Samuel Wendell Williston.

Manual of the families and genera of North American Diptera online

. (page 10 of 18)
Online LibrarySamuel Wendell WillistonManual of the families and genera of North American Diptera → online text (page 10 of 18)
Font size
QR-code for this ebook


distinct terminal style; very large, robust, tliickly pilose species.

Hyperechia Schiner.

Hind femora thickened toward the end; antennae without terminal

style; more elongate, less pilose species. . . Nusa Walker.

11. Thorax and abdomen nearly or quite bare; hind femora with spinous

tubercles below Lampria Macquart.

Thorax and abdomen pilose; larger species usually. . . .12

12. Densely pilose species; the abdomen short, broad, usually broader

beyond the middle; proboscis thick. . . Dasyllis Loew.

Less pilose, more elongate species ; proboscis more elongate and slender.

Laphria Meigen.



ASILID^. 59

ASILINiE.

1. Bristle of antennae plumose. . . . Ommatius Wiedemann.
Bristle not plumose . 2

2. The veins closing the discal and fourth posterior cells in the same

straight line or parallel (Central, S. America). Atractia Macquart.
The veins closing the discal and fourth posterior cells not parallel. 3

3. The posterior branch of the third vein curves forward to meet the costa

before the tip of the wing. ....... 4

The posterior branch of the third vein terminates beyond the tip of the
wing. ............ 5

4. Oviduct cylindrical, with a terminal circlet of spines.

Proctacanthus Macquart.
Oviduct laterally flattened, without circlet of spines. Erax Macquart.

5. Two submarginal cells (Asilus sens. lat). . . . . . 7

Three submarginal cells. . . . ' . . . . . 6

6. Abdomen shorter than the wings ; body thickly pilose, claws obtuse.

Mallophora Macquart.
Abdomen longer than the wings ; body thinly pilose. Promachus Loew.

7. Oviduct laterally compressed. ■ . 8

Oviduct conical. . . • IH

8. Face without gibbosity, narrow throughout, not at all carinate, the

mystax composed of a few long hairs. Stenoprosopus Loew.

Face with gibbosity, or not carinate or unusually narrow. . . 9

9. End lamellge of the oviduct wedged in. . . Eutolmus Loew.
End lamellse free, style-like 10

10. Posterior border of the last ventral segment in the ^ more or less

widened Machimus Loew.

Posterior border (^) not widened. 11

11. Legs prevailing shining yellow in color. . Heligmoneura Bigot.
Legs prevailing black, or light and opaque colored. ... 12

12. Abdomen shining black above and below. - Stilpnogaster Loew.
Abdomen not shining above and below. ... - . 13

13. Male genitalia club-like Neoitamus Loew.

Male genitalia not club-like; the sixth and seventh segments take no

part in the formation of the oviduct. . . . Tolmerus.

14. Abdominal segments with bristles before the incisures.

Philodicus Loew.
Abdominal segments without bristles before the incisures. . . 15

15. Bright colored large species Asilus Linne.

Small, ash-gray species - . Rhadiurgus Loew.



60 NORTH AMERICAN DIPTERA.

18. APIOCERID^.

Eatlier large, elongate, chsetophorous, thinly pilose flies.
Antennae with a simple, short style. Front not excavated,
broader in the female. Ocelli present. Face short. Probos-
cis with pseado-tracheate labella. Third longitudinal vein of
the wing usually furcate ; basal cells large ; five posterior cells
present. Empodia wanting. Male forceps enlarged.

Less than a dozen species of this family are known through-
out the world, six of which have been described from North
America. The flies have much the appearance of large The-
revids or Asilids, from which they will be at once distinguish-
ed by the anterior curvature of the outer veins of the wings.
The larvae are wholly unknown. For a discussion of the rela-
tionships of the family, as also a bibliographical list, see
Kansas University Quarterly i, 101.

TABLE OF GENERA.

1. Palpi two-jointed, large; the second vein from the disoal vein termi-

nates beyond the tip of the wing. . . Apiocera Westwood.

