so a ee i ee

. Biological
vf | & Medical
S Serials
49 Gniversity of Maine.

E3
no.r53

Biological ; JAN
—& Medical | \ NZ Gat
* Serials “Egy ~ASITY, OF

a
“

Maine Agricultural Exp

THE ROYAL CANARIA STITUTE

BULLETIN 253 JULY, 1916

SYRPHIDAE OF MAINE

OLT 14 1916

This bulletin contains a general discussion of a group of
flies which are, for the most part, not injurious, but beneficial
in destroying crop-pests. Their life-stages, habits, structure
and economic importance are described, and practical measures

Sis for increasing their usefulness are suggested.
A detailed summary is given on pages 193 to 197.

MAINE
AGRICULTURAL EXPERIMENT STATION
ORONO, MAINE.

. THE STATION COUNCIL.

PRESIDENT ROBERT J. ALEY, President
DIRECTOR CHARLES D. WOODS, Secretary
CHARLES IL. JONES, Corinna, Committee of

FREELAND JONES, Bangor, Board of Trustees
WILLIAM T. GUPTILL Topsham, Commissioner of Agriculture
EUGENE H. LIBBY, Auburn, State Grange
WILSON H. CONANT, Buckfield State Pomological Society
FRANK §S. ADAMS, Bowdoinham, State Dairymen’s Association

LEONARD C. HOLSTON, Cornish, Maine Livestock Breeders’ Association
WILLIAM G. HUNTON, Readfield, Maine Seed Improvement Association

AND THE HEADS AND ASSOCIATES OF STATION DEPARTMENTS, AND THE
DEAN OF THE COLLEGE OF AGRICULTURE.

THE STATION STAFF.

( CHARLES D. WOODS;-Se .D: Dtrector

ADMINIS- 4 BLANCHE F. POOLER, Clerk
TRATION } GEM M. COOMBS, Stenographer
(JANIE L. FAYLE, Stenographer

( RAYMOND PEARL, Pu. D., Biologist

| FRANK M. SURFACE, Pu. D., Biologist

BIOLOGY -~ MAYNIE R. CURTIS, Pu. D., Assistant

| JOHN R. MINER, B. A., Computer

| MILDRED REBECCA COVELL, Clerk

| JAMES M. BARTLETT, M. S., Chemist

HERMAN H. HANSON, M. S., Chemist

CHEMISTRY 4 JOHN H. PERRY, Assistant
| WILLIAM H. RICH, B. S., . Assistant

; WALTER W. WEBBER, B. S., Assistant

| HARRY C. ALEXANDER, Laboratory Assistant

ENTOMOL- EDITH M. PATCH, Pu. D., Entomologist
OGY ALICE W. AVERILL, Laboratory Assistant

( WARNER J. MORSE, Pu. D., Pathologist

PLANT 4 tMICHAEL SHAPOVALOV, M. S., Assistant
PATHOLOGY | tGLEN B. RAMSEY, A. M., Assistant
DONALD S§S. CLARK, Laboratory Assistant

AROOSTOOK \ JACOB ZINN, Acr. D., Assistant Biologist
FARM C. HARRY WHITE. Scientific Aid

| JEREMIAH E. SULLIVAN, Superintendent

HIGHMOOR WELLINGTON SINCLAIR, Superintendent
FARM WALTER E. CURTIS, Scientific Aid
ROYDEN L. HAMMOND, Seed Analyst and Photographer
CHARLES C. INMAN, Assistant

tin collaboration with U. S. Department of Agriculture.

BULLETIN 253

SeREHIDAH* OF MAINE **

C. L. METCALF.+

SUMMARY.

ene Ore Pe Ee Bs Se A OR SEE A gence

Man’s greatest allies in controlling destructive insects are other
species of insects having the predaceous and parasitic habits;
without the help of which he would doubtless be unable to

protect his crops against the multitudes of destructive pests....

It is therefore deemed important to study our native beneficial

insects in detail as a basis for increasing their usefulness......

One of the most important groups of natural enemies of the Aphi-
didae or plant-lice is the family of Flowe1-flies or Syrphidae

which are not well-known and are much misunderstood........

This bulletin deals with the structure and habits especially of the

immature stages, and of both beneficial and injurious species. .

MN oR RRO ee ain cg Sins iors en hee ig wale

The two-winged flies of this family are easily recognized by the

“false vein” on their wings. (Figs. 31-64, 35-1).........++.
Le OR ee ee ee

OC FES ee) EV re oe doh dees « tHe et in ines

The Flower-fly has a complete metamorphosis including four dis-

aE nt Fe i, sot 2S Rpg onc din piney ber aa * eGov ve

Egg.

The eggs are deposited by the flies in a great variety of situations...
They have a somewhat characteristic appearance................

*Pronounced Surf’-i-dee.

**Papers from the Maine Agricultural Experiment Station:

mology 87.
Member of the Station summer staff.

.198

> EGS

a OO

200

was see CPE

armen One

194 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

Larva. PAGE
The eggs hatch into slender, headless, footless, blind maggots of
remarkably varied appearance, but all with the posterior spir-
acles borne on the end of a short, or very long, double, but

never forked, tube... ao ss. ox sont 5 ee eq: Ot Ts = 2 oe 202
There appear to be twelve larval somites usually marked by a
transverse row of twelve segmental bristles.............--.-+-+: 203
Other charactensSines? VA"".5" oes SS 2 ee ths ee 203
Pupa.

When the larva is full grown its skin inflates and hardens, and in-
side of the puparium, so formed, the transformation from

maggot to winged fly takes place.............--..-22++--eeee: 204
Charactetisties.: .... 000... Ae a ee 204
Adult,

When this change is complete the fly pushes off the front of the
puparium, crawls out of the skin, and is soon able to fly away... . .205
It feeds on mectar and: pollen... 60... acs.gie =<’ i40)5,75.0 eee 205
Mating. 3,5 -5.Ficyes's a's eg vide i Bokeieces = anal? Ot Fede ae Se 205
Oviposition for the next gemeration..........-.. 2+ sees creer eeteees 206
HABITS OF THE LARVAE, Oho cacy sonata co nemeeea Lh eee
The great variety of larval habits, with the species known to fol- Pee
low each, ‘is summarized in Figure 28...) 25... .. 45 y2055 -~e eee ey
STRUCTURE ‘OP “THE LAR WBE ois es . girs) 9+ nln 708

Careful study of the larvae following different habits shows a num-

ber of different structural types of larvae, the species of each

type for the most part following the same habit................. 208
(1) The aphidophagous type, which is of prime importance since

it includes the valuable predaceous species, and also one crop-

pest, is cCharheterizeds. . 6 F000 ear in cee eon oe oe Oe 208
(2) The boring type of larva, including several serious pests of
bulbous crops likely to be spread in the State, is characterized... .. 209

(3) The short-tailed, filth-inhabitating type of larva, which em-

braces two species not hitherto described as breeding in human

excrement, is characterized... ..::...7.....300 0 210
(4) The long-tailed (or rat-tailed) filth-inhabiting type of larva,

which includes a number of species with a very remarkable

adaptation for breathing while feeding below the surface of

water, is characterized ..0). oo. o5 a s0e,5seucin, suse dye = 0 oe ee 210
(5) The Microdon type of larva, which includes species of that

genus that live in the nests of ants; and are so anomalous in

appearance that they were several times described as new

species of Molluscs and Coccidae, before their true nature as

the young of flower-flies was recognized, is characterized.........- 211

SYRPHIDAE OF MAINE.

ECONOMIC IMPORTANCE OF THE LARVAE................

A. Beneficial Habits

(1) The larvae destroy myriads of aphids and arebelieved to be the
most important natural check on these destructive crop-

es ag koa ASL aa ee a
They sometimes occur in enormous numbers.....................
And may practically exterminate their prey in a given locality.....

But are of most value in constantly and everywhere tending to
keep the aphids from increasing to seriously destructive num-

Several observations show their remarkable capacity for destroy-

OS Okey Sone hee ee
ee gS OR oer a
(2) The larvae are of recognizable value as scavengers............

Their breeding in filth does not seriously endanger human health,

because they do not visit human food or human habitations..... .2

B. Iniwrious Habits.

(1) The larvae of one species occasionally occur in great numbers

on corn, sucking the sap and eating the pollen................

While two other European species, introduced to this country,

feed in the bulbs of certain flowers and vegetables.............

(2) The larvae which normally live in filth are occasionally intro-
duced alive into the human or animal alimentary canal, or

other body cavities, causing serious functional disturbances. .

The probable sources of such infection to be guarded against are

ECONOMIC IMPORTANCE OF THE ADULTS................

The adult Flower-flies are exclusively beneficial and of great im-
portance in pollenizing many fruit and shade trees, flowers,

ee ee ett oe UTS See ce ey

en NE

= eG

ees

an SET

196 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

PAGE
PRACTICAL MEASURES: «./....54).. 2iy. 9 220
(1) These Flower-flies which are often mistaken for stinging wasps

or bees are entirely harmless and should not be killed............. 220
Several methods of distinguishing them from wasps and bees,

which they closely resemble, are givem...<.... 07. ...,. eee 220

(2) The larvae among aphids on plants should never be destroyed
but carehully protected ........0. 04. 2 oe es oe oe 225
(3) Investigations under way, indicate that certain contact in-
secticides can be used to kill the aphids, which will not kill
the larvae of Syrphidae, and thus leave these beneficial larvae
fot further: usefuiness: os gs. oe ee eo a ts ee 221
(4) In late summer many of the Flower-flies are destroyed in the

puparia by small Hymenopterous parasites..............-...... 221
Infested puparia may be recognized and should be destroyed wher-

OWEL TOU 6. 55 ea an sig PG encod os nee ee 221
EXPERIMENTS DURING’ yors te OR. tae OO. 2a eee 221
About twenty species of Flower-flies have been reared in the State

and studies made of their habits and life stages................. 222
PREY ATTACKED BY FLOWER-FLIES |. ...:... 2: (2 222
Aphidophagous larvae were found feeding on thirty or forty

species of aphids and two species of psyllids................ eek

DESCRIPTIONS OF IMPORTANT OR INTERESTING
MAINE SPECIES.
Pipiza pisticotdes Williston, an important enemy of the Woolly
Apple Apiusiy. Lee Oe ek eee 22
DBE VG Si ob te Bas eat Soo PLA Boas, See tae Bld ee ae hd 225
PUPATIBA S055. Se 8 ORS acc FS ae he oy We nn ce 226
|| ee eT OM MLE 226
Melanostoma mellinum Linné, reared from among M yzus persicae
Of erueiferotis eropS iin. Fa.!s4. 6g FE iors oes eh ee eee 226
MOS oh Ss Eee ae Re a ee 228
Larva foie. oes UR A er ie eee 229
Puparium (of peculiar structural interest):................ 220
AMAR 5s ewe MOORS. eG ae 'g Dus Vas VAs ne 230
Sphaerophoria cylindrica Say, is a common and important enemy
of aphids on fruit trees and other plants. ». ... +. 2065. 231
Bet Peet ee ee, hs ae ol int see. eae 232
LAGvOl 2 ir erwihh soos cabans 0. oily chaldloulda sae 232
PHAM 6.25. 0 Se. eR 233
AUER aoc. kee i iow 1 gees Saeki eh 233
Alloygrapta obliqua Say, a species apparently rare, but occurring in
the State, is distinguished from the last two species which it
Closely sesemibles. 5 i.e 0 ccied woe 5G wha. te Pe oe 234
CS | Se SO, Pane PRD ON, fegterlty ct ee 234

SYRPHIDAE OF MAINE. 197

PAGE
ZENG SA Pe Pt OEE ae ee ee, 235
ek TUE ee on ee ee 236
The American Syrphus-fly, Syrphus americanus Wiedemann, a
very general feeder, is one of the most valuable species in the
eS ne ee Lee Me OREM a etsy acta s-0el WS va ee hee 226
a rae ile idk AP I RS Wc a gins em ANY 9» > 237
iain Ae fae iat tae. shri d. OMS, 80S 99S. HEP 247
ARIE ater tat 8 epee win Ahi vive «2.2 +o, a ¥inwteisrecey oan ee > 238
TE og at LC ee aes a ee 239
Syrphus torvus Osten Sacken also occurs in great numbers among
Cele renee CUMIN Se eis Pe ed ven eee el RE PSS 240
Speen eed td. AO oi Oi SoH lO. PsSLONY. 241i: 240
PINON. LSEaey Ridkatvae: igh 4 2 4 dp ase y ey > <pyert nares s 241
er I ee ghee gisele oho dg bine 241
Syrphus nitens Zetterstedt, a European species not heretofore
recorded from North America, is aphidophagous and of par-
ticular biological interest, because of structural peculiarities..... 242
ere. See) oe reels. ee eb hsree: seks 6 datas sf ogres 242
RMUORIIINENE GTR AGEs he Re de oe end win ee, «pine n't 244
poo rele OS ART operetta hare iniet ci ge 244
Didea fasciata Macquart var. fuscipes Loew occurs feeding among
fae Winsew grove /F mam -sosese 2S . Pe RUG 2D. 246
ee ee Oe) | FOF. Sai. AB bt HS ie JR. oa 246
ES een. Dur ty PAN on. aoe Sa vy shad <eaeE vi rl be «rine ea eey
EE SA ecry hg t S SAnR I noel e eee ae 248
A NE RE ny ye ee ag Syl o es SN Se eee os as 248
Tropidia yuadrata Say whose larval habits are here recorded for
the first time, was found breeding in human excrement........... 248
ieee Mer wertety. thier. sbearbuee lag. Sai selespclveie see) weed hy 249
SR OE ee tt cee csc gk so sake <otaa lag ed Rolne cokes 250
ee Ey a SR apg BR gee are era 251
MERA APe Ate, SRG eee ego ate lies Gees te rane + ote ew a Bee 252
The very common Syritta pipiens Linné was also reared from
human excrement and from guinea-pig manure................... 253
ES ES ee, ee en ee 253
PE casio A on opel EE dyes ee Se 254
SSR SIERO, BAe Ne a, ese oe et ds doe be 254
PUR ay Hs GG SKN eae Bi. Sees ea eS SARS LA 255
ARTIFICIAL KEYS TO THE LARVAE AND PUPAE OF
ok gee A re calla ah tiie tet a es, aes 256
GLOSSARY OF NEW OR UNUSUAL THEMS. 2000. 200. fl. 258
BIBL AAP! «el viee ie yarh etic. doelbey. arlgpamaares «5 261

On OS EIS © MEE iN aA igh cee Gee! Cay re 264

INTRODUCTION.*

Entomologists are realizing more clearly every year the tre-
mendous importance to agriculture and human economy of the
groups of insects having the predaceous or the parasitic habit.
There has long been a strong suspicion that without these
natural enemies of insects man would be helpless in combating
destructive crop-pests. The recent great destructiveness of
certain insects introduced from foreign countries, followed by
the successful repression of these pests in certain instances
with their natural insect enemies (likewise introduced from
foreign lands), has emphatically confirmed this opinion.

There seems to be not the slightest doubt that predaceous and
parasitic insects are man’s greatest ally in keeping destructive
insects in control. They work without the necessity of any
attention on the part of man and for the most part so unob-
trusively, that most of us are unaware of their existence. It
is only when some combination of conditions checks their
numbers that we experience for a year or two a serious out-
break of the pests which these beneficial insects have been
holding in submission and which would otherwise be seriously
destructive every year.

It therefore seems desirable that we ous as much as pos-
sible about the life-histories, habits and biological relation-
ships of such of these insects as occur in our own country. Not
only because of the scientific interest which such facts may
have, or so that we may learn to appreciate their value, but
also in the hope that we may be able to conserve these natural
resources, and possibly artificially foster, encourage, increase
and transport, or extend the distribution of, the most useful
ones.

One of the most universally distributed and destructive of
insect groups is the Homopterous family Aphididae, or as they
are commonly called, plant-lice or aphids. This group owes

*The numbers in parentheses in the text refer to papers in the
bibliography, which are serially numbered.

SYRPHIDAE OF MAINE. 199

its success not to the hardiness or resistance of the individuals
but to their remarkable fecundity, for the individual aphid is
conspicuously frail, defenseless and exposed throughout its
life.

Because of this frailty aphids are attacked by large numbers
of predators and parasites. The best known of the groups of
aphid enemies are: (1) the parasitic Hymenoptera; (2) the
Ladybird Beetles or Coccinellidae; (3) the Lace-winged Flies,
Aphis-lions or Chrysopidae; and (4) the Flower-flies or Syrph-
idae. The parasitic Hymenoptera complete their transforma-
tions from eggs to minute wasps inside the body of a single
aphid. The latter three groups are predaceous and grow, not
at the expense of a single aphid, but by catching and eating
dozens or hundreds of them. The Coccinellidae have achieved
a good deal of popular interest so that there is hardly a school
boy but knows that the Lady-birds eat plant-lice and are the
farmers’ friends. The Syrphidae, on the other hand, seem to
be little known and much misunderstood by the farmer, This
deplorable lack of a better popular knowledge of this group
is a little hard to explain. Perhaps the principal reason is that
they have been so little discussed in entomological and popular
literature; and the lack of a good common name may have
had its influence. Although it gives little or no intimation
of the economic importance of the group, and may even be
misinterpreted as indicating a habit injurious to flowers, the
name “Flower-flies’ seems to be the most satisfactory of the
names in use; because it is based on the most characteristic
habit which is uniformly true for the adults of the family:
viz, that of visiting flowers for the purpose of getting food.

As contrasted with the Lady-birds, the movements of the
Syrphid larve are slow, their colors subdued and their general
appearance quite inconspicuous,—even repulsive. Their elon-
gate flattened bodies are often nearly or quite covered from
view by the aphids or their secretions. They are consequently
usually overlooked or ignored; or the adults persecuted as
“sweat-bees,” under the wholly erroneous idea that they can
sting; or, worse still, the flies may be accused of being respon-
sible for the presence of the lice on the plants, or the larve
for the damage resulting from the plant-lice.

200 MAINE AGRICULTURAL EXPERIMENT STATION. Ig 16.

In spite of their lack of popular recognition, I have become
convinced during several years’ study of this group, that, in
the sections observed, the Flower-flies are a more important
enemy of aphids than are the Lady-bird Beetles, and that
probably they are the most important of the natural enemies
of aphids. I have been gratified to find this opinion confirmed
by Dr. Edith M. Patch after many years’ extensive observa-
tions of the aphids of Maine.

The present bulletin deals with only one of the groups of
insect enemies of aphids,—the Syrphidae. Its aim has been
to elucidate the life-economy of these little-understood Flower-
flies, so that the agriculturist may come to look upon them as
his friends and give them his well deserved protection. And
that as a basis for fostering and increasing their numbers we
may have an intimate knowledge of their structure, habits and
transformations. And since the larval habits are very diverse,
not all being enemies of aphids and a few quite injurious, it
has been deemed important to study all the species of whatever
larval habit so that we may learn to distinguish the injurious
and the beneficial ones.

Wuat FLower-F Lies ARE.

The family Syrphidae is one of a number of families com-
prising the great order of insects known as the Diptera, or
two-winged flies, (characterized especially by the possession
of a pair of knobbed threads, halteres, on the thorax in lieu
of the second pair of wings) and to the sub-order Cyclorrhapha,
section Aschiza.

They are medium to large flies, sometimes uniformly black
but usually very brightly-colored; being characteristically
striped, spotted or banded with bright yellow on a blue, black
or metallic ground-color. The yellow occurs especially com-
monly as transverse bands or fasciae on the abdomen, but also
on thorax and head. This black and yellow coloring gives them
a general, and often a particular and very striking resemblance
to wasps and hornets for which they are commonly mistaken.
Other species are covered with long black and yellow hairs
and resemble bumblebees. This resemblance to Hymenoptera
is further heightened by their habit of visiting flowers for
nectar and pollen.

SYRPHIDAE OF MAINE. 201

The Syrphidae may be distinguished readily from all the
other Diptera by the so-called false or spurious vein, which
is a vein-like thickening of the wing-membrane between the
third and fourth longitudinal veins (radius 4+5 and media
I+ 2) and running through the anterior (radio-medial) cross-
vein. It can be distinguished from the true veins by the fact
that it is not so clear-cut nor so deep in color and that it ends
freely without joining other veins. This false vein is present
in all but a very few Syrphidae and not found in the flies of
any other family. In the few cases where it is wanting
the fourth vein (media 1+2) terminates in the third (radius
4+5) a considerable distance from the margin of the wing.
The following combination of characters will always distin-
guish them.*

Head at least as broad as thorax. Front never excavated, often
swollen. Face excavated under the antenne and projecting below,
or with a distinct tubercle near the middle. The antenne are three-
jointed with a dorsal arista or tapering into a terminal style. Ocelli
present, three. Tegule of moderate size. Empodia not pulvilliform.
Bristles (macrochaetae) almost always wanting, never on the head.
Second (radius 2+3) and third (radius 4+5) longitudinal veins
never forked; fourth longitudinal vein (media 1+2) joins the third
before the margin of the wing. Three posterior cells; the anal
(cubital) cell long, acutely closed before the border of the wing;
basal cells (radial and medial) large; between the third (radius
4+5) and fourth (media 1+2) veins and nearly parallel with them
there is a false or spurious vein nearly always present and charac-
teristic of the family. The post alar membranes or squamae with
peculiarly-formed, forked and fan-like ciliation, and an elongate fringed
filament-like projection, the plumula, from the upper margin of the
pteropleura beneath the squamae (Verrall).

How FLower-F ties LIvE.

Any one of these flies during its entire existence passes
through four quite different and distinct conditions or life-
stages: The egg; the larva; the pupa; and the adult.

(1) The Egg. The eggs of Syrphidae are placed by the
parent fly in many different kinds of places, depending on the
species, but generally in such a situation that the young when
they hatch may easily find at hand an abundance of the par-

*Williston (62, p. xxvi).

202 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

ticular kind of food on which they may thrive. Certain kinds,
to take an example, glue their eggs to the surface of parts of
plants which are infested with plant-lice or aphids. In this
case they may be actually placed among the aphids or, more
often, on a part of the leaf or stem within easy crawling dis-
tance of the aphids. The eggs of other species are laid upon
moist nlth, in the nests of other insects, in decaying wood, etc.,
depending on the feeding habits of the forthcoming young.

In whatever situation found, the eggs of Syrphidae have a
somewhat characteristic appearance as indicated by Figs. 30-
Ty °2)' 35°°31-61; 02; 637" 32°4r; 42,45 96S rae
I, 2, 3. They are chalk-white, shiny, elongate-ovate or sub-
cylindrical with rounded ends. The micropylar end more trun-
cate. Flattened slightly to the surface on which they are de-
posited, slightly humped above. Commonly about I mm.
(1-25 inch) long by a third of a millimeter in diameter,—so
small that they are seldom noticed yet they can easily be seen by
the unaided eye. However, when viewed under a microscope
the characteristic thing appears; viz., a delicate and beautiful
sculpturing of the shell (chorion) consisting typically of ele-
vated oval areas (bodies) separated by depressed areas, but
each elevation surrounded by radiating and interlacing, some-
times branched arms, also elevated, which they give off into the
depressed areas and which often completely cover the latter
with a fine elevated network.

