolidated with
the mesothorax, but capable of independent motion.

The mesothorax (Fig. 177, 4’) is greatly developed
and immovably soldered to the metathorax, and its
scutellum (4°) extends backward. ‘The narrow meta-
thorax (Fig. 177, 4’) is closely connected with a
specialized ring, which is the first abdominal ring, and
for this reason is marked c’ in the plate. This ring
is carried forward to form a part of the thoracic
region.

The abdomen (Fig. 177, C) is short, and connected

3952
ae

224 HYMENOPTERA.

with the thorax by the abdominal ring (c*), which is
in the form of a slender peduncle. ‘The basal portion
is hollowed out so that the convex, posterior part of
the thorax can fit into it. Now it will at once be seen
that this peculiar connection enables the insect to
raise its abdomen and bring it downward and for-
ward with considerable force. ‘The abdomen also pos-
gesses great pliability as well as the power of driving
the blow of a thrusting instrument, like a sting. ‘The
development of the sting, and the necessity for its
effectual action, probably explains the small, wasp-like
waists of many Hymenopterous insects.

Thé compound eyes (Fig. 177, ev; Fig. 176) are
hairy, and in the workers, widely separated; the
three ocelli (Fig. 177, oc') are prominent. Accord-
ing to Lubbock’s observations bees possess a keen
sense of vision, being often much affected by light, as
shown by a bee following a lighted lamp down cellar,
“ flying round and round like a moth.” ‘Their power
of distinguishing colors is apparently excellent, and
this capacity, together with the bee’s acute sense of
smell, has probably exerted a determining influence
upon the color and fragrance of flowers. It is well
known that insects carry pollen on their bodies from
one flower to another, and in this way effect the plant’s
healthy fertilization. That there should be this mutual
dependence existing between plant and insect, notably
between plant and bee, is a matter of very great inter-
est, and no one can read the observations of Henslow,}

1 Origin of Floral Structures, International Scientific Series,
Appleton & Co., New York, 1888.

PLATE X.

1p

ES a
;

ev HYMENOPTERA. 225

Miiller,) Darwin,? and Lubbock,® without being im-
pressed by the wonderful part played by these ani-
mals in the evolution of the flora now existing upon
the surface of the dry land.

Henslow’s views represent more nearly those given
in this Guide, and his interesting speculations upon
the development of the complicated modifications of
flowers which are dependent upon insects for fertili-
zation should be carefully read by all who desire to go
beyond the superficial views of most Darwinists. It
is very important that teachers should be cautious in
allowing themselves the free use of explanations which
the doctrine of Natural Selection seems to furnish.
The danger lies in the fascination of the logical form
presented by this doctrine, the ease with which it
seems to explain even the most complicated relations
of organic beings, and the general although unfounded
belief that it is universally accepted and believed in
by naturalists. They will find, if they read the works
of Packard, Riley, Cope, Ryder, one of the authors of
this Guide, and other naturalists, that this doctrine is
not used by any investigators in accounting for the
origin of structures and their modifications, and only
to a limited extent by those quoted above and others
of the same school, in explaining the preservation of

1 Fertilization of Flowers. English translation. London.

2 On the Various Contrivances by which British and Foreign
Orchids are Fertilized by Insects, 1862; Different Forms of
Flowers. 1880.

3 British Wild-Flowers in Relation to Insects. 1875; Ants,
Bees, and Wasps, Chap. X.

226 HYMENOPTERA. a

structures and modifications after they have been orig-
inated by the action of physical and other causes.’

The antenne (Pl. X., Fig. 177, af) are distinctly bent
or elbowed. ‘The strong, horny mandibles (Fig. 177,
md) are used for biting, like the same organs in the
mandibulate insects, while the two pairs of maxille
(see Pl. X., Fig. 178) are for piercing, sucking, and
lapping. Fig. 178, 70, are chitinous rods connecting
the first pair of maxillee with the second ; 2’, the funnel
or sucking-disc of the ligula; and /g?/, two leaf-like
sections or secondary palpi known as the paraglosse.
The other parts are lettered as before. The ligula (Z)
is the part which is popularly known as the proboscis,
trunk, or tongue, and is not solid, but a tube-like suck-
ing-organ for obtaining fluids.” The length of the pro-
boscis varies in different species, being adapted to the
varying length of the tubular corollas of flowers. The
mouth parts of the honey-bee offer one of the best
illustrations of the process of specialization by addi-
tion. ‘This process has been carried so far that the
organs have become greatly differentiated from the
primitive type, complex in structure, and capable of
performing skilfully different kinds of work.

The legs..( Pl. X., Fig. 177,.7, 7.2") ate -sinenes
hairy organs adapted for walking. ‘The last pair (7'’)
in the worker are also used for storing pollen, the under
side of each tibia, which is protected by long, curving
hairs, being used for this purpose. ‘The first section
of the foot is very large, and marked by lines of bril-

1 See pp. 16, 40-42.
2 For figures, see Amer. Quart. Micr. Fournal, Vol. 1., No.

4, July, 1879.

HYMENOPTERA. 227

liant golden hairs which are used in collecting pollen.
The two pairs of wings (Fig. 177, w', w'') are similar
in structure, though the hind pair is less than one-
half the size of the fore pair. Both pairs are scaleless
and membranous, having few veins, in accordance with
the position of the bee as a species of the order Hymen-
optera -(juyv, membrane ; nvepov, wing) or membrane-
winged insects. The two wings on either side are
united by a number of hooks, so that a continuous
surface is presented to the air, and in this way the
power of flight greatly increased. ‘The Hymenoptera
are, in fact, very swift fliers, and, with the exception
of selected forms in other orders, are able to keep
on the wing longer than other insects.
_ The abdomen bears the long, pointed sting, which is
the ovipositor transformed into an organ of defence
and offence, and connected with the sting are two poi-
son-glands. The important part played by the use of
the sting in modifying the basal connection of the ab-
domen with the thorax has already been suggested
(see p. 224). In the skin there are many minute
glands which secrete wax. These open by small canals
on the surface. After the wax is secreted, it is excreted
in much the same way as is the scale of the scale-
insect and the powder of the aphis.

The home-making instinct is strong in bees. When
hives are not provided, even the domesticated insects
often select hollow trees. In one hive there are some-
times fifty thousand bees. The colony consists of
workers, males, and a-queen. ‘The workers build and
repair the comb, collect the honey and pollen, and
take care of the young. As we have already seen,

228 HYMENOPTERA.

they have short bodies, with well-developed mouth
parts, legs, and wings. ‘The genital organs are, how-
ever, nearly aborted. The males perpetuate their
kind, and when this work is accomplished either die
or are killed. ‘Their mouth parts are reduced in size,
and the hind-legs are not modified for collecting and
storing pollen. The queen lays eggs, and from two to
three thousand may be laid in a day. Her body is
longer than that of a worker, her hind-legs are not
modified, and her wings are shorter ; she has no glands
for secreting wax, and no honey-bag. The cells of the
comb serve as nurseries and also as storehouses. The
statement is not infrequently made that these cells are
mathematically exact, although Dr. Wyman! showed,
nearly twenty years ago, that this is not the case, the
perfect hexagonal cell being the ideal rather than the
real form. Darwin had previously brought out the
fact, interesting in this connection, that a constant
progress towards the ideal form is observable in pass-
ing from the cells of the simpler cell-making insects,
such as the humble-bee, wasp, hornet, and Mexican
bee, to those of the hive-bee.”

Special cells are reserved for the eggs. The larvee
(Pl. X., Fig. 179) differ from those of more generalized
insects in their extreme helplessness. They are color-
less, footless creatures, wholly unable to provide for
themselves, so that special workers, called nurses, take
care of them. ‘These provide food of different quali-
ties, giving the secretion formed from pollen by diges-

1 Proc. Amer. Acad. Arts and Sciences, Vol. VII.

2See Lxtomology for Beginners, Packard, Chap. IV. on
“Insect Architecture.”

HYMENOPTERA. 229

tion, which, according to Cheshire,’ is a highly nitrog-
enous tissue former, possessing apparently a singular
power in developing the generative faculty, to the
queen and drone larve and different nourishment to
the workers. ‘The tender treatment on the part of
the old bees towards the larve is in strong contrast to
the indifference shown the young locusts by their par-
ents, and seems to differ only in degree from that fos-
tering care which becomes the constant characteristic
of the higher vertebrates in maternal nursing and the
protection of the young by both parents, and which,
in human life, finds its noblest result and highest ex-
pression in our systems of education.

The larva, within its cell, spins a thin cocoon about
itself in five or six days, and passes into the pupal stage
(Pl. X., Fig. 180, side view; Fig. 181, ventral view of
the same). ‘This last stage lasts about ten days, when
the winged insect appears. This metamorphosis, like
that of the fly (see p. 255), illustrates the law of
accelerated development ; for here we have the larval
and pupal stages covering only a period of fifteen or
sixteen days, while the worker-bee often lives eight
months, and the queen has been known to live five
years. During adult life the art of building homes
has been gradually developed, habits of industry and
economy have been formed, and rude laws govern-
ing the community as a whole have been enforced ;
in brief, we have in a colony of bees specialization of
structure and function, resulting in a stage of social
life which it is difficult to account for unless we admit

1 Bees and Bee-Keeping. London, 1886.

230 HVMENOPTERA.

that these tiny animals possess intelligence in some
measure.!

The Hymenoptera are divided into two groups, the
Terebrantia, in which the ovipositor is a boring or
sawing implement; and the Aculeata, in which it is
converted into a true sting.

1 For further information on the structure and habits of bees, —
see Shuckard, British Bees; A. J. Cook, Manual of the Apiary ;
Lubbock, Ants, Bees, and Wasps.

TEREBRANTIA.

TENTHREDINID/..

THE saw-flies (Fig. 182, the pear-slug, Se/andria
cerast, Peck) have the thorax composed of three rings

and a sessile abdomen, the thoracic
and abdominal regions having a broad
connection. The mouth parts are for
biting, and are much simpler than
those of the bee. The
ovipositor is not mod-
ified into a sting, but
is a saw used for cut-
ting holes in leaves,
in which the eggs are deposited.

The larve (Fig. 182, a, represents
the larve feeding on a leaf of the
pear ; @, larva enlarged), having many
of the habits of the Lepidopterous
larvee, are caterpillar-like in form, and
are provided with mandibles for bit-
ing. They also have three pairs of

Fig. 182.

Fig. 182, a.

thoracic legs for locomotion and eight pairs of prop-
legs. They are not helpless creatures, but are able
to take care of themselves like the larvz of butterflies.
The caterpillar of the pear-slug burrows into the

ground, where it passes the pupa state.

231

232 HYMENOPTERA.

UROCERID. -

In the horntail (Fig. 183) the body is long, and
the thoracic rings (Fig. 183, 4', 6", 6'") are more
loosely connected than in bees. The waist is large,
the abdomen not being fastened to the thorax by a
peduncle. The tendency of the first abdominal ring
to become united with the thorax which we have ob-
served in the Orthoptera (locusts, grasshoppers, etc.),

Fig. 183.

and which also exists among certain forms of the Co-
leoptera and Hemiptera (Heteroptera), as pointed out
by Hammond, is found in both the Tenthredinidze
and Uroceride, but the junction is actually known to
take place only in the Hymenoptera Aculeata, and
there it is correlative with the stinging habits of the
insects and the pedunculated abdomen. ‘The oviposi-
tor (vs) of the horntail is not a saw, but a borer, and
is attached near the middle of the lower side of the

HYMENOPTERA. 233

~abdomen, beyond which it extends some distance. It
consists of a long, pointed implement encased in horny
sheaths. The larvze resemble those of saw-flies in
having thoracic legs, but have no abdominal prop-legs.
As has been noted above in many other examples,
the absence of these appendages is correlative with
habits which have probably made them useless, and
they have consequently disappeared. ‘The larvz are
wood-borers, and often injure shade trees.

The next family, Cynipide, includes gall-produ-
cers and a few parasites, while the succeeding fami-
lies, Chalcididz, Proctotrupidz, and Ichneumonide,
are mostly parasitic.

CYNIPID.

These gall-flies are small insects. The head is
usually broad with quite long antenne, the thorax is
thick, and the short abdomen flattened sideways. The
wings have very few veins. Gall-flies usually lay their
eggs in living plants, each species, as a rule, selecting
its own particular kind. The larva produces an irrita-
tion in the living tissues, and an abnormal growth ora
gall is the result. Within this gall the larva spends its
life. It has little need of antenne, and no use for
biting or piercing mandibles ; indeed, it has little use
for mouth parts of any kind, since it takes scarcely any
nourishment, and consequently these organs and the
antenne, although they still exist, are in an extremely
degraded condition. The nut-galls, or ‘ oak-apples,”
so common on oak trees, are familiar. Fig. 184 shows
the gall broken open with the larva (a) in its cell,

Zot HYMENOPTERA.

Between this cell and the exterior is a spongy sub-
stance. During the month of June many of the larve
transform within the cell, and the winged insect makes
its exit through the little opening at 4. These are
known as the spring gall-flies (Cynips guercus spongt-
fica, O. S.), and consist of both males and females.
Others remain within the gall till about October, and

these are the fall gall-flies (Cyzzps g. aciculata, O.5S.).
The later brood differs from the earlier by being en-
tirely composed of agamous females. Descriptions of
the Cynipidz of the North-American oaks and their
galls are given by Baron Osten Sacken.'

1 Proc. Ent. Soc. Phil. Vols, 1.-I1., 1861-64; Vol. IV., 1865.

HYMENOPTERA. 235

CHALCIDID/E.

The Chalcidide are mostly small in size, and are par-
asitic upon the eggs or larvee of other insects. Accord-
ing to Westwood, the males of the genus Blastophaga
are wingless, while the females are winged, which is
exceptional among insects.

ICHNEUMONID.

Fig. 185, natural size, represents an ichneumon-fly,
Thalessa atrata, Fabr., which was collected by a boy

Fig. 185.

of thirteen from one of our common shade trees.
The power possessed by the insects of raising and
lowering the abdomen, and the efficient aid given, in

236 HYMENOPTERA.

consequence, by this part of the body to the extremely
long ovipositor (es), is well shown in the drawing.
It was generally supposed until two years ago that
this insect bored into the trunks of trees and pierced
the bodies of grubs, especially those of Tremex, for
the purpose of laying its eggs. Definite knowledge
on the subject was wanting until Dr. C. V. Riley’ pub-
lished his observations. His detailed description, with
figures illustrating the method of oviposition in Thal-
essa, the structure of the ovipositor, etc., are of great
value. The trees in which the eggs are laid are in
most cases somewhat affected, so that the wood is not
firm and healthy. The larve of Thalessa are found in-
variably external to the Tremex grub ; z.e. “ not within,
but holding on to its victim and sucking the latter’s
life away, without in any case entering its body.” After
careful observations of the female while ovipositing,
Riley came to the conclusion that she did not attempt
to reach the Tremex larva, but only its burrow, and
that the young parasitic larva after hatching must in-
stinctively seek its victim. He continues, “The truth
of the whole matter is, that Thalessa, like all other
insects, is liable to suffer from fallible instinct, and
that while she doubtless has better means of distin-
guishing a tree infested by ‘Tremex than we have, she
nevertheless often makes mistakes, and the unerring
instinct, which book entomologists are so fond of
dwelling upon, is often at fault.”

