Samuel Wendell Williston.

Manual of the families and genera of North American Diptera online

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days and escape from the lower end; here they grov»^ rapidly,
at times moving quickly, at other times resting quietly near
the surface, breathing through the stigmatic tube at the tail,
which tube has at its end a fringe of hairs that serves to close
the opening when under water, and to suspend the larvae from
the surface Avhile breathing. They are usually known as
'•wrigglers". The head in the larva is fully differentiated
and usually has eyes ; the jaws are tliickly ciliated and fringed
with hairs, by means of which a cui-rent of water is produced



22 NORTH AMERICAN DIPTERA.

that brings little particles of food within reach of the mouth.
After changing their skin two or three times they assume a
more club-shaped appearance, in which the parts of the adult
insect are indistinctly seen. The abdomen terminates in two
leaf-like appendages that act as propellers ; but in general
these pupae remain near the surface, except when disturbed,
and take no food. The breathing organs are no longer a tube
at the tip, but there are now two that spring from the si'des of
the thoracic segments. Finally when the perfect mosquito is
ready to emerge from the pupa, the back of the skin, which
has now come to the surface and is exposed, splits, and the liy
carefully and gradually extricates itself from the membrane
which thus serves the place of a raft till the legs and wings
are sufficiently firm. But right now is the period of the mos-
quito's life most fraught with danger ; a wavelet, a breath of
air, or a raindrop, hopelessly shipwrecks the frail bark. This
is why running waters are free from these insects.

TABLE OF GENERA.

1. Proboscis short, not longer than the head ; metatarsi longer than the fol-

lowing joint. ...... CoRETHRA Meigeii.

Proboscis much elongated, longer than the head and thorax together. 2

2. Proboscis strongly curved, palpi of the male very long, of the female

short. .....

Proboscis straight. ... *

3. Palpi in both sexes of equal length.
Palpi in the male long, short in female.

4. Palpi longer than the antennge.
Palpi shorter than the antennae.



Megarrhinus Rob. Desv.

3

. . . . 4
. CuLEX Liime.

Anopheles Meigen.
iEoKS Meigen.



5. CHIRONOMID^.

Gnatlike flies of slender form, the males conspicuous for
their plumose antennae, seldom reaching ten millimeters in
length. Head small, spheroidal, more or less concealed by a
projecting, hoodlike thorax. Antennae threadlike or beadlike.



CHIRONOMIDiE. 23

with not less than six nor more than fifteen joints ; in the
male usually with a long dense plumosity ; in the female wdth
inconspicuous hairs and sometimes with a smaller number of
joints ; the first joint short and thick. Eyes reniform or oval ;
ocelli wanting or rudimentary ; proboscis short ; palpi four-
jointed ; the last usually elongated. Thorax ovate, very con-
vex, usually projecting above in front more or less over the
head ; without transverse suture ; scutellum small, hemispher-
ical. Abdomen usually narrow and long, composed of eight
segments ; hypopygium projecting forcep-like ; ovipositor very
short, but little developed ; legs usually slender and long ;
especially the front pair; coxae of moderate length. Tarsi often
much elongated. Wings narrow and long ; bare or uniformly
hairy ; anterior veins stronger and darker colored than the
others ; auxiliary vein complete, but usually weak and slender ;
second longitudinal vein usually wanting; third vein some-
times forked close to its origin, the upper branch often rectan-
gular and having the appearance of a supernumerary cross-
vein; fourth vein sometimes, the fifth usually, furcate ; poste-
rior cross-vein often wanting ; the costal vein terminates near
the tip of the wing at the termination of the third vein.