(2). The Larva. Upon hatching there appears from the
egg, not a miniature fly as some might expect, but a very small,
slender, headless, footless, blind, creeping maggot, known tech-
nically as a larva. The exertions of splitting the shell and
escaping from the egg may require a brief rest; but very soon
the larva seeks out the food-supply. There follows a period of
almost constant feeding, covering from one to several weeks,
during which the maggot increases many hundreds of times in
size and deposits within its body a great excess of fatty mate-
rial of use in the third stage.

The larvae of the different species are by no means all simi-
lar in appearance. In fact they differ so much that no one
would suspect some of them of being the young of closely-
related flies. All of them agree in being eruciform, slug-like,
without true legs and only the most rudimentary of pro-legs or

SYRPHIDAE OF MAINE. 203

none. They also agree in lacking a specialized head, the ante-
rior segments being usually bluntly accuminate, and in no way
constricted or marked off from the rest of the body. A few
filth-inhabiting larve have the anterior segments globose and
slightly constricted from the succeeding ones making a feebly-
differentiated false-head. All the larve of Syrphidae carry on
aerial respiration through stigmata or spiracles near the ante-
rior and posterior ends of the body,* and lack them on the
intermediate segments. The posterior spiracles are always situ-
ated on the ends of two elongate or very short tubes which are
fused mesad throughout their length, never forked or divergent,
except very slightly at the tip or in very young larve; and
consist of three pairs of slit-like spiracles and a pair of circular
plates or “buttons.” The anterior larval spiracles (Fig. 33-12;
34-2; 36-4) are small, situated dorso-lateral near the ante-
rior end and may be somewhat elevated on cornua or quite
sessile. The head-segments bear a pair of short, fleshy, sen-
sory structures corresponding to antenne and certain chitinized
external mouthparts. The oesophagus has also a chitinized
cephalo-pharyngeal framework or skeleton. The mouth and
anus are terminal or slightly ventrad at the two extremities.
The somites are not clearly differentiated and in some genera,
notably Microdon, are indistinguishable. Usually they are indi-
cated externally by groups of transverse wrinkles between
which groups the body is slightly constricted. But more espe-
cially by the presence of a transverse row of specialized vestiture
consisting typically of twelve hairs or spines either with or
without subtending, conical, wart-like papilla, called the seg-
mental spines or elevations (35, p. 18). Sometimes these
spines are very inconspicuous, sometimes instead of the single
spine we have a clump of several soft hairs; but in all the larve
I have examined, except the species of Microdon, the segmental
vestiture is specialized or differentiated in some way from the
other vestiture of the body, the integumental vestiture.
Although the segmentation is obscure in this family, for
convenience of description I have assumed (35, pp. 18 and 20)
that there are twelve somites represented in the larva. I have

*I have so far failed to find anterior spiracles on the larve of
Microdon which I have examined.

204 MAINE AGRICULTURAL EXPERIMENT STATION, I9Q16.

considered that there are two head segments cephalad of the
anterior spiracles; and that these spiracles are borne on the
third or prothoracic segment. On the basis of the segmental
spines there are usually eight similar and sub-equal segments
caudad of the one bearing the anterior spiracles, and one ter-
minal segment which bears the posterior respiratory process,
making twelve in all.

(3) The Pupa. When the larva is fully grown, commonly
about a half inch in length, it comes to rest in some suitable
place in or near the larval habitat and prepares for the trans-
formation to the winged fly. It fastens its caudal segments to
a leaf or twig or other support with glue from anal glands, or
buries in the ground. Its skin inflates dorsally and laterally,
nearly obscuring the wrinkles characteristic of the larva,
shortens on the ventral line and becomes much indurated by the
deposition of chitin, thus forming the pupa-case or puparium.
Within this case certain complicated changes take place during
which legs and wings and hair and eyes and mouth parts and
the other features of a winged fly, like the one that laid the
eggs, gradually make their appearance.

Since the pupa is concealed in the puparium throughout this
stage, the characteristics readily observable are those of the
larval skin which are, except for shape, mostly the same as
during the larval period. The trachez leading from both ante-
rior and posterior larval spiracles are atrophied during this
stage and respiration is provided for by a pair of stigmata which
pierce the puparium in the region of the fourth or fifth larval
segment. From each of these stigmata a large tracheal trunk
leads downward to the prothorax of the developing imago. In
some species the pupal respiratory stigmata are much elevated
on cylindrical cornua (Figs. 36-84; 37-64); in others they
are sessile, exceedingly small and often indistinguishable or
apparently wanting (Fig. 30-74). The characteristics of the
larval skin, such as anterior and posterior larval spiracles, pro-
legs and vestiture, usually remain practically unchanged through-
out this period.

The coarctate pupa (Fig. 32-57, 54) is protected by the hard
puparium and, within this, a thin, delicate, transparent mem-
brane (Fig. 32-54a) encases the developing wings, legs, and
other parts of the body. The segmentation and appendages of

SYRPHIDAE OF MAINE. 205

the fly are produced very gradually. The legs, mouth-parts
and wing-pads differentiate first while the dorsal part of the
body and especially the abdomen is still eruciform as in the
larva. Antenne and eyes next take form followed by the seg-
mentation of the abdomen the appearance of the vestiture and
the differentiation of the thorax. The hind leg during this
stage 1s bent at the middle of the tibia at an angle of about 150
degrees. The coloration of the adult is well developed some-
times several days before emergence; and in species where the
puparium is quite transparent it is often possible to identify the
species through the puparium.

(4) The Adult. When fully formed the adult pushes off a
lid-like portion of the anterior end of the puparium by the dila-
tion of its face and crawls out of the opening so formed.
Emergence often requires several hours’ time and not infre-
quently a specimen dies in the attempt to disentangle itself from
the puparium. By the time emergence is accomplished the insect
has practically assumed the adult form. The principal differ-
ence is that the wings are thick, crumpled and folded (Fig. 32-
54) and must expand to a much greater area, become flattened
instead of bag-like and hardened to form an effective organ of
flight. The coloration of the fly is pale and the whole body
somewhat soft and worm-like. But within an hour, sometimes,
indeed, within a few minutes, the body has become perfectly
indurated, the wings completely expanded, and the color-mark-
ings fixed to that of the imago.

After emergence the life of the fly is dominated by two 1m-
pulses, the instinct to feed and the instinct to reproduce its
kind. The food of the adult is practically always secured from
flowers and consists of nectar and pollen. The flies seem to be
strongly influenced by heliotropism or sunlight. They are almost
always active in the sunshine and the brighter and warmer the
day the more active they become. These facts may be taken
advantage of by the person who wishes to collect Flower-flies.
The most fruitful collecting is to be found about melliferous
flowers and in the sunshine, particularly in very early spring.

Mating may take place on the wing with both sexes actively
flying (hovering) and oriented in the same direction, the male
uppermost (Sphaerophoria, Sphegina, etc.) ; or the pair may
come to rest on foliage, in which case the two are usually facing

206 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

in opposite directions, either resting or the male being passively
dragged about from leaf to leaf by the female (Temnostoma).
The process of copulation has been observed to continue for
many hours at a time,

The next and final step in the completion of the life-round
or life-cycle is oviposition for the next generation. The female,
no longer closely attended by the male, hovers about the medium
on which the larve are to feed settling down at intervals to
place the eggs. The terminal segments of the abdomen with
the ovipositor are greatly extended and the egg passes between
the vulva to its position on leaf, filth, or other medium, accord-
ing to the habits of the particular species. The eggs may be
placed singly and greatly scattered, as in most of the predaceous
species; or several may be placed closely side by side
(Melanostoma mellinum, q. v.); or they may be deposited in
great numbers in a mass, as in most of the filth-inhabiting
species. In the latter case some of the species seem to rank the
eggs in quite regular order; in others they appear to be simply
extruded in a pile with little regard to their orientation. Often
a gluey substance is passed with the egg which fastens it securely
to some surface. Eggs succeed each other commonly at inter-
vals of about a minute.

HABITS OF THE LARVA.

The habits of the larve of Syrphidae, which are remarkably
varied, have formed an interesting subject of study for a num-
ber of years. Perris in 1870 (41) gave a brief resumé of the
modes of life of these larve as known to him. Williston, 1886,
(62, p. 271), Verrall, 1901, (55, p. 674) and the writer, 1913,
(35, pp. 38-42) have amplified and extended this table to include
additional habits and species as determined.

I have attempted to outline our present knowledge of the
habits of these insects in a logical way in Figure 28. In the
first column of this plate is a systematic analysis of the known
larval habits. In the second are listed the North American
species or genera known to follow any particular habit. And
in the third the structure of these larve, so far as the writer
has personally studied them, is indicated.

SYRPHIDAE OF MAINE. 207

EXAMPLE STRUCTURE

(AS PERSONALLY
OBSERVED)

H
A, HB ody US:

L FEEDING EXTERNALLY ON LIVING PLAMTS>-Mesogramma polita (¥4,45,53,52,35 p30,42)--
ZFECOING INTERNALLY ON LIVING PLANTS
aln sfemaotharksorfrunka cf tress S Ohileaia ($52 207, 622 27/)
est rle (£69 5560559, 380135)

rodon e
bln bulbe:----------------—- Eumeras Strigatus (55 pp-6/S*622,6)
Jum marginatum (63)
e.In cacti:-------------------- Wnetia avida (/9)
Yolucelia fois (63,54)
Pee. Fe. ESL) losia Pp
d.Jn fungi: Platychirus seutatus (55 p263)
2
B,CARNIVOROUS : Pipe pisticoides (q.v. )------------
PREDACEOUS ON OTHER (bat "piza modesta (58)
ge APHIDS AND NYMPHS OF Pipes radicum (482 (21,49 52,5753, lp 350M)
OTHER HOMOPTERA: a ragus (S5p 50% 674%) A .
pe rage anguefilrons gS et sepnapacenpas T H E
5 ragus eee or. tf 8 Saag eee
@aragus FRSC pen 2 eee ersee
Baceh, 2 APHIDOPHAGOUS

a (55 p.456. 271,37, 40)
Baccka habista (16)

Baccha cognata (/8)

Baccha /ugens (1/3)

Ocyptamus goa“ aten ? (/5 p /¥8)

Melanostoma mellinum (ee ooeo--
@ Externally among colonies of P/a eg grad rate US p 148)

Bidea
rphus amar loans (32 3,/5p 148)-°~
Syrbhas mitens (q. v. j------------"-
Sorph us pyrastri (SS p 336 ./p 363)
cee ribesii (@ v.,15)------7°"-
ere us Torvus (30, 52)-----------
Sores xanthostoma (4. v.,3¢}---
Atte rapta obligua (75, 23.33,43 }-----
Mesogramma marginata (/5)
gegagremma. po imal fea 85 =
aerophoria cylindrica (F5p947, 43/543,
Within galls of the hos teapot ae nue xanthastoma (3¢¥)=-==~=-==== TYPE
c.Catthing active wi insecls:-*1elanostoma mellinum (Sap. 303)

2. Parasitic ON PUPRE OF PLUSIA SPP :~Syrphus pyrastri (5,/p.I63,35p 40)

C,SCAVENGERS:

FEEDING ON EXPOSED, DECA CAYING, Chrysotoxum?(62p.27/. SS p. G42)
ANIMALOR VEGETABLE MATTER: rey ex a ape aereag ? (357.63)
folepta (55a 573, 62 p. ae
(feioght lus fatifrons(@v-,
Xanthogramma emarginata ede 97)
(oe ee Pe elle (KG) )
‘ otal a 62-27)
@In decaying parts of trees: Xylota pigra (12, 20)------------=---
Brachypel, fpus (55-573, 62 p-27/)
Brachypaipus frontosus (24%, 28)
Pocota (55>. 587)
sae oproca (62,-27/)
tlomyia (@2p.27/
emnostoma aegualis (¥b
Pesnusteund boméylans (¥5)
Ee bcbeach ngs (SS p- 642)
Brachyopa bicolor (S5p.475, G2 p 271)
Xylota (62 p.R7/)
Carys ochlamys (55a 623, 62p27/)
&: rhina2 (FS PS ISAG
Cerja(é2 71,553 6674665)
Certa wi fistone z:
Platychirus scutatus S5p.263)
Platychirus guadratus? (353 6s)
Chrysogaster spp. (S5p (86)
Xanthogramma ($5 p.¥48)
Eristalis Tenax (8.
Eristalis arbustorum @)
Criorhina cxyacantinne | (SS p 5764570
Seriocomyia we) 637,

c s
THE
SHORT-TAILED,
FILTH-INHABITING
TYPE

b.In diseased orflowing sap:

c.Jn decaying herbaceous plants,

d. rs in ere. turf for, soft mud

Je matter:

eln sta Sfogrant pita as water z ris ia 2. is — a
pon ar cze re
= ft ta is te ed (chirtus) @) D s

elophilus pendulys (SSP S24)

4 In watering Troughs or wellsl Eris ta/ts (tenax 2) G7, (ep (76 THE
dn watt: ed — Helephtlus pa phe ee) ?

gdn Sewage-------------- Eris ee qexeulee i? a LONG-TAILED,
whingia CSP 478) py FILTH-INHABITING
g Pitta ee {4 Ca IT) TYPE

hTn manure orhwnan ristalls dimidi ates Ag: v. Je

2.FEEDINGAS ACCIDENT:
IN THE ANIMAL BODY, Cqusine: wi Syrphus sp.(2)

ristalis arhustorum (56)
a. Intestinal myiasis ---- ristal tis fenaz (2,6, S739)

‘elo, lus pendulus? (36
b.Nasal m latices een a AS, 46)
SEF eae Fl +---- -Zristalis dinidia ws (¥6)

16 p.778)
+ ree Gas SE NOK OE Fermites:---Microdon (66) ry
M THE

Mizrodon mutabilie 213)

bJn the nests of Ant3:------- {crodon mutahils Z el

“7 a (S74, 5: G62

ah egy fg + au MICRODON
Microdon (64,

c. Inthe nests of Wasps ane, Voluce/la tnanis (SS abi he
VoluceHa bhombylangd (/4.

LARVAE OF SYRPHIDAE

Fig. 28. An outline of the known habits and structure of the larvae
of Flower-flies. The numbers following the names of species refer to
papers in the bibliography.

== w= 2 ------ Zristlalis sp.

208 MAINE AGRICULTURAL EXPERIMENT STATION. I9QIO6.

Although the larva of each species will doubtless be found
to vary in a measurable degree or perceptible way from every
other species, it appears that these various larve can be assem-
bled into five groups, collectively distinct from each other, while
the larve in the group have many important points in common.
I have, therefore, separately described them and shall, for con-
venience, speak of them as types of larve.

STRUCTURE OF THE LARVA.

I. THE APHIDOPHAGOUS TYPE OF LARVA.

Body sub-cylindrical, flattened ventrally and much attenuated
anteriorly. Posterior respiratory process short, the spiracles
either straight or convoluted, never denticulated. Inter-spira-
cular ornamentation consisting of bare hairs, nodules, ridges or
lamelle, never of plumose hairs. Mouthparts of two A-shaped
jaws. Segmental hairs single. If prolegs present, without
specialized vestiture. Anterior pupal respiratory cornua appar-

ently wanting.

This type of larva, named from the most characteristic habit, has
the posterior larval spiracles at the apex of two very short, rigid,
heavily chitinized, cylindrical breathing tubes which are fused mesad
throughout their length (except in very young larve) never bifurcated
except very slightly at the extreme tip; situated terminally or on the
dorsum of the depressed twelfth segment. This short double tube
bears on its tip three pairs of slit-like spiracles elevated on radiating
carine, usually nearly straight, never branched or denticulate; and
a more or less prominent circular plate or “button.” The interspiracular
ornamentation (between the spiracles) may consist of hairs, spines,
nodules, ridges or perpendicular plates,—never of plumose hairs. The
anterior spiracles are sessile or nearly so, rounded or lunate, very
small. The body is elongate, slender, tapering to a point at the
anterior end, somewhat flattened ventrally.

The body is wrinkled transversely and the wrinkles or folds grouped
in such a way as to imperfectly mark the body segments, which are
further indicated by the segmental spines, a transverse row of twelve
hairs, spines, or bristles on each segment, sometimes obscure, some-
times very prominent, but always present and differentiated from the
remaining integumental vestiture.

The mouth-parts consist of two V-shaped, jaw-like pieces working
vertically and associated spines or hooklets; .which, with the terminal
anterior segments, are strongly retractile.

The integument is tough but thin and more or less transparent,
either glabrous and papillose or closely set with minute stiff hairs

SYRPHIDAE OF MAINE. 209

(the integumental vestiture). The colors are various but commonly
some shade of green, brown or pink, striped or blotched with white
or black. Usually the dorsal blood-vessel (heart-line) shows as an
interrupted black mid-dorsal line throughout most of the length.

In the pupa stage this type has a somewhat characteristic shape,—
subovate, bulbous in front and tapering to the posterior respiratory
process (which retains its larval characteristics) behind.

It is separated from the other types I have examined in lacking a
conspicuous pair of anterior (prothoracic) stigmata developed and
pushed through the puparium for pupal respiration. These pupal
respiratory cornua appear to have been heretofore overlooked. They
are so minute that even when one knows they are present it is only
with the greatest difficulty that they can be demonstrated. In
Melanostoma mellinum (q. v. ), a species with unusually trans-
parent integument, they can be located readily because the trachee
leading from them are easily visible.

II. THE BORING TYPE OF LARVA.

Body nearly cylindrical, less attenuated anteriorly. Posterior
respiratory process short, the spiracles convoluted, inconspicu-
ous; circular plate sunken. Inter-spiracular ornamentation of
short, palmately-branched, plumose hairs. Mouth-parts fitted
for rasping, of two ventrally directed hooks uniting basally into
a mouth-hood. Segmental hairs single.

This type is represented in my collection only by the larve of Merodon
equestris, collected from Narcissus bulbs in British Columbia, for
which I am indebted to Dr. C. Gordon Hewitt, Dominion Entomologist.
These larve are superficially much hike the first type but the body is
more nearly cylindrical, less flattened ventrally, and less attenuated
anteriorly. Segmental hairs single, prominent. The posterior respira-
tory process has lost nearly all trace of its double nature and appears
as a truncated cone. The circular plates are deeply sunken and occupy
a central rather than a dorsal position. The spiracular slits are very
inconspicuous and are irregularly and much convoluted. The inter-
spiracular ornamentation consists of short, palmately-branched, plumose
hairs.

The anterior three body segments are directed ventrad and termi-
nate in the mouth-parts. The latter entirely different from aphido-
phagous species, consisting of two black, heavily-chitinized, rasping,
recurved hooks, each with a small, inner, basal spur, fused basad to
form a heavy, black, ventrally-concave hood beneath which is the
mouth opening.

I have not, seen the pupa of this type.

210 MAINE AGRICULTURAL EXPERIMENT STATION. Ig16.

III. THE SHORT-TAILED FILTH-INHABITING TYPE OF LARVA.

Body cylindrical with the anterior segments modified into a
“false-head.” Posterior respiratory process short, the spiracles
convoluted and denticulated. Inter-spiracular ornamentation of
short, palmately-branched, plumose hairs. No external mouth-
parts but a chitinizged mouth-hood. Three pairs of lateral,
fleshy, conical protuberances on segment twelve. Segmental
hairs triple or quadruple, flexible, inconspicuous. Rudimentary
prolegs. Pupal respiratory cornua prominent, morel-shaped.

This type of larva is superficially like the Boring Type, but the
anterior three or four segments instead of being accuminate are
rounded out, globose, as broad as, or broader than, the succeeding
segments, and somewhat separated from them by a slight neck-like
constriction to make a kind of false head. There are no external,
chitinized mouth-parts, the mouth opening being covered by a mod-
erately-chitinized, striated mouth-hood, the termination of the cephalo-
pharyngeal skeleton; and guarded on each side by a poorly defined,
piliferous fold of skin.

The posterior respiratory process shows its origin from two tubes;
the circular plate is on a level with the apex of the tube; and the
slit-like spiracles which are more prominent are convoluted and also
ornamented with more or less numerous lateral projections or denti-
cles. The inter-spiracular ornamentation consists of plumose, pal-
mately-branched hairs. The segmental vestiture consists of clumps of
about three or four fine, flexible hairs, a little longer than the inte-
gumental vestiture, and all arising together. The larve have seven
pairs of prolegs along the ventral side of the body, which consist of
elevated folds of the body-wall over which the integumental vestiture
is specialized into heavier, rigid and retrorse hooks of varying size.

This and the following types of larve differ strikingly from the
first in producing for the pupa stage a pair of very conspicuous tubular,
anterior respiratory cornua, studded with minute nodules and con-
nected with the nymphal prothorax, as in the first type, by large
tracheal trunks. These cornua in the three species examined are more’
or less mushroom- (morel-) shaped.

IV. THE LONG-TAILED (RAT-TAILED) FILTH-INHABITING TYPE.

Body cylindrical with a false head, and long tail. This
posterior respiratory process elongate, telescoping, flexible, at
least half as long as the body. The spiracles on its end entirely
inconspicuous. Inter-spiracular ornamentation of single, long,
plumose hairs. No external mouth-parts except the mouth-
hood. Segmental hairs double or triple, flexible, inconspicuous.

SYRPHIDAE OF MAINE. 211

Rudimentary prolegs present. Anterior pupal respiratory
cornua elongate, cylindrical, very promiment.

This type is most closely allied to the third type but differs from
it and from all the others in the remarkable elongation of the pos-
terior respiratory organ, which, in these species, is tube-like, three-
jointed and telescopic; and may be extended to several times the
length of the body although commonly contracted to about body-
length. This remarkable and highly specialized organ enables the larva
to carry on aerial respiration while feeding at various depths beneath
the water level. It is of two tubes fused mesad and enclosing two
trachee which open at the tip. The inter-spiracular ornaments con-
sist each of a single, unbranched, but plumose, long hair instead of a
palmate group of short plumose hairs as in the two previous types.
The prolegs are similar to type III. The anterior larval spiracles are
unusually conspicuous, borne on a pair of cornua which are capable
of considerable elevation although usually rather closely retracted.

The shape of the body is sub-cylindrical with the anterior segments
forming a false head, and the mouth-hood as in type III. The terminal
segment tapers strongly into the respiratory process. The integument
is very flexible and transparent; segmental hairs double, similar to
type III. The anterior pupal cornua are longer than in type III and
nearly cylindrical, the enlarged distal part much longer than the basal
stalk, hence the whole less mushroom-shaped.