The ovipositor is extremely long, measuring not less.
than four and a half inches; it is protected by two

1 See Insect Life, Dept, Ag., Vol, I., No, 6, December, 1888,

HYMENOPTERA. 237

sheaths which, when united, form a tube, being convex
on the outer side and concave on the inner. In Fig.
185 the three parts are separated from each other, but
in Fig. 185, a, which is a diagrammatic cross-section
of the three parts, their relative position is clearly
shown.

Many ichneumon-flies have a short ovipositor (see
Fig. 185, x, Eiphosoma), and some of these lay their
eggs on the skin outside or within the bodies of cater-
pillars. When hatched, the larval flies feed upon these
caterpillars. Sometimes the latter pass into the chrys-

0

Fig. 185, x. Fig. 185, a.

alis state, but they cannot escape, and the ichneumon
parasites finally feed upon their internal organs. The
larve are footless ; they pass the pupa state within the
integument of the caterpillar or chrysalis, and emerge
as winged insects. These flies are really very useful in
killing harmful insects, such as Preris rape, “ canker-
worms,” and the like. Figures of many species of
Ichneumonide are given in Snellen Van Vollenhoven’s
Pinacographia.

ACULEATA.
FORMICID.

THE ants (Pl. XI., Figs. 186-189, p. 238, Formica
Pennsylvanica, De Geer) have the rings of the thorax
much more loosely connected than in the typical
Hymenoptera. There is also less concentration of
these parts in the wingless workers (Pl. XI., Fig. 188,
b', 6", o'") and soldiers (Pl. XL, Fig-48¢7 20
6") than in the winged males (Fig. 186, 4’, 3", 6'")
and females\(Pl. XI., Fig. 187, 0’, 6") 8"). aie
is only another illustration of what we have already
pointed out, viz. that the consolidation of the thorax
depends upon the insect’s power of flight, and is great-
est in the best fliers, and least in the poorest. The ab-
domen is pedunculated in all the forms; but in the
stingless ants the peduncle has only one joint, while in
many of the stinging species it has two. This last
fact favors the view advanced above, that the peduncu-
lated abdomen is probably a result of the habit of
using the ovipositor as an offensive weapon.

The male and female have both compound eyes
and ocelli (see Figs. 186, 187), but the worker and
soldier have no ocelli (see Pl. XI., Figs. 188, 189).
The mandibles of the soldier are organs of defence,
and are, therefore, larger and stronger than in the
other forms. The legs are strong: Pl. XI., Fig. 190, is

235

PLATE XI.

(Facing page 238.)

HYMENOPTERA. 239

the termination of the foot of the worker; Pl. XL.,
Fig. 191, that of the male.

The nest, or formicary, is often excavated in trees,
and consists of many chambers and galleries.'. The
colony is composed of males, many females (instead
of one as with bees), workers, and soldiers. The males
live only long enough to take the marriage flight : after
this flight the females lose their wings, and may live
several years. The workers are immature forms having
the ability to labor and but little power of reproduc-
tion. They can lay eggs in small numbers ; but these
are not impregnated, and produce only males. The
soldiers are devoted to the special work of protecting
the colony rather than of building the nest or repro-
ducing their kind.

The larve (Pl. XI., Fig. 192) are white, footless in-
sects, and diminish in size towards the head. They
are so extremely helpless that the nurses are obliged
to feed them from their own mouths. It is interesting
to note that the larve of one species, Formica fusca,
sometimes spins a cocoon, and at other times remains
naked. The pupa stage with most ants is passed
quickly.

Social life has existed so long among these insects
that they have acquired habits of co-operation ; they
assist each other in work, in taking care of the young
and of females. They help the pupz out of their
cocoons, clean them, ete. They can also communi-
cate with each other to a certain extent, make slaves

1 For drawings illustrating the architecture of this species of
ant, see Zrans. Amer. Ent. Soc. Phil., Vol. V.

240 HYMENOPTERA.

of other species, store and take care of grain, build
roads, and domesticate and rear animals (like the
aphides), whose secretions they make use of for food,
as human beings make use of cows. So much has
been written on the habits and sagacity of these insects,
and the knowledge is so easily obtainable," we need
only refer here to Lubbock’s’ experiments, which have
demonstrated that the intelligence of these insects
does not differ so much in kind as in degree from the
intelligence of man. This fact would place ants at the
head of the invertebrates, were physiological character-
istics, such as mental qualities, rather than structure
and development, made the basis of our classification.

SPHEGIDAL.

Fig. 193 is one of our common digger or solitary
wasps, Sphex ichneumonea, Linn. ‘The head is large,
and the abdomen is connected with the thorax by a
long, slender peduncle, which gives the desired plia-
bility when the sting is performing its function of par-
alyzing insects. ‘The mandibles are strong, and aid:
the long, bristled legs in digging nests in the earth.
Only one egg is laid in anest. ‘The larva is footless
and helpless. Its diet consists of the animal food, by
preference grasshoppers, which the parent has stung
and paralyzed, but, as a general thing, has not killed.
Some species prefer caterpillars ; some, aphides ; and
others, flies or spiders. The larvee live several weeks

1 See H. C. McCook, Agricultural Ant of Texas ; Mary
Treat, Chapters on Ants, Forel, Les Fourmis de la Suisse.
2 Ants, Bees, and Wasps.

HYMENOPTERA. 241

before they are ready to form their cocoons, so that
the insects must be stung in the right place and sim-
ply paralyzed ; if killed, as they sometimes are, de-
composition takes place, and they become not only
unfit for food, but are apt to be dangerous in other
ways to the health of the larvz confined in the same
cell. Sphex represents the fossorial Hymenoptera,

Fig. 193.

such as the Mutillide (“solitary ants”) and Pompi-,
lide (‘‘sand-wasps”’). Among the latter is the inter-
esting “ tarantula-killer,”’ or “ tarantula-hawk,” Pompi-
‘lus formosus, of Texas and Arizona. Specimens of
this wasp, and the great spider, A4vgale Hentzii (erro-
neously called tarantula), which it paralyzes, can be
sent by mail to Eastern teachers. It is a powerful
wasp as compared with our hornets. The body of

ZAz HYMENOPTERA.

the specimen in hand is one and a half inches long,
with small waist, stout, spiny legs, and large, yellowish
brown wings. Strong as the insect is for a wasp, it
seems hardly possible for it to render powerless so
large and formidable an animal as the Mygale spider.
This it does, however, most successfully. When the
wasp discovers a spider, it circles about it in the air
until a favorable moment arrives, when it darts down
and thrusts the sting, with its load of poison, into the
body. ‘This is sometimes repeated two or three times.
When the spider is paralyzed, it is dragged to a suit-
able place, where a hole is dug for it, one egg is laid
near the body, and the hole is filled with earth. Some-
times the wasp in other species, and probably in this
one, kills the spider; but it never seems to know the
fact, and the consequences to the larvz are probably
fatal, especially where only one spider is supplied for
food."

VESPID~.

The paper or social wasps are represented by Vespa
maculata, Linn. (Fig. 194, 2). When the hairs are
cleaned from the body, the prothorax is seen as a nar-
row collar soldered to the mesothorax above. The
mesothorax (Fig. 194, 4'') is large and rounded, bear-
ing the larger wings. At the basal joint of these wings
are small, horny, movable shoulder lappets (4), which
we have already seen in the Lepidoptera, and which.
are concave on the inner side. The extreme poste-

1 For further information, see Dr. Lincecum, “ The Taran-
tula-Killer of Texas,” American Naturalist, Vol. 1., p. 1373
Riley, American Entomologist, Vol. L., pp. 111, 128. |

HYMENOPTERA. 243

rior edge of the mesothorax on either side is modified
in such a way as to suggest a second pair of lappets ;
the basal joints of the lower wings move freely under
these modified portions. ‘The abdomen is connected
with the thorax by an extremely small waist, and can
be raised some distance before coming in contact with
the thorax. The legs of Vespa are shorter and with
fewer bristles than those of Sphex.

These wasps live in colonies and build their homes
of paper. Harris happily calls them “natural paper-
makers,” as they scrape off wood with their mandibles,
chew it, and convert it into the coarse pulp which is
used in making their nests. The eggs are laid in the
cells of these nests. The larva (Fig. 195, 2) looks
not unlike the larva of the bee and fly, but the forward
end of the body is much larger than the posterior end.
This is owing, probably, to the position of the larva

ZA4 HYMENOPTERA.

within its cell. It does not work its way through sub-
stances like the maggot of the fly, but remains in the
cell, head downward,
being held there during
the latter part of its lar-
val life by the size of
the body, which exactly
| fits the opening. The
larvee are fed by the older wasps till they are ready
to take care of themselves.

Fig. 195.

APIDZ:.

The solitary, humble, and social bees are included
in this family, the most specialized of which is the
honey-bee, Apis mellifica.

The Hymenoptera’ are commonly placed at the
extreme end of the classification, and considered as
if they were the most aberrant of all insects, or, to use
the ordinary nomenclature, the “ highest,” on account
of their beauty of proportion, the complexity of their
mouth parts, which are fitted for biting, sucking, and
piercing in some groups, and the tendency in several
families to gather into communities with so high a
degree of specialization that they have different castes
distinguished from each other in structure and func-
tion; also because the first abdominal segment is
transferred to the thorax, so that by some entomolo-
gists this region is described as having four rings in-
stead of three in all the groups except the saw-flies
and horntails: and, finally, because they have the

1 See especially Packard, Entomology for Beginners, p. 162.

HYMENOPTERA. 245

indirect mode of development, some larvze being foot-
less, and so completely helpless that they are fed by
their parents.

According to the standards we have adopted, the
most specialized insects in other orders have been
those in which the mouth parts have been fitted for
one office, that of sucking fluids (Hemiptera, Lepi-
doptera) ; or else in large part suppressed, the work
of the insects being narrowed down to the perpetua-
tion of its species (Ephemeridz): in fact, any sort of
a modification of the parts of the body, either result-
ing from extra development or suppression, which has
removed the adult more widely from its own young or
its supposed Thysanuran ancestor, or from both of
these forms, and narrowed its field of work, has been
deemed a sure index of extreme specialization.

In the Hymenoptera the complexity of the mouth
parts fitted to do so many different kinds of work is
not, therefore, a mark of the highest specialization.
The tendency to gather into communities is found in
groups of other orders (white ants) having similar
habits, and the effects upon structures are not so fun-
damental that we are thrown into any doubts with
regard to the order to which any of the social insects
belong. The indirect mode of development is evi-
dently a characteristic shared in common with several
other allied orders, and occurs as well in smaller groups
of the first series of orders, wherever habits make
this method necessary or useful. Friederich Brauer,
although considering them the “highest” of insects,
points out that, notwithstanding the “higher’’ mode
of development, the Hymenoptera remind one more

246 HYMENOPTERA. /

of the genuine Orthoptera than of the otherwise nearer
allied Lepidoptera and Diptera.

Thus while the habits, general aspect, and compli-
cated nature of their external skeleton leads one to
consider the Hymenoptera as a highly specialized type,
it is evidently one that exemplifies specialization by
addition and not by reduction. So far as other struc-
tural and larval characteristics are concerned, they are
not therefore entitled, according to the standard here
adopted, to be considered the most highly specialized
of all insects.

Although entomologists as a rule do not seem dis-
posed to consider that the three rings of the thorax
and the caterpillar-like larvae of the saw-flies indicate
affinities with the Lepidoptera, nevertheless this family
is evidently the most generalized of its order, and the
thorax, sessile abdomen, and mode of development
not only separate it widely from the great body of the
Hymenoptera, but remind one strongly of the Lepi-
doptera. ‘Thus, although it would be an error, as
pointed out by Brauer and others, to consider the
saw-flies as transitions to the Lepidoptera, this family
is obviously more closely allied to Lepidoptera than
any other of its order. One cannot avoid also giving
some weight to the larval form, especially when it
occurs in association with such a generalized adult
form, and this leads one to suspect that the Hymen-
optera and Lepidoptera may have had a common an-
cestor in spite of the anatomical differences which
now distinguish them. The absence of the caterpillar-
like stage of the Tenthredinidz may have been due
to its obliteration by the law of acceleration acting

HYMENOPTERA. 247

upon the characteristics acquired by the larvee in fam-
ilies which provide their young with food by laying
their eggs in plants, in the bodies of other animals,
or that rear them in nests, as is customary among
the more specialized forms of Hymenoptera Aculeata.
The larvze under these conditions would naturally and
inevitably lose the useless legs, and even in some cases
more or less of the mouth.parts whenever these be-
came also useless, and the soft, fleshy, grub-like form
would replace the more active caterpillar-like larva.

Other evidence of the convergenee of these two
orders is not wanting. Walters, after extensive inves-
tigations, has shown that true biting mandibles exist in
some of the more generalized forms of the moths,
being especially well developed and furnished with
teeth in Micropteryx, and also shows that in this
genus the mouth parts can be compared part for
part with those of the Tenthredinidz (saw-flies),
concluding that the latter approximate most closely
to the generalized (“‘lower”’) forms of the Lepidop-
tera than the insects of any other order."

1 « Beitrage sur Morphologie des Schmetterlinge,” Zezéschrift
Jf. Medicin u. Naturwissenshaft, Jena, 1885, XVIIL., p. 799.

ORDER XVia) DIPGERRAS

Tuis order is by far the most interesting if we con-
sider structural characteristics and development. The
reasons for assigning the group its position as repre-
sentative of extreme specialization are suggested in
the descriptive work on the type and succeeding fam-
ilies, and stated in comprehensive form in the con-
cluding remarks (see pp. 273, 274, 287). We regret
that space will not permit us to give detailed descrip-
tions and figures of the many interesting modifications
of structure which characterize pre-eminently both
the larval and adult stages of this large order.

As arule the Diptera are small insects, and there-
fore good specimens for close observational work.
Scholars should become acquainted with their struct-
ure and transformations, and this can be done if it is
remembered that after continued observation the eyes
distinguish characteristics which are not at first visible,
and that magnifiers of cheap construction will do a
surprising amount of work in the hands of any one
with sufficient perseverance.

The familiar house-fly, Wusca domestica, Linn., can
be used as the type, if other species are not at hand.
The horse-fly, or “ green-head,” Zaéanus “neola,
Fabr. (Pl. XII., Fig. 196, p. 248), is larger, and its
mouth parts are more perfectly developed, so that it
can furnish good examples for class instruction,

248 ;

PLATE XII.

ts? bir

br

(Facing page 248.)