Pa^lpi one-jointed, small; the second vein from the discal cell terminates

before the tip of the wing. . . . . . . .2

2. Anal cell closed Rhaphomidas Osten Sacken.

Anal cell open. Apomidas Coquillett.



19. :n^emistrinidj5.

Species of moderate size, not elongate, thinly or densely
pilose. Neuration complicated, the fourth and fifth veins are
curved forward to terminate before the tip of the wing, the
anterior cross-vein is obsolete, that is the third and fourth
veins coalesce for a short distance ; basal cells long. Antennae
small, short; third joint simple, with a terminal, slender,
jointed style. Proboscis sometimes elongate. Ovipositor of
the female elongate, often slender. Tibiae without spurs ;



NEMISTRINID^.. 61

empodia developed pulvilliform, but, with the pul villi often
minute.

Throughout the world about one hundred species of this
family are known, the larger part of which are from South
America and Australia. Only six species are known from
North America and two or three from all Europe. Some of
the species have the wings with numerous cross-veins, almost
recticulate in appearance. Megistorliynclmis longirostris from
Africa, though only about two-thirds of an inch in length has
a proboscis nearly three inches long. The flies are flower
flies, resembling in their habiis the Bombyliidse.

But little is known of the larvse. The females of Hir^mon-
eura ohscura have been observed laying their eggs deeply
within the burrows of Anthaxia, a wood-boring insect, in the
pine rails of fences. The eggs were found in clusters and the
young larvae hatched from them differed very singularly from
those of a more mature growth. They are more slender, but
differ chiefly in having each of the abdominal segments from
the sixth to the twelfth provided with a pair of false legs
bearing a single elongate seta at the tip, the hooks j^ointing
backward ; on the thirteenth segment there are two pairs of
similar setae, the hooks of which, however, point forwards,
thus enabling the larva to attach itself firmly and raise itself
erect. These young larvae issued in great numbers from the
burrows in which they were hatched and, placing themselves
erect, w^ere blown away by the wind. Here for a time they
have not been followed, but it is probable that they attach
themselves by the aid of the ventral hooks to the bodies of
large-sized beetles, by which they are carried into the ground
when the female enters to deposit her eggs. This is probable
from the fact that hundreds of pupae and pupa skins were
observed near the fence. On searching below these the larval
skins were found at a depth of about two inches and still
deeper were found the remains of the beetles, Rhizoti'ogias
solstitialis, in some instances with the larvae yet within them.



62 NORTH AMEEICAN DIPTERA.

TABLE OF GENERA.

1, Proboscis short, protruding but little from the oral opening; eyes bare
or pilose; two or three submarginal cells. Hirmoneuba Meigen.

Proboscis long, directed backwards; antennae broadly separated; eyes
bare; ovipositor of the 9 composed of two slender lamellae; three
submarginal cells present. . . Rhynchocephalus Fischer.



20. MYDAID^.

Rather large to very large, thinly clothed or bare, elongate
flies. iSTeuration complicated, the basal cells long; the fourth
vein always terminating at or before the tip of the wing.
Antennae elongate, the third joint flattened, with a terminal
lamella. Front excavated between the eyes. Ocelli wanting.
Proboscis short, with fleshy labella and without palpi (in our
species). Empodia very little developed, not pulvilliform.

The family Mydaidae comprises only about one hundred
known species, but among them are the largest of the order,
a few measuring two inches in length and rivaled only by the
Acanthomeridse among the other families of diptera. The
larvae of species of Mydas live in decaying wood, and it is
probable that all the members of the family have similar
habits. They are known to be predaceous in some cases upon
the larvse of beetles. The larvae of M. fulvipes are nearly
two inches in length, with swellings below the abdominal seg-
ments for locomotion ; the body is depressed and somewhat
widened, with the posterior extremity broader and obtuse.
The pupa of M. clavatus has as its anterior end two strong,
sharp, outwardly curved hooks ; the first abdominal segment
has, on its anterior border above, a row of very long, erect
spines curved backward at the tip. Another series of spines
is situated on the anterior border of the last segment, and, on
the same segment there is a pair of hooks at the tip curved
downward.