V. THE MICRODON TYPE OF LARVA.

Body hemi-spherical; the flat surface ventrad, with a row of
spines around its margin; dorsum reticulated. Posterior respi-
ratory process short, the three spiracles on each half together
making nine loops, convex outwardly and denticulated on thew
outer margin. Inter-spiracular ornamentation of non-plumose
fine hairs. Mouthparts consisting of a ventral A-shaped jaw
and two dorsal pieces placed A-shaped, but not fused at the
apex. Segmental hairs and prolegs wanting. Anterior larval
spiracles apparently wanting. Pupal respiratory cornua morel-
shaped.

The larve of this genus are very aberrant and superficially show
no relationship with the other larve of Syrphide, differing strikingly
from all the others in shape. Instead of the elongate, sub-cylindrical
body we have a nearly hemi-spherical body. The outline is short
elliptical, the ventrum very much flattened forming a ventral sole
around the margin of which is a circlet of ornamental spines. Dorsum
almost uniformly rounded up. Mouthparts open in a longitudinal slit
on the cephalic part of the ventral sole. Posterior respiratory process
dorso-caudad, short, tubular, but with some indication of its double
nature; circular plate medio-dorsad. The spiracular slits each of three,

212 MAINE AGRICULTURAL EXPERIMENT STATION. Ig16.

outwardly directed loops, denticulated only on the outer side, almost
arborescent in appearance but still divisible into three pairs. The
interspiracular ornamentation of small, delicate, non-plumose hairs.
No anterior larval spiracles have been demonstrated.

In place of the transverse folds or wrinkles on the dorsal surface,
it is evenly convex and beautifully reticulated, with lines of papflle.
I find no evidence of the segmental hairs.

The pupal respiratory cornua are similar to those of type III being
much shorter than in type IV.

EcoNoMIc IMPORTANCE OF THE LARVA.

The principal economic importance of the larve is four-fold,
two of these relationships being beneficial and two of them
detrimental to human interests.

A. BENEFICIAL HABITS.

1. As predators. By far the most important economic bear-
ing of Syrphidae arises from the predaceous habit of many
common species. Of the prey affected, aphids compose prob-
ably ninety-nine per cent. Coccidae and the young of Aley-
rodidae, Jassidae, Psyludae and Membracidae are also attacked,
and occasionally even active winged insects such as Diptera may
be caught (55, p. 311) or the larve of other Syrphidae devoured.

With the vast majority of species there is no close restriction
to particular species of prey; although a few species such as
Didea fasciata and Pipiza pisticoides have been found among
only one or a few species of aphids.

For the most part the service of these insects is in preventing
the abnormal increase of the various injurious species of aphids
rather than in exterminating the colonies in any particular place;
although the latter result is by no means uncommon. Their
value is ordinarily due to their very uniform distribution and
constant occurrence, rather than to tremendous numbers at any
time or place. Nevertheless, instances of the occurrence of
enormous numbers of them are not lacking. Perhaps the most
notable of such records is that by W. G. Johnson (23, p. 97)
regarding the abundance of larve during an outbreak of the
pea-louse (Macrosiphum pisi Kalt.) in southern Maryland in
1899. I quote from Mr. Johnson as follows:

SYRPHIDAE OF MAINE. 213

“The real importance of the Syrphus-fly larve in the reduction of
the species [the pea-louse] was shown beautifully in southern Mary-
land, where they were so abundant the first and second weeks in June
as to almost completely destroy the lice.” And quoting further from
his correspondent: ““The insects (lice) started to disappear lest
week and are now about all gone . . . The last few days I packed,
the separators sieved out about 25 bushels of green worms [larve of
Syrphide, chiefly Allograpta obliqua] which no doubt proves that they
destroyed the lice.’”

Mr. Johnson states further that the Syrphid-flies did not save
the crop that year but calls attention to their probable value in
relation to future ravages of the pest. A conservative estimate
shows that twenty-five bushels of the larve of Allograpta
obliqua could scarcely represent less than 3,000,000 individuals.
Presuming that the larve lived ten days and ate on the average
twenty aphids a day (which I believe also to be a conservative
estimate) such a multitude of larve would be responsible for
the destruction of over half a billion aphids.

Another example of the extermination of aphid colonies by
these predaceous larve is afforded by the attacks of Pzpiza
pisticoides on the Woolly Apple Aphis. These aphids became
evident as above-ground colonies on apple, at Orono, about the
first of August. At the same time several species of Syrphid
larve also made their appearance among them, chiefly the larve
of Pipiza. Shortly the Woolly Apple Aphis began to disappear,
the aphids becoming scarcer and scarcer and the predaceous
larve more and more evident, until by early September I found
myself with many larve on hand and almost no aphids any-
where to be found as food for them. Doctor Patch tells me
she has found this a rather common experience; and that year
after year, the colonies of Woolly Apple Aphis on apple have
practically disappeared in the presence of these predaceous
larve, by mid-September. See also page 224.

The relentlessness of these enemies of aphids is illustrated
in a peculiar way by the experience of the Station Entomologist,
who for a number of years has been studying the aphids of the
State. It is an altogether too common experience that aphid
material mailed to her for study has been absolutely consumed
en route by Syrphid larve, inadvertently introduced into the
package by the correspondent.

214. MAINE AGRICULTURAL EXPERIMENT STATION. IgI6.

Hardly a colony of aphids can be found that is not being
preyed upon by from one to half a dozen species and from one
to dozens of individuals. They kill the individual aphids out-
right but on account of the rapid rate of reproduction of the
latter the colony usually exists for some time at least.

I have been interested in getting some definite data as to the
capacity of these larve for devouring their prey.

Specimens of Aphis brassicae proffered to a four-day old
unfasted larva of Syrphus americanus were devoured at the
following rate: Four minutes and 30 seconds, 2 minutes, I
minute, I minute, 30 seconds, 3 minutes and 15 seconds, 2
minutes, 1 minute and 45 seconds, and 1 minute and 30 seconds ;
a total of nine aphids in seventeen and a half minutes (32, p.
481). In this test the aphids were touched to the mouth-parts
of the larva as rapidly as the previous skin was discarded. It
was thought that this represented an abnormal rate of feeding.
Last summer the larva of Syrphus nitens was observed while
feeding normally on the large aphids Pterocomma flocculosa.
During a period of twenty minutes, twenty-one aphids were
caught and destroyed. The larva had not been kept away from
food nor were the aphids supplied for it or the process in any
way hurried or artificial. °

How much longer feeding at this rate may continue or how
frequently such periods of rapid feeding may succeed each
other, observations have not yet shown. However, it seems
certain that the number of aphids destroyed by a single speci-
men during its larval existence of one or two weeks or longer
must be very considerable.

Particularly when we consider the enormous numbers of
progeny which may be prevented from developing ‘by the
destruction of even a single agamic female, the value of these
agricultural benefactors may be more correctly judged. A
point of great importance in this respect is that the Flower-
flies infest the aphid colonies very early in the establishment of
the latter; indeed, sometimes the Syrphid eggs are deposited
on a plant in advance of its infestation by the aphids; so that
numerous voracious larve may be awaiting the first appearance
of the stem-mother and her progeny.

Another important point which enhances the destructive
powers of the Syrphid larve, is that they eat—not the entire
aphid—but only the soft and rapidly digestible body-contents.

SYRPHIDAE OF MAINE. 215

“These aphidophagous larve, although frequently found entirely sur-
rounded by an abundance of prey, are very often obliged to search about
for food. Their characteristic, looping movements are very familiar to
many people. When used for progression alone, these movements may be
very rapid. Their progress is very similar to that of a ‘measuring-worm’
though the body is not so long. When-the larva is searching for food,
the anterior half or two-thirds of the body is raised in the air, very
much extended, and lashed from side to side. It is then attached and
the posterior parts pulled up, when the movement is repeated. Thig-
motropism, and not chemotropism, seems to be involved in locating food.
Hungry larve frequently pass by aphids so closely as almost to touch
them, and go on in search of others. When a suitable aphid is found
the larva frequently grasps it first by the leg or antenna and clings to
this appendage until the thorax or abdomen can be reached. The
mouth-parts are firmly attached to the body, the body-wall is punctured,
and the aphid usually lifted high in the air. Then begins a process of
slowly picking and sucking out all the body contents, which may con-
tinue from a fraction of a minute to more than an hour (in the case
of very young larve). The action of the mouth-parts is very char-
acteristic and very well adapted to the needs of the case. Many different
muscles, which have their origin on the body-wall in the region of the
head, are inserted upon the cephalo-pharyngeal skeleton, the jaws, and
the mouth-hooklets. Some of them operate the framework in and out
like a battering ram. Others at the same time open and close the jaws.
The anterior two or three segments are inserted completely within the
body wall of the aphid. The jaws are directed into every corner of the
body and even into the bases of the appendages as they pick and suck
out the soft contents. The skins, absolutely empty, are then discarded
by retraction of the segments, the hairs or spines on those outside serv-
ing readily to dislodge the skin. These dead skins usually drop down
or blow away but may sometimes be seen in numbers on the host-plant.”
(The Author, 35, pp. 26, 27).

2. As Scavengers. The other important way in which the
larve of Syrphidae are beneficial to human interests is by their
activities as scavengers. Considerable quantities of dead animal
and vegetable matter are in this way reduced to simpler com-
pounds, more readily assimilated by plants; and certain ma-
terials which are obnoxious, and may be a menace to health, are
transformed to innoxious forms.

To quote from Comstock (10, p. 415):

“Although the habits of these creatures, which revel in all kinds of
filth are very disgusting, we cannot help admiring that arrangement by
which a mass of filth, instead of being left to poison the atmosphere,
is transformed into myriads of living beings whose swift flight and
delicate forms lend life and beauty to the landscape.”

216 MAINE AGRICULTURAL EXPERIMENT STATION. IQIO.

Happily, the breeding of these flies in excrement ordinarily
causes no menace to human health; because (unlike the house-
fly) they do not commonly visit human habitations and human
foods, but confine their explorations as adults almost exclu-
sively to flowers out-of-doors.

B. INJURIOUS HABITS.

Few large families of insects are on the whole less detrimental
to human interests than the Syrphidae. Yet it is incorrect to
state, as some of our text-books do, that none of the species
are injurious; for although the family includes no well-known
pests in this country, there are two important ways in which
the Flower-flies are injurious in the larval stage.

1. As Crop-Pests. The few species which are phytophagous
are occasionally seriously destructive to crops. The most
notable of them in America is Toxomerus* politus which has
come to be known as the Corn-feeding Syrphid-fly. This
species has been reported as feeding on corn in abundance as
follows: New Jersey, 1885 (44), 1899 (53) and 1913 (42);
Florida, 1886 (44) ; Missouri, 1889 (45); Delaware, 1900 (50) ;
and North Carolina, 1913 (35). I found them (pupez) abund-
ant on field corn (in the axils of the leaves) at the Ohio State
University farm, September, 1915; and Professor Z. P. Metcalf
sent me larve and pupe (attached among the glumes on the
tassels) from West Raleigh, North Carolina, in late August,
1915 with the statement that they were again plentiful there.

The species is evidently widespread and common on corn,
but only a few cases are known where its attacks were con-
sidered serious; notably in Florida and Missiouri -(loc. cit.).
They feed on pollen grains and on the saccharine cells'at the axils
of the leaves. The former habit might seriously interfere with
fertilization and the consequent yield of grain, if the larve were
abundant; while the latter attack was stated to produce a wilt-
ing and browning of the lower leaves similar to the injury from
chinch-bugs. This species is not yet recorded from Maine but
will probably be found to occur within the State. The puparia
are often heavily parasitized which may explain why they are
not oftener seriously destructive.

*Mesogramma.

SYRPHIDAE OF MAINE. 217

In Europe the larve of Merodon equestris (55, p. 556) and
Eumerus strigatus (55, p. 615) are pests of flowers such as
Narcissus and Amaryllis, and of the onion among vegetables.
The larve burrow into, and promote the decay of, the bulbs of
these plants; in certain instances having destroyed thousands
of plants. They have been introduced into North America and
are transferred from place to place in infested bulbs, and there
is reason to fear that their range will continue to be extended
and that they may become serious pests in this country.

On July 25, 1916, a number of the adults of each of these
two species was taken about blossoms in a nursery at Bar Flar-
bor. No damage by the larve had been recognized by the
nurserymen, but the number of adults present indicates that
the species are established in the State or are quite likely to
become so.

2. As Transitory Animal Parasites. The fourth important
way in which larve of Flower-flies affect us is by their occa-
sional occurrence in the living human or animal body and the
accompanying disturbances or destruction of tissues. Myiasis
is known to be produced by Syrphidae in four ways: First, by
their presence in the alimentary canal (intestinal or gastric
myiasis) ; secondly, by their introduction to the nasal cavities
(nasal myiasis) ; thirdly, by their introduction to the auditory
cavities (auricular myiasis) ; and fourthly, by their introduction
into the vagina (vaginal myiasis).

The first of these is the more common. Probably it not infre-
quently occurs and is not recorded. On the other hand, many
reported cases of larve having been passed from the bowel are
doubtless erroneous due to the stools having become infected
after passage. Hall and Muir, 1913, (16) have summarized
the published data relative to myiasis due to Syrphidae and
described an additional case. It appears that there are certain
authentic cases on record where such larve have been passed
alive, sometimes as many as twenty or thirty at a time. The
presence of the larve in the intestine caused some of the fol-
lowing symptoms: Intestinal pains, vertigo, nausea, vomiting,
constipation, headache, nervousness, weakness and emaciation.

The species known to be concerned in such infestation are
Eristalis tenax (2, 46, 51, 29), Eristalis dimidiatus (46), Eris-
talis arbustorum (56) and possibly Helophilus (Musca) pen-

218 MAINE AGRICULTURAL EXPERIMENT STATION. IQI16.

dulus (36). These are all larve of the long-tailed, filth-inhab-
iting type which live normally in sewage, putrid or stagnant
water, in ditches or even in watering troughs (27), and wells
(47; 16, p. 5).

The source of infection in certain cases has been explained
as follows: By ingestion of eggs laid on cream, sour milk cr
cheese; by ingestion of eggs or larve in drinking water from
springs, contaminated by the drainage from compost heaps or
from stagnant pools or ditches; by eating water-cress or over-
ripe fruit in which larve may be present; or by deliberate inges-
tion on the part of children. Any of these methods seems p«s-
sible and all, except the first and the last, quite probable.

It is not difficult, as pointed out by Wagner (56), to see how
these larve are able to exist in the alimentary canal, where the
conditions would not differ greatly from their normal habitat
in feces. The food is similar, plenty of air is supplied by
swallowing, and the mephitic gases are not greatly different. It
is not quite clear how the larve manage to resist passage for
many weeks, as certain cases indicate. They have no hooks
which would enable them to attach to the intestinal wall unless,
indeed, it be the minute ones on the prolegs, which seem inade-
quate.

Austen (2) reports two cases of intestinal myiasis due to the
larve of Syrphus, which are not so easy of explanation ; because
what is known of the larval habits of this genus does not indi-
cate a ready source of infestation, nor a likelihood that these
larve would readily adapt themselves to the conditions of the
alimentary canal.

The other kinds of myiasis due to Syrphidae are exceedingly
rare. Leidy (25) has recorded a case of a rat-tailed larva stated
to have been removed from the nasal cavity; Austen (2) a case
of the invasion of the external auditory meatus by a Syrphus
larva, resulting in pain and deafness; and Hall and Muir (16)
record a case, reported to the Bureau of Animal Industry, U. S.
Department of Agriculture, from Maryland in 1909, where eight
larve of Eristalis were stated to have been passed in a jelly-like
substance from the vagina of a cow. The source of infestation
in such cases as these is doubtless oviposition by the fly directly
in these natural cavities of the body; especially if the latter
were in a diseased or uncleanly condition.

SYRPHIDAE OF MAINE. 219

In this connection, I wish to emphasize the practical impos-
sibility, at our present state of published knowledge, of referring
larve found in such circumstances to a definite species, or even
to the genus, unless specimens are reared to the adult. It seems
to be the custom to refer any rat-tailed larva to Eristalis tenax,
or at least to the genus Eristalis. Such records, unless based on
adults reared from the larve, must, it seems to me, be discarded
as of no specific importance. I am working on the problem of
separating these different species in the larval stage, and have
examined a dozen species of rat-tailed larve belonging to sev-
eral genera, the separation of which is exceedingly puzzling
and difficult, and any one of which might easily be mistaken for
the larva of Eristalis tenax.

Other biological relations of the larve, of more or less eco-
nomic importance, may arise from their association with other
insects, in aphid colonies, or in the nests of colonial insects;
and with their predaceous and parasitic enemies.

EcoNOMIC IMPORTANCE OF THE ADULTS.

While the principal economic importance of Syrphidz arises
from the habits of the larve, the adults are by no means devoid
of importance in this respect. The adults, so far as known,
feed almost exclusively on the nectar and pollen of flowers or
the honey-dew of insects. Anyone who has observed the tre-
mendous numbers of these flies which mingle with Hymenoptera
about all sorts of melliferous flowers, will be able to appreciate
their importance in the cross-fertilization of entomophilous
plants. All sorts of fruit and shade trees, wild and cultivated
flowers, and certain field and garden crops, are regularly visited
by these flies. Some of the flies, which possess an abundant
vestiture, often of spurred and branched hairs, are very admir-
ably adapted for the carrying of pollen. This is a subject deserv-
ing of careful observation. But in the absence of much definite
data it seems safe to ascribe to this family a very large share of
credit for this beneficient work, which is usually attributed to
Hymenoptera alone.

220 MAINE AGRICULTURAL EXPERIMENT STATION. IQ16.

PRACTICAL MEASURES.

Since the above analysis shows that the economic importance
of the Syrphide is overwhelmingly beneficial, one is naturally
desirous of knowing what could be done to favor, or foster them
and increase their numbers.

I. The first thing to be done it seems to me is to educate
people and especially agriculturists to discriminate between these
Flower-flies and stinging Hymenoptera. The writer knows
from personal observation that many of these beneficial insects
are constantly being killed as “sweat-bees” under the impression
that they can sting. Whereas, they are absolutely unable to
harm the person in any way; and furthermore, are, both as
larve and adults, (with the exception of a very few species)
among the farmer's most valuable animal friends,

There are several simple ways in which these two groups can
easily be distinguished in spite of the great resemblance in color,
form and habit. Jf the imsect ts flying, the Flower-fly can be
recognized by its distinct manner of flight, which has given the
group the name of “Hover-flies.” They constantly poise in the
sunlight, or about flowers, remaining suspended in one place
for a considerable time without any apparent movement of the
body, the wings beating so rapidly as to be practically invisible ;
then dart away and quickly return, the body always in a tense
horizontal position. Bees, when flying, habitually weave back
and forth or bob up and down. On closer inspection most of
the species can be distinguished by the shorter antenne
(“feelers”) which are not easily seen in flight ; while the antenne
of the bee are usually visible in front of the head. Jf the insect
comes to rest, the Flower-fly is apt to keep its wings partly
spread, the bee or wasp to fold them closely or cross them at
the tips. If you have the insect in your hand, see if the wings
on one side can be separated into two readily. The bees have
two pairs of wings hooked together, but easily separable; the
Flower-flies of course have only one wing on a side. Back of
the base of the wing in the Flower-flies is a small knobbed thread
(Fig. 29-4) visible to the naked eye on very careful examina-
tion, wanting in the Hymenoptera. And, finally, if a hand lens
is available look for the false vein (Fig. 34-7) on the wing,
which is the most distinctive characteristic of the Syrphide.

SYRPHIDAE OF MAINE. 221

2. Not only should the adults be spared but the larve
(Figs. 29-1; 30-6; 34-1) on plants, among aphids, should be
given careful protection. Too often they are killed under the
supposition that they are damaging the plant. The figures and
descriptions should enable one to distinguish these larve; but,
if there is any doubt, careful observation will ‘usually be
rewarded by seeing one of them attack and devour an aphid.

3. The writer, with the assistance of Mrs. Cleo Fouch
Metcalf, is investigating the effect of contact insecticides, such
as are used for plant-lice, on these predaceous larve, in the
hope that an effective spray for the aphids may be found which
will not destroy the larve. In this way the latter might be left
on the plants to seek out and destroy any aphids which escaped
the spray, and thus tend to make the control measures perfect.
The investigation has not gone far enough to justify conclu-
sions, but it may be said that in laboratory tests a solution of
Black Leaf 40*, 1 to 1000 of water with soap added, killed every
aphid and only a small percentage of the larve. The effect of
this insecticide on the larve under field conditions will be fur-
ther observed.

4. During late summer and autumn, especially, a large per-
centage of the puparia of Flower-flies are parasitized by a small
wasp which kills them. Such puparia can be easily told, after
a little experience, by the fact that they do not completely
inflate dorsally and soon become darker in color than normal.
Much good could be done by careful observers in destroying
such parasitized puparia wherever found.

SPECIES REARED IN THE STATE.

During the summer of 1915 at this Station, I succeeded in
rearing from eggs or larve twenty species of Syrphide, nine of
which have apparently not previously been described in the
immature stages. These species fall into three of the structural
types of larve already described, as follows:

*Made by the Kentucky Tobacco Product Co., Louisville, Kentucky.

222 MAINE AGRICULTURAL EXPERIMENT STATION. Ig16.

I. Aphidophagous Species.

Paragus angustifrons Loew.
Pipiza pisticoides Willist.
Melanostoma mellinum Linné.
Sphaerophoria cylindrica Say.
Sphaerophoria sp.

Syrphus sp.

Syrphus americanus Wied.
Syrphus ribesii Linné.
Syrphus torvus O. S.

Syrphus xanthostomus Willist.
Syrphus nitens Zett.

Didea fasciata Macq. var. Fee: Loew.

II. Short-tailed, Filth-inhabiting Species.

Tropidia quadrata Say.
Syritta pipiens Linné.

III. Long-tailed, Filth-inhabiting Species.

Eristalis bastardii Macq.

Eristalis dimidiata Wied.

Eristalis arbustorum Linné.

Fristalis tenax Linné.

Tubifera lineata Fabr. (Helophilus conostoma Willist. )
Tubifera trivittata Fabr. (Helophilus latifrons Loew.)

The Short-tailed and Long-tailed Filth-inhabiting species
were, all except the last species, reared from decomposing human
feces at the mouth of a sewer. Tubtfera trivittata (Helophilus
latifrons) was breeding in old and dried, but recently water-
soaked, droppings of cattle, and soft black mould about stumps
in an old stumpy pasture where heavy rains had left numerous
pools of shallow water.

The aphidophagous species named above and others not deter-
mined were found preying on 33 species of Aphididae and two
species of Psyllidz as follows:

SYRPHIDAE OF MAINE.

223

List OF HOMOPTERA* ATTACKED BY SYRPHIDAE IN MAINE AS

APHID.

Aphis viburnicola

Aphis viburniphila.........