This family comprises a large number of very delicate, often
minute flies, which have not been much studied by entomolo-
gists ; about one thousand species are known throughout the
world. They will be distinguished from the mosquitoes, which
they resemble very much, by the costal vein not being contin-
uous on the posterior side of the wing. The antennae are
conspicuous, especially in the males, although agreeing in this
respect with male mosquitoes. The larvae are soft-skinned,
worm-like, often blood-red in color and usually aquatic, as are
also the active pupae, though some live in decomposing veg-
etable matter, or in the earth. These midges are often seen,
especially in the early spring or in the autumn, in immense
swarms, dancing in the air, and have doubtless in many cases
given rise to exaggerated stories of mosquitoes. Over mead-



24 NORTH AMERICAN DIPTERA.

ows in the Eocky Mountains the writer has seen them rise at
nightfall in the most incredible numbers, producing a hum-
ming noise like that of a distant waterfall, and audible for a
considerable distance. While at rest they usually raise their
forelegs in the air and keep them constantly vibrating.
Aquatic larvse may be frequently met with in standing water,
often extremely delicate little creatures, so transparent as to
be hardly distinguishable ; they have been dredged from
nearly one thousand feet below the surface of Lake Superior.

Most of the species are inoffensive, or actually beneficial as
scavengers. There are some, however, belonging to the genus
Ceratopogon, and its allies, and known generally as midges,
or punkies, which have the power of sucking blood and are
extremely annoying. In the White Mountains, at the sea-
shore, along mountain streams generally, and in the West
Indies they are especially troublesome. The larvae live in the
flowing sap of trees, in decaying vegetation or under fallen
leaves.

The following table, largely adopted from V. d. Wulp,
contains many genera heretofore known only as exotic, not a
few of which will doubtless be found in the United States
when the family has received more attention with us.

TABLE OF GENERA.

1. Antennas of the J long-plumose or penicillate 2

Antennae of the ^ with short hairs. ..... lo

2. Second posterior cell wanting and hence no second basal cell. . 3
Second posterior cell present, the second basal cell complete. . 12

3. Fourth longitudinal vein furcate. ...... 4

Fourth longitudinal vein not furcate; antennae with an unequal num-
ber of joints in the two sexes; antennal joints of the ^ plumose to
the tip; thorax projecting in front over tlie head. ... 5

4. "Palpi composed of three joints". . . Tersesthes Townsend.
Palpi composed of four joints ; antennae of the male penicillate,

the last joint bare ; dorsum of the thorax not produced over the
head. ....... Ceratopooon Meigen.



CHIRONOMIDiE. 25

5. Anal angle of the wings obsolete. . . Corynoneura Winnertz.
Anal angle prominent. ......... 6

0. Wings bare. ........... 7

Wings hairy. . . . . . . . . . . 10

7. Front metatarsi as long or longer than the tibiae. Chironomus Meigen.
Front metatarsi distinctly shorter than their tibiae. ... 8

8. Legs black and white annulate. . . Cricotopus V. d. Wulp.
Legs unicolorous or with portions darker. . . . . . 9

9. Posterior branch of the posterior furcation sinuous.

Camptocladius V. d. Wulp,
Posterior branch of the posterior furcation straight.

Orthocladius V. d. Wulp.

10. Front metatarsi longer than their tibiae. Tanytarsus V. d. Wulp.
Front metatarsi shorter than their tibise. ..... 11

11. Thorax produced conically in front over the head ; hind tibise dilated

and hairy Euryxnemus V. d. Wulp.

Thorax moderately produced; hind tibiae not dilated.

Metriocnemus V. d. Wulp.

12. Antennae with an unequal number of joints in the two sexes ( J 14, 9 ^);

penultimate joint of the front tarsi usually short and broad.

DiAMESA Meigen.
Antennae with an equal number of joints in the two sexes (15); the
penultimate joint of the front tarsi longer than the ultimate joint.

Tanypus Meigen.

13. Proboscis and palpi rudimentary ; abdomen shorter than the thorax.

Clunio Haliday.
Proboscis and palpi as usual; abdomen at least as long as the thorax. 14

14. Palpi three-jointed Tersesthes Townsend.

Palpi four-jointed. ......... 15

15. Antennae with the same number of joints in both sexes. . . 16
Antennae with an unequal number of joints in $ and 9 J ^^S^ mod-
erately long, the front tarsi the longest ; thorax produced over the
head ; wings shorter than the abdomen. . Hydrob^nus Fries.

