Samuel Wendell Williston.

Manual of North American Diptera online

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The costal vein reaches only to the tip of the third vein. . 3

3. Auxiliary vein vestigial, projecting only a short distance beyond

the humeral cross-vein; furcations of fourth and fifth veins near-
ly opposite each other (15) . . . . Mycetophila.
Auxiliary vein complete, longer than the humeral cross vein; end-
ing in first vein (17) Dynatosoma.

4. Auxiliarv vein complete, terminating in the costa. . . 5
Auxiliary vein not terminating in the cosla, rudimentary or ter-
minating in the first vein. . . . , . . .12

5. Proboscis much elongated ..... Gnoriste.
Proboscis short. ......... 6

6. Auxiliary vein connected by a small cross-vein with the first longi-

tudinal. .......... 7

Auxiliary vein not connected by a cross- vein with the first longi-
tudinal. . . . . . . . . . Leia.

7. Fifth vein furcate. . .8

Fifth vein simple, not furcate. .... Acnemia.

8. Origin of the third vein perceptibly past the middle of the wing,

the anterior cross-vein longer than the distal section of the first

vein (13) Neoglaphyroptera.

Origin of the third vein distinctly before the middle of the wing,
the anterior cross-vein much shorter than the distal section of
the first vein. ......... 9



9- Upper branch of the fork of the fourth vein incomplete at the

base; third vein sinuous {Odontopoda) . . . Anaclinia.

Fork of fourth vein complete; third vein not markedly sinuous. lo

10. Furcation of the fifth vein before or opposite the furcation of the

fourth. II

Furcation of the fifth vein distinctly more distal than that of the
fourth (12) Phthinia.

11. The costal vein continues beyond the tip of the third vein; abdo-

men cylindrical. ....... Boletina.

The costal vein terminates at the tip of the third vein; abdomen
compressed Leptomorphus

12. Auxiliary vein elongated, terminating angularlj^ in the first vein,

near the origin of the third. .... Syntemna.

Auxiliary vein vestigial or ending acutely in the first vein before

the origin of the third. ....... 13

13. Fifth longitudinal vein not furcate . . . Zygomyia.
Fifth longitudinal vein furcate. ...... 14

14. The costal vein extends a little beyond the termination of the

third vein. .......... 15

The costal vein terminates at the tip of the third vein. . 17

15. Forked cell of the fifth vein acute proximally, the branches grad-

ually and but little divergent Epicypta.

Forked cell of fifth vein less acute proximally, the branches more
widely and rapidly divergent, the upper branch curved. 16

16. Auxiliary vein of considerable length, terminating in the first vein.

Auxiliary vein short, ending free a little beyond the humeral cross-
vein Phronia.

17. Auxiliary vein reaching beyond middle of first basal cell, and ter-

minating in first vein. ..... Trichonta.

Auxiliary vein vestigial, or not reaching as far as the middle of the
first basal cell. ......... 18

18. Furcation of the fourth vein before the first section of the third

vein. ........... 19

Furcation of fourth vein beyond the first section of the third
vein. ........... 20


19. Furcation of fifth vein more distal than that of the fourth.

Furcation of the fourth vein more distal than that of the fifth.


20. Furcation of the fifth vein more distal than the junction of the

fourth with the anterior cross-vein. ..... 21

Furcation of the fifth vein more proximal than the junction of the
fourth with anterior cross-vein. . . Brachycampta.

21. Furcation of fifth vein more distal than that of the fourth.

My c other a.
Furcation of fourth vein more distal than that of the fifth.


1. Wings and halteres wholly wanting. . . Epidapus 9*
Wings and halteres as usual. . . . . . . .2

2. The fourth vein springs from the third at an angle, i. e. the anterior

cross-vein is obsolete. . , . . . Epidapus $ .

. Anterior cross-vein not obsolete. ...... 3

3. Proboscis much elongated, longer than the thorax. Eugnoriste.
Proboscis short. ......... 4

4. Wings very distinctly hairy; claws not denticulate. Trichosia.
Wings bare or slightly hairy. ....... 5

5. Antennal joints of male pedicillate and with whorls of hair; forks

of fourth vein arcuate. Zygoneura.

Antennal joints not pedicillated, bare or with short hairs. . 6

6. Claws denticulate. . . . . . . . Odontonyx.

Claws not denticulate. ........ 7

7. Face strongly produced Rhynchosciara.

Face not produced. . . . . . . . . Sciara.

Additional Generic References.

Odontonyx Ruebsaamen, Berlin. Ent. Zeit. xxxix, 25, 1894.
Rhynchosciara Ruebsaamen, 1. c. Mexico.