OBSERVED IN IQI5.

HOST PLANT.

Viburnum opulus...........

SYRPHID.

Syrphus ribesii
Sphaerophoria cylindrica

Re CERMPE ARATE EN LELEES <9’ sp tse oun crass sve > ciaha les Wad cedex Unc oloiicce wa Biommelate

Patch mss.
ABTS: COPOUBS a0 50 concede vies oes LeLISTST Ley See See in ire a ee ee
Aphis cerasifoliti .......... Pronus ‘vireiniana:. .. ..)02.
PEE OINE Bia kod = gieidn, + ee nS Ce ec Se

Aphis spiraecola...........

Aphis spiraephila

pane aestg cs © 6 Moe See RA ress

Ve

Syrphus sp.
Sphaerophoria sp.
Sphaerophoria cylindrica
Syrphus sp.

Syrphus americanus
Syrphus torvus
Sphaerophoria sp.
Paragus angustifrons
Paragus angustifrons
Sphaerophoria sp.
Sphaerophoria cylindrica

Ak ee | Re Se ee ee a ee ee a er |

ease So cylindrica
Sphaerophoria sp.

PC eee eee eee or ted os ae, os a a tS aw due

Sphaerophoria cylindrica

PILE SANDOTNE =. os oon = = Flowering Currant..........
Aphis rumicis ............ Sa eee aerge corer
Aphis rumicis .........5.. Evonymus alatus...........
Aphis TUMICTS. |... sos os Broad-leaf Dock

Aphis helientht............ NT a Ea ae toe
Aphis cornifoliae.......... bo TE es Oe ceaberns
Macrosiphum rosae........

Macrostphum solantfolti.. ..|Rose........-..2.-eccer eee
Macrosiphum zudbeckiae ..|Goldenrod

Macrosiphum sp........... i

EUAUSLCEL ASD, oe, wee

PRYZR Covaste 25. Pe Pe ae Wila Ghetry:..' se
MGS CEP ast 8! ss 26 2B er teas ays ks eee es ea
REUZUT DETSTCAC score oe wc ve, « HERSANO): Soc Seta eneMe act ona es Sh aera Bs
JAYS TES 9 RINE, ARs ne ot Ma Currant

Rhopalosiphum nymphaeae .

Rhopalosiphum nabali
Phorodon humuli

Pterocomma flocculosa

Siphocoryne wrylostii........
Symdobius oblongus........
Chaitophorus populifoliae ..
Chaitophorus sp...........
Schizoneura americana.....
Schizoneura lanigera.......
Tetraneura graminis.......
Prociphilus corrugatans.. .
Prociphilus fraxinijolii.....
Thecabius patchit..........
Hamamelistes spinosus.....

PSY LLID.
Psylla striata Patch........

Psulla cerasi Patch........
|

Willow

b él wis icle Gia >. 6 wipe, <6 lols we

Syrphus sp.
Sphaerophoria cylindrica
Sphaerophoria sp.
Sphaerophoria cylindrica
Melanostoma mellinum
Sphaerovhoria cylindrica
Sphaerophoria sp.

Syrphus ribesit
Syrphus sp.
Sphaerophoria cylindrica

Syrphus ribesii

Syrphus torvus

Surphus sp.
Sphaerophoria cylindrica
Surphus nitens

Syrphus americanus
Lidea fasciata fuscipes

Snowberry........ hi Pigeh:| WhO Stik ooroaee ea ont nad Stet

OW histe, Birehs 2.502). Se tae

OD Pa I Oise es I ee et a
(sn pve ao miei els = ower ie = Be

ee (Cock s Comb Gall)
PRION S See eee se. te ie

Birch

Od «<u, © 6a, 6 = =) Sum & © 0) &. Le ©

Syrphus americanus
Syrphus ribesiz

tl AmmelanGhier eAaARACensigt «4.9 1's toumuitas «soo tk dinve deren. «alle

Syrphus sp.

* Identifications by Dr. Edith M. Patch, Entomologist.

224 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

DESCRIPTIONS OF LIFE-STAGES AND LIFE-HIsToRIES OF MAINE
SPECIES.

PIPIZA PISTICOIDES Williston.

This species is one of the most important if not the
most important natural enemy of the Woolly Apple Aphis
(Schizoneura lanigera) about Orono. The larve were plenti-
ful among the above-ground colonies of this aphid, especially
during August. The eggs are laid by adults, doubtless of a
spring generation (developing among one of the elm Schi-
zoneura?), as soon as the aerial colonies of the aphis are estab-
lished on the apple.

Good-sized larve were collected August 3, 16 and September
I. Pupz were formed August 14, 21 and 24, the adults emerg-
ing from 11 to 13 days later.

So rapacious are these larve that they practicaily exterminated
the Woolly Apple Aphis about Orono by the first half of Sep-
tember. Dr. Edith M. Patch tells me this is the usual experi-
ence year after year.

Walsh and Riley (48, 49, 57) have described and figured a
species of this genus, which was found feeding on Schizoneura
lanigera and Phylloxera vastatrix, under the name of “The
Root-louse Syrphus-fly (Pipiza radicum n. sp.).” Osten Sacken
(38, p. 120) listed this species as a synonym of femoralis as
did also Williston (62, p. 26) with a query. The type specimen
appears to be lost but Coquillet (11) concludes from a com-
parison of the original description with the type of Pipiza
pistica Williston that they are the same, hence the latter a
synonym of radicum, and consequently that “the root-louse
Syrphus-fly” should be known as Pipiza radicum Walsh and
Riley, being distinct from femoralis Loew.

Williston (62, p. 29) at the same time that he described
Pipiza pistica described another species, P. pisticoides, from a
single female from Mount Washington, as follows:

“Resembles P. pistica very much but seems evidently different. The
third joint of the antennz is orbicular, as broad as long; the pile through-

out is shorter on the abdomen scarcely discernible; the size is also dis-
tinctly smaller.”

Certain specimens collected in Ohio and one specimen, reared
from an overwintering puparium among Schizoneura americana

SYRPHIDAE OF MAINE. 225

on Elm agree with Williston’s description of (pistica=)
radicum. In these species the third joint measures, — maxi-
mum width, .32 mm. by maximum length about .5 mm., the
ratio being roughly 1 :1.6.

However, the specimens reared in Maine are much less
evidently pilose, and have the third antennal joint noticeably
smaller and more elongate; measuring, maximum _ width,
.25 mm., maximum length .42 mm., the ratio being roughly

LB are

Another difference between the above groups of specimens
(which may or may not hold true for a larger series) is in
the length of the posterior, or medio-cubital, cross-vein at the
outer end of the discal cell. In the Maine specimens
(pisticoides) this vein is about .45 mm. long, one-fourth shorter
than in the Ohio specimens (radicum) where it measures nearly
.6 mm.

The above specimens are therefore referred to Pipiza pistt-
coides.

Larva. (Fig 29-1) Dimensions, average of eight, length, 6.75 mm.,
maximum width, 2.3 mm., height 18 mm. A wrinkly, moderately spiny,
pale-yellowish or flesh-colored larva, usually much obscured by the
woolly excrescence of the aphids among which it is found. Segments
5 to I1 inclusive of nearly equal width, the fourth and twelfth a little
more than half as wide. The remaining anterior segments retracted
except when the larva is active, then strongly accuminate to the terminal
mouth-parts. Mouth-parts of the aphidophagous type with slender
accessory thorns and a pair of prominent, short and heavy lateral mouth-
hooks. The anterior larval spiracles slender, inconspicuous.

Each segment with one prominent, and two less prominent, transverse
wrinkles, the latter sometimes sub-divided. The produced edges of the
segments form two, zig-zag, lateral carine one above the other, com-
posed chiefly of the fleshy, conical elevations which bear the dorso-
lateral and lateral segmental spines. The entire dorsum covered with
minute, close-set pale integumental spines, .o15 to .03 mm. hong, with
broad bases and acute tips. The segmental spines likewise pale, about
.I to .15 mm. long, of two sub-equal parts, the terminal part slender,
accuminate, the basal part more than twice as broad.

The posterior respiratory process with a moderate constriction about
mid-length; the basal half sub-conical fleshy and papillose, the distal
half polished sub-cylindrical, a little flattened dorso-ventrad, at the tip
evidently of two tubes fused mesad. The entire process is elevated to
a length of about .5 or .6 mm.. the polished distal part measuring about
.25 mm. in length; maximum width about .25 mm., maximum heigth
about .15 mm. The spiracular slits prominent, usually raised on radiating

3

226 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

carine. Length of median spiracle about .065 mm., its width abou:
015 mm. The two stigmal plates separated by a median incision. The
circular plates or “buttons” prominent, situated a little dorsad, .035 to
04 mm. in diameter, their inner margins separated by about half their
diameter. The inter-spiracular ornamentation consists of four pairs of
prominent slender bristles or hairs (Fig. 29-2) about .04 to .o5 mm.
long, a pair dorsad and ventrad of the circular plate, respectively, and
one in each of the other interspiracular spaces.

Puparium. (Fig. 29-3). Length about 4.75 mm., height about 2 mm.,
width 2.25 mm. to 2.4 mm. Ventral line strongly concave, the dorsal
line moderately elevated, producing almost a semi-circular curve from
mouth-parts dorsally around to the posterior respiratory process. Great-
est depth and width about the anterior third, tapering moderately on
each side to within one millimeter of the posterior respiratory process,
thence rapidly to that organ, which occupies a terminal position. Nearly
circular in outline as seen from in front, slightly flattened ventrally.
Color testaceous brown. Segmental and integumental spines not visible
to the naked eye, but giving the puparium a spinulose appearance when
somewhat magnified. Other characteristics as in the larva.

Adult. (Fig. 29-4). Uniformly black, about 6 mm. long. Antenne
black above, lower half of first and second joints and third joint on
basal half of lower side yellow; the distal half and upper side all black.
Arista as long as second and third joints together. Front black pilose,
a few white hairs across the middle. At each side midway between
ocelli and base of antenne a white pollinose spot. A similar, narrow,
elongate stripe of the same pollen on upper part of facial orbits. Face
with rather sparse white pile, the eyes and posterior orbits short, white
pilose. Thorax and abdomen shining metallic black, finely ruguloso-
punctate, with very fine short white pile. Legs black with white pile, the
following parts yellow; tips of all the femora, the broad base and nar-
row tip of the four front tibie, the narrow base of hind tibie and
basal joints of the four front tarsi.

MELANOSTOMA MELLINUM Linne.

One of the most common species throughout North America
and in Europe. Of their abundance Schiner (Fauna Austr. 1.
291) says (translating freely) :

“T have brought in thousands from all possible situations. They are
found on every trip and finally tire the poor dipterologist because, while
always apparently new, they nevertheless prove, upon closer examina-
tion to be nothing but varieties of the same variable species.”

Verrall (55, p. 311) writes: “The larve of this species are believed
to be aphidophagous as they have been bred from Aphides on Chrys-
anthemum leucanthemum, but M. A. Giard in Bul. Soc. Ent. France,
1806, p. 234, traced and bred many larve which occurred on the umbels
of Daucus carota (on plants which bore no aphides) and which lived

SYRPHIDAE OF MAINE. 227

on the bodies of Musca domestica and Chortophila pusilla; the larve
attacked these flies at the junction of the neck with the thorax and held
on for one or two days before pupating.”

On July 24, 1915, I found in a field of oats and wild mustard
on the Station farm, many females of this species, their abdo-
mens greatly distended with eggs. They seemed to be feeding
on the blossoms of the mustard and no signs of oviposition
were found. No aphids could be found on these plants. The
ova of the flies were plainly visible through the thin, distended
and transparent abdominal sterna and pleura, especially of the
posterior half of the abdomen. Only a single male was taken
and no others seen. Whether this indicates a relative scarcity
of males or simply that the gravid females were more easily
taken I am unable to say,—propably the former.

Twelve females were placed in jars with the single (avail-
able) male. Two days later July 26, 7 A. M., a large number
of eggs had been deposited on the sides of the jar and on grass
enclosed; probably having been laid during the night. July
28 by 8 A. M., the eggs were hatching, the duration in the
egg stage having been between two and two and a half days.
Not being certain of the larval habits, I placed the young in a
variety of situations and offered them a variety of substances
for food. The only noticeable result was the decided prefer-
ence shown by the larve for very moist situations. From the
variety of aphids offered them they seemed to show a preference
for Aphis cornifoliae from Cornus although no larve were
found among this species in the field. |

The larve fed in captivity developed rapidly and began
pupating August 14.

The following are the dates of pupation and subsequent
emergence of adults from the eggs laid July 26.

Pupated August 14 Parasite emerged August 26

16 3 4 26
c " ‘7 9 3 2 23
* 4 20 Q . a 27
cd si 20 2 Pa i 30
r aio 423 ? ra Sepes 403
&¢ is9 26 it3 cc 4

Again on August 12 a female in captivity deposited a num-
ber of eggs. They were placed quite rapidly at intervals of

228 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

about a minute. The following is the rate at which ten suc-
cessive eggs were laid: 48 sec., 3 min., 2 min., 3 min., 4 min.,
I min. and 20 sec., I min., I min., I min., I min.

The above eggs had practically all hatched over night pre-
vious to 8 A. M., August 16; the duration in the egg stage
having been about 4 days.

On August 7 a number of females were found hovering
about among a very dense growth of rape on the Station farm.
Careful examination revealed an abundance of eggs, which
later proved to be this species, deposited on the under side of
the lower leaves near the ground where it was constantly wet
or damp. The eggs were ranked quite closely side by side in
groups of from 2 to 8, more commonly 4 or 5 (the sides of the
eggs touching each other). These eggs hatched August II.
The larve were apparently half-grown by August 23, and
began pupating August 31 to September 4.

At the same time (August 7) a large number of larve of all
sizes, and pupz in all stages of development, were found on
the under side of the leaves among the rape. The larve appar-
ently sought out the moist places near the ground. These
plants were infested with Mysus persicae but the aphids present
at this time were fewer in numbers than the predaceous larve.
It seems to me likely that here is a case where an infestation
of aphids, which must have been severe to mature so many
hundreds of larve, had been all but exterminated by the pre-
daceous larve. This opinion gains confirmation from the fact
that many of the pupz present were undersized and somewhat
misshapen, such as often results from starving larve. The
larve collected were placed in all conceivable situations to see
if possibly they might feed on some other food; but all foods
were refused except aphids. They showed a preference for
Myzus persicae and Aphis corntfoliae from Cornus. Fed on
these aphids in captivity the larve pupated between August 7
and 11, and adults or parasites emerged August 14 to 18.

Of larve collected August 16 two pupated August 24, one
emerging as adult August 28 the other August 31; another
pupated September 4 and emerged as adult September 9.

Egg. (Fig. 30-1, 2, 3). Of the usual Syrphid shape, sub-cylindrical,
a little broader and more rounded at one end, narrower and truncated at
the micropylar end. The dimensions of 56 eggs from several different

SYRPHIDAE OF MAINE. 229

females were as follows: The length ranged from .8 mm. to 1.057 mm.,
with an average of .96 mm.; the maximum width ranged from .315 mm.
to .4 mm. with an average of .36 mm, Figure 30-7 and 2 is from camera-
lucida drawings of three masses of eggs as found in nature. The
sculpturing on the egg-shell (Fig. 30-3) consists of irregularly-shaped
elevations 5 to 10 times as long as broad and separated by depressed
areas several times their width. Each elevation has around its border a
varying number (commonly about a dozen) of short, irregularly-sized
and unsymmetrically-placed, lateral extensions. Forty-five to fifty of
these elevations occur end to end the length of the egg, and eighty to
ninety side by side around its circumference. Color: chalk white.

Larva. (Fig. 30-4, 5, 6). Length when well extended 8 to 9 mm.,
width about 2.5 mm. Color saturate lettuce-green, a little more yellow-
ish mediad. One of the most characteristic things about this species is
the unusual transparency of the integument and the unusual plainness
with which much of the viscera shows through the body wall. Integu-
ment finely papillose but without vestiture. The segmental spines con-
sist of a fleshy, sub-conical base surmounted by a slender blunt peg of
about equal height, the whole small, light-colored, entirely inconspicu-
ous. The greenish color is usually entirely obscured mediad, from a little
in front of the middle, backward, by a black mass of visceral matter.
This mass extends nearly half the total width but is overlaid on each
side by several longitudinal chains of whitish, adipose cells, which ex-
tend throughout about the posterior two-thirds of the body. Between
the latter is a longitudinal, pulsating heart-line——entirely dull black
except where it is crossed by folds of the intestine. Laterad of the
several whitish chains of cells, and to some extent among them, the
black again appears. Near the mid-dorsal line in the second fourth of
the body on each side is a single chain of black polygonal cells. The
lateral third of the body and all of the anterior end entirely greenish,
except for a slender white line on each side formed by the longitudinal
tracheal trunks, which run from anterior to posterior spiracles. These
trunks give off fine superficial branches mediad at each segment.

The transverse folds of the integument and the division into somites
are inconspicuous, as are also the antenne and anterior spiracles. The
latter are a little more than usually elongate and conical. The double
A-shaped mouth-parts may be seen through the segments at the anterior
end or terminally when extended. There is a pair of heavy, black,
lateral mouth-hooks. Just in front of the posterior respiratory organ,
between the two tracheal trunks, is a mass of very finely-divided white
filaments (trachee?) especially noticeable when the larval skin is moist.

The posterior respiratory process is about .3 mm. broad at the end,
about .17 mm. in depth, and elevated above the surface of the last seg-
ment only to a length of about .1 mm. or .12 mm. Circular plate evi-
dent; the three pairs of spiracles unusually short, less than twice as
long as broad—.o5 mm. long by about .0o3 mm. wide. The inter-
spiracular ornamentation consists only of four pairs of short, rounded
nodules. A moderate emargination between the two stigmal plates.

230 MAINE AGRICULTURAL EXPERIMENT STATION, IQI6.

Superficially the larva resembles most closely those of
Sphaerophoria cylindrica or Allograpta obliqua (q. v.) being
about the same size and similar in color and structure. How-
ever, besides the greater transparency of the integument in
this species, Melanostoma mellinum can be very certainly sepa-
rated from the other two species; first, by the shorter, more
nearly sessile, posterior respiratory organ which is less than
half as long as broad, whereas in Sphaerophoria cylindrica and
Allograpta obliqua it is considerably longer than broad; sec-
ondly, by the greater-length of the individual spiracles on the
posterior respiratory process in S. cylindrica and A. obliqua.
In M. mellinum the slit-like spiracles are less than twice as
long as broad, while in the other two species they are each at

least three times as long as broad.

Puparium. (Fig. 30-7, 8, 9). Length 6 to 7 mm., width about 2 mm.
to 2.25 mm., height about 1.7 mm. to 2 mm. Usually broadest and
highest about the anterior fourth. Very moderately elevated, the pos-
terior half of the body being especially attenuated, the dorsal line
descending very gradually to the posterior respiratory process. Color
dilutely greenish or yellowish. The larval skin retains its great trans-
parency in the puparium so that the developing imago is quite plainly
discernible. On this account this is one of the very few puparia of the
aphidophagous type on which anterior pupal spiracles or cornua can
be detected. These (Fig. 30-7 4A) are located near the cephalo-dorsal
corner of the puparium and appear as mere specks even at moderate
magnification, being about .025 mm. across. Hence they would be entirely
obscure (as they are in most related species) if it were not that the
relatively large tracheal trunks leading from them to the prothorax of
the nymph can be discerned through the puparium.

When highly magnified (Fig. 30-8, 9) the pupal respiratory cornuum
is seen to be a nearly cylindrical elevation, a half longer than broad
and the end differentiated into eight denticles, evenly distributed and not
contiguous, around the circumference of the apex and extending a short
distance down the sides. Each denticle oval in outline, several times as
long as broad.

Adult. (Fig. 30-10, 11, 12, 13). Length 6 to 7 mm. A ODrillianily
shining, metallic black species with bright yellow spots on the abdomen;
facial tubercle small; hind metatarsi not thickened

In the male the frontal triangle a little prominent with a pit in the
middle; in the female the frons with a broad shallow transverse de-
pression. Frons and face shining, whitish-dusted on the sides. Antenne
yellow to black, usually brownish on upper half, yellowish below except
at tip of third segment, arista very briefly and short pubescent, nearly
bare, yellow at the base. Abdomen in the male (Fig. 30-13) about four
times as long as broad, dull black with three pairs of yellow spots; the

SYRPHIDAE OF MAINE. 231

first pair on the middle of the second segment, inner ends rounded; the
others at the basal corners of the third and fourth segments, sub-
quadrate, a little longer on the median side extending broadly over
the margins. In the female the abdomen (Fig. 30-12) is shorter and
oval, shining, with four pairs of orange spots the first pair small, iso-
iated, near the middle of the segment; the third and fourth pairs sub-
triangular, touching the anterior margins, the posterior point rounded,
the spots (either isolated or) narrowly reaching the side margins at
the extreme base of the segment; the fifth segment with a pair of small
slender basal spots. Legs variable, yellow to black.

SPHAEROPHORIA CYLINDRICA Say.

(See also 33, p. 538 and 35, p. 59).

This is an exceedingly common, and one of the most valu-
able aphidophagous species about Orono, and probably through-
out North America. It has a variety of species of prey and
may be expected in almost any colony of aphids.

Partly grown larve were taken June 17 from among Aphis
viburnicola on Viburnum opulus; were full grown by June 28,
in puparium June 30 and emerged as adults July 7. Other
larve collected from the same source June 25, pupated July 2
and emerged July 9.

On July 7 four larve and one pupa were collected on Rose
among Macrosiphum solanifolu, but all were parasitized.

A small larva collected July 14 among Aphis rumicis on
Evonymus alatus was full grown and pupated July 24, emerging
July 30. On the same date larve were collected from Myzus
cerasi on wild cherry and a pupa from Phorodon humuli on
plum. The former pupated July 17 and all emerged July 22.

On July 16 a pair were taken in cottu about blossoming turnip
at 10 A. M. By 3 P. M. of the same day the female was ovi-
positing which continued until the death of the female on
July 19. By the latter date many of the eggs were hatching.

July 26 two parasitized larve were taken from Aplus
cerasifolii on Prunus virgimana and July 28 two puparia from
the same host, the flies emerging August 3 and 6. July 31 a
puparium was taken from flowering currant, the adult emerg-
ing August 7. And on the latter date larve and pupe were
found in all stages of development on rape, sparingly infested
with Myzus persicae. Adults from these puparia emerged
August 14.