DIPTERA. 249

The rounded body is compact, showing marked con-
centration of parts. The short, broad head (Pl. XIL.,
Fig. 197, 4; Fig. 196) is attached to the thorax by
a pivot-like neck. The prothorax (Fig. 197, 3’) is
merely a little collar-like ring, but unlike that of the
Lepidoptera and Hymenoptera, is immovably consoli-
dated with the forward part of the mesothorax. It is
seen in Pl. XII., Fig. 198, 4', which is a drawing of
the head and thorax of another species of horse-fly.
Fig. 198, s', is the prothoracic spiracle.

The mesothorax (Pl. XIIL., Figs. 196, 197, 4!) is the
largest ring, and at first sight the whole thorax appears
to be made of this segment; its chitinous scutellum
(Fig. 197, 4°) extends backward and slightly upward,
concealing the narrow dorsal portion of the metatho-
fSeeptsseen. in Pl. XIL., Fig. 198, 47.. Fig. 198, s°, is
the mesothoracic spiracle.

The metathorax (Pl. XII., Figs. 197, 198, 4'"') is
reduced in size, but is complex in structure. It con-
sists dorsally of the small ring just referred to (see Fig.
198, 6'"), which is uncovered by the abdomen. The
part usually called the scutellum (Figs. 197, 198, 5°)
is bulbous, and wholly concealed by the basal ring of
the abdomen (Fig. 197, C).

The complexity of the thorax in the Hymenoptera and
Diptera has been the subject of much discussion among
entomologists, and the different opinions held in regard to
it are stated ina carefully prepared paper Ox Latrezlle’s
Theory of ‘‘Le Segment Mediaire,” by C. C. A. Gosch.}

1 Naturhistorisk, Tidsskrift Schiodte, Copenhagen, 3d ser.,
XXX., 1883, pp- 475-531.

250 DIPTERA.

Latreille maintained that in Hymenoptera with peduncu-
lated abdomens the first abdominal ring was transferred to
the thorax, forming the posterior part of that region, and
concluded, hescnac that the peduncle was the second
abdominal ring. He also thought that a similarity existed
between the thorax of Hymenoptera and Diptera, main-
taining that in the latter also the first abdominal segment
joined the thorax. He, however, refused to accept the
view that the balancers represented the second pair of
wings. His theory in regard to the structure of the hy-
menopterous thorax is now generally accepted, but the
burden of evidence concerning the dipterous thorax is in
favor of Reinhard,! Weismann,? and Hammond,? who
maintain that it is made of three rings only. Dr. Weis-
mann while holding this view says, in speaking of the
abdominal rings in the pupz of Muscidae, ‘‘ At first the
foremost of thescioltha fifth * larval sesmient— eae
the posterior part of the newly formed thorax, so that the
latter in a certain way grows out of it” (p. 254); and
again (p. 316), ‘‘On the third day the three segments of
the thorax form together a small ring which towards the
hinder part has joined the edge of the fifth segment of the
larva.” Dr. Palmén® opposes the view that the thorax is
made of three rings, asserting that in Corethra it is formed
of four segments, which he believes to be the case, more
or less, in all Diptera. Exhaustive investigations on the
anatomy of adults and the development of the larve and
pup are needed, as pointed out by Gosch, to settle this
question.

1 Berliner Entomologische Zeitschrift, Vol. 1X., 1865, 2d to
4th quarter.

2 Zetts. f. wiss. Zool., 1864, 1866.

3 Yournal Linn. Soc., Vol. XV., 1880-81.

4 The fifth segment when the head is counted as one ring, but
the eighth when it is held to be made of four segments.

° Zur Morphologie des Tracheensystems, 1877.

DIPTERA. 251

The peculiar connection of the thorax with the
abdomen in the horse-fly makes the latter appear to
be sessile, but it is very different from the true sessile
abdomen of the more generalized insects of the first
series of orders, and we propose to speak of it asa
pseudo-sessile abdomen. The basal portion of the
abdominal region has been carried forward and has
united with the thorax, thus covering up and reducing
to the condition of internal parts the posterior por-
tions of the metathorax. ‘That these were originally
external is shown by their dark color, and also by the
fact that in the more generalized forms of the Dip-
tera they are fully exposed. In this way it is possible
to conceive of a mode in which an insect with pedun-
culated abdomen could have become evolved into one
with a pseudo-sessile abdomen, but the difference
between this type of sessile abdomen and that of
generalized orders, like Orthoptera and Hemiptera,
must be clearly borne in mind. It has been produced
probably by a process ,of specialization by reduction
out of a pedunculated abdomen, whereas the true
sessile abdomen is a primitive Thysanuriform charac-
teristic. The abdomen of Zadanus dineola has a light-
colored band extending down the middle, as seen in
Pl. XII., Fig. 196, by which the species is easily dis-
tinguished. Its terminal rings are withdrawn into the
body, but can be extended like a telescope and serve
as an ovipositor, though a weak one ; as, however, the
eggs of most flies are laid in or on soft substances,
horny digging implements are not needed.

The compound eyes (Pl. XIIL., Fig. 197, ev; Figs.
196, 198) make up the greater part of the head: in

252 DIPTERA,

the male they are in close contact, but are separated
in the female. The two ocelli cannot be seen from
above, but only in a front view of the head. The
antennz (Figs. 197, 199, a7) are short, with the third
joint very much enlarged. ‘They are often carried for-
ward, as seen in Pl. XII; Figs. 196, 198.0 ,PIe
Fig. 199, represents the mouth parts, which are com-
plex in structure and fitted for piercing, sucking, and
lapping. The mandibles (md) and maxille (mz',
mx'') are like sharp lances, and pierce the hide of
horses and cattle, sometimes causing their death. The
palpi of the first pair of maxillz (x') are large and
stout. The second pair of maxillz forms the tongue
or proboscis, and this pair is without palpi. The
operation of lapping food can be observed by chil-
dren if sweetened water is given a common house-fly.
In this insect the mandibles and first pair of maxille
have become obsolete, but the proboscis is finely
adapted for lapping, having two broad, flat leaves
at its end. These are strengthened by bars which
roughen the inner surface so that a rasping organ is
produced (see p. 265).

The legs (Pl. XII., Fig. 197, 7, 27', 7"), anew
long, and the feet have five joints, two claws, and a
fleshy two-lobed cushion furnished with hairs which
excrete an adhesive liquid, enabling the insect to walk
on a ceiling with safety. Home!’ gives magnified
figures of the last joint of the toe of a blue-bottle fly
as seen when the insect is walking in such a position.

1See Lectures on Comparative Anatomy, Volv IV., Pls.
LXXXI.-LXXXVI.

DIPTERA. 253

The possession of this structure is of great advantage
to the insect, since it increases its chances of obtain-
ing food.

The fly has only one pair of functional wings, and
this characteristic has given the name of Diptera (dis,
double ; zrepov, wing), meaning two-winged, to the
order. ‘These wings (Fig. 197, w’; Fig. 196) are
strong organs, and are borne by the large, muscular
mesothorax, so that the flight of the insect is swift,
the fastest horse not being able to outstrip it. The
point of insertion of the wings is indicated in Pl. XII.,
Fig. 198, w'. Attached to each wing, and moving
with it, are two small, flat scales, or winglets, called
alulets (Pl. XII., Fig. 197, sc), the use of which is
unknown. ‘The second pair of wings (Figs. 196, 197,
w''; Fig. 198, w'', indicates the point of insertion) are
reduced to a pair of knobbed balancers, or halteres.
It is interesting to note in this connection the decrease
in size and efficiency of the hind wings in passing
from the Lepidoptera to the Diptera. Hammond! has
shown that there is not only this reduction, but also a
corresponding change in the segment which bears the
posterior wings, and the muscles which move them.
In the Lepidoptera the fore and hind wings are more
nearly equal than in the other two orders; in the
Hymenoptera the posterior wings are much reduced
in size, as we have seen, and in the Diptera they are
only represented by the diminutive halteres, while
the metathorax, in the specialized forms, is so small it
cannot be seen from above, and the metathoracic
muscles exist only as remnants. The buzzing of the

1 Fourn. Linn. Soc., London, Vol. XV., p. 16, 1880-81.

254 DIPTERA.

fly is largely due to the rapid vibrations of the wings,}
and it may be, in lesser degree, to the spiracles of the
thorax.

The development of Tabanus has not been fully
worked out. ‘The larva of one species is of large size,
measuring nearly two inches in length; the head is
retractile and is provided with jaws. Along the body
are projections or warts used in locomotion, and at
the end are fleshy processes.

The development of the house-fly has been de-
scribed and figured by Packard.” The eggs are laid in
the manure of stables, and under favorable conditions
require about twenty-four hours for development ; but
when the heat and moisture are not sufficient, the
time is longer, and the larva is smaller when hatched.
Pl. XII., Fig. 200, is a dorsal view of the young larva,
or maggot, as it is usually called. The two main
tracheze are represented with the anterior and pos-
terior commissures (4). Pl. XII., Fig. 201, is the
larva after it has moulted once. It is not a general-
ized, but an extremely specialized form. Although
living in such soft substances, it is, nevertheless, a
boring creature, and the head is therefore small and
suitable for penetration, the propelling power being
placed in the larger, posterior end. The body con-
sists of a succession of similar rings without feet, but
with setz to help the animal when boring. “Pl. XII.,
Fig. 203, shows the forward end, which is not differen-
tiated into a head; a¢ are the antenne. The man-

1 See Burgess, “ Recent Studies in Insect Anatomy,” Psyche,

Vol. III., No. 71, March, 188o.
2 Proc. Bost. Soc. Nat. Hist., Vol. XV1., 1873-74.

DIPTERA: 255

dibles (#@) are modified into hooks for dragging the
insect along ; wzx' are the maxille ; 4% is probably the
labrum. Pl. XII., Fig. 201, s’, is the prothoracic spir-
acle; and Pl. XII., Fig. 202, the spiracle enlarged.
The larval stage averages from five to seven days,
then the larval skin hardens and gradually separates
from the pupa within. ‘This larval skin is known as
the puparium (PI. XII., Fig. 204). Within this case
the coarctate pupa (Pl. XII., Fig. 205), as it is called,
transforms into a fly in five or seven days. ‘The meta-
morphosis is completed, therefore, in the short period
of from ten to fourteen days. The mature insect
remains in a torpid state through the winter, and
appears the following May or June. It does not lay
its eggs till August, after which it dies.

The Diptera include an immense number of fami-
lies, from which it is only possible to select a few of
the commonest and most instructive. The order has
been divided by Brauer into two large groups, — the
Orthorhapha and Cyclorhapha,— and _ this classifi-
cation is based upon larval and pupal characteris-
tics. In the Orthorhapha the larval skin opens at the
last moulting along the middle of the back, from the
second to the fourth segment, and to this longitudinal
fissure is joined, near the forward end, another short
cross-fissure, so that a T-shaped orifice is produced.
It also happens in some species that the pupa escapes
through a transverse rent between the seventh and
eighth abdominal rings.

In the Cyclorhapha the larval skin hardens into a
puparium, which is seldom similar in form to the
larva, and the pupa escapes from this puparium

256 DIPTERA.

through a circular orifice in the anterior end. We
have placed the semi-parasitic fleas after these two
groups, and following these, the true parasites, or
Pupipara, which are included in the Cyclorhapha in
Brauer’s classification.

ORTHORHAPHA.
TIPULID.

THE crane-flies are larger than most flies and show
many of the parts distinctly, especially the balancers.
They have long bodies, and the general aspect of the
elongated thoracic region reminds one of the Lepidop-
tera. The posterior part of the metathorax is here

Fig. 206.

wholly exposed to view, both from above and from
the sides (see Fig. 206, §, which is a side view of the
thorax and basal portion of the abdomen of Tipula ;
Fig. 206, a, §, dorsal view). In the first series of
orders, as represented by the locust, squash-bug, etc.,
the true sessile abdomen makes such a broad connec-
tion with the thorax that slight, if any, vertical or

spe T

258 DIPTERA.

lateral constriction takes place between the two regions.
In the more specialized Lepidoptera (butterflies) and
in others of the second series of orders, the thorax
appears to be constricted vertically, narrowing down-
ward posteriorly, to become attached to the abdo-
men. A somewhat similar condition is found to exist
in the Tipulidz, as seen in Figs. 206, 206, a. As these

b!

Fig. 206, a.

flies, like other members of the order, have no sting,
it is probable that they do not need the perfectly
formed pedunculated abdomen, such as is found in the
Hymenoptera Aculeata, and therefore the basal por-
tion of the abdomen is not constricted laterally so as
to form a pivot-like ring as in bees and wasps.

DIPTERA. 259

Unlike most Diptera, crane-flies have an external,
horny ovipositor, which is used for making holes in
earth, mould, fungi, etc., as the larve of many species
are terrestrial. ‘The latter feed upon the tender roots
of grass, clover, and grain, having mandibles and max-
ill that are more or less horny and adapted for bit-
ing." They move by means of swellings on the ventral
side of the body, which are provided with bristles.
According to Williston” those larve of the Tipulide
which live on the leaves of plants are “almost like a
caterpillar in appearance,” some species being green,
with tubercles along the back. It is also stated by
Kirby and Spence’ that one species of Tipula (7:
Agarict seticornis, DeGeer) is provided with two sepa-
rate spinnerets. While the Tipulid larvae resemble in
these respects the more generalized larval forms of the
Lepidoptera and Hymenoptera, they are like the spe-
cialized larvz of the last-named group in not possess-
ing either thoracic legs or abdominal prop-legs. The
pupz of this family are not covered by a puparium,
but are free or obtected.

CULICID/:.