10. Antennae with seven joints in $ and 9- Chasmatonotds Loew.

Antennae witli fifteen joints in $ and 9- • • • • • ^"

17. Wings hyaline Macropeza Meigen.

Wings spotted (West Indies) (Ecacta Poey.



26 NOETH AMERICAN DIPTERA^,

6. OEPHNEPHILID.E.

Small, obscurely reddish yellow, bare flies of peculiar appear-
ance. Head small, round; eyes round, contiguous in front ;
ocelli wanting ; proboscis short; palpi longer than the antennae,
five-jointed, the first joint short, the second the thickest ;
antennae situated near the oral margin, apparently consisting
of a small first joint, an oval second joint and a terminal
arista; the second joint and the arista are, however, complex,
the first composed of three and the latter of seven segments,
the last of which terminates in a bristle. Thorax strongly
convex, robust, without transverse suture, somewhat impressed
before the scutellum. Scutellum rather large, obtusely three
cornered; metanotum arched. Abdomen narrower than the
thorax, cylindrical, composed of seven segments ; male geni-
talia thick, the basal piece swollen, bladder-like ; ovipositor
with broad, rounded lamellae. Legs simple, comparatively
short ; coxae not elongated ; tibiae without spurs ; tarsi mod-
erately long; the front pair longer than the tibiae, the penul-
timate joint short; claws small; pulvilli distinct. Wings
longer than the abdomen ; auxiliary vein short, terminating
in the costa; second longitudinal vein sinuous; third and
fourth veins not furcate ; anal angle rounded ; basal cells short.

But two or three species of this singular family are known,
and of them even, so far as I can learn, the larval habits are
yet unknown. The species all belong to one genus, Oriihne-
jjhila Haliday. The small fly is found on the banks of streams.



7. PSYCHODIDyE.
Very thickly haired, minute flies, in appearance lepidoptera-
like. Head small ; ocelli wanting. Antennae as long as the
head and thorax together, bead-like ; thickly haired, composed
of from twelve to sixteen joints ; the two basal joints thicker
and short-cylindric. Proboscis usually short ; in some exotic
genera {Fhlebotomus) elongated and horny ; palpi incurved



PSYCHODIDiE. 27

and liairy; composed of four joints of nearly equal length.
Thorax not very convex, without transverse suture ; scu-
tellum rounded. Abdomen cylindrical, composed of from
six to eight joints; male genitalia prominent. Legs very
short, densely hairy ; claws small ; pulvilli rudimentary.
Wings large, ovate in shape ; when at rest lying roof-shaped
over the abdomen ; densely covered with long hairs or tomen-
tum, which also forms a fringe around their margin ; the
costal vein continuous around the wing; veins strong, for
the most part concealed beneath the hair; neuration
formed almost wholly by longitudinal veins; the anterior
cross-vein is very short, and lies very near the root of the
wing ; auxiliary vein weak or indistinct ; first longitudinal
vein very near the costa ; second longitudinal vein arises very
near the origin of the first, and is usually twice forked, that
is, the upper branch of the furcation is again furcate ; third
vein simple, terminating at or beyond the tip of the wing ;
fourth vein furcate ; fifth and sixth terminating in the border
of the wing; seventh vein usually distinct, reaching to the
margin of the wing, sometimes wanting.

The members of this family are often very minute, rarely
exceeding the length of four millimeters ; they occur in shady
places, on windows, about outhouses, and will be readily recog-
nized from their peculiar moth-like appearance ; they run
about nimbly, but their flight is weak. The larvae live in
rotting vegetable material, or in water, especially stagnant
water; they are cylindrical, with the posterior end termi-
nating in a short, usually firmly chitinized, stigmatic tube ;
the maxillae are imperfectly developed, there are eye-spots on
the head, and the segment behind the head are without feet.
The pupae are inactive, with two long tube-like, anterior
stigmata.