232 MAINE AGRICULTURAL EXPERIMENT STATION, IQI6.

Egg. Of the usual shape, less pointed anteriorly than that of Allo-
grapta obliqua (Fig. 31-61, 62). Length of twelve eggs measured, ranged
from .9I mm. to 1.015 mm., with an average of .958 mm.; the maximum
diameter from .32 mm. to .37 mm., the average .34 mm. Color, chalk
white, sculpturing similar to that of A. obliqua (Fig. 31-63) but the ele-
vated bodies a little shorter and broader than in that species, about two
or three times as long as broad; distance between bodies about half
their width; number of arms around each, I2 to 20; rather short, not
much branched, many ending at half the distance across the intervening
space. Number of bodies around the egg at the middle about 50; number
the length of it about 30.

Duration in the egg stage about two or three days. The
eggs are laid singly at short, varying intervals of time. In
captivity the female always moved about after each egg was
laid before depositing another. The actual process of placing
the egg is speedily accomplished, the egg slipping out of the
much extended ovipositor very quickly. The end is touched
to a leaf where the “glue” fastens it and the ovipositor is then
quickly drawn away from it, retracted, and the fly crawls away
some little distance when the process is repeated. In the field
the insect flies about from place to place, occasionally resting
briefly on the under side of a leaf for the deposition of an
egg. This habit of scattering the eggs of aphidophagous
species is of value in preventing the too great congregation of
larve and consequent scarcity of food. In captivity the insect
frequently rested and manipulated the extended ovipositor with
her hind legs, rubbing the metatarsi over it. Whether this is
a natural habit or induced by some artificial condition (as, pos-
sibly, contact with the sugar solution supplied as food) I ao
not know. The female laid eggs at the following rate: 4
minutes, 74 minutes, 4 minute, ? minute, 2} minutes. About
60 eggs were laid by a female taken in coitu and kept confined.

Larva. (Fig. 31-76). Length 9 to Io mm., height 1.25 mm., width
2.25 mm. Elongate oval, tapering at anterior end, somewhat truncate
except for respiratory appendage at posterior end, depressed. Outline
irregular, dorsal integument much wrinkled transversely, and with lateral,
longitudinal carine. Color pea-green with two, narrow, longitudinal,
white stripes, laterad of and paralleling the rather conspicuous dark
heart-line. The stripes attenuated and confluent a little before the an-
terior end, not reaching the respiratory appendage posteriorly. Respira-
tory appendage brownish black at the tip. The skin papillose, bare
except for the usual segmental bristles which are here short, light-
colored and inconspicuous. There are a number of poorly defined pro-
leg-like projections of the body on the ventral side. The mouth-parts

SYRPHIDAE OF MAINE. 233

(Fig. 31-77) consist of three pairs of hooklets in addition to the pair
of jaws. One pair of hooklets is short and heavy, triangular, lateral in
position (Fig. 31-77 d), the other two pairs, situated close beside the
jaws (c), are slender, elongate, slightly curved. The jaws (b) are of
the usual type but U-shaped rather than V-shaped, the shoulders rather
prominent, with a median, terminal, pointed projection.

The antenne (Fig. 31-77, a), and anterior spiracles are rather well
elevated. The latter on a fleshy base with a prominent constriction
beyond the middle showing at the apex a small number of rounded teeth
or lobes about three larger and three smaller ones, (Figs. 31-74, 75).

The shape, color and general appearance is very similar to
the larva of Allograpta obliqua.

The two species can, however, be very certainly and definitely sepa-
rated on the basis of the posterior respiratory appendages. These are
about the same length and other dimensions; the difference lies in the
distal end. As described in Allograpia obliqua the two tubes are
slightly divergent at the tip making them broader here than at mid-
length, and bear between each two spiracles a short, but readily visible,
spur-like elevation continued as a slight ridge down the side of the
tube. In Sphaerophoria cylindrica the end of the tube is very nicely
and evenly rounded off; the spiracles very slightly elevated; the two
tubes slightly emarginate but not at all divergent, and all trace of
inter-spiracular spines or projections lacking. The posterior respiratory
appendage .35 to .415 mm. long, .31 to .335 mm. wide, .I5 to .175 mm.
high. The median spiracle about .065 mm. long. The circular plates
.035 to .04 mm. in diameter, their inner margins about .065 mm. apart.
With the aid of a good hand-lens one can always separate these two
species at a glance when the characters have once been fixed in mind.
(See Figs. 31-72 and 73 and compare Fig. 31-66 and 68).

Larve were taken almost continuously from mid-June to
mid-August and probably occurred before and after these dates.
The duration in the larval stage appears to be about two weeks.

Puparium (Fig. 31-78). Length, exclusive of respiratory process,
about 5.3 mm., height about 2 mm., width about 2 mm. In general
shape, color and appearance so similar to A. obliqua as scarcely to per-
mit of separate description. The puparium is generally less strongly
elevated on the posterior part. The characters of the posterior respira-
tory appendage, however, remain as in the larva and will always serve
to distinguish these two species.

Puparia were taken from June 30 to August 7. In all cases these were
found glued by the posterior part of the venter to the leaves of the
host plant. The duration in the pupa stage ranged from 5 to 9 days.

Adult (Fig. 31-71). The following description adopted from Willis-
ton (62, p. 105) applies to the adults reared from the above described
larve and pupe. Length 6 to 8mm. 6. Face and front light yellow,
shining; tubercle somewhat fuscous. Antenne reddish yellow. Dorsum

234. MAINE AGRICULTURAL EXPERIMENT STATION, I9I16.

of thorax dark greenish olivaceous with a yellow lateral stripe, indis-
tinct or wanting back of the suture. Pleurze with light yellow spots as
shown in Figure 31-77. Scutellum sulphur yellow. Abdomen slender,
second segment with a broad yellow cross-band in the middle, and a
brown or black band in front and behind, not reaching the lateral
margin. Remaining abdominal segmenitts variable, third with a broader
yellow band and more narrowly brown or blackish in front and behind.
Hypopygium wholly reddish-yellow, globose, with a tuft of pile below
in front. Legs yellow including the coxe.

@. Front shining black, yellow on the sides Silouk yellow lateral
stripes of thorax extending only to the suture. Abdomen moderately
broad, shining black, with the extreme lateral margins continuously
vellow and a moderately arcuate, entire, yellow band, reaching the
yellow on the sides, on each of the segments from two to four inclusive.
These bands cover about one-third the length of the segment. Fifth
segment with a similar but slenderer yellow band interrupted in the
sniddle. Sixth segment yellow with some black on the disk. In other
respects as in the male.

ALLOGRAPTA OBLIQUA Say.

(See also 33, p.4533 and, 35, p. Sec)

This species which ranges throughout much of this country
and is often common, was very rare about Orono during 1915,
being represented in the collections by a single male taken
about blossoming cabbage, July 29. The immature stages were
not encountered. However, on account of its close resemblance
to Sphaerophoria cylindrica and Melanostoma mellinum, and
the certainty that it does occur here, the following brief descrip-

tions are included from the author’s Ohio report (33).

Egg. (Fig 31-67, 62, 63). Elongate oval in outline, narrowing to
the roundly-pointed anterior end and the truncate micropylar end.
Length about .8 mm., diameter about .3 mm. Color chalk white, with
the usual microscopic sculpturing (Fig. 31-63). The main bodies of the
elevations are broader than in Syrphus americanus, three or four times
as long as broad; sub-oval, the arms thicker and shorter than in S.
americanus, usually about fifteen around each body. The depressed
space between the bodies about two-thirds as wide as the body. About
28 of these elevated bodies the length of the egg; about 55 around it at
the middle.

Larva. (Fig. 31-65, 66, 67, 68). When just hatched (Fig. 31-65) the
larve have a length of 1.2 mm., width .25 mm. They are irregular in
outline, nearly cylindrical, broadest near the middle; feeble and inactive.
Color whitish, with a yellowish or greenish tinge. The usual small,
fleshy, conical, segmental elevations are present, twelve to each segment,

but no bristles were discernible on them. The posterior breathing

SYRPHIDAE OF MAINE. 235

appendages are rather prominent, longer than in a young larva of S.
americanus, and light in color like the rest of the body. Their tips are,
at first, rather remote from each other though with subsequent growth
and their greater elevation above the general body surface they become
contiguous. The two longitudinal fat bodies are discernible as a white
line on each side of the dorsal blood-vessel which is more prominent
in the posterior half of the body. The skin is faintly wrinkled trans-
versely.

From this condition there seems to be a gradual growth until the
larva, when full-grown has reached a length of about 8 mm., width
2 mm., height 1.25 mm. It may then be described as follows: Shape
elongate oval, but much more pointed at the anterior end when extended
The outline is somewhat irregular due to folding and wrinkling of the
skin. The posterior end is rounding, truncate except for the projections
of the posterior breathing organ; (Fig. 31-66).

Color green, with two longitudinal white stripes. This color is due to
colored visceral bodies which show through the transparent skin. Along
the mid-dorsal line for two-thirds the length can be seen the ‘narrow,
dark, pulsating blood-vessel. It is irregularly limited at the sides by a
narrow mass of greenish, fatty globules changing gradually to whitish.
This whitish adipose matter forms the two prominent longitudinal white
stripes, .2 or .3 mm. wide and extending to within a few millimeters of
either end where they become much attenuated. The rest of the body,
except the appendages is green, darker on the sides. The breathing
tubes are light brown, black at the tips where the spiracles are located.

The skin is finely papillose when magnified, bare except for the seg-
mental bristles which are light in color, not elongate and not conspicu-
ous. The outer pair of mouth-hooks (Fig. 31-67, c) is present. The
posterior respiratory appendage is prominent, elongate, about .5 mm. in
length, .33 to .4 mm. in breadth and a little less than .2 mm. in height;
the two fused tubes diverging slightly at the extreme tip (Fig. 31-66, c;
68). The median spiracle .08 to .o9 mm. long, about .o15 mm. broad,
the carina bearing the spiracle about three times as long as broad. The
circular plates about .05 mm. in diameter, their inner margins about .o8
mm. apart. There is a short, but distinct, spur-like nodule on each
interspiracular space, which is continued down the side of the tube as
a more or less evident ridge.

Puparium (Fig. 31-69, 70). Dimensions, average of eight: Length
about 5.25 mm., maximum breadth 2.5 mm., maximum height 2.3 mm.
This neglects the breathing tubes at the posterior end of the body
which may project .5 mm. farther posteriorly or be directed more dor-
sally.

The puparium is broadest and deepest in front of the middle, the
anterior end bulbous; strongly and evenly depressed and compressed to
the posterior end, the posterior elevation very gradual. (See Fig. 31-69
and 70).

230 MAINE AGRICULTURAL EXPERIMENT STATION. IgI6.

The color in this stage changes very decidedly during the develop-
ment of the nymph within the translucent puparium. The color being
due almost entirely to the inclosed matter is consequently at first the
color of the larva—light pea-green with a brownish remnant of the
dorsal blood vessel and, at the sides of this, the two whitish lines. The
flattened posterior end of the puparium, including the breathing tubes,
however, is light testaceous brown, the tips about the spiracles black.
Midway on the length of the breathing appendages is a dark brown
ring.

As the pupa develops within, the color changes, gradually losing all
trace of the green and assuming more and more the colors of the adult.
The first thing to be noticed is the reddish brown color of the eyes
replacing the green in the anterior third of the pupa. Later the black
and yellow abdominal markings become apparent.

The puparium is smooth, bare; the segmental spines inconspicuous.
The breathing tubes as in the larva, prominent sub-cylindrical. The
wrinkles of the skin often remain rather prominent.

Adult. (Fig. 31-64). Description after Williston (62, p. 96). “do. 2.
Length, 6 to 7 mm. Face yellow, often with a bluish reflection, slightly
brownish on the tubercle. Frontal triangle yellow; front in the female
shining black on the vertex, continued as a broad stripe (broadest
below) to the antennze; on the sides the yellow of the face continues
up along the eyes nearly to the ocelli. Antenne reddish-brown, black-
ish on the upper part of the third joint. Thorax deep shining green, on
the sides with a yellow stripe reaching from the humeri to the suture,
where it is sharply truncate; post-alar callosity also yellow. Scutellum
wholly light yellow, faintly reddish on the disk; pile black. Abdomen
black or brown; first segment, except a slender transverse spot on each
side behind, yellow; second segment with a slender yellow anterior
fascia, and a broader one in the middle, about a third of the width of
the segment; straight and but slightly widened at the sides; third seg-
ment with a broad arcuate band, not quite touching the posterior angles
on the sides; fourth segment with two slender parallel stripes, leaving
a slender black stripe between them, on each side a broader, oblique,
oval spot, touching, or narrcwly separated from the anterior end of
the yellow longitudinal stripe, and reaching to the posterior angles; fifth
segment similar, but the side spots less oblique. Legs light yellow; last
three joints of all the tarsi, the hind tibiz, except the base and a middle
ring, and a ring on outer part of hind femora, brownish. ‘Wings hyaline,
veins black.”

SyRPHUS AMERICANUS Wiedemann.

(See also 32, p. 477 and 35, p. 55.)
This American Syrphus-fly apparently ranges throughout
North America and ranks along with Sphaerophoria cylindrica
as one of our most valuable predaceous forms. The larve have

SYRPHIDAE OF MAINE. 237

been found preying on the following aphids in this State:
Aphis pomit on apple; Pterocomma flocculosa on willow;
Symdobius oblongus on white birch; Aphis spiraecola on
spiraea; Schizoneura lanigera on apple and Microparsus
variabilis and Chaitophorus viminalis. The larve were com-
mon during late July and early August. Pupz were noted July
29 to August 2, the adults emerging ten to eleven days later.
The office records show that larve, pupz and adults occur in the
State almost continuously from mid-June to mid-September
at least.

Egg. (Fig. 32-41, 42, 43). Elongate-ovate in outline, sub-cylindrical,
narrower and truncate at micropylar end, nicely rounded off at the oppo-
site end, broadest in front of the middle (Fig. 32-42); somewhat flat-
tened to the surface to which it is attached, slightly humped or rounded
up above (Fig. 32-41). Length about 0.9 mm., diameter at middle
about 0.3 mm. Color chalk white.

The sculpturing of the chorion consists of microscopic projections of
the surface arranged in lines running longitudinally-obliquely around
the egg. Each projection consists of a long, slender, irregular body
(seven or eight times as long as broad) sometimes bent, with about
twelve to twenty slender arms reaching out in all directions from it.
The space between these bodies is roughly a half wider than the body
itself. Into these spaces the arms project, most of them meeting
similar projections from the same or another body, many branching so
as to form a delicate network of slender white arms between the larger
bodies. Figure 32-43? is a fair representation of a small part of the
surface of the egg-shell, highly magnified. The projections are chalk
white, the depressions between them shaded, appearing grayish or yel-
lowish. The bodies are of such a size that one may count about 25 the
length of the egg and about 50 around it, transversely.

Larva. (Fig 32-45, 46, 47, 48, 49, 50). Just after hatching (Fig. 32-
45), length 1.2 mm., width .2 mm. to .3 mm. Shape sub-cylindrical,
broadest at the posterior end, narrowing evenly to the anterior end,
not enlarged in the middle. Color light yellow or with a greenish
tinge. Body surface wrinkled, the sides irregular. Segmental spines
on the fourth to eleventh segments, inclusive, and the dorso-lateral ones
on the third segment, very long, slender, black; giving the young larva
a very hairy appearance, so far as I know characteristic of this species.
The posterior breathing appendages short, slightly divergent (Fig. 32-
45, a). No integumental vestiture. Dorsal blood-vessel faintly dis-
cernible in the posterior half of the body. During subsequent growth
these slender segmental hairs are replaced by shorter, stouter, more
spine-like bristles; the posterior breathing appendages are slightly ele-
vated becoming united on the median line; and minute black spines
appear all over the dorsal surface of the body.

238 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

Mature larva: Length about If mm., width about 2.5 mm., height
about 2 mm. (Fig. 32-46). Compared with many other aphidophagous
larve this species is noticeably elongate, slender, with more nearly
parallel sides. Segments 6 to 11 of nearly equal width, the twelfth
narrower and much depressed. Anterior to segment six the body tapers
evenly to the mouth-parts when extended, or rounds off at segment four
when at rest, with the head segments retracted. Body-wall prominently
wrinkled and with the usual two longitudinal carinze at each side.
General color yellowish, or salmon-brown, marked with black and
white. The whitish markings consist of a transverse, rectangular bar
on each segment, from six to eleven, and a narrow line along each
side of the larva in the dorsal lateral carina. Interrupted by the
transverse white bars at each segment, is the mid-dorsal heart-line,
consisting of six elongate, wedge-shaped, black marks, broadly mar-
gined with brown. Laterad of the brown are other prominent black
blotches extending obliquely outward and back to the whitish lateral
carine. The anterior two or three segments unmarked with black or
brown, light greenish-yellow in color. The amount of brown color
variable, frequently covering the entire dorsum except the heart-line
in segments ten to twelve.

The entire dorsum of the larva covered with short, close-set, black,
integumental spines. The segmental hairs larger but light in color and
not conspicuous, situated on slight elevations.

The posterior breathing appendages on the dorsum of the last seg-
ment, (Fig. 32-46, c; 49; and 50) are short (0.2 to 0.25 mm. long) and
nearly twice as broad (0.4 to 0.5 mm.); divergent for half their length;
the dorsal spiracular spines (Fig. 32-49 and 50, a) moderately long,
sharply conical, with a very small lateral sub-basal spur. The six
elongate spiracles (b) are irregularly and considerably curved, about
0.2 to 0.25 mm. long, the median one on each side nearer to the ventral
than to the dorsal one.

The anterior prothoracic spiracles on the third segment (Fig. 32-
46, b; 47, a) are small,, subcrescent shaped, the lip of the spiracle
marked by nine rounded, tooth-like lobes, (Fig. 32-48).

The mouth-parts (Fig. 32-47, c, d, e) consist of the usual pair of
beak-like jaws (c, d) and three pairs of mouth-hooks (e). The jaws
are A-shaped, sharp, slightly hooked at the tip, somewhat shorter than
usual, the dorsal extending slightly beyond the ventral when apposed.
The latter has a ventrally projecting basal spur on each side. The
mouth hooklets are unequal in size the outer pair largest; the other
two pairs are situated close beside the jaws, the dorsal ones heavier,
the ventral pair small, slender.

Puparium. (Fig. 32-51, 52, 53, 54, 55, 56). Dimensions, average of
15: Length 6.5 mm., height 2.5 mm., width 26 mm. The head seg-
ments of the larva are retracted ventrally so that segments 3 to 5 lie
at the anterior pole and the tip of the mouth-parts (terminal in the
larva) are about 0.5 mm., back on the ventral side. The wrinkling of

SYRPHIDAE OF MAINE. 239

the skin, characteristic of the larva is largely lost, due to the inflation.
The vestiture remains as in the larva, the segmental spines inconspicu-
ous, but the exposed parts of the wrinkles of the larva, densely cov-
ered with very small, short, sharp, black spines. Sometimes this gives
a rather prominent transverse banding of black where the spines are
thickest.

The posterior three segments are proportionately less inflated than
the middle ones. Shape from dorsal aspect ovate with the last seg-
ment and its respiratory appendage projecting; very slightly broadest in
front of the middle, nicely rounded out in front. From the side
(Fig. 32-56) the anterior and dorsal inflation is evident; the puparium
is not strongly elevated posteriorly, being convexly depressed gradu-
ally from about the middle. From in front the puparium appears nearly
circular in outline, very slightly flattened ventrally.

Color of the puparium, empty: pale brown, transparent; with pupa
enclosed: variable, darker brown, strongly tinted with salmon. A day
or two before emergence the prominent colors of the adult become
plainly visible.

Adult. (Fig. 32-44). Description after Wiedemann (61) and Osten
Sacken (39, p. 145).

6. 9. Length 8 to 10 mm. Female. Face yellow, in certain positions
with a pearly luster, with a brown stripe in the middle, which begins at
the oral margin but does not reach the antenne; the latter brownish-
black, reddish on the underside of the third joint. Cheeks blackish,
but separated from the mouth by a narrow yellow border, which on
the underside of the mouth completely cuts off connection between the
black color on both sides. Front brownish bronze color, powdered with
yellow on each side. Immediately above each antenna there is a
brownish spot sometimes continued above into an indefinite black stripe;
vertex metallic bronze or black, eyes bare. Thorax metallic greenish
black, unstriped; with scattered luteous pile; on the sides, in front of
the base of the wing, yellowish; elsewhere metallic green; scutellum
metallic yellow, with a-bluish reflection and sparse yellow pile. First
abdominal segment metallic blue; the rest of the abdomen black with
bright yellow cross-bands. The first abdominal cross-band is not
interrupted but co-arctate in the middle; its ends do not touch the
margin of the abdomen, but are separated from it by a narrow black
border; sometimes a brownish mark in the middle of this band gives
it the appearance of being sub-interrupted. The second cross-band is
nearly as broad as the black cross-band between it and the next yellow
band; it is usually perfectly straight (in some specimens the hind mar-
gin is gently sinuate); its ends do not touch the lateral margin of the
abdomen; they are cut obliquely, forming a sharp angle anteriorly, and
a rounded one posteriorly; the former almost touches the margin of
the abdomen. The third band is similar to the second, only its hind
margin is more perceptibly arcuated. The posterior margin of the
fourth segment has as usual, a narrow yellow border; the fifth likewise,

240 MAINE AGRICULTURAL EXPERIMENT STATION. 1910.

and two yellow spots at the base besides. Femora yellow; the four
anterior ones in some specimens brownish at the extreme base only;
the hind pair with a more or less distinct brown ring on the distal half;
four anterior tibia and tarsi yellow; the hind tibie sometimes with a
brownish ring, the hind tarsi brownish.

Male (Fig. 32-44). Front yellow, with a more or less distinct brown
spot above each antenna; cross-bands on the abdomen broader than in
the female, and distinctly broader than the black interval between them;
posteriorly, they are often nearly straight, sometimes distinctly arcuate,
especially the third band. The yellow spots on the second segment
are not coalescent, but separated by a narrow black interval (in some
specimens sub-coalescent); the fifth segment is yellow, with a black
spot in the middle. The four anterior femora are black at the base;
the hind femora are usually black, with a yellow tip; sometimes there
is a trace of yellow at the base; hind tibiz usually with a brown ring
in the middle.

SyRPHUS TORVUS Osten Sacken.

(See also 30, p. 341 and 35 p. 57.)

Common to abundant throughout June and first half of July;
rare during late July and throughout August. Reared from
among Aplis spiraecola on spiraea and Phorodon humuli on
plum seedlings. Hundreds of adults were noted about these
colonies, feeding on the honey-dew secreted by the aphids.
One male in the collection bears the label: “Hibernating
puparium under leaves, Houlton, Maine, May 7, ’07.”