Mosquitoes have a long body, like crane-flies ; the
head is small, the thorax is not so elongated as in the
Tipulidze, although it is wholly exposed, and the abdo-
men is slender. The mouth parts, like those of the
horse-fly, are well developed. The female feeds upon

1 See “The Meadow Maggots or Leather Jackets,” Szxteenth
keport Noxious and Beneficial Insects of Illinois, 1887-88.

2 Stand. Nat. Hist., Vol. I1., p. 415.

3 Introduction to Entomology, Vol. IIL. p. 125.

260 DIPTERA.

liquids, but apparently prefers the blood of animals,
while the male, if it feeds at all, which seems to be
doubtful, must, according to Dimmock,’ take liquid
food, although in smaller quantities than the female.
The structure of the head and mouth parts of Culex
rufus is shown in Pl. XIII., Figs. 207-213, p. 260,
taken from Dimmock’s paper, to which we have
already referred. Pl. XIII., Fig. 207, is a dorsal view
of the head; Pl. XIII., Fig. 208, a side view of the
same, with the appendages. ‘The mouth parts are
somewhat complex. Fig. 208, /ae, is the labrum and
epipharynx, which are united throughout their length,
forming one piece; yp is the hypopharynx, a part
not found in many insects; md are the mandibles ;
mx', the first pair of maxillz. All these parts are re-
ceived into a groove on the upper side of the second
pair of maxilla (sx''); x’ are the maxillary palpi
(see Pl. XIII., Fig. 207, \x'); cz, the clypeus> 2a
Fig. 209, is a cross-section through the middle of the
proboscis, showing the arrangement of the parts. The
mandibles (md) and first pair of maxillz (sx') are
enclosed in the second pair of maxillz (#zx''). Above
the mandibles is the hypopharynx (Ayp), and resting
upon the latter is the epipharynx (efx) and the la-
brum (Zz) (these two parts are lettered /ae in Pl. XIIL.,
Fig. 208) ; “ represents the trachez, and z the mus-
cles of the second pair of maxille. When the insect
bites, all the parts excepting the second pair of max-
illee (which bend backward under the breast) are thrust

1 The Anatomy of the Mouth Parts and of the Sucking Appa-
ratus of Some Diptera, Boston, A. Williams & Co., 1881, p. 22.

PLATE XIII.

(Facing page 260.)

DIPTERA. 261

into the flesh. The blood is then sucked up the tube
formed by the labrum-epipharynx (Pl. XIIL., Fig. 208,
Jae) and the hypopharynx (Fig. 208, hyp; see PI.
XIII., Fig. 210, longitudinal section of the head),
and passes into the pharynx (Fig. 210, p/), cesopha-
gus (@), and cesophageal bulb (@é), the valve (gz)
preventing its return. At the same time it is prob-
able that a poisonous liquid passes downward along
the upper side of the hypopharynx: 7 is the infra-
cesophageal ganglion ; sf, supra-cesophageal ganglion ;
cl, clypeus.

The eggs of mosquitoes are usually laid in boat-
shaped masses on the surface of standing water, and
the larve (Pl. XIII., Fig. 211) are familiarly known
as “wigglers.”” They have a distinct head, and jaws
fringed with hairs, which help to catch the food. The
thorax is without legs, but both this region and the
abdomen are provided with clusters of hairs. The
larvee swim with the head downward, and breathe by
means of the respiratory tube (¢z) at the end of the
body, which connects with trachez. They also often
suspend themselves just below the surface of the water
for the purpose of breathing. The pupz (PI. XIIL.,
Fig. 212) respire by two tubes (¢) on the thorax,
and motion is effected by leaf-like appendages (PI.
XIII., Fig. 213) attached to the abdomen. They
take no food, and usually remain quietly near the sur-
face of the water, with the head upward ; though if
disturbed, they become active, their movements being
produced by the muscles of the abdomen, unaided
by those of the thorax. When they moult, the cast-
off skin serves as a raft, on which the insect rests till
its wings are ready for flight.

262 DIPTERA.

ASILID/E.

The Asilidze resemble the Tipulidze in the general
shape of the body, but the thorax is somewhat short-
ened, and its posterior part is not wholly exposed.
If the abdomen is separated from the thorax on the
dorsal side, it will be seen that a part of the meta-
thorax fits into its basal portion as a ball fits into a
socket. These insects (Fig. 214) are rightly named
robber-flies, insect-
hawks, and Missouri
bee-killers, for they
have the habit of
attacking bees, bee-
tles, dragon-flies,and
even other robber-
flies, sucking out the
soft parts of the
body and _ leaving
the chitinous skin.
This habit is corre-
lated with the follow-
ing peculiarities in
structure. The body is long (one species having a
length of two inches), and covered with stiff, bristling
hairs. The eyes are large and projecting, and the
black proboscis is powerful enough to severely sting
the hand of a man. The legs are armed with bris-
tles, and the wings are strong organs adapted for
swift flight. Many of the larve are carnivorous like
the adults. Those living in the earth bore into the
grubs of beetles and devour them. They have a head
with two hook-like mouth parts. The pupe are free.

DIPTERA. 263

TABANID.

In the Tabanidz we have the body very much short-
ened and the parts extremely concentrated. The pos-
terior portion of the metathorax, instead of being ex-
posed, as in the Tipulidz, or partially covered, as in
the Asilidz, is here entirely concealed by the basal
ring of the abdominal region, and is what we have
called a pseudo-sessile abdomen. The different spe-
cies of horse-flies belong to this family, represented by
the typical form of the order, Zadanus hineola.

CECIDOMYIDE.

The gall-gnats constitute a large and aberrant fam-
ily. They produce the “pine cone” galls found on
willows, also the bushy tufts of leaves on golden-rod,
besides galls on the oak, hickory, and other trees.
The famous Hessian-fly, or wheat-midge, Cec:domyia
destructor, Say, belongs to this family. The Cecido-
myidz are of minute size and have few veins in their
wings, resembling in this respect the Hymenopterous
gall-insects (Cynipidee). The larve do not have a
differentiated head, and the mouth parts have become
reduced in size, as the insects probably take little food
in the larval stage. The pupz of some species are
free, and others are covered with a puparium. In the
latter case the insect pushes itself out backward
through an opening in the puparium between the
seventh and eighth abdominal segments.

CYCLORHAPHA.

SYRPHIDA..

In the Syrphidze the scutellum of the mesothorax is
in contact with the upper part of the abdomen as in
some of the Tabanide, so that the metathorax cannot
be seen. When, however, the basal part of the abdo-
men is gently pressed downward, a portion of the
posterior part of the metathorax, marked as the meta-

i Z

thoracic scutellum in Pl. XIT., Fig. 198, 4s’, is brought
into view. It is seen that in Syrphus the abdomen
makes a broad junction with the thorax near the mid-
dle of this scutellum. If now a portion of the abdo-
men is cut away, and all its contents removed, the lower
and concealed part of the scutellum is exposed, as
seen in Fig. 215, 4°. In other words, the abdomen is
attached near the middle of the scutellum rather than
264

DIPTERA. 265

at its apex as in the Tabanidz, or near its base as in
the CHstride. Fig. 216 represents the species Sy7-
phus politus, Say. Its larve are without a distinct
head, the first ring being membranous. They devour
plant-lice by sucking the fluids of the body, and their
mouth parts are therefore adapted for suction. The
fly lays its eggs among the aphides, so that the larvee
find their food within easy reach. Mrs. Mary Treat!
relates how an unlucky Syrphus happened in the way
of an ant. The ant took it in its mouth and shook
it “as a dog will shake a woodchuck.” L£vstahs
tenax, with its “ rat-tailed larva,” belongs to this family.
This “tail” is really a tube by means of which the
larva breathes while lying in water or concealed in
mud.

MUSCIDE.

The true house-fly, Musca domestica, is much smaller
than several species of flies that are often seen indoors.
The scutellum of the mesothorax extends backward in
a blunt point, beneath which may be seen from behind
or from the side, if one wing and alulet are cut away,
the horny, shining posterior portion of the metathorax.
The mouth parts of this insect have already been briefly
described (see p. 252). Kraepelin® gives thirty-eight
beautiful figures illustrating the anatomy and physi-
ology of the proboscis, two of which are reproduced
by Packard.*

The larve (Pl. XII., Fig. 200), as we have already

1 American Entomologist, Vol. I1., p. 143.
2 Zeit. f. Wiss. Zool., Vol. XXXIX., p. 683, 1883.
3 See Entomology for Beginners, Figs. 137, 139.

266 DIPTERA.

observed, are without a distinct head, the forward part
of the body being membranous, as in the Syrphide.
The observations of Weismann! upon the development
of the Muscidz throw light upon the subject of the
systematic position of the Diptera. He considers that
the metamorphosis of these flies is far more complex
than that of butterflies and other insects. During
their development nearly all the systems of internal
organs of the larva are destroyed, and out of their
remains the new organs of the imago are formed. ‘This
last statement is not sustained by M. Ganin (see his
paper referred to below). ‘The process is slow, as
the systems are not all destroyed at once. ‘The dis-
integration is far less thorough in the butterflies than
in the Muscidz ; for in the former the muscles of the
abdomen are preserved, so that this part is capable of
motion, and the pupa does not for a single moment
cease to be a moving animal, while the life of the pupa
of the Muscidz is as absolutely latent as that of the
fertilized egg (p. 325).

M. Ganin, after careful study of the post-embry-
onal development of insects, has arrived at the con-
clusion that the organization of the Muscide has
undergone greater modification during its evolution
than that of other insects.”

1“ Die nachembryonale Entwicklung der Musciden nach
Beobachtungen an J/usca vomitoria und Sarcophaga carnaria,”
Zett. f. Wiss. Zool., Vol. XIV., p. 187, 1864.

2 See M. Ganin, “ Materials for a Knowledge of the Post-
Embryonal Development of Insects,” Warsaw, 1876; extract in
American Naturalist, Vol. X1., 1877, p. 423.

—— a

DIPTERA. 267

CESTRIDE.

The (éstride have a deep, vertical constriction
between the thorax and: abdomen, and the latter is
joined near the base of the metathorax, giving a more
or less pedunculated appearance to this part of the
body. In the larval state bot-flies are parasitic on
mammals, such as the, horse, sheep, ox, and man.
The sheep bot-fly, @s¢rus ovis, Linn. (Fig. 217, 1, 2)

Fig. 217.

causes the disease known as “grub in the head,”
which often proves fatal. The flies place the living
larve (Fig. 217: 4, dorsal view; 5, ventral view; 6,
the same when young) in the nostrils of sheep ; these
ascend and attach themselves to the frontal sinuses by
means of the two hooks (Fig. 217, 4, @). They have
two spiracles (Fig. 217, 6, ¢) and two horny appen-
dages (Fig. 217, 5, 4) near the anus. In about nine
months the larva is full-grown; it then drops to

268 DIPTERA.

the ground, buries itself, and transforms to a pupa.
Fig. 217, 3, is the puparium from which the fly has
escaped.

The larvee of different species of bot-flies offer many
modifications of structure. Those living within cuta-
neous tumors of mammals have fleshy tubercles for
mouth parts, instead of hooks like the species inhabit-
ing the head and stomach. ‘The horse bot-fly, Gas-
trophilus equi, lays its eggs on the hairs about the
knees of horses, often on the inside. Five hundred
or more may be laid on one horse. The eggs when
deposited contain the larve in a more or less per-
fectly developed state, so that they hatch in a few
days. ‘The young (and also the eggs frequently) are
transferred by the horse, when licking its own skin,
to the mouth, and from thence they pass to the
stomach and intestines. Here they fasten themselves
by their hooked mouth parts, and remain for nine or
ten months. If they are very numerous they create
a dangerous irritation, from which the animal may
suffer great agony and finally perish. In other cases
they are ejected in the excrement, and pass the pupa
state of from forty to fifty days in the earth."

PULICID/.

The family Pulicidz is regarded by some entomolo-
gists as a distinct order under the name of Siphonap-
tera and Aphaniptera; by others it is placed among
the Diptera. Specimens of fleas can often be col-

1 See A. E. Verrill, “‘The External and Internal Parasites of
Man and Domestic Animals,” Rep. Coun, Board Ag., 1870.

DIPTERA. 269

lected from dogs, hens, pigeons, and birds. The fleas
are semi-parasitic in habit, the adult living among the
hairs of mammals and the feathers of birds, and suck-
ing the blood of these animals. The larval and pupal
stages are passed, however, in the dirt and refuse on
the ground. The adults present interesting modifica-
tions of structure, as they are well adapted for the life
they live (see Fig. 218, which represents one species

Fig. 218,

of flea). Their skin is tough and capable of resist-
ing pressure. ‘There are no compound eyes, but only
two ocelli. The mouth parts (see Fig. 218) are fitted
for piercing and sucking the blood of animals. The
wings are reduced to mere scales (not clearly shown
in Fig. 218) which can be of little or no use, and this
condition is correlated with the structure of the tho-
racic rings, these having lost their complex modifica-
tions, and become distinct and similar to the abdomi-
nal segments. With the loss of the power of flight,

270 DIPTERA.

the power of leaping seems to have increased, so that
these insects can perform remarkable muscular feats
with their long leaping-legs (see Fig. 218). The larve
are footless and feed upon both animal and vegetable
matter: the pupz are naked.

PUPIPARA.

Tue three following families of parasites pass either
the whole or a part of the larval state within the body
of the parent, and are, therefore, grouped under the
head of the Pupipara.

BRAULINID#.

The bee-lice (Fig. 219, enlarged) are well adapted
to live among the hairs of the bee by having flattened,

Fig. 219. Fig. 220.

wingless bodies. Like many other parasites, these in-
sects are blind. Fig. 220 is the larva, which becomes
a pupa covered by the puparium the day it is hatched.

NYCTERIBID.

The bat-ticks (Fig. 221, much enlarged) resemble
minute spiders. ‘The head is without a distinct neck,

271

212 DIPTERA.

and appears like a part of the thorax, reminding one
of the cephalothorax of the Arachnida. ‘The ocelli
are present, but not the
compound eyes. ‘The
legs are most peculiar
in structure, their many
joints, hairs, and hooks
enabling the creature to
cling securely to the
hairs of the bat. Wings
i. and halteres, not being
Fig aax. . needed, have been lost ;

the comb-like organs

just back of the first pair of legs may be the modified
remnants of the wings. ‘This view is supported by
the fact that the flies of one genus of the Pupipara
(Lipoptena) have wings when young, and live on birds ;
afterward they fly to their final destination on quad-
rupeds, and then, the wings having become useless,
are at last cast off. The whole larval life of the bat-
tick is passed within the body of the parent, so that
when the insect is born it is covered with a puparium.

HIPPOBOSCIDZE.

The sheep-tick, AZelophagus ovt-
nus, Linn. (Fig. 222, with pupa-
gy rium) is parasitic on sheep and
lambs. The head and thorax in

| this insect are small as compared
with the enlarged abdomen; the
ania: legs are strong, with claws adapted
Fig. 222. for clinging. By means of these

DIPTERA. 273

organs the Hippoboscidz, according to Verrill, are
able to run forward, backward, or sideways.

The forest-fly or horse-tick, AWippobosca eguina
(Fig. 223), belongs to this family. Its mode of
development differs from that of all other insects,
and remotely imitates some features in the embryonic
development of mammals. The oviduct has a sac-
like enlargement, within which the larva is developed
and nourished by a milk-like secretion. The larval
and incipient pupal states are passed within the body

of the parent, so that when the young insect is born it
is covered with a puparium.

The young of even the generalized forms of Diptera
are as a whole farther removed from the Thysanuri-
form type than those of any other group. The sec-
ondary larval form, which in the case of the Diptera
is always footless and often an almost headless maggot,
has complete possession of the younger stages. As
Friederich Brauer has pointed out, the general absence
in the larve of Diptera of the thoracic legs, even

274 DIPTERA,

although living in situations that seem to demand their
development, shows that they must have inherited this
peculiarity from an ancestral form whose larva had
lost them. ‘This comparative inflexibility of the larval
stage is sufficient of itself to show that there is now a
wide gap between the existing Diptera and all other
orders of insects, and that this chasm is not closed by
the resemblances of the parts in the adult to those of
the Lepidoptera or isolated forms in other orders.