MYDAIDiE. 63

TABLE OF GENERA.

1. Terminal segment of the 9 abdomen with a circlet of spines. . 2
Terminal segment without circle of spines.* . Mydas Fabricius.

2. A small cross- vein runs into the hind margin of the wing between the

anal cell and the tip; hind tibiaa of 9 with spurs.

EcTYPHus Gerstaecker.
No such small cross-vein ; hind tibiae of 9 without spurs at the tip.

Leptomydas Gerstaecker.



21. BOMBYLIID^.

Medium sized to small flies ; often with abundant, long, del-
icate pile. Head as broad or narrower than the thorax, often
spherical in shape, closely applied to the thorax. Eyes large,
often contiguous above in the $ and rarely also in the 9.
Antennae porrect, usually of but moderate length ; third joint
simple ; style usually small and indistinct and sometimes
wholly wanting. Ocelli present. Proboscis usually project-
ing from the oral cavity, and slender ; sometimes elongate ;
at other times short, with broad labella. Abdomen composed
of from six to eight segments, slender in a few genera only.
Legs moderately long, weak, with short, weak bristles or
spines. Pulvilli sometimes rudimentary, the empodia almost
always so, the tarsi and claws small. Tegulse small. Wings
often with dark markings; two or more submarginal, three or
four posterior cells present; discal cell present in all our
genera ; anal cell closed in or near the border of the wing, or
narrowly open.

The family Bombyliidse comprises about fifteen hundred
known species. Most of them are swift flying insects, often

* "Generis Ectyphi proximum, differt: antennis elongatis, segmento pe-
nultimo cylindrico, ultimo, 9) ^irciter diiplo longiore, compresso, basi
parum dilatato, apice obtuse acuminate 9> duplo breviore, obtusiore, abdo-
minis segmento ultimo inermi, cyathiformi, utrinque, parum dilatato.
Long. c2o mm. undique niger, abdomine nitente, alis violaceo micanti-
bus, extremo apice albidis — P. phyllocerus, Rocky Mts."

Phyllomidas Bigot.



64 NORTH AMERICAN DIPTERA.

hovering motionless in the air for a time and darting away
like a flash. They seek sunny places in woodland roads,
about blossoms or on rank vegetation. The Anthracinae are
a group especially characteristic of arid regions. In general
the members of the family are prettily and delicately marked,
and their life histories are often very interesting. In the
adult state they are flower flies, feeding upon the pollen and
honey deep within the blossoms, extracted by aid of their long
proboscis. The larvae of species of Aiohmhantiis and SystcecMis,
occurring in western America, are found in the egg-pods of
the locust, Caloptenus spretus. "The larvae begin to trans-
form themselves into the pupa state early in the summer, and
the pupa pushes itself half way out of the ground in order to
disclose the fly. They continue to issue during the summer
months. As a rule but one year is required for full develop-
ment. Aphoebantus is first observed as a yellowish white
grub, about half an inch long when extended, it being usually
curved so that the head and tail nearly meet. It is usually
found in a case of locust eggs which it has devoured, pushing
the empty shells aside, and at last occupying the space where
were twenty-one to thirty-six eggs. Often it is found in a
little space below a number of egg-cases, as though it had
feasted off the contents of several nests" (Riley). The larvae
of Anthrax have been found parasitic upon Megachile, Osinia,
Odynerus, Mamestra, Noctua and Agrotis ; those of Argyra-
TYiwha upon Pelo-pceus, Megaehile, Cemonus, Osmia and Calico-
dovia ; those of Bombylius upon A7idrena and Colletes ; those
of Toxophora upon Eimienes ; those of Callostoma in the egg-
cases of Caloptenus itaiicce; those of Systropus ui^oii Lima-
codes, etc.

TABLE OF GENERA.