Larva (Fig. 33-10, II, 12, 13). Length, 10 to 12 mm., width 3 to 4 mm.,
height about 2 mm. Shape sub-cylindrical, tapering rapidly in front
to the mouth-parts, slightly narrowed but blunt and emarginate at
posterior end; integument raised into numerous transverse folds con-
tinued laterally into a distinct longitudinal keel on each side (Fig. 33-70).
First three body segments small, retractile, gradually thicker; next
eight sub-equal; terminal segment flattened, bearing on its dorsal sur-
face the posterior respiratory process (Fig. 33-10, b; 13). The spiracles
narrow, elongate, nearly straight. The interspiracular ornamentation
of slightly elevated, inconspicuous ridges. Circular plate dorso-mediad.
Mouth-parts (Fig. 33-17) with a prominent pair of lateral mouth-hooks
(c). Between the second and third segments dorsally is a pair of
small brownish anterior spiracles (Fig. 33-10 a, 11 g); conical, the semi-
circular slit guarded by seven rounded teeth (Fig. 33-12).

The general color of the larve is brown pink. The integument is
tough but transparent; naked but very finely papillose. The black mid-
dorsal blood-vessel is prominent and in the living active larve the
blood may be seen pulsating regularly from posterior to anterior end.
Laterad of this blood-vessel are two long yellowish bundles of fat,

SYRPHIDAE OF MAINE. 241

irregularly outlined, extending practically the full length and varying
in width. ‘At the approach to metamorphosis these adipose masses in-
crease in extent sometimes covering nearly the entire dorsum except
the blood-vessel. At times also the body fluid invades more or less the
fatty bodies appearing as outlying pulsating pockets.

Puparium (Fig. 33-14, 15). Length 8 to 8.25 mm., width 3.5 to 4.3 mm.,
height 3.75 to 4 mm. Testaceous brown, naked, smooth except for
slight remains of the transverse wrinkling of the larva. Broadest in
front of the middle, nicely rounded in front, descending rapidly at
the posterior end to the projecting respiratory process.

Adult (Fig. 33-9, 16). Length dg, 9, 10 to 12.5 mm. Description,
slightly modified after Osten Sacken (39, p. 139).

Female (Fig. 33-9): Face and cheeks yellow, a faint grayish spot
on the cheeks under the eyes. Front and vertex shining black with
black pile; the front on both sides along the eyes with a broad border
of yellowish pollen sometimes meeting the similar border of the oppo-
site side. This pollen continues in dilute form down the sides of the
face crossing narrowly beneath the antenne. Eyes pubescent (in many
specimens the pubescence is very much rubbed off and very difficult to
perceive). Antenne inserted beneath a double arched ledge of front.
The dark color of the front begins immediately above their root
forming a blackish brown arch with a projecting angle in the middle.
Antenne dark brown; third antennal joint below and the bare arista
sometimes more or less reddish. Face in profile perpendicular beneath
the antenne produced but little below the eyes, slightly concave
beneath the antenne to oblique tubercle, receding below (Fig. 33-16).
Thorax dull greenish with but little luster; in well preserved speci-
mens with three faint dorsal longitudinal darker stripes, divergent
posteriorly; scutellum dull yellowish with a slight bluish reflection.
The black pile of scutellum and dorsum of thorax changes to yellow
on the sides of the latter where it is also much thicker and longer.
Third longitudinal vein nearly straight; anterior cross-vein a third of
the way from base to apex of the discal cell; anterior outer angle of
first posterior cell acute. Entire sub-costal cell brown; root of wings
as far as humeral cross-vein and the costal cell slightly tinged with
brown. Legs slender; coxze and basal third of femora black; on the
hind pair the black reaches beyond the middle of the femora; hind
tibiz often with a brownish ring; four anterior tarsi brown the root
of the first joint often reddish; hind tarsi dark brown.

Abdomen oval slightly broader than thorax; about twice as long;
with three prominent yellow cross-bands, the first interrupted in the
middle, all attaining the lateral margins. First segment entirely black;
second segment with a yellow elliptical spot about the middle on each
side prolonged usually as a narrow neck which reaches forward and
touches the margin. Third and fourth segments each with a yellow
cross-band on its anterior half, the hind margins of these bands very
gently biconvex with a very shallow sinus at the middle; on each side

4

242 MAINE AGRICULTURAL EXPERIMENT STATION. IQ16.

the cross-bands are attenuated and curved forward so as to reach the
anterior margin of the segment. The band on the fourth segment
also touches its anterior margin in the middle, while that on the third
is more remote from the anterior margin; the black interval between
the bands is twice as broad as the bands. The fourth and fifth seg-
ments have yellow posterior margins, the fifth usually with two yellow
spots on each side at the anterior margin.

Male. “Similar to the female but abdominal cross-bands broader,
the biconvexity on their hind side stronger, and the sinus in the middle
deeper; the gray spot on the cheeks under the eye often larger, some-
times occupying a considerable portion of the cheek; the brown ring
on the hind tibie usually expanded so as to reach the tip of the tibiz.
The eyes (contiguous) are more distinctly pubescent, the front is beset
with yellow pollen except a narrow black space above the antennz.”

SYRPHUS NITENS Zetterstedt.

Syrphus nitens Ztt. D. Scand. ii. 712 9, viii 3137 (Scaeva).
Verr. Ent. M. Mag. v. 193; Brit. Fl. Syrph. 377, figs. 295, 296.

Larve of this European species, hitherto not recorded for
North America, were found on the campus of the University
of Maine, July 23:to August 11. Some of them were full
grown on the former date, others only about half-grown on the
latter date. They were taken among colonies of the Willow
Grove Plant-louse (Pterocomma flocculosa Weed) on _ the
branches of a willow tree. The aphids were very ravenously
devoured. One larva under normal conditions was observed to
destroy twenty-one of these large aphids in twenty minutes.
Six empty, and one inhabited puparia were found glued to the
small branches of the willow on July 26. The adult from this
puparium emerged July 31. One of the larve collected July
26 pupated July 27 and emerged as adult (2) August 6.
Another pupated August 1 and emerged (4) August 12. The
duration in the pupa stage is therefore about 10 to 12 days.

Besides extending the known distribution of this species,
this record is of particular interest because the larve are the
only ones of the aphidophagous type I have seen in which the
spiracles on the posterior respiratory process are not straight
but remarkably convoluted (See Fig. 34-3 and 4).

Larva (Fig. 34-1, 2, 3, 4, 5). Length about 15 mm., width about
3 mm., height about 25 mm. An unusually slender, elongate species
broadest about the eighth segment, but of nearly equal width from

segment seven to eleven. The twelfth is nearly a third narrower and
somewhat depressed, the posterior end squarish. Anterior to segment

SYRPHIDAE OF MAINE. 243

seven the body tapers evenly almost to a point at the mouth-parts,
when extended; when at rest. the anterior three segments retracted and
rounded off at segment. four.

In their natural habitat the larve were so covered with threads of
flocculence from the aphid host as to appear light grayish in color.
When this matter is removed the color is yellowish brown, consid-
erably mottled with black. The most conspicuous black markings are
due to masses of body fluids showing through the integument; but
others are formed by particularly thick areas of the black integumental
spines which cover the entire dorsum, but are so minute on the venter
that the latter appears bare. The largest of these spines about .04 mm.
long. The arrangement of these spots is shown in figure 34-r, where
only the ones due to integumental spines are shown. There are nine
such areas on each somite, three on the middle line and three at each
side. The integument is folded transversely, there being about five
folds to each somite on the dorsal side. On the ventral side in
segments five to eleven, inclusive, are nude elevations suggesting
prolegs. The segmental spines are situated on moderate, conical eleva-
tions and are about .I0 to .15 mm. in length, but light in color. The
head segments bear the antenne and mouth-parts of the kind usual in
aphidophagous larve. There is a pair of very heavy, black, lateral
mouth-hooks. The anterior larval spiracles on the third segment
(Fig. 34-1) are barely visible to the naked eye. When magnified
(Fig. 34-2) the surface is found to bear about a dozen, elongate nodules
arranged in a semi-circle.

The posterior larval spiracles are unique among aphidophagous larve
so far observed. They are borne on a very short, double process rather
more than usually emarginate distally, about half a millimeter broad,
.25 to .33 mm. long and about .33 mm. high. The slit-like spiracles
instead of being nearly straight are remarkably and irregularly sinuate,
convoluted or undulated in a very ornamental manner as shown in
figure 34-3 and 4. This extensive convolution makes the length unusu-
ally great for the spiracles in this type of larva. Between the spiracles
the surface of the tube is deeply constricted so that each is situated
along the summit of a broadly rounded carina, the most dorsal one
the most prominent. The circular plate is only moderately conspicuous,
about .055 to .075 mm. in diameter, their inner margins .o8 to .I mm.
apart. The inter-spiracular ornamentation consists of small, blunt,
rounded knobs sometimes double, entirely inconspicuous.

On several occasions larve of this species were noted extrud-
ing from the anus on the ventral side of the caudal segment,
four finger-like flabelle similar to those previously described
for Eristalis aeneus (34, p. 86) but not heretofore noted among
aphidophagous larve. Buckton (8) considers that these organs

have a renal function.

244 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

Puparium (Fig. 34-6). The dimensions of ten specimens were as
follows: The length ranged from 7.25 to 8 mm., with an average of
76 mm.; the width 3.5 to 4 mm., the average 3.75 mm.; the height
3.6 to 4 mm., the average 3.85 mm. The puparium bulbous in front,
a little broader than high. The ventral line usually quite concave;
the dorsal line well elevated, attaining its greatest height about mid-
length. The greatest width about the anterior third, but diminishing
very little either in height or width until within about 2 mm. of the
posterior end; thence quite rapidly to the last segment which is com-
monly about one millimeter wide, half a millimeter high, and a milk-
meter long, uninflated. A prominent mid-dorsal carina, widening out
anteriorly extends forward from the posterior respiratory process.
The latter structure retains its larval characteristics. The color of the
puparium is grayish-brown, with a mid-dorsal, broken, blackish line
and an oblique lateral black stripe on the side of each segment due
to the integumental spines. The segmental spines are easily detected,
but remain inconspicuous because of their fineness and pale color.

Adult (Fig. 34-7). I reproduce Verrall’s description of this
species in full (55, p. 377), and append some brief notes on the
Maine specimens.

“Eyes bare; abdomen ovate, with undulated entire yellow bands
which scarcely reach the side-margins; thorax shining; antenne con-
siderably luteous but darkened above; anterior tarsi mainly yellowish.”

“g. ‘Resembling S. nitidicollis but quite distinct; it is broader and
flatter both on the thorax and abdomen. Face more blackish about
the mouth-edge, until in dark specimens the whole mouth-edge, the
jowls, and a middle facial line extending above the central knob are
black; on the other hand the black may be restricted in a very pale
specimen to a narrow mouth-edge and all the jowls; the pubescence
on the face is usually more black, and the pubescence behind the eyes is
deep orange instead of whitish as in S. nitidicollis. Frons almost
always with blackish spots or lunules above the antenne, but otherwise
all yellow or orange, as is the face even up to the extreme top angle
instead of being, as in S. nitidicollis, blackish grey on the upper part.
Antenne much darker than in S. nitidicollis, as they are at least
darkened above the third joint, and usually have the whole of the
upper part and end of third joint blackish or brownish as well as the
upper part of the second joint, or occasionally the antenne are alto-
gether brownish with only obscure orange spaces beneath the joints;
the third joint is distinctly longer than in S. nitidicollis, being on the
inside much longer than deep after the end of the second joint;
arista shorter and inserted farther from the base, with its basal joints
more distinct, and after the basal joints more luteous and with a
rather shorter thickened portion.”

“Thorax brightly shining blue-black with deep orange pubescence.
Scutellum with mostly black pubescence.”

SYRPHIDAE OF MAINE. 245

“Abdomen with more isolated and much more undulating bands,
especially as regards the fore-margins of the bands on the third and
fourth segments; the spots on the second segment are either isolated
or only reach the side-margins at the upper corners, while the bands
on the third and fourth segments do not quite reach the side margins
and are beautifully undulated especially on the fore-margin; the hind
margins of the fourth and fifth segments are less broadly orange;
apparently the belly also gives a good distinction as S. nitens has
isolated central black spots on the second, third, and fourth segments,
while S. nitidicollis has only the hind margins of the third and fourth
segments black; a very important character occurs in the marginal
pubescence, which is all black after the basal corners, proving that
normally the abdominal yellow bands do not reach the side margins
and thereby thoroughly distinguishing it from S. nitidicollis.”

“Legs quite distinct, as the basal two-fifths of the anterior femora
and the basal four-fifths of the hind femora are black; the anterior
tarsi have the three middle joints darkened, while the hind tarsi are
usually more blackish. Pubescence behind the anterior femora almost
all black.”

“Wings less orange hued, the whole wing and especially the front
part being more smoky.”

“2. Similar to the male, but also differing from S. nitidicollis by the
undulating abdominal bands, darker antenne, and flatter more ovate
shape. Vertex brilliant purple, which is extended forwards down the
middle of the frons for a short distance, which is more obvious when
viewed from in front but which leaves the front half of the frons
much more yellowish than in S. nitidicollis; the dark spots or streaks
above the antennze are small and sometimes inconspicuous; the mouth-
edge is usually black, but there is only a trace of the middle facial
line.”

“Thorax brilliantly shining.”

“Abdomen more ovate than in S. nitidicollis, with the basal pair of
spots less sharply triangular, while the undulating bands are broader
and may just indistinctly touch the side-margins at their upper cor-
ners, though not enough to cause pale marginal pubescence; the peculiar
ventral spots seem very much as in the male.”

“Legs paler than in the male, as in the original specimen upon which
the species was introduced as British they are entirely orange down to
the base of the femora, but usually the basal fifth of the anterior, and
the basal two-fifths of the hind, femora are black; tarsi as in the male.”

“Wings rather more orange than in the male................. Length
abont10-S-90M.. onde cane Rare

In the Maine males the face across the knob with a black stripe,
abbreviated much short of the base of the antenne, prominent in all
except one specimen. This stripe is continuous with the narrow black
margin of the anterior mouth-edge. The latter black stripes turned
obliquely outward toward the eye, cutting off a small, triangular, yel-
lowish spot next the mouth edge before the jowls which are again all

246 MAINE AGRICULTURAL EXPERIMENT STATION. I9QI16.

black and across behind the mouth. Pubescence behind the eyes whitish
below, orange above.

Spots on the second abdominal segment in most specimens quad-
rangular rather than triangular. All the yellow bands distinctly sepa-
rated from the side margins. The bands on the third and fourth
abdominal segments, in both male and female, on the middle line, with
a small anteriorly and posteriorly directed pointed projection, not shown
in Verrall’s figure 2096.

The anterior femora are black on the basal fourth, the hind femora
on a little more than the basal half.

In the females the lunate, black spots above the base of the antenne
are rather prominent and, in one specimen, almost continuous with the
widened black extension from the vertex. The black stripe over the
facial knob is present but the stripes across the cheeks not developed,
the latter yellow to the jowls.

Hind femora entirely yellow the anterior ones black on about the
basal sixth. The third joint of the antenne in both sexes only a little
longer than deep after the end of the second joint.

DIDEA FASCIATA Macq. var. FUSCIPES Loew.

(See also 30, p. 337, 34, p. 90 and 35, p. 58.)

This species which in Ohio I have found breeding only on
Longistigma caryae infesting sycamore and basswood, was
found among the Willow Grove Plant-louse (Pterocomma
flocculosa) on the University of Maine campus the last of July
and first of August, at which time most of the larve were full
grown. Pupation took place about August 10. Adults were
captured July 15 about infested twigs of green apple aphis
(Aphis pom).

The following descriptions are abbreviated from my previous
publications on this species (30; 34, p. 90; 35, p. 58).

Egg. (Fig. 29-5). Of about the usual shape; broadest about the
middle. Length 1.3 to 1.7 mm., diameter 0.4 to 0.6 mm. Color chalk
white. The chorion is sculptured in a characteristic manner. The pro-
jecting bodies are close together, not highly elevated, each one two to
four times as long as broad. There are 55 to 60 of these bodies length-
wise of the egg and 80 to 100 around it at the middle. The egg of
Didea differs from all the others I have seen in that the projecting
bodies are not smooth on the top but ‘each one has a small number
(6-10) of more or less angular, irregular-shaped, pit-like depressions
hollowed out of it. These are so arranged as to leave between them
an elevated part of the body with more or less parallel sides. The whole
effect is to give the arm-like network appearance over the elevated body
somewhat like that between these bodies, without the outlines of the
bodies being obscured. The arms between these bodies are irregular,

SYRPHIDAE OF MAINE. 247

slightly branched, for the most part rather short, sometimes long, from
10 to 15 radiating from each body.

Larva (Fig. 35-2, 3, 4, 5). Length, 12 to 15 mm., width 5 to 6 mm.,
height 3 to 4 mm.; testaceous brown; flattened, sub-cylindrical, blunt
at the posterior end, tapering and obtusely pointed in front when ex-
tended (Fig. 35-2). The head segments usually much retracted giving
to the anterior end a bluntly rounded appearance. Each of the body
segments, except the first two and the last, with several transverse folds
of the integument and a transverse row of twelve segmental bristles
each about .15 mm. long. The median and dorsal ones crown the sum-
mits of conspicuous, conical elevations which, like the rest of the
dorsum, are close-set with short, radiating, black, integumental bristles
about .065 mm. long. The transverse body wrinkles are continued
laterally into distinct V-shaped prominences bearing the dorso-lateral
segmental bristles and forming a zig-zag longitudinal carina along each
side of the body. The lateral segmental bristle is situated at the apex
of a similar cone or V underlying the dorso-lateral; and in front of it
a small ventrally-directed fold bears the two ventro-lateral segmental
bristles on smaller spiny prominences. The lateral border has thus a
very irregular outline of sharp angular projections.

‘Mouth-parts with three pairs of small thorns close beside the V-
shaped jaws. The prominent lateral mouth-hooks, found in so many
aphidophagous species, wanting.

In the middle of the third segment is a pair of anterior spiracles.
These are light brown, conical, with a semi-circular slit near the apex
(Fig. 35-4).

On the dorsum of the last segment is situated the posterior breathing
organ (Fig. 35-2, b; 5). This consists of two closely apposed, short,
cylindrical breathing-tubes, united along the middle line, slightly diver-
gent at the tip. They are hard, black, firmly chitinized structures, each
with three slit-like spiracles raised on radiating carine. Dorsad near
the middle line each is marked by a smooth circular plate about .o9 mm.
in diameter, their inner margins about .175 mm. distant from each
other. The surface of the stigmal plates between the spiracles is very
much roughened the inter-spiracular ornamentation consisting of thin
laminate ridges, about as high as the carine, on which the spiracles are
located; only the summits of these ridges are indicated in figure 35-5;
about two such ridges on each interspiracular space and continued down
the sides of the short tube. The median spiracle at least .25 mm. in
length and slender.

The integument of these larve is exceedingly tough but transparent.
The entire dorsal and lateral surfaces are beset with numerous, minute,
short black bristles. The ventrum is bare. Along the mid-dorsal line
for the greater part of its length the dorsal blood-vessel is visible
through the body-wall. It is a poorly-defined, dark line with five or
six lateral expansions.

As the larva approaches metamorphosis the anterior segments are
retracted, the skin becomes inflated filling out the wrinkles character-

248 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

istic of the larva. It rounds out anteriorly and dorsally, the point
midway between the fourth and fifth segments coming to lie at the
anterior pole, the mouth being shunted backward on the ventral side.
The pupa is concealed in this indurated, inflated, sub-ovate, larval skin
or puparium.

Puparium (Fig. 35-6, 7). Length 9.5 to io mm., width 4.5 to 5 mm.,
height about 4.5 mm. Color, Roman sepia, a little darker than the
larva. Broadest a little back of the sixth larval segment, nicely rounded
in front, tapering gradually to the last segment which remains some-
what flattened, especially at the sides. The covering of small black
bristles is retained and the black conical prominences become even
more conspicuous owing to the inflation (Fig. 35-6, 7). The posterior
breathing appendages retain the larval condition.

Adult (Fig. 35-1). Description slightly modified from Williston
(62, p. 89). 2 do Length 11-15 mm. Face yellow, with a small elongate
brownish spot on the tubercle. Front yellow, with two brownish spots
above the antenne, or, in the female, with an inverted V-shaped brown
stripe connected with the black of the upper part of the front. Eyes
bare. Orbits thickly yellowish pollinose, posteriorly with a fringe of
yellowish-whitish pile. Antennz black, the third joint at the base some-
times reddish, elongate oval, obtusely pointed at the tip; arista reddish.
Thorax shining greenish black, on the meso-, ptero-, and sterno-pleure
yellow, thickly covered with similar colored pollen and pile. Scutellum
light yellow, translucent. Wings grayish hyaline, the base before the
humeral cross-vein and the stigma brown; the remainder of the sub-
costal cell and the costal cell may be brownish; third vein rather
deeply curved near the middle of the first posterior cell. Legs brown,
the posterior tibiz and all the tarsi blackish; sometimes the legs are
luteous, the base of femora, distal portion of tibize, and the tarsi brown.
Abdomen black, with four yellow cross bands, the first consisting of
two large ovate spots, narrowly separated and reaching the lateral mar-
gins in nearly their full width; second and third cross-bands broad
separated from the lateral margins by a black narrow keeled border ;
they are much narrower in the middle of the segments, the front
margin straight, touching the anterior edge of the segments; fourth
band similar, but much smaller and attaining the margin; all the black
is velvety opaque except the narrow posterior margin of the As res
which is shining, dilated in the middle.

TROPIDIA QUADRATA Say.

This common, widely distributed species has been well known
for many years, but no record has been made of the larval
habits of this or any other species of the genus. No record
had been made of its immature stages previous to the descrip-
tion by Mr. J. R. Malloch in December, 1915 (28, p. 343), of

SYRPHIDAE OF MAINE. 24Y

the puparium which was found floating on the water of a lake.
The larval habit was not determined.

On July 7, 1915, at Orono a larva of this species was col-
lected in partially decomposed human excrement near the mouth
of a sewer. It was apparently full grown by July 19, pupated
between the 21st and 27th and emerged from the puparium
August 6.

On July 10 a gravid female was captured at the same spot
and enclosed with a male over a small mass of the moist excre-
ment. By one o’clock of the same day a mass of several
hundred eggs had been deposited by this female. By July 14,
7 A. M., nearly all of the eggs had hatched and the young
larve were submerged except for the posterior respiratory
appendage in the moisture at the bottom of the jar. The larve
were kept in cages and were about full grown on September 9.
Three hundred and eighty-seven eggs were dissected from the
ovaries of a female taken about human excrement on July 21.
On July 27 seven puparia were taken from the drier parts of
the mass of excrement. One of them which had apparently
just pupated emerged August 8; others from July 28 to August
_

Egg. (Fig. 36-1, 2 3). Sub-cylindrical, elongate-ovate in outline, a
little smaller and more truncate at the micropylar end, slightly curved
on its long axis. The length of specimens measured varied from .82
to .£6 mm., with an average of .84 mm; the maximum diameter was
very uniformly .255 mm. Color white, glistening. The markings or
sculpturing of the chorion (Fig. 36-2) are characteristic, although ap-
proached closely by Syritta pipiens (See p. 253). It consists of small,
irregular, polygonal areas, which are slightly raised, leaving between
them narrow, parallel-sided and rather smooth-sided channels; the
latter connecting with each other to make a fine dark network over
the surface of the egg. Each of the areas thus marked off is further
ornamented on its surface with about 20 to 4o circular areoles by the
slight depression of the surface between them. When viewed under
very high power (oil-immersion objective and 3-4 inch ocular) the
minute circular areoles are seen to be formed by the arrangement of
very fine finger-like elvations, (Fig. 36-1).