But two genera are known to occur in North America;
Psychoda and Ferieoma, which may be distinguished from
each other by the termination of the third vein of the wing,



28 NORTH AMERICAN DIPTERA.

which is at or before the tip in Fsychoda, and distinctly be-
hind it in Pericoma. In their study, one should use prefer-
ably a compound microscope, and it may be necessary either
to mount a wing, or at least to remove the scales. Attention
should be paid to the shape of the antennae and palpi, as well
as the genitalia, legs and wings. Fsychoda alternata Say is
our most common species, apparently extending over all the
United States.



8. DIXID^.

Eather small, slender, nearly bare species. Proboscis some-
what projecting; palpi four-jointed; antennae long, the basal
joints thick, those of the flagellum hair-like, and the joints
indistinctly distinguishable. Eyes round, dichoptic ; no ocelli.
Thorax strongly convex, without transverse suture ; scutellum
transverse ; metanotum arched. Abdomen long and slender,
composed of seven or eight segments, thickened posteriorly in
the male, pointed in the female. Legs long and slender ;
coxae somewhat elongated; tibiae without terminal spurs.
Wings comparatively large ; auxiliary vein present, termina-
ting in the costa before the middle of the wing ; the second
vein arises from the first near the middle of the wing and
appears to be the beginning of the third vein, which continues
its direction while the second arches suddenly forward at the
anterior cross-vein and is furcate ; fourth vein furcate ; four
posterior cells present ; the two basal cells very large ; the
anterior cross-vein is placed at the beginning of the third
vein, where the second vein curves forward.

The family Dixidae comprises about a score of known species
belonging to the single genus Dixa. It has been placed among
the Tipulidae and Culicidae, but seems best isolated into a sep-
arate family. The larvae are aquatic, resembling those of the
mosquitoes. The flies are found in bushy, moist places about
forests, and have been observed by Winnertz dancing in the
air in swarms.



TIPULIDiE. 29

9. TIPULID^.

Large to moderately small, slender flies, with long, slender
legs. Head spherical, occiput strongly developed ; face often
produced snout-like. Eyes round, separated by the broad
front ; sometimes approximated below the antennse ; ocelli
usually wanting. Antennae rarely shorter, usually longer
than the head and thorax together; bead or thread-like,
composed of from six to nineteen joints ; the joints of
flagellum never plumose, but usually with more or less
conspicuous, bristly hairs; the joints sometimes serrated.
Proboscis more or less projecting, in a few genera very much
elongated; palpi four or live jointed; the terminal joint often
elongated, whiplash-like. Thorax convex, usually with a very
distinct suture in the form of a shallow V ; pro-thorax usually
distinct, collar-like ; scutellum half round ; metanotum strong-
ly developed. Abdomen cylindrical, composed of seven or
eight segments; genitalia prominent, in the male very varia-
ble in structure ; in the female the ovipositor with two pairs
of long, horny, pointed valves. Legs very long and slender ;
the tibiae sometimes with terminal spurs. Wings long, but
comparatively narrow ; in rest spread apart or lying par-
allel over the abdomen ; always six longitudinal veins ; usually
a complete discal cell ; both basal cells long ; the anal cell
usually open ; seventh vein distinct (save in the Ftycliop-
terince) and of variable form ; alulets rounded, rarely angular.