1. The bifurcation of the second and third veins takes place opposite or
nearly opposite the anterior cross- vein, the distance not exceeding
the length of the cross- vein; the second vein forms a knee at its
origin, the third vein in a straight line with the pref urea. . 2



BOMBYLIID^. 65

The bifurcation of the second and third veins takes place at a greater
distance from the cross-vein, usually at an acute angle. . . 13

2. Antennal style distinct, that is it is separated from tlie third joint or

from the styliform prolongation of the joint by a distinct suture. 3

The third joint not with a distinct style separated by a suture, the style

when present very minute. . . . . . . . 8

3. Antennal style with a pencil of hairs at the tip; pulvilli distinct; front

tibiae with bristles. ......... 4

Antennal style not terminating in a pencil of hairs ; three or four sub-
marginal cells present. . 5

4. Outer submarginal cell bisected by a cross-vein {Spogostylum Coquil-

lett non Macquart) Coquillettia, nov.

Outer submarginal cell not bisected by a cross-vein, the anterior branch
of the third vein sometimes connected with the second by a cross-
vein (Argyramoeba Schiner). . . Spogostylum Macquart.

5. Pulvilli distinct Aldrichia Coquillett.

Pulvilli rudimentary or wanting . . . . . . .6

6. The outer submarginal cell divided by a cross- vein, making four sub-

marginal cells. ..... Hyperalonia Eondani.

The outer submarginal cell not divided by a cross-vein. . . 7

7. First posterior cell bisected near its middle by a cross-vein.

ExoPTATA Coquillett.
First posterior cell not bisected ; posterior claws with a basal tooth.

ExopROSOPA Macquart.

8. Eyes of male contiguous at the vertex ; anal cell closed.

AsTROPHANES Ostcu Sackcu.
Eyes of male not contiguous at the vertex; anal cell open. . . 9

9. Anal cell widest at its middle. . . . . . . .10

Anal cell widest at the margin. . . . . Makcia Coquillett.

10. The second vein strongly contorted at the end in the shape of a recum-

bent letter S ; three submarginal cells present.

DiPALTA Osten Sacken.
The second vein not strongly contorted at the end. ... 11

11. Three submarginal cells normally present; proboscis elongate.

Stonyx Osten Sacken.
Two submarginal cells normally present 12

12. The contact of the discal cell with the third posterior not much longer

than its contact with the fourth posterior; proboscis long; sides of
the abdomen with fringe of scales and not with hairs only.

Lepidanthrax Osten Sacken.



66



NORTH AMERICAN DIPTERA.



The contact of the discal cell with the third posterior at least twice as
long as its contact with the fourth posterior, the latter contact often
merely punctiform. . . . . . Anthrax Scopoli.

13. Wings with three posterior cells. 39

Wings with four posterior cells 14

14. First posterior cell closed 15

Eirst posterior cell open. . . , . . . . . 22

15. Three submarginal cells present. 10

Two submarginal cells. ........ 17

16. Head broader than the thorax ; posterior orbits not excised.

Pantarbes Osten Sacken.
Head narrower than the thorax ; posterior orbits excised.

Triplasius Loew.

17. First basal cell longer than the second. . . . . . 18

First basal cell not longer than the second. .... 21

18. Proboscis very short, not protruding beyond the oral margin ; anal cell

usually closed; large species (Cen. America). Anisotamia Macquart.
Proboscis more or less elongate ; anal cell open. ... 19

19. First posterior cell closed at some distance from the border of the

wing. ........... 20

First posterior cell narrowed, or closed in or near tlie margin of tlie
the wing; small species (5-6 mm.) . Thlipsogaster Rondani.

20. Head comparatively small; the emargination of the oceipal orbits al-

most imperceptible BoMBYLiLS Linne.

Head broad ; emargination of the occipital orbits distinct.

Heterostylum Macquart.

21. Face thickly clothed with pile.
Face sparsely clothed with pile.

22. Two submarginal cells present. .
Three submarginal cells present.

23. Bare species; tibias without bristles.
More or less pilose species ; tibiae with bristles. .... 24

24. Antennae as long as the head, the third joint not longer than the first

two together. .......... 25

Antennae shorter than "the head, the third joint twice as long as the first
two together. ...... Exepacmus Coquillett.