There are in this order also marks of extreme spe-
cialization in the mouth parts of the adult, which are,
as a rule, modified for the office of sucking. The
abdomen has not the flexibility of the pedunculated
abdomen of the Hymenoptera Aculeata, no stinging-
apparatus being present, but it is, nevertheless, nar-
rowly pedunculated in some forms. The aspect of
the highly complicated and concentrated thorax ac-
companies the reduction of the wings to one func-
tional pair. ‘This last characteristic and the tendency
to reduce the useless pair of wings is carried to an
extreme throughout this order, and can thus be
compared as a whole with such isolated specialized
types in other orders as the Coccidze among Hemip-
tera, and the Stylopidz among Coleoptera.

The tendency to the enlargement of one pair of
wings, like the tendency to the enlargement of certain
pairs of thoracic legs and the reduction of other pairs,
or a change in their structure and function so that the
insect makes a departure from the conventional nor-
mal type of four equal membranous wings and six
equal-jointed legs, is everywhere an index of speciali-
zation.

GENERAL REMARKS.

THE mode of development in all of the first series
of orders from I.—IX. is as a rule direct, and this neces-
sarily unites the Thysanuriform larva, when it is pres-
ent, more or less closely with the adult stages, and
the adults are apt to show traces of this connection
in the retention of certain primitive characteristics.
The absence of a waist or deep constriction between
the thorax and the abdomen is due to the fact that
the junction with the metathorax remains in most
adults as it is in the larva and in Thysanura. The
mouth parts also are for biting, except in the highly
specialized Hemiptera, in which, although the suc-
torial characteristics of these parts are developed early,
the larve, with this exception, have what may be
called a Thysanuriform stage. The highly specialized
adults of groups having indirect development (Coc-
cidz) are not exceptions to this rule, and retain to a
recognizable degree the primitive form of the larve.

The second series of orders from X.—XVI. have, as
a rule, more complicated modes of development, intro-
ducing various intermediate and often extraordinary
stages, such as grubs, caterpillars, etc. Following
Brauer and some other entomologists, we have re-
garded these as more or less degraded modifications
of the primitive Thysanuriform larva, but have spoken

275

276 GENERAL REMARKS.

of them collectively as the secondary larval stages.
They appear subsequently to the Thysanuriform stage,
when that is present, or between the ovarian and pupal
stages when that is absent. The pupal stage is similar
to that of the first series of orders in all respects ex-
cept that, as a rule, it is incapable of motion, or is
what is called quiescent, and is usually more or less
protected. The complicated development of individ-
uals in the second series of orders has led several
authors to designate the first series of orders as Amet-
abola, and the second series as Metabola.

The use of the term “ ametabola,’ as applied to
the orders from I.-IX., involves an exaggeration, since
it implies that they have no metamorphoses ; whereas,
as pointed out by Comstock and others, the Coccide
have a “‘complete” series of metamorphoses, or in-
direct development, even including a quiescent pupal
stage in the development of the only winged form,
the male. The quiescence of the pupal stage loses
much significance in view of this exception, and also
when it is noted that an extra quiescent larval stage
may occur in the second series of orders, as in some
beetles, whose extraordinary habits render two qui-
escent stages essential in their development.

It is a remarkable fact that, as a rule, the larve of
the second or specialized series of orders have the
habit of feeding voraciously. In this way the larvee
store up fats and food matters in their own bodies in
preparation for the quiescent and helpless pupal stage,
during which they live upon these accumulations, they
being taken up by the cells of the tissues and used in
building up the organs and parts of the adult (see

GENERAL REMARKS. 277

pp. 160, 199). ‘The pupal stage is passed, as a rule,
in more or less sheltered situations, and it is either
enclosed in a special covering, a cocoon, woven by
the animal, or else protected by one acquired through
the moulting and hardening of its own cuticle. ' The
difference between this last and the ordinary process
of moulting consists in the retention of the moulted
skin, the animal shrinking within it for shelter as its
fatty parts are consumed, instead of casting it off alto-
gether.

Lubbock, in his Origin and Metamorphoses of In-
sects,' has shown that the inactivity of the pupa in the
second series of orders is not a novel condition, but
a mere prolongation of the shorter periods of inactivity
which necessarily accompany every change of skin or
moult. These facts and the obvious want of any
common structural differences in the quiescent pupe,
as compared with the similar stages of active pupe,
show that quiescence must be reckoned as a habit of
resting from active exertion during a more or less
prolonged period of their growth which has been
acquired by the more specialized forms of insects,
not only generally among the members of the second
series of orders, but also by many among the first
series. The degraded larve of individuals in these
specialized forms are as a rule farther removed struc-
turally from their own adults, than in forms having
a direct mode of development, and the changes to
be gone through before reaching the adult stage are
greater and more numerous. The habits of the ani-

1 See pp. 67-70.

278 GENERAL REMARKS.

mal during the pupal stage have consequently changed
in proportion to these requirements from the active to
the quiescent condition.

There are other series of facts equally important
and significant. While the Thysanuriform stage is
present more or less in Coleoptera and Neuroptera,
which have the indirect mode of development, it is
absent in the orders from XII. to XVI. inclusive,
having been replaced by the secondary larval stages
in accordance with the law of acceleration in develop-
ment.

The tendency of the more specialized forms in the
orders I. to IX. to accelerate the development of
the earliest stages is shown in various ways. In the
grasshoppers,’ Mantidze, etc., the inheritance of the
adult peculiarities of the type affects the young at
such early stages that, as has been described above,”
the primitive larval Thysanuriform stage is skipped or
omitted from the development.

In Coleoptera and in the highly specialized orders
of insects (XI. to XVI.) a novel and disturbing in-
fluence appears, due to the extraordinary importance
of the functions of larval life. ‘This period in the
larger number of groups in other classes of animals is
much less variable than the adult stage, and it is really
very often a mere vehicle for the record and trans-
mission of hereditary characters. In some of the
orders of insects, however, it is as efficient for the

1 Packard’s illustrations on p. 60 of his Lxtomology for Be-
ginners give an excellent series of one species, Caloptenus
femur-rubrum.

2 Sée polit.

GENERAL REMARKS. 279

manifestation of new modifications and adaptive char-
acters as the adult, and often perhaps more variabie.
This is an exceptional rather than the usual aspect
of the larval stages, and makes the study of insects
remarkably difficult and interesting.

Sometimes in the orders I. to IX. (Coccide, Ci-
cada), as well as more generally in X. to XVI., the
larve carry the line of development and modification
a long way outside of what can be termed the normal
or direct course, but these deviations lead, as a rule,
back again through similar pupe to the same goal in
the imago, a typical adult insect. Epicauta, the
blister-beetle, is a good example (see pp. 157-159).
Fig. 98 shows the active Thysanuriform larva, and
Figs. 102, 106, 107, the grub-like larva which passes
through two stages (Fig. 108, representing one stage)
before becoming the true pupa (Fig. rr2) that trans-
forms into the imago (Fig. 113). These complica-
tions were probably due originally in each type to the
plastic nature of the organism, which enabled it to fit
itself to different conditions and surroundings during
its passage through the younger stages of growth. The
history of parasites, whose loss of parts and correlative
modifications are plainly adaptations to the nature of
the surroundings in all branches of the animal king-
dom, shows this to be sound reasoning. Among some
of these types there are all kinds of metamorphoses
and very complicated modes of development, so that it
is not difficult to surpass even those of insects. One
can apply a similar nomenclature and the same laws
in explanation of the often curious and sometimes
extraordinary metamorphoses, and these changes are

280 GENERAL REMARKS.

often, as in Tzenia, accompanied by corresponding
acceleration and loss of primitive stages. The curious
transformations of Echinodermata are plainly adapta-
tions of the larve to a free life in the water before
they become attached or sink to the bottom and begin
their proper life as crawlers. In this class there are a
number of examples of acceleration (Comatula, Spa-
tangoids, etc.). Such life-histories and those of Epi-
cauta, Sitaris and Meloé among Beetles which run out
the gamut of changes from the simplest Thysanuri-
form larva through several grub stages to the quiescent
pupa, show that the most complicated metamorphoses,
called hypermetamorphoses by entomologists, must
have arisen in response to the changes of the surround-
ings. No other hypothesis can account for the num-
ber, variety, and novelty of these metamorphoses and
their suitability to the number, variety, and novelty of
the changes in the surroundings and the corresponding
changes in habits of the larve at different stages of
growth.

The occupation of the larval stages by strange and
curious forms, like caterpillars, grubs, etc., naturally
attracts attention and at first makes one wonder at the
apparent eccentricities of nature’s ways. But in reality
they serve to throw a strong side light upon the normal
mode of action of the laws of heredity, and show us
that, in spite of its enormous conservative force, hered-
ity is subservient to the effects of habit or use of parts.

That these secondary larval forms are more re-
duced, although more specialized organisms than the
primitive Thysanuriform larvee, has already been stated.
Among Coleoptera and Neuroptera this is obvious

GENERAL REMARKS. 281

whenever the Thysanuriform and secondary adaptive
forms are present in the growth of the same individ-
ual. No one can compare the swollen, soft, round-
bodied grubs with the active Thysanuriform larva,
especially when occurring in the growth of the same
beetle, without realizing that the former is due to
specialization by reduction. That their structures,
although degraded by this process, are suitable to the
conditions under which they live has been pointed
out by many writers ; notably, Graber, Riley, Lubbock,
and Packard. ‘This reduction becomes still more ap-
parent when we regard the larve of Diptera and the
grubs of the weevils among Coleoptera, the latter being
generally without legs, and the former also deficient in
these organs and in large part without a differentiated
head. If these or the caterpillars or other secondary
larval forms similar to them were isolated, and their
subsequent development into pupze and adults un-
known, naturalists would not admit that they pos-
sessed close affinities with the adult insects of the
same groups, and they would be considered as more
rudimentary or simpler in structure than any Thy-
sanuran or ‘Thysanuriform larva. In the most
specialized forms of Coleoptera, the weevils, the early
development of a footless grub, a reduced form
similar to the maggot of the Diptera, replaces both
the Thysanuriform larva and also the active six-
footed grub of the normal groups of beetles. The
Insecta furnish such apparently isolated examples,
and, on account of the absence of intermediate forms,
it has been supposed that these could be put in evi-
dence against the derivation of the orders of which

282 GENERAL REMARKS.

they were members from Thysanura, as has been
stated above! with reference to the saltatorial Orthop-
tera, but the researches of Brauer, Packard, and Lub-
bock, demonstrating that the secondary larval stages,
grubs, maggots, etc., are modifications of the Thy-
sanuriform larval stages, show that this use of them
cannot be admitted. If this be granted, it becomes
possible to account for the phenomena as follows.
The modified, and adaptive, larval characters of the
grubs, caterpillars, etc., having become fixed in the
organization of such groups as the weevils among
Coleoptera, and in some whole orders, as in the
Lepidoptera and Diptera, have been inherited at such
early stages in accordance with the law of acceleration
in development that they have replaced the useless
Thysanuriform stage. In other words, the absence of
this primitive larval stage in the young of many spe-
cialized forms of insects now living is due to the ten-
dency to earlier inheritance of the later acquired,
adaptive characters of the secondary larval forms.
It is very important for these considerations to
notice that after the insects possessing the indirect
modes of development have passed through their re-
ductive secondary larval stages, they return to the
more normal or direct mode of development in the
pupa. In doing this, they clearly illustrate the excep-
tional and adaptive nature of their deviations from
the direct mode during the larval stages, and show
that this resumption of the older beaten path marked
out by heredity is essential in order that a typical hex-

See pycrrts

GENERAL REMARKS. 283

apod form may be evolved in the adult stage. The
pupa is always a six-legged form, with the legs more
or less developed, and being common to all insects,
whether quiescent or active, is really a part of the
direct mode of development wherever it occurs. It
is as universal and essential as are the typical ovarian
and adult stages. Indirect development is, therefore,
composite. It is first a deviation in the larva from
the direct mode, and then a return in the pupa of
the direct mode, and this return necessarily brings
the organism back again into the normal line of evo-
lutionary changes, and the normal form of insect is
the result of this return and the resumption of pro-
gressive specialization.

The reverse of this process, z7.e. when direct develop-
ment is not resumed, is shown in the case of parasites
like the female of Stylops.

If it be true that the stages of development in indi-
viduals are abbreviated records of the modifications
undergone by the group during its evolution in time,
and that as a rule the characteristics of adults of the
more generalized or primitive forms of any order, or
even of smaller divisions, in all groups of the animal
kingdom, show a tendency to occur in the young of
more specialized forms of the same group or division,
it follows, that in each natural group the specialized
forms have been evolved from the generalized forms.
This tendency to accelerate and abbreviate the record
preserved by heredity in the growth and development
of each individual can be understood if one imagines
a series of forms evolving in time. First, the repre-
sentatives of the simple, primitive ancestor; then

284 GENERAL REMARKS.

one form after another coming into being successively
would each introduce some novel modifications, ac-
cording to its place in time and the structural series.
These modifications being inherited at earlier stages
in descendants than those in which they originated in
the ancestral forms, would crowd upon the character-
istics already fixed by heredity in the growth of the
young. By and by, as characteristics accumulated, it
would become not only inconvenient to repeat all the
characteristics of its ancestors, but it would be a phys-
ical impossibility for any individual to reproduce them
all in the same succession in which they had arisen ;
life would not be long enough nor vital powers strong
enough to accomplish such a process. Nature pro-
vides for such emergencies by a law of replacement ;
and as stated above, when a part or characteristic
becomes useless, if it stand in the way of the devel-
opment of other parts or other characteristics of the
same part, it is replaced to a greater or less degree by
the newer and more useful modifications. ‘This is the
rule so far as relates to an ordinary normal series of
forms when such a series can be traced with abundant
materials through a sufficiently long period of geologic
time, as has been repeatedly shown by Cope and one
of the authors. Made confident by such experiences
we do not hesitate to apply it to the insects where
positive evidence of this sort is not yet forthcoming.
If this be correct, it is evident for example that the
sucking-tube and other correlative internal modifica-
tions originated in the pupal or adult stages of the
primitive Hemipteron, then became fixed in the organ-
ization of the order, and are now inherited at an early

GENERAL REMARKS. 285

age, having replaced or driven out the ancestral, prim-
itive, perhaps Thysanuriform mouth parts from the lar-
val stage. The assumption that the sucking mouth parts
originated in the pupal or adult stages is considered
probable, because, although there are many exceptions,
characteristics usually originate in the later stages in
other branches of the animal kingdom. In Lepidop-
tera and Diptera, which resemble the Hemiptera in
having the highly modified mouth parts with a tubular
arrangement, these characteristic peculiarities are con-
fined to the later stages of development, and are not
found in their larvze. The larvae of Hemiptera are
also decidedly Thysanuriform, and that they origi-
nated from a modified Thysanuroid form having bit-
ing mouth parts in the larva and sucking mouth parts
in the later stages, seems to be indicated by this fact.
We have already seen in such examples as the locusts,
etc., that an earlier development in the inheritance of
the characters of adults may effectually obliterate the
Thysanuriform larva, and in the Coleoptera, Neurop-
tera, etc., that it is the earlier inheritance of the sec-
ondary larval characteristic which accomplishes this
result. In no case do the pupal or adult character-
istics become accelerated in development so as to
replace the larval stage in the second series of orders
except in parasites such as the parasitic Pupipara
(ticks). The young are in some of these species born
as pup, and the ovarian and larval stages are passed
within the mother.’