The polygonal areas are of such a size that about thirty occur end to
end the length of the egg and about fifty or sixty side by side around it.

Egg-laying was observed from July 10 to July 21; but, since
a good-sized larva was found as early as July 7 and since
adults continued to emerge at least until August, the egg-laying

250 MAINE AGRICULTURAL EXPERIMENT STATION. I9QI6.

period is doubtless much more extended. In the case observed

(laboratory) the egg-stage lasted between 72 and go hours.

Larva (Fig. 36-4, 5 6, 7). At a very early stage (2 or 3 mm. long)
the young larva shows the characteristics of the full grown one, seem-
ingly differing only in size. Full grown larva about 16 mm. long;
maximum width 3.75 mm., maximum height 3.5 mm. Nearly cylindrical,
broadest in the middle; the anterior segments forming a globose, false
head; the posterior segments tapering rather rapidly throughout the
caudal eight (about 2 mm.) of the length to the posterior respiratory
appendage. The latter structure terminal; about .75 mm. long, .66 mm.
broad at its base, .5 mm. broad at its apex, and about .4 mm. high. The
double nature of the appendage indicated by moderate impressions on
the mid-dorsal and mid-ventral lines.

The distal end is truncated, and the stigmal plates ornamented with a
pair of circular plates, three pairs of spiracles and four pairs of pal-
mately-divided, plumose, interspiracular hairs. The circular plates
occupy nearly a median position, dorso-ventrad, and are situated near
the median line. Each has a diameter of .085 to .o95 mm. and their inner
margins are less than .o2 mm. apart. The spiracles are roughly S-
shaped, each ornamented with about twenty short, rounded, lateral
denticles, irregular in size and irregularly distributed. The right median
spiracle forms an S, the left one a reversed S. In other words the dorsal
free end of the S on either stigmal plate is directed laterad, the ventral
free end, mesad. The interspiracular ornaments consist each of about
five plumose or feathered hairs arranged palmately. Some of the hairs
are further divided; all are united at the extreme base; and occasionally
two are united for some distance from the base.

Immediately cephalad of the posterior respiratory appendage at each
side of the twelfth segment are three fleshy, conical lateral protuber-
ances, the posterior one about .75 mm. long, the others about half that
length, each pair connected by a prominent wrinkle across the dorsum
of the segment. The first four body-segments composing about the
anterior sixth of the body (2 or 3 mm.) is head-like globular, and
separated by a slight neck-like constriction from the succeeding seg-
ments; with several faint longitudinal furrows on its sides. At the
anterior end this false-head bears a pair of small antenne, each of a
fleshy base, surmounted by two, minute, sub-equal, rounded nodules
side by side at its apex. Just ventrad of the antenne is a rounded,
somewhat-chitinized mouth-hood, concave ventrally, within which is the
buccal cavity. The mouth opening further guarded by a fleshy fold
at each side, covered with long flexuous hairs, of service in straining
the food. The dorsal part of the bulbous false-head is ornamented
with a characteristic group of black, chitinous hooks or thorns. There
are two large hooks about .25 mm. long on each side, situated about
one millimeter dorso-laterad of the mouth-hood, their bases about .35
mm. apart. Extending between, and dorsad, of them are three irregular,
transverse rows of smaller and various-sized thorns, most of them

SYRPHIDAE OF MAINE. 251

barely visible to the naked eye. The most posterior of these rows
(Fig. 36-7A) consists of a large thorn at each side and six to ten smaller
ones between them. In the middle row near each side, and looking
much like a thorn, is located the sessile, anterior larval spiracle (Fig.
36-7B). There is a small hook or thorn laterad of each spiracle, a
large one mesad and, between the latter, about three smaller ones. The
anterior row consists of six to ten thorns of moderate size. Cephalad
of these three rows and above the mouth-hood is a semi-circular band
of numerous microscopic hooklets. The surface of the anterior larval
spiracle bears four rounded nodules.

The entire surface of the body is covered with microscopic, close-set,
pale brown, short, soft hairs. The segmental hairs are longer flexible
and about three in a clump. Eight transverse rows of them can be
made out posterior to the anterior spiracles. The body segments are
further indicated each by a group of about four transverse wrinkles.
About seven pairs of prolegs, consisting of ventral fleshy projections,
each bearing a clump of recurved hooklets; five pairs on segments
five to nine, inclusive, about equally developed and with a dozen or
more hooklets, the anterior ones largest; one pair on the venter of the
third segment which usually has fewer hooklets, and a smaller pair
on segment ten. The anus is a prominent transverse slit about 2 mm.
cephalad from the base cf the posterior respiratory organ, on the
venter of the eleventh segment.

Color dirty white or clay yellow.

Under laboratory conditions the larval period extended over
about two months from July to September. Although the larva
has been found only in human excrement, there is no reason to
believe it would not develop in other kinds of filth or decaying
material.* The larve were found in the moist, but not watery,
portions of the mass and several inches beneath the surface.

Puparium (Fig. 36-8, 9, 10). Pale brown. Length 8 to 9 mm; maxi-
mum width 3.25 to 3.75 mm.; maximum height 2.75 to 3.25 mm.
Broadest a little in front of the middle where it is nearly circular in
cross-section. Only a little narrowed and globose in front, but evenly
tapering caudad to about one-third the width just in front of the pos-
terior respiratory process. As viewed from the side, ventral line nearly
straight to within about two millimeters of the posterior end, thence
elevated; the dorsal line a little more strongly and abruptly elevated
anteriorly than posteriorly.

*Since writing this, I have found the larve and puparia at Presque
Isle and Houlton, July 8 and 9, in masses of rotting potatoes which had
beep swept out of store-houses and allowed to lie on the ground until
well-decayed. Adults emerged from the puparia, July 19 and 20.

‘Many adults were noted hovering—apparently for the purpose of ovi-
posting—about the above masses and also about decaying masses of
“sprouts” from potatoes used in planting.

252 MAINE AGRICULTURAL EXPERIMENT STATION. I916.

The anterior end bears, in addition to the characteristics remaining
from the larval stage, a pair of pupal respiratory cornua situated well
dorsad, their bases about .75 mm. apart (Fig. 36-8A, 10d). Each
cornuum strikingly like a common species of morel mushroom in
appearance; about .4 mm. broad and .5 mm. long, the basal third or
fourth slenderer. Its surface bears a hundred or more of minute
papillae each when very highly magnified (Fig. 36-9) showing a further
ornamentation of its surface with five to eight nodules.

The buccal hood of the larva occupies a position at the anterior
extremity of the ventral line (Fig. 36-10C), and although they are
much less conspicuous, the arrangement of thorns and hooklets remains
essentially as in the larval stage. For the emergence of the adult the
anterior end splits into a two-piece operculum; one transversely elon-
gate piece surrounding the pupal respiratory cornua; the other an
ovate piece, cephalad of this and including the anterior larval spiracles,
but not the two pairs of largest hooks. The posterior end of the
puparium much as in the larva; the respiratory process terminal and,
at each side of it, the three pairs of lateral processes of the body-wall,
somewhat shrunken and indurated. Slight traces of the transverse
wrinkling remain and on careful examination the larger hooklets of
the prolegs can be distinguished.

The duration in the pupa stage was between g and 15 days,
this stage being noted during late July and early August. The
pupz were found a few inches under the surface in the mod-
erately-dry parts of the excrement in which the larve had fed.
Pupation is accompanied by the induration of the larval skin
with chitin and the great inflation especially of larval segments

five to eleven.

Adult (Fig. 36-12, 13, 14). Eyes bare, face with a median keel-like
ridge, marginal cell open, third vein curved, anterior cross-vein beyond
the middle of the discal cell; hind femora extraordinarily thickened with
an angular projection below near outer end; abdomen of nearly equal
width.

Length 9 to 12 mm. Front in female narrow above; face gently
convex in profile in the male, a little concave near the middle in the
female; densely covered with yellowish gray pollen, leaving a slender
median stripe and a spot on the cheeks black. Antenne yellow, third
joint nearly square. Dorsum of thorax shining, greenish black, with
two rather distinct median pollinose stripes in front, two spots of the
same colored pollen in front of the scutellum, another in front of each
postalar callus, on the humeri, and a spot along the dorso-pleural
suture immediately behind the humeri. Scutellum yellow along the
border. First abdominal segment black, yellow on the sides; second
segment in front (but not reaching the sides) and a narrow median
stripe black, behind extending narrowly to the sides, more brownish,
forming an inverted T; third segment with a similar T but more
brownish, less distinct. In the female the black on the second segment

SYRPHIDAE OF MAINE. 253

is broader, the third segment black except a quadrangular spot in front
on each side. Front and middle legs yellow, except on the basal half
or more of the femora, black; hind legs black, the knees only yellow.
Description adapted from Williston (62, p. 207) and Verrall (55,

p. 571).
SyRITTA PIPIENS Linné.

This is one of our most abundant and wide spread species,
apparently occurring throughout most of Europe and North
America and common from spring to autumn. It has been
recorded breeding in horse-dung and cow-dung in Europe (17),
and Dr. L. O. Howard has noted the capture (but not the rear-
ing) of an adult about human feces.

The larve were found breeding in large numbers in moist
masses of guinea-pig manure in the animal room at Ohio State
University during the winter and spring of 1915. On July 7
at Orono, two puparia were taken from a drying mass of
human excrement at the opening of a sewer. Adults emerged
from them August 2 and 3. On July 7 and 12 a number of
females were found hovering about the above-mentioned mass
of filth. Two of them were enclosed in a vial and had soon
deposited a mass of several hundred eggs. They began hatch-
ing on July 16, the duration in the egg-stage having been
almost exactly four days.

This species in all its stages shows a close resemblance to
Tropidia quadrata and it will be described in comparison with
that species.

Egg. (Fig. 37-1, 2, 3). Swub-cylindrical, tapering toward the ends;
the micropylar end somewhat truncate, the opposite end rounded out;
nearly straight on the ventral side, somewhat rounded up dorsally.
Dimensions (ten specimens): Length .6325 to .6875 mm., average .665
mm.; maximum diameter .213 to .24 mm., average .23 mm.

The sculpturing of the chorion consists of polygonal elevated areas,
separated by narrow depressed lines which form a darker network
over the entire surface. About thirty such elevations the length of
the egg, fifty to sixty around it. With higher magnification (1-4 in.
objective) these elevated areas are seen to be finely papillose, and on
closer examination the papillae are seen to be grouped into areoles of
greater elevation, with depressions between them. As contrasted with
T. quadrata, it is evident that the grouping of the papillz into definite
rounded areoles is much less pronounced and that the areoles are
much more irregular in shape (Fig. 37-2; cf. fig. 36-7). For example
on the egg of T. quadrata the areoles are quite easily seen with a 2-3 in.

254 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

objective; while in Syritta pipiens they are hardly made out with less
than a I-4 in. objective and are not as definite at any magnification.
Color white.

Larva (Figs. 37-4, 5, 9). Superficially resembling the larva of T.
quadrata, especially in the differentiation of the anterior segments into
a false-head and in the possession of three pairs of lateral fleshy pro-
jections just anterior to the short, posterior respiratory process. It
differs from T. quadrata in its much smaller size, in being less nearly
cylindrical, broader in the median segments, and somewhat flatter; the
posterior respiratory organ is relatively longer and slenderer and the
constriction between segments three and four (at the side of the false
head) more marked.

Length about 10 mm., maximum width about 2.75 mm., maximum
height about 2 mm. Broadest in the region ef segments seven to nine.
Tapering moderately backward to less than half the width at the
base of segment twelve; much more moderately toward the head.
The false head 1.75 to 2 mm. broad, not as well developed as in
T. quadrata. Color dirty yellowish. The entire integument covered
with pale and delicate, close-set microscopic hairs, longer on the more
exposed portions. The false head lacks the conspicuous hooks or
thorns of T. quadrata, the vestiture being specialized only into the
transverse band of microscopic hooklets above the mouth. Antenne,
mouth-hood and lateral mouth-folds not differing noticeably from T.
quadrata. The false-head with about a dozen longitudinal furrows,
one on the mid-dorsal line. The anterior larval spiracles located
between the first and second furrow from the mid-dorsal line, sessile;
each apparently with three rounded nodules on its summit. There
are seven pairs of prolegs on segments 3 and 5 to Io, inclusive, the
first pair situated more widely apart than the others, the last pair
smaller, each with about two dozen hooklets of varying size.

The posterior respiratory organ is a brown, chitinized, polished tube,
projecting about .75 mm. (.5 to I mm.) its width ranging from .25 to
235 mm., its depth from .2 to .25 mm. A little broader at base than at
apex, the latter truncated. The tube is semi-transparent and the two
large tracheal trunks can be seen throughout its length. The stigmal
plates similar to those of JT. quadrata but with distinct differences.
The most important difference is that the three pairs of spiracles are
less distinctly S-shaped and each is ornamented with from nine to four-
teen (compared with about twenty for T. quadrata) of rounded lateral
projections or denticles irregular in size and irregularly distributed.

Puparium (Fig. 37-6, 7, 8). Dimensions (15 specimens): Length,
inclusive of the posterior respiratory appendage which retains the same
dimensions as in the larva, 5.9 to 7.9 mm., average 6.8 mm.; maximum
width 2.75 to 3.4 mm., average 2.95 mm.; maximum height 2.65 to
2.95 mm., avefage 2.68 mm. In outhkine elongate ovate, a little more
attenuated posteriorly, this attenuation more pronounced than in T.
quadrata. Nearly circular as seen from in front a little flattened on
the venter. The ventral line as seen from the side, straight from mouth-

SYRPHIDAE OF MAINE. 255

parts almost to the posterior respiratory process before which it
becomes a little elevated. The dorsal line begins with a very sharp,
nearly rectangular elevation in front, followed by a gentle flexure
reaching its greatest height a little in front of the middle. The descent
is gradual throughout the third quarter of the length, thence more
abruptly to the posterior respiratory organ.

The pupal respiratory processes (Fig. 37-64, 8) penetrate the pupa-
rium near the antero-dorsal flexure, about 2 mm. from the ventral line
and half a millimeter caudad. Each measures .35 to .5 mm. in length,
maximum diameter about .2 mm. Morel-shaped, the proximal half
being somewhat more slender, the distal half dilated and studded with
about seventy-five minute nodules. Each of these nodules when very
highly magnified (Fig. 37-7) is seen to consist of four, five or six oval
elevations each with a median slit. The anterior face of the expanded
part traversed by a branching shallow groove. The clumps of hooklets
on larval prolegs are conspicuous along the mid-ventral line and the
posterior respiratory process retains its larval characteristics.

Adult (Fig. 37-10, 11). A small slender, nearly bare, fly, black with
yellow markings and very thick hind femora; marginal cell open, third
vein gently curved, anterior cross-vein near the middle of the discal cell.
Description adapted from Williston (62, p. 240) and Verrall (55, p. 612).

Length, 7 to 8 mm. Face and front satiny yellowish white. Front of
female narrow above, shining black, with two small pollinose spots;
vertical triangle of male elongate. Antenne reddish yellow. Dorsum
of thorax black, nearly bare, in front with two approximate pollinose
spots. The humeri and to the suture and all the pleure yellowish or
whitish pollinose. Abdomen: opaque black in front, shining behind;
narrow sides of first segment and a broad spot at each side of the
second, yellow, somewhat whitish pollinose. “At the extreme produced
base of the second segment a remarkable fringe of whitish hairs,

the only obvious pubescence on the abdomen” (55, p. 613) ;

third abdominal segment with a smaller yellow spot at each basal corner
and the fourth with a narrow, interrupted yellowish-white pollinose
cross-band, the hind margin narrowly yellow. In the female the spots
smaller, the sides of the third segment in front metallic, scarcely at all
yellow, but with a light pollinose spot. Legs yellowish-red with obscure
brownish markings; hind femora black, with the base and a usually
incomplete ring near the middle, reddish yellow; hind tibie at the
middle and tip brown or black.

2560 MAINE AGRICULTURAL EXPERIMENT STATION. I9QI16.

ARTIFICIAL Keys TO THE KNOWN LARVAE AND PUPAE OF SYRPHIDAE

KEY TO TYPES OF LARVAE

1. Body terminating in a long, flexible and extensile, rat-tail-like
respiratory appendage (often longer than the body). Larvae
aquatic, semi-aquatic, or living in moist decaying materials.
The puparium with a pair of prominent, anterior, respiratory
cotnna. .( See. also), p.. 210) Vs.052)- « » jeden ¢--us oe
Iv. THE LONG-TAILED FILTH-INHABITING TYPE (Genera Eristalis,
Helophilus, Chilosia, Chalcomyia, Sericomyia, Mallota, etc.)

Posterior respiratory appendage considerably shorter than one-
fourth the length of the body, rigid. Habits various, but not
meqatic Marwan werd Sk «niche edged an es oe ee 2

2. Larvae short-oval or rounded in outline, convex above, and with
a very flat, creeping-sole, ventrally, around which is a fringe
of spines. The shape constant and sub-hemispherical; na
evident transverse wrinkling of the body-wall, but the dorsum
often nicely reticulated. Larvae living in ant-nests. The pu-
parium sub-hemispherical, and with prominent anterior cor-
nua.‘ (See also p. 211 )< 4. csnediiy. o103 5s ee ee eee
rade Nae eed aires ate v. THE MICRODON TYPE (Genus Microdon)

Shape of larva elongate-oval with the venter flattened, or sub-
cylindrical; the outline not constant, but the body especially
the anterior end, capable of considerable extension when
aetive: inlet 2 pte eee ewe’ th Meio. Fea ee eee 2

3. Body nearly cylindrical, the anterior end not attenuated, but
rounded out, forming a false-head. ‘Three fleshy, finger-like
processes at each side of the last body-segment. No external
mouth-parts. Puparium with prominent anterior cornua. (See
also pi 210)... stl. ac. ooo io, Ser ee, eee ee ee
111. THE SHORT-TAILED FILTH-INHABITING TYPE (See key below)

The anterior end of the body considerably attenuated, when active;
no false-head. Black, chitinized mouth-parts present........ 4

4. Body nearly circular in cross-section. Mouth-parts of two re-
curved hooks, uniting basally into a mouth-hood. Stigmal
plates with groups of minute, palmately-arranged, plumose
hair's. |) €See “also ip,’ 209): oe Die . 2 Fn RE a ee
ee een 11. THE BORING TYPE (Merodon equestris Fabr.)

Body always noticeably, often much, flattened. Mouth-parts of
two, A-shaped jaws. Stigmal plates with various ornamentation
but not with plumose hairs. Puparium rounded in front, at-
tenuated behind, and apparently without pupal respiratory cor-
nua (See also p; sa08). 20 esi Ss Ga oe os + Se ae
es I. THE APHIDOPHAGOUS TYPE (See key below)

Lael
.

SYRPHIDAE OF MAINE. 257
I. THE APHIDOPHAGOUS TYPE

Key to Species

Dorsal pair of slit-like spiracles much shorter than the other pairs,
its carina rounded. Larvae phytophagous...........+..e++se0-
0 OT Bo lah IE ei OP ies papi oe Toxomerus politus, p. 216.
All the slit-like spiracles elongate, at least several times as long as
broad, or at least the dorsal pair not conspicuously shorter.

PE SC ARIAS Lo ho cle nn dips ha ora hh ee eae a 9 2
Posterior slit-like spiracles greatly elongate and extensively sin-
uate or undulate. (Fig. 34-3) ......... Syrphus mtens, p. 242.
Posterior slit-like spiracles straight or somewhat curved, never
MUTA MMEEAE Sag oa cx cc & ow Segne eee and eee ee aranhs ee 3

General color greenish, with white longitudinal stripes. Rather
smooth-bodied larvae with no integumental vestiture and the
Meameniat. sence NOt PTOMUMEN! . 00s << cenapapaes en ane« e000 4

General color yellowish, reddish or brownish ................04. 6

Posterior respiratory organ less than half as long as broad. Slit-
like spiracles less than twice as long as broad. Viscera usually
plainly visible thru the skin. (Fig. 30-5 and 6) ..............
a ee ee ee Melanostoma mellinum, p. 226.

Posterior respiratory organ considerably longer than broad. Slit-
like spiracles each at least three times as long as broad....... 5

Stigmal plates roughened, the spiracles well elevated and separated
by spur-like elevations. The two tubes very slightly divergent
eemene tat, (eis. 792-00 and 68.622 225 eM, nn one ve
os SES a are Allograpta obliqua, p. 234.

End éf posterior respiratory appendage nicely rounded off, smooth,
the spiracles not elevated, and not separated by perceptible
spurs. The two tubes not at all divergent. (Fig. 31e72 and 73).
J ee a ge ee ee Sphaerophoria cylindrica, p. 231.

Integument of the larva bare except for the segmental spines..... 7

The entire dorsal surface of the larva covered with short, micro-
scopic spines, black, or sometimes light in color and then not
ete, 3th, Ce nas naman oho eee eee tasmine aol ea 8

Posterior respiratory appendage longer than broad; inter-spirac-
ce aeines Tater prominent... ol ol ck ee tee re teases
ou NL? ee oh ne eee aie Syrphus xanthostomus (34, p. 81).

Posterior respiratory appendage broader than long; inter-spirac-
mat oddlcs ot prominent. (Fig 33-13) si. .sccecccsweccrsce
we Be 3 ot eer Syrphus torvus, p. 240.

Segmental spines conspicuous or raised on prominent, fleshy or

spiny, conical elevations easily seen by the naked eye ......... 9

Segmental spines not prominent and not. raised on conspicuous,
conical projections; sometimes hard to distinguish from the
Miteroinenial ‘spines | o.i2.3 vex dew' Hains eh tes. aosesak, II

258 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

9. All of the segmental elevations and segmental spines, on the dorsal
surface of the body, of nearly equal size. The inter-spiracular
spaces on the stigmal plates with lamellate, upright ridges.
(Pig. 35-2. anid) 59) a0.06,.0% eee Didea fasciata fuscipes, p. 246.

The dorsal, segmental elevations (ones next the median pair) in
the principal body-segments much reduced in size. The dor-
sal spiracular nodule long and prominent; the other inter-

spiracular spaces with small nodules or delicate hairs........ 10

10. Posterior respiratory appendage broader than long ...............

bro, Ap Rnenae a Be Sete ete wine eine aN Paragus bicolor (31, p- 397).
Posterior respiratory appendage considerably longer than broad.