25. First antennal joint not thickened. ...... 20

First antennal joint extraordinarily thickened. . Ploas Latreille.

26. "Scutellum deeply sulcate longitudinally". Geminaria Coquillett.
Scutellum convex, not sulcate. .... Lordotus Loew.



Anastcechus Osten Sacken.
Systcechus Loew.

... 27
.... 23

Amphicosmus Coquillett.



BOMBYLIID^. 67

27. Anal cell open 30

Anal cell closed 28

28. Proboscis short . Oncodoceea Macquart.

Proboscis elongate. ......... 29

29. Third joint of the antennas with long bristly hairs ; face with long hair.

AcREOTRiCHUs Macquart.

Third joint of the antennae without or with short bristly hairs above ;

face bare or shortly pilose Phthiria Meigen.

30. Body clothed with more scales than hairs, gibbose; antennas long, the

first joint unusually long. . . . Lepidophora Westwood.
Body clothed chiefly with hair, or else nearly bare. ... 31

31. Body more or less pilose; tibiae usually bristly. ... 32
Body bare; tibiae bare or feebly bristly. . . . . . 37

32. Both basal cells of equal length. . . . Sparnopolius Loew.
First basal cell longer than the second 33

33. Third antennal joint but little longer than the first; mesonotum of

male sometimes muriacate and the costa denticulate. Eclimus Loew.
Third joint of the antennae more than twice the length of the first, bul-
bous at the base. ......... 34

34. The origin of the second vein takes place before the proximal end of

the discal cell at an acute angle. . . . . . . 35

The origin of the second vein is beyond the proximal end of the discal
cell and is rectangular. . . . Desmatoneura Williston.

35. Third antennal joint scarcely longer than wide. Eucessia Coquillett.
Third antennal joint much longer tlian wide. . . . .36

36. Face projecting in profile. . . . . Epacmtjs Osten Sacken.
Face retreating. Aphcebantus Loew.

37. Ocellar tubercle situated near the hind edge of the front. . . 38
Ocellar tubercle situated near the middle of the front.

Metacosmus Coquillett.

38. Antennae elongate, third joint flattened, the style flattened and com-

posed of two distinct segments. . . Desmatomyia Williston.
Antennae not elongated and with a distinct bisegmentated style.

Paracosmds Osten Sacken.

39. Slender, elongate species. . . • , • • .• • • 40
Shorter, more thick-set species, the abdomen never cylindrical. 41

40. Females holoptic like the males ; abdomen enlarged at its extremity.

Systropus Wiedemann.
Females dichoptic; abdomen cylindrical, not enlarged at the extremity.

DoLicHOMYiA Wiedemann.



6S NOHTH AMERICAN DIPTERA.

41. Three submarginal cells. . . ^ * . . . . 42
Two submarginal cells. . . . - . Geron Meigen.

42. Body clothed with more scales than hairs; abdomen decunibent; an-

tennse long. . , . . . . Toxophora Meigen.

Body clothed chiefly with hair ; abdomen not decumbent.

Rhabdopselaphus Bigot.



22. THEREVID^.

Rather small or moderate sized, elongate, bristly, sometimes
pilose, predaceous flies. Eyes of the male contiguous ; front
in the female not excavated. Antennae composed of three
joints, the third simple, with a terminal style, sometimes
Avanting. Proboscis projecting, the labella broad. Ocelli
present. Abdomen elongate ; genitalia moderately or but lit-
tle prominent. Legs with bristles ; empodia wanting. Third
longitudinal vein of the wings furcate, the posterior branch
terminating beyond the tip of the wing ; five posterior cells,
anal cell closed toward the margin of the wing.