1 Among the orders having the direct mode of development
a similar case to the Pupipara is ta be found in the plant-lice.
These being viviparous, the young are born in an advanced

286 GENERAL REMARKS.

As a rule, then, the orders having indirect modes of
development do not show to any marked extent accel-
eration in the inheritance of adult or adolescent
(pupal) characters, but, on the contrary, the char-
acteristics of these later stages remain remarkably
constant in the ages at which they are inherited.
They do not encroach upon or replace the larval
stage to any very marked extent, as in the examples
cited above, among the Orthoptera or Hemiptera.
This might be considered as fatal to the application
of the law of acceleration, and this would be the case
if that law were anything more than the expression for
a general result of causes which underlie the action of
heredity. One of these causes is what we have al-
ready expressed as a law of replacement.

Two modifications cannot occupy the same space,
and the secondary larval forms having become fixed
in the organization, they hold their own in the devel-
opment of individuals against the encroachment of
the pupal and adult characters by virtue of their suit-
ability and the conservative power of heredity. The
few cases in which acceleration of the pupal stages at
the expense of the larval stages does take place in
the second series of orders seem to show this, since
they occur not in the normal forms having the ordi-
nary habitat, but in parasites like the Pupipara.

Teachers who read Sir John Lubbock’s interesting
chapter on the Nature of Metamorphoses (oc. cz7.) will

stage, and are in reality, although wingless, comparable with
active pupz. In the case of the sexually perfect forms which
emerge from pseudova, they are, according to Comstock, in a
still more advanced condition.

GENERAL REMARKS. 287

find opposite views expressed in regard to the rank
of metamorphoses, and these may confuse them unless
explained. He speaks, on page 41, of the maggots
of flies as belonging ‘“‘to a lower grade” of metamor-
phoses than the grubs which have biting mouth parts
and heads, and of the caterpillar as on a higher level
than the vermiform larve of Diptera and Hymenop-
tera. ‘This, literally translated, means that larve, like
those of the grubs of most Coleoptera and Lepidop-
tera, have heads, mouth parts, and legs which have
not yet suffered from reduction; but in speaking of
these as “lower grade,” Lubbock makes a mistake
in systematic perspective. If, as he holds, the sec-
ondary larve are all primarily the outcome of the
Thysanuran form, they are all what he ought to call
“higher grade,” being more specialized and farther
removed from this primitive insect standard than the
larve of the more generalized or first series of orders.
The same and, we think, more philosophical mode of
dealing with the facts leads to the corollary that among
themselves the larve of the more specialized orders
are really “higher,” if the use of this word is consid-
ered essential, or more specialized in proportion to
the extent of their structural deviation from the Thy-
sanuran standard. Thus the larvee of Diptera are, as
a rule, more specialized than any other, and have to
be set on the extreme left in our table on this
account. The words “higher and lower grade”’ are
extremely confusing, since they embrace three differ-
ent classes of ideas, — anatomical and_ physiological
facts and teleological notions. Nature leads us along
lines of modification which sometimes rise through

288 GENERAL REMARKS.

continuous progressive specialization to more and
more differentiated structure with correspondingly
increased functional powers, or larger or different
fields of work. At other times it may lead us in a
wave line, which follows a devious course, rising part
of the time through progressive specialization, and then
falling for another period of time through specializa-
tion by reduction. If the animals under consideration
be parasites, they may continue on this descending
plane both in the growth of the individual and the
evolution of the group. Nevertheless the resulting
adult is not necessarily of “low grade” in any scien-
tific scheme of arrangement founded upon the princi-
ples of evolution. It is, however, farther removed
from the primitive type, and is extremely specialized.
The use of the eesthetic terms “low” and “high”
have come from a period in the history of our science
when nature was made to assume a rigidly progressive
aspect, each division of the animal kingdom represent-
ing a finger-post pointing towards the so-called perfect
animal, man, each rising higher and higher in the
scale of perfection whose standard was the human
organization. Such artificial ideas revenge themselves,
and words become their ready instruments, first to
express what is false, and then to help in binding the
mind with the conservative fetters of habit.

LT BX.

A.

Abdomen, 47, 49,97, 102, 107, 126,
132, 136, 140, 142, 151, 153, 156, 161,

166, 168, 173, 196, 231, 232, 236, 238, |

243, 257, 258, 262-264, 206, 267, 272,
274, 275. [See Descriptions of
types.

Acceleration in development, 143, 144,
283, 285, 286.

law of, 112, 163, 229, 246, 278,
282, 286.

Achoreutes nivicola, 66.

Acridian Orthoptera, 4o.

Acrididz, g, 109.

Acridium, 25.

Actias Luna, 208.

Adaptation of animals, 28, 108, 165.

Adaptive characters, 58, 77, 91, 102,
105, ITI, 112, 121, 129, 163, 269, 271,
279, 280. [See Correlative struc-
tures. ]

fEschna, 82.

Affinities of Lepidoptera, 221.

African Termites, 97.

Agrion, gills of, 84.

Agrionidz, 74, 81.

Agrotis, 207.

Air-sacs, 38, 39, 67.

Alulets, 253, 265.

American copper butterfly, 218.

Eclipse Expedition, 71.

silkworm, 196, 207.

Ametabola, 276.

Ammonia, 73.

Anabolia, 178.

Anal area of wing, 30.

Anasa tristis, 115.

Ancestral characteristics, 54.

Ancient cockroaches, ros.

Anisopteryx pometaria, 203.

Antennz, 9, 97, 103, 106, 107, 109,
122, 132, 135, 139, 158, 163, 164, 196,
200, 203, 212, 233. [See Descrip-
tions of types. |

Antenne, functions of, 22, 23.
Anthophora, 159.

Anthrenus scrophulariz, 153.
Antispila, 183, 202.

Ant-lions, 170, 173-175.

Ants, 92, 93, 136, 238-240, 265.
Aphaniptera, 268.

Aphides, 97, 135-137, 240, 265.
Aphididz, 135.

Aphis, 135.

Aphis-lions, 173, 175.

Apical margin of wing, 30.
Apide, 244.

Apis mellifica, 223, 244.
Aguatic Heteroptera, 121.
Arachnida, 272.

Arachnids, 47, 16s.

Archaic butterflies, 222.
Arizona, 241.

Army-worm, 205.

Arthropoda, 12, 24.
Articulata, 11, 12, 165.
Artificial wing, 31.

—— directions for making, 31, 32.
Asilide, 262, 263.

Aspidiotus conchiformis, 138.
Aspidisca, 202.

Attacus Promethea, 208.

B.

Back-swimming water-boatman, 121.

Balancers, 250, 253, 257- [See Hal-
teres. |

Balaninus, 24.

caryatrypes, 165.

Balfour, 111.

Bamboo, 31.

Basilarchia Disippus, 219.

Basis of classification, 240.

Bat-ticks, 271.

Beak, 121, 123, 125.

Bed-bugs, 127, 129.

Bee-lice, 271.

Beetles, blister, 157.

289

290

Beetles, burying, 166.

carpet, 152.

—— diving, 156.

— goldsmith, 151.

— ground, 156.

—— Lamellicorn, 151, 167.

—— Longicorn, 163.

—— May, 145, 148, 151, 167.

—— oil, 157.

—— parasitic, 157, 161.

—— potato, 145, 149.

—— rose, I5I.

rove, 166.

—— tiger, 157.

—— water, I55-

Beetles, proboscis of, 161.

Belostoma, 122, 124.

Belostomide, 122.

Benzine, 73.

Bibliography, 48.

Bilateral symmetry, ro.

Bipeds, 28.

Bisulphide of carbon, 154.

Blastophaga, 235.

Blatta, 25.

orientalis, 39.
orientalis. |

Blattariz, 50.

Blattidz, 102.

Blood-vessels, 39-

Bombycic acid, 200.

Bombycide, 207.

Bombyx mori, 207.

Book-lice, 98.

Boreus, 177:

Bot-flies, 267.

Brain, 27, 35-

Brauer, Friederich, 46, 48, 59, 99, 101,
142, 174, 245, 273, 275, 282.

Braulinide, 271.

Brehms, 82.

Bristle-tails, 66.

Brongniart, 47.

Buffalo-beetle, 153.

Burgess, 35, 188, 189, 254.

Burmeister, 179.

Bursa copulatrix, 37-

Butterflies, 212.

brush-footed, 219.

— classification of, 212.

—— directions for preparing, 186.

—— gossamer-winged, 218.

[See Periplaneta

C.

Cabbage butterfly, 186, 214, 215.
Caddis-flies, 178, 181-184, 201.

INDEX. ~

| Caddis-worms, 178.

Caloptenus atlanis, 24.

—— Dodgei, 45.

—— femoratus, 8, 109.

— femur-rubrum, 35, 109, 110, 278.
spretus, 13, 24, 10g.

Campodea, 47, 49, 53,54, 64, 68-129,

159. :

— Cooke, 65.

Campodez, 64, 66.

Campodeaform, 54.

Compound eyes, 103, 107, 109, 127,
131, 155, 162, 163, 172, 238. 262, 2690,
272. [See Descriptions of sical

structure and physiology of, 20-

22.

Canada, 216.

Canker-worms, 203-205, 237.

Carabidz, 68, 156, 157, 166.

Carabus, 25.

Carboniferous formation, 47.

Cardo, 24.

Carmine, 141.

Carpet-beetle, 153.

Carteria lacca, 141.

Case-worms, 178.

Caterpillar. [See Larva.]

Caucasian race, 129.

Cecidomyidz, 263.

Cecropia, 208.

Centipedes, 47, 48.

Cephalic trachez, 38.

Cephalothorax, 272.

Cerambycidez, 163, 167.

Cere1, 285 23:

Chalcididz, 233, 235-

Chambers, 202.

Changes in methods, 44.

Cheshire, 229.

Chestnut-borer, 165.

China, 207.

Chitine, 11, 15, 147, 150-

Chloéon, 70.

Chloroform, 73.

Chrysalis, 193, 194, 213-215, 217, 2195
222, 237-

Chrysomelidz, 149, 167.

Chrysopa, 172.

Chub, 123.

Chyle-stomach, 35.

Cicada, 8, I31T, 133, 1345 143, 279-

Cicadidz, 131.

Cicindelidz, 157.

Cimex lectularius, 127.

Cimicide, 127.

Circulation of blood in insects, 39.

Clarke, 181.

INDEX.

Classification, a natural, 52.

—— of insects, 46.

—— principles of a, 63.

Claus, 93-

Claws, 27, 103, 272.

Clemens, 183, 202.

Clothes moth, 154, 196, 200.

Clypeus, 13, 23, 77, 146, 261.

Clytus pictus, 163, 164.

Coccide, ea 138, 142, 143, 168, 275,
276, 27

aces 155, 166.

Coccus cacti, 141.

Cochineal bug, r4r.

Cockroach, 49, 57, 59, 102-105, I10,
IIt.

Cocoon, 149, 156, 165, 174, 199, 200,
204, 208, 214, 239, 241, 277:

Coenis, 72.

Coleoptera, 21, 62, 68, 144, 145, 278,
280, 285, 287.

Colias, 22.

philodice, 214.

Colon, 35.

Colorado potato-beetle, 149.

Colorlessness of Termites, 94.

Comatula, 280.

Complemental females, 94.

males, 94.

Comstock, 29, 46, 62, 122, 125, 128-
130, 137, 140, 141, 171, 172, 276, 286.

Cook, 230.

Cope, 225, 284.

Coreidz, 125.

Corethra, 250.

Corisa, 122.

Corisidz, 142.

Corpuscles, 39.

amoeboid movements of, 39.

Correlative structures, 27, 95, 109,
ENO 110, LOo,, 23252335) 202, 209;
270. [See Habits and Structure. ]

Corrosive sublimate, 154.

Corydalites, egg-mass of, 171.

Corydalus cornutus, 170.

Costal margin of wing, 30.

Cotalpa lanigera, I51.

Coxa, 27.

Crane-flies, 257, 259.

Crawler, 170.

Crescent-shaped bands, 222.

Crickets, 106, 107.

Crop, 35.

Croton bug, 104, ros.

Crustacea, 10, 12, 15, 47, 59, 123, 165.

Culex, 23.

—— rufus, 260.

—————_$_——$$$ $$ ————— eee

291

Culicidz, 259.

Curculionidz, 163, 164.
vils. |

Cushions, 27.

Cuticle, 11, 134, 277.

Cuticula, ro, 11.

Cut-worms, 207.

Cuvier, 12.

Cuvierian classification,
form of, 12.

Cyanide of potassium, 73.

Cyclorhapha, 264.

Cynipidz, 233, 263.

Cynips quercus aciculata, 234.

quercus spongifica, 234.

[See Wee-

modified

D.

Dactylopius, 141.

Danais Archippus, 186, 188, 192, 219.

Darning-needle, 78.

Darwin, 151, 190, 225, 228.

Day-fly, 69, 70.

Degradation of types, 50.

Degraded forms, 52, 126,
281. [See Parasites. ]

Dermaptera, 61, 99, 100, tor, 114, 166.

Dermestidz, 153, 154.

Development, effects of temperature
On, 137, 200, 254.

Diagrams I.-III., 60

—— explanation of, 60-62.

Diapheromera femorata, 105.

Dictyophorus reticulatus, 8.

Digger wasp, 240.

Dimmock, 122, 152, 260.

Diplax, 80.

Diptera, 21, 51, 68, 72, 248, 266, 274,
282, 285, 287.

Direct and indirect metamorphosis,

275, 277»

44.

Directions for collecting and preserv-
ing insects, 9, 10, 45, 73, 84, 98, 113,
II5, 119, 121, 134, 137, 145, 149, 156,
173, 186, 207, 219, 223, 241.

Disinfecting cones, 154.

Dobson, 171.

Dolomedes, 174.

Dorbug, 145-

Doryphora decem-lineata, 149.