Rei oe Reine tags Seen Hee Paragus tibialis (31, p. 402).

11. Integumental spines black. Inter-spiracular spaces with short,

stout; black ‘spurs.’ (Fig, 32-46, 40 and 40) ~aaneee eae

Do eiee Cie aie eae ne seh ease we Syrphus americanus, p. 236.

Integumental spines light yellow. Inter-spiracular spaces with long

slender hairs, (CP ig? 20-2)" o..; ee ss. - Pipiza pisticoides, p. 224.

III THE SHORT-TAILED FILTH-INHABITING TYPE

Key to Species

1. False-head of larva without any conspicuous, black, anterior
thorns or chitinized hooklets. Posterior respiratory appendage
about three times as long as broad. The spiracles on stigmal
plates with about ten lateral denticles. (Fig. 37-5 and 9)......
Pati Ratha bectann erie cis See De oe Syritta pipiens, p. 253.

Antero-dorsal part of false-head ornamented with black hooks or
thorns, visible to the naked eye. Posterior respiratory appen-
dage less than twice as long as broad. The posterior spiracles
with more than fifteen lateral denticles oct eae 2

2. Two prominent hooks on each side of the false-head, their bases
united into one chitinous plate. The posterior spiracles with
forty to eighty lateral denticles........ Zelima (Xylota) pigra.

Two prominent hooks on each side of the false-head, their bases
separated by a little more than their length; also several trans-
verse rows of slightly smaller thorns between these pairs. The
posterior spiracles with fifteen to thirty lateral denticles. (Fig.
20-5, 1G. .c7 Pa AS” eeak ial: mine teense Tropidia quadrata, p. 248.

GLOSSARY OF NEW or UNUSUAL TERMS.

Anterior larval spiracle: The breathing pore, or opening to the
trachea, situated at the side of the third body segment of the larva
(Figs. 34-2; 32-46b; and 36-5B).

Anterior stigmata: See anterior larval spiracle or pupal respiratory
cornua.

SYRPHIDAE OF MAINE. 259

Areolés: As applied to the sculpturing of the chorion or egg-shell,
a minute differentiated spot on the surface of a body (q. v.).

Arm: As applied to the sculpturing of the chorion or egg-shell, a
slender, root-like, elevated process from a body (q. v.), extending into
the depression between the bodies.

Aschiza: (Brauer) a section of the dipterous sub-order Cyclorrhapha
in which the frontal lunule and suture above the root of the antenneze
are wanting. It includes the families Syrphidae, Pipunculidae, Platy-
pezidae and Phoridae.

Body: As applied to the sculpturing of the chorion or egg-shell, a
microscopic elevated area surrounded by a depression.

Carina: An elevated ridge; see dorso-lateral carina, ventro- battial
carina; and also under slit-like spiracle.

Circular plate: “Button” of authors: a usually smooth, or rough-
ened, circular or oval area of the stigmal plate situated, typically,
dorso-mediad on the latter; and usually distinct in color or texture
from the rest of the stigmal surface; sometimes partially or completely
surrounded by a ridge (Figs, 30-5B; 34-3A and 36-6B).

Cyclorrhapha: (Brauer) a sub-order of the Diptera in which the
larve lack a differentiated head; the pupe are always enclosed in the
hardened larval skin or puparium, from which the fly escapes through
a circular orifice or operculum at the anterior end.

Dorsal line: The upper margin of the puparium, when viewed from
the side, extending from the position of the larval mouth-parts in front,
dorsally around to the base of the posterior respiratory process behind.

Dorsal spiracular spine, ridge or nodule: A chitinous elevation of
the stigmal plate mesad from the circular plate (q. v.) (Fig. 32-50a).

Dorso-lateral carina: An irregular, longitudinal, zig-zag ridge along
the side of the body of the larva (formed by the fusion of the ends of
transverse folds of the integument) above the ventro-lateral carina,
and bearing the dorso-lateral segmental bristles of successive segments.

False-head: A globose grouping of the anterior segments of cer-
tain larve, partially constricted from the succeeding segment.

Integumenta] vestiture: Minute, close-set, short, microscopic hairs
or bristles covering the integument of the larva at least on the dorsal
surface; contrasted with the segmental vestiture (q. v.).

Interspiracular ornamentation, hairs, spines, spurs, nodules, ridgés,
or lamellae: Armature of various kinds occurring in the interspira-
cular spaces (q. v.). See also, dorsal spiracular spine.

Interspiracular spaces: The areas between and around the slit-like
spiracles on the apex of the posterior respiratory process. These are
four in number on each stigmal plate; one between the dorsal slit-like
spiracle and the circular plate; one between dorsal and median spiracles;
one between median and ventral spiracles; and one mesad from the
ventral spiracle.

Jaws: Of aphidophagous larve, a pair of chitinized, A-shaped lips
above and below the mouth-opening (Fig. 30-4C).

200 MAINE AGRICULTURAL EXPERIMENT STATION. I9I6.

Jowls: The part of the head below the cheeks and the eyes
(Wingate) ; also known as the cheeks or gene.

Lateral mouth-hooks: JHeavy, black, chitinized, curved hooks or
thorns on the head segments but separated from the jaws by an inter-
vening space, in which respect they differ from the mouth-hooklets
(q. v.), as also in being usually shorter and broader at the base (Figs.
30-4A ; 31-67c; and 33-IIc).

Mouth-hood: A dorsally convex, ventrally concave, chitinous termi-
nation of the cephalo-pharyngeal skeleton of the larve of certain types,
which covers the anterior opening of the alimentary canal. (Fig. 34-
FE y;

Mouth-hooklets: Chitinized, black, microscopic thorns, elongate
and slender or short and thick, situated closely at the sides of the jaws
and evidently of assistance in prehension (Figs. 33-r1d; and 35-3c and
d).

Posterior larval spiracles: See posterior respiratory organ.

Posterior respiratory or breathing organ, appendage, tube or
process: An appendage borne terminally or dorsally on the twelfth
(last) larval segment, consisting of two tubes more or less completely
fused mesad throughout their length, enclosing two large trachee and
bearing on their ends the posterior larval spiracles (q. v.) through
which the trachee open. This tube is considered for descriptive pur-
poses to have been originally a terminal appendage; consequently its
length is the distance from its base (where the tube becomes differ-
entiated from the last segment) to its apex; its width is the maximum
transverse diameter across both stigmal plates (q. v.); and its depth
or height is the maximum dorso-ventral distance at the tip when ori-
ented as described above; (when the tube is very short and directed
dorsad, what appears to be the cephalo-caudad distance).

Pupal respiratory cornua: (A pair of chitinous terminations of the
trachee leading to the prothorax of the developing fly, which are pushed
through the puparium, dorso-cephalad, for respiration during the pupa
stage. Their surface bears a few or many denticles or papille about
which the air enters. Sometimes very conspicuous, sometimes (especi-
ally on the puparia of aphidophagous larve) exceedingly minute and
indistinguishable (Fig. 30-74).

Segmental bristles, hairs, spines or vestiture: A transverse row
of more or less prominent hairs or other armature, specialized from the
integumental vestiture (q. v.) across the dorsum and sides of each
larval segment. These hairs are twelve in number, and for convenience
in description, I have named them in order, beginning with the pair
nearest the mid-dorsal line and proceeding laterad and ventrad: a,
median; b, dorsal; c, dorso-lateral; d, lateral; e, posterior ventro-lateral;
and f, anterior ventro-lateral.

Segmental elevation or cone: A more or less prominent conical
fleshy elevation subtending a segmental bristle (q. v.).

Slit-like spiracle: One of the three pairs of openings of the
trachee at the posterior end of the body of the larva, on the stigmal

SYRPHIDAE OF MAINE. 261

plate (q. v.); usually straight or slightly curved but often sinuate,
convoluted or undulated, and may bear lateral projections or denticles.
They usually radiate and are usually elevated on carine. They are
named dorsal, median and ventral pairs the former usually nearest
the circular plate.

Spiracle: An opening to a trachea, or breathing pore. See anterior
larval spiracle, slit-like spiracle, stigmata.

Stigmal plate: Either half of the truncated apex of the posterior
respiratory process, usually separated from the other lateral half by a
distinct median dorso-ventral incision. It bears three slit-like spiracles
(q. v.), the circular plate, and the interspiracular ornamentation.

Stigmata: See spiracle, pupal respiratory cornua.

Ventral line: The margin of the puparium, when viewed from the
side, extending from the position of the larval mouth-parts in front,
along the venter to the base of the posterior respiratory process at the
posterior end.

Ventro-lateral carina: An irregular, longitudinal, fleshy ridge along
the side of the body of the larva underneath the dorso-lateral carina
and bearing the lateral segmental bristles.

BIBLIOGRAPHY.

1. AwpricH, J. M. Catalog of N. A. Diptera, Smithsonian Miscella-
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2. AusTEN, E. E. British flies which Cause Myiasis in Man. Reports -
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3. BAKER, Cart F. Biological Notes on Some Colorado Diptera, Ent.
News, VI, 174, 1895.

4. Banks, NaTHAN. Note on Ceria Willistonii Kahl, Proc. Ent. Soc.
Wash. v. 310, 1903.

4b. Barser, H. S. Notes on a wood-boring Syrphid, Proc. Ent. Soc.

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BLOoMFIELD, E. N. Ento., Month. Mag. XXXIV, 244.

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7. BRAUER, FrrepricH. Die Zweiflugler des Kaiserlichen Museums zu
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8. Bucxton, G. B. A Natural History of Eristalis tenax, the Drone-
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9. CuHacnon, E. Preliminaires sur ies Syrphides de la Province de
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10. Comstock, J. H. A Manual for the Study of Insects.

11. Coguittett, D. W. Notes on the Syrphid Fly, Pipiza radicum
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1904.

12. Darcxe, V. A. E. Note on rearing of Xylota pigra Fabr., Ent.
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a de

262 MAINE AGRICULTURAL EXPERIMENT STATION. IQI6.

13.

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46:

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27.

33.

34.

Exvpitt, Beitrage zur Verwandlungsgeschicte von Microdon muta-
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Fotsom, J. W. The Insect Pests of Clover and Alfalfa, Univ.
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Hatt, M. C. and Mum, J. T. A Critical Study of a Case of Myiasis
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Howarp, L. O. ‘A Contribution to the Study of the Fauna of
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Husparp, H. G. Insects Affecting the Orange, U. S. Dept. of Agr.
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Jounson, Cuas. W. Notes on Some Dipterous Larve, Psyche,
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JoHnson, CHas. W. Report on the Insects of New Jersey, Diptera.
From Annual Rept. N. J. State Mus., 1909.

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Martiocu, JoHn R. Some Additional Records of Chironomidae
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McCAmpsBeELL, E. F. and Corprer, H. J. Myiasis intestinalis due to
Infection with three Species of Dipterous Larve. Jour. Am.
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Metcatr, C. L. A Preliminary Report on the Life-Histories of
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35.

52.
53.
54.
55.

50.

57-

58.

59.

SYRPHIDAE OF MAINE. 263

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* 1870.

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1894.

Reference to the following important paper on the habits of the
genus Chilosia was inadvertently omitted from the table in Figure
28, page 207. .

66. Burke, H. E. Black Check in Western Hemlock, U. S. Dept. Agr.,
Bur. Entomology, Circular 61. Discusses habits and life-history
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their injury to Western Hemlock and Lowland Fir, respectively.

FIGURES AND EXPLANATIONS

EXPLANATION OF FIGURE 20.

Pipiza pisticoides Willist.

t Side view of larva x12; A, lateral mouth-hook, immediately in front
of which is the antenna; B, anterior larval spiracle; C, posterior
respiratory process.

2 End view of posterior respiratory process x185; showing the two

stigmal plates, each with a circular plate, interspiracular hairs and

slit-like spiracles.

Side view of puparium x12.

4 Dorsal view of adult female x18.

Didea fasciata Macq. var. fuscipes Loew.
5 Sculpturing on egg-shell of Didea fasciata fuscipes (q. V.)

wy

of Pipiga pisticoides Willist.

Fig. 29. Life-stages

Ny

nr

EXPLANATION OF FIGURE 30.

Melanostoma mellinum Linné.

Masses of eggs as deposited by female on leaf of rape x12.
Egg-mass from another female, showing the characteristic ranking of
eggs side by side, x12.

A small area of the egg-shell highly magnified, showing nature of
sculpturing.

Ventral view of head-segments of larva much enlarged; A, lateral
mouth-hook; B, antenna; C, upper jaw; D, anterior larval spiracle.
End view of posterior respiratory organ x 175, showing the two
stigmal plates; A, the carina bearing left, dorsal, slit-like spiracle;
B, right circular plate; C, one of the inter-spiracular nodules.
Dorsal view of larva x 10; A, left longitudinal tracheal trunk; B,
antenna; C, termination of the right tracheal trunk in the anterior
spiracle; D, posterior respiratory organ.

Dorsal view of puparium x 10; A, right pupal respiratory cornua
with trachea leading from it; B, posterior larval respiratory organ.
The outline of head, thorax with wing-pads, and abdomen of the
developing fly show thru the puparium.

Side view of pupal respiratory cornua, highly magnified.

End view of pupal respiratory cornua with afferent trachea, highly
magnified.

Side view of head of adult &.

Wing.

Abdomen of @.

Posterior part of thorax and abdomen of ¢.

wea\

-_
MEST

inne.

Melanostoma mellinum Li

s of

stage

EXPLANATION-OF FIGURE 35.

61-70 Allograpta obliqua Say.

Egg x 20, from the side.

Dorsal view of egg x 20.

The sculpturing of the egg-shell, highly magnified.

Adult female x 7.

Young larva just hatched, x 50; a, antenne; b, internal esophageal

frame-work; c, the posterior respiratory tubes.

Mature larva x 9; a, antenne; b, position of anterior spiracles; c,

posterior respiratory tubes.

Antero-ventral view of head of larva much enlarged; a, antenna; b,

upper jaw; c, outer pair of mouth-hooks; d, lateral mouth-hooklets ;

e, internal esophageal framework; f, lower jaw.

End view of posterior respiratory appendage, much enlarged; a, one

of the spiracles; b, the circular plate; c, the interspiracular spines.

Dorsal view of puparium x 5; a, posterior respiratory appendage.

Lateral view of puparium x 3; a, posterior respiratory appendage.
71-78 Sphacrophoria cylindrica Say.

Adult male from the side x 7.

Dorsal view of posterior respiratory appendage, much enlarged; a,

spiracles; b, circular plate.

End view of posterior respiratory appendage, much enlarged; a,

circular plate; b, one of the three pairs of spiracles.

Anterior larval respiratory cornua with spiracles from the side,

highly magnified.

End view of the same.

Mature larva from the side x 6; a, posterior respiratory appendage.

Ventral view of head of larva much enlarged; a, antenne; b, upper

jaw; c, lateral mouth-hooklets; d, the outer pair of mouth-hooks; e,

esophageal framework; f, lower jaw.

Lateral view of puparium x 7; a, the posterior respiratory append-

age; the dotted lines represent other shapes in which the pupal

envelope may indurate.

o\

.)
AD,

j0G

se

Oy

7

BN

Life-stages of Allograpta obliqua and Sphaerophoria cylindrica

Pig..31.

(After Metcalf, from The Ohio Naturalist.)

52
aS

EXPLANATION OF FIGURE 32.

Syrphus americanus Wied.

Egg from the side x 17.

Dorsal view of egg x I7.

A small part of the surface of egg-shell showing sculpturing, highly
magnified.

Adult male about 5 times natural size.

Larva just hatched x 59; a, posterior respiratory appendage.
Full-grown larva x 7; a, antenne; b, anterior spiracle; c, posterior
respiratory appendage.

Anterior view of larva, much enlarged, showing mouth-parts, anten-
ne, etc.; a, right anterior spiracle; b, antenna; c, upper jaw; d, lower
jaw; e, the three pairs of mouth-hooks.

Dorsal view of right anterior spiracle, highly magnified.

End or posterior view of posterior respiratory organ x 55; a, dorsal
spiracular spine; b, one of the three pairs of slit-like spiracles.
Side or dorsal view of posterior respiratory organ x 55; lettering
as in Fig. 49.

Appearance of a part of the puparium externally in the region of
the mouth-parts much enlarged; a, right anterior spiracle with short
piece of trachea attached; b, lower jaw of larva; c, upper jaw of
larva; d, chitinous esophageal framework; e, mouth-hooks of larva.
Hind leg of pupa showing flexure of tibiz at a.

An early pupal stage from the side; a, b, and c, developing legs; d,
wing-pad; e, mouth-parts.

A much later pupal stage, ventral view; a, the delicate investing
membrane.

Dorsal view of puparium x 5; a, posterior respiratory organ.

Outline of puparium from the side. The dotted outline is given te
show the typical shape of a parasitized puparium.

Lateral view of head of female x 7.

Larva of parasite, Bassus lactatorius; mouth-parts at a, ventral view.
Pupa of B. laetatorius, ventral view.

Figs. 53, 54, 58, and 59 each about 5 times natural size.

a\

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ca

=

Life stages of Syrphus americanus Wied.
from The Ohio Naturalist.)

(After

Metcalf,

IO

II

12
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14

£5
16

EXPLANATION OF FIGURE 33.

Syrphus torvus Loew.
Adult male, natural size and enlarged.
Larva, natural size and enlarged; a, anterior spiracle; b, posterior
spiracle.
Antero-ventral view of head and mouth-parts much enlarged; a and
b, upper and lower jaws partially separated; c, outer pair of mouth
hooks; d and e, two inner pairs of mouth-hooklets; f, antenna; g,
anterior spiracle; h, sense papille.
Anterior spiracle of larva highly magnified.
Posterior breathing appendages much enlarged; a, one of the six
caudal spiracles.
Puparium from above, natural size and enlarged; a, posterior spira-
cles.
Puparium from side showing line of cleavage for escape of adult.
Head of female in profile.

a)

is

Fig. 33. Life-stages of Syrphus torvus Loew. (After Metcalf, from
The Ohio Naturalist.)

EXPLANATION OF FIGURE 34.

Syrphus nitens Ztt.
Dorsal view-of larva x 7.5; A, antenna; B, posterior respiratory
organ.
Anterior larval spiracle, highly magnified.
End view of posterior respiratory organ x 75, showing the two
stigmal plates; A, circular plate; B, one of the inter-spiracular
nodules; C, median slit-like spiracle.
Postero-ventral view of posterior respiratory organ x 75, showing
the position of the three pairs of extensively-convoluted, slit-like
spiracles; the carine on which they are elevated; and the ridges
median to the circular plates.
The retractile, renal? flabellz, as protracted from the anal opening.
Dorsal view of puparium x 7.5; showing shape, markings, and at
A, the posterior, larval, respiratory organ.
Dorsal view of adult d, x 7.5.

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Fig. 34. Life-stages of Syrphus nitens Ztt..

EXPLANATION OF FIGURE 35.

Didea fasciata Macq. var fuscipes Loew.

Adult female x 6.

Larva about six times natural size; a, anterior spiracle; b, caudal
spiracles.

Antero-ventral view of head and mouth-parts of larva, enlarged;
a, upper jaw with a small pair of hooklets at the side; b, lower
jaw; c and d, lateral hooklets; e, antenna; f, sense papille.

Right anterior spiracle much magnified.

Posterior breathing organs enlarged; a, one of the radiating spiracles.
Dorsal view of puparium a little more than five times natural size;
a, caudal spiracles.

Puparium from the side showing arrangement of spines and line of
cleavage for escape of adult.

Head of male in profile.

See also Figure 29-5.

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7

MYM

Dr

i

With

(After Metcalf, from The Ohio Naturalist.)

i Life-stages of Didea fasciata Macq. var. fuscipes Loew.

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IO

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TZ

13
14

EXPLANATION OF FIGURE 36.

Tropidia quadrata Say.

A few areoles from one of the bodies on the surface of the egg-
shell, very highly magnified.

A small area of the chorion or egg-shell, highly magnified, show-
ing the elevated bodies each of which is further ornamented with a
number of rounded areoles.

Dorsal view of an egg x 22.

Anterior larval spiracle highly magnified.

Dorsal view of larva x 6; A, antenna; B, anterior larval spiracle,
just laterad of which are the two large lateral hooks; C, posterior
respiratory organ, at each side of which are the three lateral fleshy
processes from the body-wall.

End-view of posterior respiratory organ, showing the two stigmal
plates; A, one of the palmately-arranged groups of plumose, inter-
spiracular hairs; B, circular plate; C, dorsal slit-like spiracle show-
ing characteristic shape and dentations; much magnified.

Anterior view of head-segments of larva, much enlarged, showing
arrangement of spines or thorns; A, the posterior row of thorns;
B, anterior larval spiracle, situated in the middle row of thorns;
C, the two pairs of large, lateral thorns, between which is the ante-
rior row of thorns; D, left antenna; E, the first pair of pro-legs;
F, the mouth-hood.

Lateral view of puparium x 6; A, left pupal respiratory cornua;
B, posterior larval respiratory organ, at the side of which are the
three lateral processes from the body-wall. Note also in the cephalo-
ventral region the thorns of the larval head.

A group of papillae from the pupal respiratory cornua, very highly
magnified, each showing a number of nodules arranged in a circle.
Anterior view of puparium x 12; A, left pupal respiratory cornua;
B, anterior larval spiracle; C, remnant of the larval mouth-hood;
D, the two large lateral thorns or hzoks of the larval head. The
heavy dotted lines erclose the two pieces of the operculum which
split off for the emergence of the adult.

Side view of head of male, showing characteristic facial carina.
Dorsal view of scutellum and abdomen of male, showing character-
istic markings.

Wing.

Hind leg showing angular projection at outer end of femur.

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Tropidia quadrata

Life-stages of

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EXPLANATION OF FIGURE 37.

Syritta pipiens Linné.

A mass of eggs as deposited by a female on filth x 20.

A few areoles from one of the bodies on the surface of the egg-
shell, very highly magnified.

A small area of the chorion or egg-shell highly magnified, showing
the elevated bodies each of which is further indistinctly marked
with rounded areoles.

Anterior larval spiracle, highly magnified.

Larva, dorsal view x 6; A, antenna; B, posterior respiratory organ.
Dorsal view of puparium x 6; A, pupal respiratory cornua; B,
posterior larval respiratory organ.

A group of papille from the pupal respiratory cornua each com-
posed of four to six nodules circularly arranged; very highly mag-
nified.

One of the pupal respiratory cornua much enlarged.

End view of posterior respiratory organ, showing the two stigmal
plates each with a circular plate, three slit-like, sinuate and denticu-
lated spiracles (A), and four groups of palmately-arranged, plumose,
inter-spiracular hairs.

Wing.

Hind leg, showing color-pattern and spines on femur.

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