The family Tipulidse comprises the largest of the Nemato-
cerous flies, some of which exceed two inches in length. The
legs are very elongate and delicate, so delicate, indeed, that one
seldom succeeds in capturing the flies without the loss of one
or more. Flies of this description with a distinctly impressed
V-shaped suture on the dorsum of the thorax will be immedi-
ately recognized as belonging to this family. The female
differs from most other flies in having the ovipositor often
adapted for depositing eggs within the ground or other firm
substances. When the weather is favorable the eggs hatch



30 NORTH AMERICAN DIPTERA.

out in a little more than a week. The larvse are ash-gray or
brownish in color, more or less transparent, composed of twelve
segments. The head is incompletely differentiated and re-
tractile, and has the maxillae and mandibles more or less horny
and stout; there are short fleshy antennae. The organs of
locomotion generally consist of transverse swellings on the
under side of the body, provided with very minute, stiff bris-
tles. The anal end of the body is truncate, with a single pair of
spiracles; and the margins of the truncature are for the most
part provided with fleshy retractile processes of variable size
and shape. In the aquatic larvae there is a long tube at the
end of the body which serves for breathing when raised to the
surface of the water.

Most of the larvae live in the earth or in soil-like, decom-
posing wood, in fungi, or in water. Others live on the leaves
of plants and are like caterpillars in appearance, the resem-
blance to which is yet more heightened by the green color,
with a crest of tubercles on the back.

The pupae, like those of many of the members of this sub-
order are free. The thorax has two horn-like processes which
represent the thoracic spiracles, one of which may acquire a
very great length, for the purpose of breathing from the sur-
face while under water. The abdominal segments have trans-
verse rows of hairs, bristles or spines, which enable the pupa
to escape from its place of concealment when about to com-
plete its metamorphosis.

The adult flies are commonly seen in the late summer
and autumn. They will be most usually met with in meadow-
lands and forests, flying awkwardly for a few steps, close to
the ground till they become entangled in the grass or twigs,
and then, extricating themselves, rising again to repeat the
same aimless, clumsy flight.

The name of "daddy-long-legs" is the one most usually
applied to members of this family in England, but in America
this term is commonly used to designate the Phalangidae or



TIPULID^.. 31

harvest spiders. The English name of "crane-flies" is prefer-
able. Commonly they are harmless, but some of the species
in the larval state are very destructive, feeding upon the ten-
der rootlets of grass and grain, and causing the plants over
large surfaces to wither and die. There are about twelve
hundred species known.

In this family are placed several wingless forms, or those
with the wings more or less rudimentary. One of the former
is Chionea, the species of which are found on snow, often in
the coldest weather.

The family Tipulidse is easily divided into three subfamilies,
which I prefer to call the Ptychopterinee, Limnobiinse and
Tipulinse, and which correspond precisely with the Ptychop-
terina, Tipulidse longipalpi and Tipulidse brevipalpi of Osten
Sacken.

TABLE OF GENERA.

1. Seventh longitudinal vein present, that is there are two longitudinal

veins between the fifth vein and the posterior margin of the wing. 2

Seventh longitudinal vein absent; no distinct V-shaped suture on

mesonotum. ....... Ptychopterin^.

2. Last joint of the palpi shorter or not much longer than the two preced-

ing together; the auxiliary vein usually ends in the costa and is
connected with the first longitudinal vein by a distinct cross-vein ;
antennae six to sixteen jointed. .... Limnobiin^,
Last joint of the palpi whiplasli-like, much longer than the three pre-
ceding together; antennse composed of not more than thirteen joints ;
the auxiliary vein ends in the first longitudinal vein by an abrupt
curvature at the tip, not connected with the first vein by a cross-
vein TlPULIN^.

LIMXOBIIN^.

1. Wingless, spider-like in appearance. . . . Chionea Dalman.
Winged. ............ 2

2. Antennae composed of apparently 28 joints, long; anal cell closed ; no

empodia or spurs (West Indies, South America).

PoLYMERA Wiedemann.
Antennae not apparently composed of more than 10 joints. . . 3



32 NORTH AMERICAN DIPTERA.

3. Posterior cross-vein situated before the middle of the wing; three pos-

terior cells present (West Indies). . . Thambeta Williston.
Posterior cross-vein not situated before the middle of the wing. . 4

4. A single submarginal cell present. . . . . . . 5

Two submarginal cells present. 7

5. Antennae 14-jointed. . . . . . . . Limnobiiki.

Antennffi 16-jointed. ......... 6

6. Tibiffi with spurs at the tip ; the first longitudinal vein usually ends in

the second Cylindrotomini.