—— juncta, 151.

Dragon-flies, 21, 26, 51, 73, 76, 78, 79-
8x, 84, 88, 166. [See Odonata. ]

Dusky wings, 214.

Dynastes hercules, 151.

Dytiscide, 156, 166.

Dytiscus, 25.

292

E.

Earthworm, 11.

Ear-wigs, 100, 101-

Echinodermata, 280.

Echinoderms, water-system of, 59.

Ectobia germanica, 104.

Edwards, W. H.., 220.

Egg-guide, 18.

Egg-pod, 43.

Eggs, 103, 110, 126, 136, 150, 151,158,
164, 173, 174, 196, 203, 205-207,
217, 218, 231, 233, 235-237, 239, 240,
242, 243, 261, 268. [See Descrip-
tions of types; also Ova. |

Egyptians, 151-

Eiphosoma, 237.

Elytra, 147, 148, 152, 159, 168.

Embryological development, 80.

Emerton, 174.

Environment, 50, 163.

Epargyreus Tityrus, 213.

Ephemera, 69. [See May-flies.]

Ephemeride, 69, 88, 245.

Ephemeroptera, 59, 61, 69-71, 73, 88,
89, 175.

Ephippiger, 33.

Epicauta, 157, 159, 279, 280.

—— cinerea, 159.

vittata, 157, 168.

Epicranium, 13.

Epidermis, 11, 15.

Epipharynx, 260.

Eristalis tenax, 265.

Eucheira socialis, 216.

Europe, 9.

Evolution, 51, 52, 168, 185, 288.

laws of, 41, 55.

Evolutionary processes, 53.

Exuviz, 45, 71-

Eye-stalks, 20.

F.
Fabre, M., 168.
Femur, 27, 123.
Fins, 41.
Fire-flies, 151, 167.
First series of orders, I.-IX., 53, 275,

276.

Fleas, 37, 52, 268, 269.
Flora, evolution of, 225.
Florence, Mass., 207.
Florida, 8, 216.
Fly, buzzing of, 253, 254.
Flying squirrel, 57.
Forel, 240.
Forest-fly, 273.
Forficula, roo.

INDEX.

Forficula auricularia, too.
Forficulidz, 100.

Formate of anylic ether, 117.
Formica fusca, 239.
Pennsylvanica, 238.
Formicary, 239.

Formicidae, 92, 238.
Fossorial Hymenoptera, 241.

G:
Galea, 24.
Gall-flies, 233, 234.
Gall-gnats, 263.
Ganin, 266.
Gastrophilus equi, 268.
Gena, 13.

| Genealogical tree of the Insecta, 62.

Generalized orders of insects, I.-IX.,

53:
General remarks, 275.
Genitalia, 18, 80.
Geologic evidence, 47.
—— record, 59.
Geometricians, 204.
Geometride, 183.
Geometrina, 53.
Geotrupes stercorarius, 37-
Germs, 29.
Gills, 56-59, 70, 84, 9o-
Gizzard, 35.
Glover, 124.
Glow-worms, 152, 167.
Gosch, 249, 250.
Graber, 127, 147, 281.
Graphic presentations, 63.
Grasshoppers, 9, 108, 109, 278.
Green-head, 248.
Grenacher, 20.
Grouse locust, 110.
Grub. [See Larva. ]
Gryllidz, 106.
Gryllotalpa borealis, 108.
Gryllus, 106, 107.
Gula, 25.
Gulf States, 216.
Gull Islands, 71.
Gyrinide, 155.
Gyrinus, 156.

Fie

Habitat, 51, 52, 88, 108, 110, 128,
149, 286.

Habits, 28, 40,
103-106, 108,
137, 144, 148,
182, 183, 191,

58, 75, 79, 95, 96,
Ito, 120,420; 5st.
167, 168, 173, 178,
199, 202, 205, 210,

INDEX.

232, 233, 245, 246, 262, 269, 276,
277, 280. [See Structure. a

Habits, social, 92, 216, 229, 239.

of. observation, 221.

Hadena, 207.

Hagen, 11, 56, 96, 99, 132, 179.

Hair-streaks, 218.

Halteres, 140, 141, 143, 162, 168, 253,
272.

Hammond, 232, 250, 253.

Harpalus caliginosus, 156.

Harris, 243.

Harvest-fly, 8, 118, 131.

Hawk-moth, 188, 208.

Head, 47, 97, 102, 106, 111, 122, 127,
131, 142, 151, 158, 161, 162, 172, 174,
200, 233, 239; 240, 259-261, 263, 265,
267, 271, 272. [See Descriptions
of types. ]

Heart;-35;.38:

Heliozela, 202.

Hemerobide, 172, 174.

Hemiptera, 8, 60, 62, 68, 115, 118, 142,
166, 245, 275, 285, "286.

Hemipterous organs, 122.

Henslow, 224, 225.

Heodes Hypophizas, 218.

Heredity, laws of, 54, 55, 111, eat

Hermit crab, 180.

Hesperidz, 212.

Hessian-fly, 263.

Heteroctra, 196.

Heteroptera, 115, 121, 142, 143, 166.

Hickory-tree borer, 163.

Hickson, 20.

Hippobosca equina, 273.

Hippoboscide, 272, 273.

Holland cloth, 31.

Home, 252.

Homoplastic forms, 141.

Homoptera, 115, 131, 141-143.

Honey-bee, 223.

Honey-dew, 136.

Hornets, 241.

Hornia minutipennis, 159.

Horntails, 232, 244.

Horse-flies, 248, 263.

Horse-tick, 273.

House-fly, "248, 254, 265.

Humble bees, 244.

Humming- bird, 210.

—— moth, 208.

Huxley, 104, 137.

Hyatt, 225, 284.

Hydrophilide, 156.

Hymenoptera, 21, 47, 51, 68, 92, 223,
227, 244, 287.

Ne —————E—————————————— eee eee

293

Hymenoptera Aculeata, 17, 230, 232,
238, 247, 258, 274.

Terebrantia, 230, 231.

Hypermetamorphoses, 159, 168, 280.

Hypodermis, 11.

Hypopharynx, 260, 261.

I.

Ichneumon-flies, 235, 237.

Ichneumonide, 233, 235, 237+

Ileum, 35.

Illinois, 207. -

Incisalia irus, 203.

Indirect metamorphosis, 44.

development, 283.

Infra-cesophageal ganglion, 37, 26r.

Insecta, 8, 62, 123, 281.

Insect migrations, 215.
tions. ]

Instinct, 227, 236.

Internal anatomy, 35.

Intestine, 35.

Ithycerus noveboracensis, 164.

ic
Japyx, 61.
Jaws, vertical motion of, 24.
Johnson, 116.

[See Migra-

K.
Kangaroos, 28.
Katydids, 9, 108.
King and queen caste, 94.
Kingsley, 64.
Kirby, 70, 100.
and Spence, 259.
Kraepelin, 265.

L.

Labrum, 23, 77, 117:

Labrum-epipharynx, 261.
Lac-insect, 14r.

| Lace- winged flies, 170, 172, 175.
Lachnosterna fusca, 145.

| Lacinia, 24.

Lacteal vessels, 35.

Lacune, 38.

Lady-birds, 155, 166

Lake Winnipeg, 71.

Lamellicorns, 147, 151, 166, 167.

Lampyridz, 151, 152, 167.

Lampyris, 152.

Land-snails, pulmonary sacs of, 59.

Larva, aquatic, 57, 58, 91, 156.

— caterpillar, 68, 153,174, 177, 221,

294

231, 237, 246, 247, 259, 275, 280-
282, 287.

Larva, coarctate stage of, 158, 159.

grub, 68, 144, 150, 163, 165, 167,

236, 247, 267, 275, 279-282, 287.

helpless, 239, 240, 244, 245.

Thysanuriform, 50, 54, 58, r10-
II2, 142-144, 166, 167, 177, 221, 273;
275, 276, 278-282, 285. [See De-
scriptions of types. |

Larvez, adaptations of, 280.

Larval life, functions of, 278.

—— stage, quiescent, 276.

Latreille, 250.

Law of acceleration in development,
112. [See Acceleration. |
heredity. [See Heredity. ]

—— replacement, 284, 286.

—— use, 40.

—— variation, 159.

Leaping-legs, 27, 107, III, 270.
Legs.

Leaping mice, 28.

Lecanium, 138.

Le Conte, 125.

Legs, 56, 98, 103, 104, 106-109,
123, 133, 134, 139, 140, 149,
158-160, 162, 163, 167, 174,
183, 196, 202-204, 212, 214, 218,
220, 231, 233, 240, 242, 243, 247,
259, 262, 272, 283. [See Descrip-
tions of types. |

Lepidoptera, 21, 51, 66, 68, 185, 190,
221, 245, 257, 274, 282, 285, 287.

Lepisma, 47, 49, 53, 54, 59, 67.

saccharina,

Lepismaform, 54.

Lepismatide, 66.

Leucania unipuncta, 205.

Leucanthiza, 202.

Leydig, 21.

Libellula pulchella, 73, 77-

— quadrupla, 77.

trimaculata, 73, 81, 84.

Libellulide, 73.

Light-giving organs, 151.

Ligula, 25.

Limenitis, 23, 219.

— Disippus, 22.

Lincecum, 242.

Linear treatment of types, 63.

Lintner, 148.

Liquid-secreting glands, 116.

Lithocolletis, 202.

Lizards, 57.

Lobster, 11, 25.

Locomotion, 28, 29, 83, 139-

[See

121,

155,
182,

INDEX.

| Locust, lubber, 8, 41.

| —— red-legged, 35, 109.

— Rocky Mountain, 24, 42, 109.

—— yellow-striped, 8, 9. [See Calop-
tenus. |

Locustarians, wingless, 9.

Locusta viridissima, 34.

Locustidz, 9, 33, 51, 108.

Longicorns, 163.

Loopers, 204.

Lubbock, 23, 46, 48, 50, 70, 142, 168,
224, 225, 240, 277, 281, 282, 286.

Lycenidz, 183, 203, 218.

Lycosa, 174.

M.

Machilis, 47.

Macrodactylus subspinosus, 151.

Macrosila quinque-maculata, 208.

Maggot, 244, 273, 281, 282, 287.

Magnifiers, 248.

Mallophagide, 98.

Mamestra, 207.

Mandibles, 51, 109, 156-158, 161,
165, 173, 174, 231, 233, 238, 240,

’ 243, 247, 259, 260. [See Descrip-
tions of types and Mouth parts. }

Mantide, 111, 278.

Mantispa, 170, 174, 177.

Marcellus, 216-218.

Marey’s flying-machine, 32.

Mask, 80-82.

Massachusetts, 92, 133, 159.

Maxille, 161, 173, 259, 260. [See De-

scriptions of types and Mouth

parts. |

Maxillary palpus, 24, 25- [See Palpi.]

May-beetle, 145. [See Beetles. ]

Mayer, 49.

tae, 5I5 50, 58; 60,-7O, grynOns
166.

McCook, 240.

Meadow grasshopper, 108, 109.

Mealy bugs, 141.

Measuring-worms, 204.

Mecoptera, 176, 177, 182.

Meinert, 66

Meloé, 159, 167, 280.

Meloide, 157, 160.

Melophagus ovinus, 272.

Mentum, 25.

Mesothorax, 97, 106, 107, 109, 124,
127, 128, 132, 135, 162, 163, 168,
196, 242, 243, 264, 265. [See De-
scriptions of types.

epimerum of, 15.

—— episternum of, 15.

INDEX.

Mesothorax, scutellum of, 15.

scutum of, 15.

sternum of, 15.

Metabola, 276.

Metamorphosis, direct, 44.

indirect, 44.

Metastoma, 25.

Metathorax, 106, 107, 109, 121,
T27s726)- 132, 133, 135) 162;
168, 196, 257, 263-265, 267.
Descriptions of types. |

—— epimerum of, 16.

—— episternum of, 16.

—— scutellum of, 16.

—— scutum of, 16.

—— sternum of, 16.

Mexican bee, 228.

Mexico, 141, 216.

Meyer, 23.

Meyrick, 52.

Miall and Denny, 22, 23, 38, 40, 56,
59, 102, 104.

Microlepidoptera, 183.

Micropteryx, 247.

Migrations, 191, 215

Milk-weed butterfly, 186.
nais Archippus. |

Millepedes, 47, 48.

Millers, 200.

Mimicry, 219.

Minot, 11, 19.

Missouri, "216.

bee-killers, 262.

Mock-chirping, 33-

Mole-cricket, 108.

Mollusca, 12, 58.

Monarch butterfly, 186.

Morse, 14, 70.

Mosaic vision, 20.

Moseley, 39.

Mosquitoes, 23, 78, 259, 261.

Moths, 196.

. Moulting, 45, 70, 105, 261, 277.

Mourning cloak, 219.

Mouth, 24, 35, 82.

Mouth parts, 49-51, 53, 97-99, 103,
TOOs= 107, 1275, D4x, 1439,) Tog, 166,
173, 175, 196, 231, 244, 245, 247,

124,
163,
[See

[See Da-

259, 260, 262, 265, 268, 269, 274,
275, . 285. [See Descriptions of
types. ]

Mulberry silkworm, 207.
Miller, F., 48, 56,57, 96.
H., 161, 225.

Musca domestica, 248, 265.
Muscide, 250, 265, 266.
Muscles, attachment of, 27.

295

Muscles, disposition of, 37.
— work done by, 30.
Muscular feats, 37, 270.
Mutillidz, 24r.

Mygale Hentzii, 24r.
Myriopods, 12, 26, 47, 48, 165.
Myrmeleonidze, 89.
Myrmeleon obsoletus, 173.

N.

Naphthaline, 154.

Natural affinities, 52.

methods, 186.

— order of lessons, 185.

paper-makers, 243.

processes, 186.

selection, 225.

Natural History, method of work in,
28, 115. [See also p. 185.]

Nemobius, 107.

Nemognatha, 16r.

Nemoura, go.

Nepticula, 202.

Nervous cord, 37.

Neuroptera, 51, 61, 62, 68, 170, 278,
280, 285.

New England, 8, 45, 96,
153, 173.

Newport, 37.

Noctuide, 205.

Northern army-worm, 205.

Notonecta undulata, 121.

Notonectidz, 121, 142.

Notthaft, 22.

Nut-galls, 233.

Nycteribide, 271.

Nymphalidz, 212, 219, 220.

Ioo, 133;

Oo.
Oak-apples, 233.
Ocelli, 20, 21, 37, 77, 117, 127, -131,
146, 188, 192, 224, 238, 252, 272.
Ocular trachez, 38.
Odonata, 21, 50, 61, 62, 73, 82, 88,
PLOsCE7 Se
CBeaphaceal bulb, 261.
(Esophagus, 35, 261.
(Estridz, 265, 267.
(Estrus ovis, 267.
Oil-beetles, 157.
Oligoneuria rhenana, 7o.
Opsiccetus personatus, 124.
Orchelimum vulgare, 108.
Order I., Thysanura, 64.
II., Ephemeroptera, 69.