This family comprises only about two hundred known spe-
cies, with but few genera broadly distributed over the world.
The flies resemble the Asilidse somewhat, and have habits
not dissimilar, though much less active. The proboscis has
fleshy labella, instead of the horny tip of the Asilidae, and the
legs are less stout- — in many species they are easily broken off
when captured. Their food is chiefly other diptera, for which
they lie in wait upon leaves and bushes, or upon the bare
ground. The larvae have a short, eyeless, nonretractile head,
the antennae small and short. The body is slender and snake-
like, showing apparently nineteen segments. Anterior spira-
cles situated at the end of the first segment behind the head ;
posterior spiracles on the apparently seventeenth segment.
The larvae live in the earth and decomposing wood, or in sand,
feeding upon other insects or upon vegetable matter, ordure,
etc. The pupae are free; they have in front laterally project-
ing spinous points.



SCENOPINIDiE. 69

TABLE OF GENEKA.

1. First posterior cell entire, not intersected by a cross-vein. . . 2
" First posterior cell divided by a cross-vein into two cells ; first antennal

joint unusually large." . , . Metaphragma Coquillett.

2. Head much broader than long. . 3

"Plead not as broad as long, vertical diameter of eyes equaling their

horizontal diameter; first joint of antennas unusually large and pol-
ished". . Nebeitus Coquillett.

3. Third joint of antennas short, the first thickened. . Tabuda Walker.
Third joint of antennas as long or but little shorter than the usually

slender first joint. ......... 4

4. Face bare or pubescent Psilocephala Zetterstedt.

Face pilose. ........... 4

5. Fourth posterior cell closed Thereva Latreille.

Fourtli posterior cell open. .... Dialineura Eondani.



23. SCENOPINID^.

Flies of moderate or small size, black in color and bare.
Front not excavated ; face bare, short and broad. Antennae
approximated at the base, the first two joints short, the third
elongated, simple, without style or arista. Proboscis conceal-
ed; palpi cylindrical, bristly at the tip. Ocelli present. Males
usually holoptic. Thorax rather long, moderately convex,
though apparently much so from the low position of the head.
Scutellum broad and short, without spines or tubercles. Ab-
domen flattened, more or less elongated, composed of seven
segments. Tegulse small. Empodia wanting. Third longi-
tudinal vein of the wing furcate ; basal cells long, the first
much longer than the second ; three posterior cells, the first
narrowed in, or closed before the margin ; anal cell closed.

The larvae resemble closely those of the Therevidse. They
are very long and slender, having apparently nineteen seg-
ments, due to each of the abdominal segments except the last
being divided by a strong constriction. The larva? have been



70 NORTH AMERICAN DIPTERA.

found in decaying fungi and wood and under carpets or in
furniture, and are supposed to be carnivorous. The flies are
not very active in their habits, and because of the frequency
with which they are observed on window-panes are usually
called window-flies.

TABLE OF GENERA.

First posterior cell narrowed ; legs rather stout. Scenopinus Latreille.

First posterior cell closed before the margin of the wing; legs slender

(Mexico). . . . . . PsEUDATRiCHiA Ostcn Sacken.



24. ACROCEEID^.

Small to large, never elongate, pilose or nearly bare flies.
Head small or very small, chiefly occupied by the large eyes,
which are usually contiguous in both sexes above or below, or
above and below the antennae; two, three or no ocelli present;
antennse composed of two or three joints, with or without a
terminal arista or style. Proboscis rudimentary or long,
sometimes very long. Thorax large, spherical ; tegulse very
large and inflated ; scutellum large. Abdomen closely united
to the thorax, large and inflated. Legs rather stout ; the tarsi
with three membranous pads under the claws. Neuration
variable, the veins sometimes weak and indistinct.

This family, the Acroceridee or Cyrtidse, comprises a small
number of curious flies with curious habits. They are easily
recognizable by their small head and large, inflated tegulse.
No family characters can be drawn from the neuration, owing
to the great diiferences often existing between forms other-
wise related. In the few forms in which the larvae are known
they are all parasitic upon spiders or their cocoons. "In
the spring of 1887, while hunting for spiders, I found hanging
in cobwebs several soft white maggots and pupse. The webs
were generally old and out of repair, and a closer examination


1 2 3 4 5 6 7 8 10 12 13 14 15 16 17 18

Online LibrarySamuel Wendell WillistonManual of the families and genera of North American Diptera → online text (page 10 of 18)