Tibise without spurs ; the first vein ends in the costa. . Antochini.

7. Tibise without spurs at the tip. . . . . . Eriopterini.

Tibise with spurs at the tip 8

8. The subcostal cross- vein is beyond the origin of the second longitudi-

nal vein. ........... 9

The subcostal cross-vein is before the origin of the second longitudinal
vein. Amalopini.

9. Antennae composed of sixteen joints. . . . Limnophilini.
Antennae composed of from six to ten joints, often much elongated.

AXISOMERINI.

LIMNOBIIXI.

1. Proboscis longer than the head and thorax together.

Geranomyia Haliday.
Proboscis shorter than the head and thorax together, ... 2

2. Antennae pectinate or subpectinate, at least, in the male.

Rhipidia Meigen.



Antennae not pectinate.



3. A supernumerary cross- vein between the sixth and seventh veins.

Throchobola Osten Sacken.
No cross-vein connecting the sixth and seventh veins. ... 4

4. Tip of the auxiliary vein usually opposite, or before, or only a short

distance beyond the origin of the second vein; marginal cross-
vein always at the tip of the first longitudinal vein ; legs slender.

DiCRANOMYiA Stephens.
Tip of the auxiliary vein usually far beyond the origin of the second
vein; marginal cross-vein sometimes at the tip but often some dis-
tance before the tip of the first vein ; legs comparatively stout.

LiMXOBiA Meigen.



TIPULID^. 33

ANTOCHINI.

1. Rostrum at least as long as the head, sometimes very long; no margmal

cross-vein. ........... 2

Rostrum shorter than the head 4

2. Wings without suhmarginal cell Toxorkhina Loew.

Wings with a suhmarginal cell 3

3. Rostrum not much longer than the head. . Rhamphidia Meigen.
Rostrum the length of the whole body. Elephantomyia Osten Sacken.

4. Discal cell open. . 5

Discal cell closed 6

5. Second basal cell considerably shorter than the first, the great cross-

vein more proximal tlian the origin of the second vein ; three

posterior cells Diotrepha Osten Sacken.

Second basal cell of about the same length as the first.

Elliptera Schiner.

6. No marginal cross-vein whatever. . . . Atarba Osten Sacken.
Marginal cross- vein present 7

7. First longitudinal vein ends in the costa nearly opposite the inner end

of the suhmarginal cell. ........ 8

The first vein ends in the costa far beyond the inner end of the suhmar-
ginal cell. .... Dicranoptycha Osten Sacken.

8. Suhmarginal cell as long or but little longer than the first posterior cell.

Teuciiolabis Osten Sacken.
Suhmarginal cell much longer than the first posterior cell.

Antocha Osten Sacken.

ERIOPTERINI.

1. Five posterior cells. .... Cladura Osten Sacken.
Four posterior cells. ......... 2

2. The inner marginal cell has almost the sliape of an equilateral triangle.

Cryptolabis Osten Sacken.
Inner marginal cell of the usual shape. . . . * . . 3

3. Wings conspicuously hairy on the whole surface or along the veins. 4
Wings not conspicuously hairy, veins bare or near]}' so.* . . 6

4. Wings hairy on the whole surface. . Rhypholophus Kolenati.
Wings hairy along the veins only. ...... 5

* Antennal joints subreniform and nodose; the eyes nearly contiguous
above and below (Central America). . Sigmatomera Osten Sacken.

5



34 NORTH AMERICAN DIPTERA.

5. Second submarginal cell longer than the first. Erioptera Meigen.
Eirst submarginal cell longer than the second. Molophilus Curtis.

6. Eirst submarginal cell short, not more than half the length of the

second. .......•••• '


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Online LibrarySamuel Wendell WillistonManual of the families and genera of North American Diptera → online text (page 7 of 18)