296

Order III., Odonata, 73.
IV., Plecoptera, go.
V., Platyptera, 92.
VI., Dermaptera, too.
VII., Orthoptera, 102.
VIII., Thysanoptera, 113.
IX., Hemiptera, 115.
X., Coleoptera, 145.
XI., Neuroptera, 170.
XI1I., Mecoptera, 176.
XIII., Trichoptera, 178.
XIV., Lepidoptera, 185.
XV., Hymenoptera, 223.
XVI., Diptera, 248.
Origin of structures, 225.
wings, 41, 56,57. [See Wings. ]
Orthoptera, 29, 30, 62, 68, 102, 110—
I12, 142.
Orthorhapha, 257.
Osage-Orange, 138.
Ova, 136, 137. [See Eggs.]
protection of, 121.

Ovary, 37.
Oviduct, 37, 273.
Ovipositor, 107, 109, 164, 231, 232,

236, 237, 251, 259. [See Descrip-
tions of types and Sting. |

ize

Packard, 22, 23, 38, 39; 46, 48-50, 52,
54, 50, 57, 59, 61, 62, 80, 82, 94, ror,
II4, 129, 138, 142, 143, 175, 183,
225, 244, 254, 281, 282.

Paleacrita vernata, 205.

Palmén, 250.

Palpi, 109, 158, 260.
tions of types. |

functions of, 25.

Panorpa, 176, 177-

Panorpide, 176.

Papilio, 214.

—— (Ageronia) feronia, 190.

—— ajax, 216.

Papilionidz, 212, 214, 216.

Papille, 24.

Paraglosse, 226.

Parallel forms, 141, 175.

series, 62.

Parasites, 52, 53, 98, 99, 126, 128-
130, 157, 161, 168, 169, 233, 256,
267, 271, 272, 279, 283, 285, 286,
288.

[See Descrip-

position of, 52, 99.
Parasitica, 128.

Parasitic Coleoptera, 157.
Parthenogenesis, 136.

INDEX.

Patagia, 187. [See Shoulder lappets. }

Patten, 20.

Pauropus, 48.

Pear-slug, 231.

Pediculidz, 129.

Pediculina, 129.

Pediculus capitis, 129.

—— vestimenti, 129.

Pedunculated abdomen, 17, 238, 250.
[See Abdomen. ]

Pentatomide, 126.

Periplaneta orientalis, 102.

Perlidz, 51, go.

Pezotettix, 45.

Phalznidz, 203, 205.

Pharyngeal sac, 189.

Pharynx, 261.

Phasmide, 165, 111.

Philadelphia, 207.

Phosphorescence, 152.

Photuris Pennsylvanica, 151.

Phryganeide, 178, 179.

Phyllocnistis, 183, 202.

Phylloxera, 138.

Phylogeny of insects, 104.

Physical causes, 226.

— conditions, 88.

surroundings, 218.

Physopoda, 113.

Pieris, 22.

oleracea, 215.

rapz, 186, 214, 237.

Pine-cone galls, 263.

Plan adopted in Guide, 13.

Plant-lice, 136, 285. (See Aphides. |

Plate I; Figs. I-12, — 10.
ae Figs. 13, 15-20, 22-26, — 38.
III., Figs. 29-32, 34, 35) 37-42, —
73-
IV., Figs. 52-60, — 102.
V., Figs. 63-67, — 115.
VI., Figs. 84-90, — 145.

VII., Figs. 97-113, — 158.
VIII., Fig. 119, — 170.

IX., Figs. 134-140, 142-148,—186.
X., Figs. 176-181, — 224.
XI., Figs. 186-192, — 238.
XII., Figs. 196-205, — 248.

XIII., Figs. 207-213, — 260.
Plateau, 21-23, 25, 26, 40, 102.
Platyptera, 68, 91-93, 98.
Platysamia Cecropia, 208.
Plecoptera, 70, go.
Plectoptera, 70.
Plectrocnemia, 18r.

Podical plates, 18.
Podisus spinosus, 126.

INDEX.

Poduride, 66.

Polymorphism, 218.

Pompilide, 241.

Pompilus formosus, 241.

Popular nomenclature, 9.

Post-embryonal development, 266.

Potato-beetle, 145, 150.

Poulton, 198.

Preservation of structures, 225.

Primitive Hemipteron, 284.

rings, 16.

Prionidus cristatus, 124.

Prionus coriarius, 56.

Proboscis, 161, 164, 252, 260, 262,
265.

Proctotrupide, 113, 233.

Progression of types, 50.

Progressive modifications, 41.

Prop-legs, 177, 183, 193, 199, 204,
205, 231, 233, 259-

Protective coloring, 106, 219.

Prothorax, 97, 106, 110, 123, 127, 131,
138, 151, 163, 166, 168, 242. [See
Descriptions of types. ]

—— postscutellum of, 13.

prescutum of, 13.

—— scutellum of, 13.

scutum of, 13.

sternum of, 14.

Pseudo-sessile abdomen, 251, 263.

Pseudova, 136.

Psocidz, 97-

Psocus lineatus, 97-

Pteronarcys, go.

Pterophoride, 113.

Pulicide, 268.

Pulvillus, 27.

Pulvinaria mnumerabilis, 138.

Pupa, 56, 134, 150, I51, 154, 159, 160,
173,174, 199, 200, 202, 208, 211, 213,

217, 231, 237, 239, 259, 201-263, 268, |

270, 271, 279, 281, 283, 285. [See
Descriptions of ada

pseudo, 158, 160.

Pupz, active, 277.

quiescent, 277.

Pupipara, 271, 285, 286.

Pyrethrum powder, 128.

Quiescence, 277. , :
Quiescent pupal stage, introduction
of, 62. [See Pupa.j

Radiata, 12. =
Rat-tailed larva, 265.

297

Rectal glands, 35.

Rectum, 35.

Reduviide, 124.

Reinhard, 250.

Replacement, law of, 284, 286.

Reptiles [Triassic], 28.

Resemblances of moth and humming-
bird, 210.

Respiratory filaments, 58.

system, 38.

tubes, 261.

Retina, 21.

Retinal purple, 2r.

Retinule, 20.

Rhopalocera, 212.

Rhynchophora, 168.

Riley, 42, 43, 103, 133, 138, 158, 168,
IQI, 205, 207, 225, 236, 242, 281.

Robber-flies, 262.

Rocky Mountain locust, 24, 42, 109.

Rolleston, 104.

Romalea microptera, 8.

Romanes, 97.

Rose-bug, 151.

Ruby-throated humming-bird, 210.

Ryder, 225.

Ss.

Salivary glands, 35.

Saltatorial Orthoptera, 111, 282.

Sand-wasps, 241.

Saperda candida, 163.

Saw-flies, 231, 244, 247.

Scale-insectS, 138, 143.
dz. |

Scarabzide, 147, 151.

Scarabzeus, 151.

School cabinets, 15, r2r.

Scolopendrella, 48.

Scorpion-fly, 176, 177.

Scorpions, 12, 47.

Scudder, 22, 24, 33, 43, 49, 59, 71, 104,
183, 188, 191, 203, 212, 216, 221.

Scutellera, 116.

Scutelleridz, 126.

Scutellum, mesothoracic, 15, 116, 120,
124, 126, 146, 188, 223, 249, 264, 265.

Sebaceous gland, 37.

Secondary larval forms, 221, 273, 280,
281, 286, 287.

stages, 221, 276, 278, 282.

Secondary specializations, 58.

—— sutures, 16.

Second series of orders, 54, 276, 285.

Segmentation, 16, 138.

Selandria cerasi, 231.

[See Cocci-

298

Sense organs, 19.

Sessile abdomen, 17, 184, 251.
Abdomen. |

Setz, 66, 70, 108.

Setting-boards, 186.

Seventeen-year cicada, 133.

Sheep bot-fly, 267.

Sheep-tick, 272.

Shellac, 141.

Shoulder lappets, 187, 188, 242.

Shuckard, 230,

Sialidez, 170.

Silphidz, 166.

Silver solution, 39.

Siphonaptera, 268.

Sitaris, 159, 167, 168, 280.

Skeleton, colors of, 11.

Skippers, 212.

—— clouded, 214.

—— sooty, 214.

Smeathman, 96, 97.

Snellen Van Vollenhoven, 237.

Snow-insect, 177.

Soldier ant, 238.

Solitary ants, 241.

bees, 244.

wasps, 240.

Songs of the grasshoppers, 33.

South America, 151, 161.

Spatangoids, 280.

Specialization, 50, 62, 245, 248, 274,
288.

by addition, 51, 226, 246.

by reduction, 51-53, 71; 72, 99;

129, 138, 157, 161, 251, 281, 2

meaning of, 50.

Specializations, acquired, 53.

Specialized orders, X.-XVI., 53.

Sphegidz, 240.

Sphex, 241, 243.

ichnenmonea, 240.

Sphingidz, 208, 211.

Spiders, 12, 26, 47, 240, 271.

Spinnerets, 193, 259-

Spiracles, 18, 38, 66, 107, 117, 147,
172, 249, 255, 267.

Spireas, 154.

Spores, 29.

Spring canker-worm moth, 204, 205.

gall-flies, 234.

Spring-tails, 66.

Stainton, 183, 202.

Standard of reference, 50.

Staphylinide, 166.

Staphylinus, 25, 26.

Sterna, 4o.

Stick-lac, 141.

[See

INDEX.

| Sting, 224, 227, 231, 240, 242, 258.
[See also p. 274. ]

beak, 121, 122, 125.

of proboscis, 262.

Stipes, 24.

Stone-flies, 58, 90, 166.

Straight-winged insects, 29, 102.

Strigillations, 33.

Structure, effects of domestication on,
208.

effects of habit on, 40, 108, 168,

202, 280.

effects of temperature on, 216.
{See Correlative structures and
Habits. ]

Stylopidz, 159, 161, 168, 274.

Stylops, 19, 161-163, 283.

Subgenital plate, 34.

Subimago, 70.

Submentum, 25.

Succincti, 220.

Sucking-tube, 122, 124, 126, 133, 135,
142, 208, 210, 284. [See’ Descrip-
tions of types and Mouth parts. ]

Supra-cesophageal ganglion, 35, 261.

Suspensi, 220.

Sympathetic nerve, 37.

Syrphide, 264.

Syrphus, 264.

politus, 265.

iy

Yr.

Tabanide, 263-265.
Tabanus, 254.

lineola, 248, 251, 263.
Teenia, 280.
Tarantula-hawk, 241.

killer, 241.

Tarsus, 27, 78, 103.
Telamonides, 216-218.
Telea Polyphemus, 196, 198.
Temperature, 207, 216.
Tenthredinide, 231, 246, 247-
Terga, 40.

Tergum, 18, 30.

Termes, 57-

—— bellicosus, 95, 97-

—— dirus, 95.

flavipes, 92, 94, 96.
Termites, 51, 94, 166.

castes of, 94.
Termitide, 92.

Terrestrial Heteroptera, 124.
Tettix, 110.

INDEX.

Texas, 241.

Thalessa, 236.

atrata, 235.

Thecla, 202, 203, 219.

Thorax, 47, 49, 183, 196, 208, 231-233,
240, 243, 257, 259, 202, 264, 267, 272,
274, 275- ee Descriptions of
types. |

Thripide, 113.

Thrips cerealium, 113.

striatus, 113.

Thysanoptera, 60, 113.

Thysanura, 47, 48, 50, 54; 55, 58, 62,
64, 66, 73, 91, 114, 275-

Thysanuriform, 54.

larva. {See Larva. ]

Tibia, 123.

Ticks, 285.

Tiger-beetles, 157.

Tinea, 196.

pellionella, 200.

Tineidz, 200.

Tipula, 257.

——Agarici seticornis, 259.

Tipulidz, 257-259, 262.

Tischeria, 202.

Tongue, 24, 25, 82.

Toothed ridges, 76.

Trachez, 30, 38-40, 58, 67, 83, 87,
254.

Treat, 240, 265.

Tree-hoppers, 138.

Tremex, 236.

Trias, 28.

Trichoptera, 178, 179, 201.

Triungulin, 158.

Trochanter, 27.

Trouvelot, 22, 198, 199.

Tubercle, 14.

Tympanal organs, 1g.

Tympanic membrane, 23.

Types, descriptions of, | see below].

locust, 8-45.

Campodea and Lepisma, 64-

67.
—— May-fly, 69-71.
—— dragon-fly, 73-88.
stone-fly, go.
—— white ant, 92-97,
ear-wig, oo.
—— Thrips, 113.
—— squash-bug, 115-120.
—— May-beetle, 145-149.
Corydalus, 170-172.
—— Panorpa, 176, 177.
caddis-fly, 178-181. :
—— milk-weed butterfly, 186-195.

299

Types honey-bee, 223-230.
—— horse-fly, 248-255.
Typical crustacean ring, 15.

VU.
Uhler, 129.
Unexpected modifications, 165.
United States, 8, 145, 216.
Uroceride, 232.
Use, effects of, 16, 30.
law of, 40.

Vv.

Vagus nerve, 37.
Vanessa Antiopa, 219.
Veinlets, 29.

Veins, 29, 30, 39.
Vermes, 12.

Verrill, 116, 268, 273-
Vertebrata, 12.
Vertebrates, 108,
muscles of, 37.
respiratory organs of, 59.
Vespa, 243.

maculata, 242.
Vespide, 242.

Ww.

Walking-stick, 105, 106.

Wallace, 106.

Walsh, 207.

Walshu, 216-218.

Walters, 247.

Water-beetles, 166.

Water-boatman, 121, 122.

Weevils, 24, 68, 145, 163-165, 167,
168, 176, 281, 282. [See Curculi-
onide. |

Weismann, 218, 250, 266.

West Virginia, 216.

Westwood, 33, 151, 177, 179, 235.

Wheat-midge, 263.

Wheel-bug, 124.

White ants, 92.

Wigglers, 26r.

Wild cockroaches, 105.

Williston, 259.

Wing-covers, 29, 100, 107, 110, 126,
147-149, 159, 162, 166. [See Ely-
tra.

Wings, 49, 59, 98, 103-107, 109, 110,
122, 124, 126-129, 133-135, 140, 159,
161, 162, 166, 172, 196, 201, 208,

[See Termites. ]

213, 215, 233, 242, 243, 262, 26
269, 272,274. [See Descriptions o

Wines ort of, 30, 31, 56, 5

» » 39, 31, 50, 57-
Woodchuck, 265.
Worker ant, 238.

—— bee, 223.

Worms, 12, 15, 47+

Wyman, 228.

f Xenos, 20.

ee
Young lepidoptero s |

Zittel, 171.

Sh Pag
oA

eee

m4