Fig. 41. Bibio albipen7tis, ^ulaLXg^d. After Washburn.

Moderately or very slender flies, of from one to twelve
millimeters in length. Head usually somewhat flattened;
front in the male usually very narrow or the eyes con-
tiguous; face short; eyes round or reniform; ocelli large,
distinct ('absent in Hesperodes'). Antennae composed of
from eight to sixteen joints, cylindrical or a little flat-
tened, rarely longer than head and thorax, the joints
usually closely united. Proboscis never much elongated,
with thickened, hairy labella; palpi variable, three to
five-jointed, sometimes long, at other times short. Tho-
rax without suture; scutellum half round. Abdomen
composed of from seven to nine segments, sometimes
elongated. Legs moderately long and strong, the hind
pair more or less elongated, the front femora often thick-
ened; front tibia often with a stout hook or coronet of
spines at the tip ; pulvilli and empodium usually distinct,
but the former in many of the smaller forms wanting.
Wings large, the anterior veins often stouter than the pos-
terior ones; costa not extending on the posterior margin;



second longitudinal vein wanting, tlie third arising from
the first; third vein sometimes furcate;^ fourth usually
furcate ; first basal and often the second basal cells com-
plete; anal cell rarely closed; posterior cross- vein always

The relationships of this small family of nematocerous
flies are very close with the Mycetophilidae through the
Pachyneurinse and Scatopsinae ; indeed there is greater
difference between some genera included in the family
than between the families themselves. One of these
annectant genera is Hespei'odes described a few years ago
by Coquillett. Because of the presence of a distinct sec-
ond basal cell, and the resemblance of its venation to
Hesperiniis, it would seem better placed here than among
the Mycetophilidae, where its author placed it. A glance,
however, at the different types of venation in the figures
will show how composite a group the family is, as at
present recognized.

Such larvae as are known are cylindrical, footless, with
transverse rows of bristles, usually with eyes ; they feed
upon excrementitious or vegetable substances, especially
on the roots of grass. The pupae are inactive, for the
most part free, living in excavated, smooth oval cavities
near the surface of the ground, which the larvae have
prepared before undergoing their metamophosis, and
where the pupae remain before emerging in the perfect

In some species the male flies differ very noticeably in
coloration from the females, so much so that they are
commonly mistaken for different species. Some of the
species, especially Bibio albipennis , are very abundant in
early spring, in meadows, about willows, upon the win-

* The anterior ])ranch is in reality the second vein.



dows, etc. They are all rather sluggish in flight, and
the males are conspicuous because of the very large and
hairy eyes. Some of the species of Scatopse are very
minute, among the smallest of all diptera. But very lit-
tle has been done in the way of critical study of the gen-
era and species of this family; it is an excellent field for

,-,,-A,/ .

Fig. 42. Bibionidae. i, Plecia, wing; 2, 3, Plecia, antennae; 4,
Bibio, wing; 5, Bibio, palpus; 6, Bibio, antennae; 7, Scatopse, wing;
8, Aspistes, wing (Wuip) ; 7, bis, Scatopse, wing; 7a, Scatopse, last
tarsal joint with claws and empodiuni ; 8, bis, Scatopse, wing ; 8a,
Scatopse, head.


1. Second basal cell present. . 2

Second basal cell wanting {Scatopsince) . . . . . . 7

2. Third longitudinal vein furcate 3

Third vein not furcate. . . . . . . , . 5

3. Palpi four-jointed; antennae slender, more than ten-jointed; slen-

der species {P achyneurincE) 4

Palpi five-jointed; antennae eight or nine-jointed; less slender spe-
cies (1, 2, 3) Plecia,


4. Antennae twelve-jointed; anterior cross-vein distinct.

Antennae sixteen-jointed; anterior cross-vein obsolete, that is the
third and fourth veins are coalescent for a short distance.


5. Front tibiae with a stout spine-like process at tip, ... 6
Front tibiae with a coronet of spines; antennae ten or eleven-jointed.


6. Anterior cross-vein distinct; antennae ten-jointed (4, 5, 6) .

Anterior cross-vein obsolete; antennae ten-jointed (?) . Bibiodes.

7. Front tibiae ending in a spine-like process; antennae twelve-jointed.

(8) Aspistes.

Front tibiae of the usual structure; antennae nine or ten-jointed (7,
7 bis. 7a, 8 bis, 8a) . . . . . . Scatopse) .


Fig. 43. Sitnuliiini veniistum; enlarged. After Washburn.

Small flies, from one to six millimeters in length, with
thick, short legs. Head hemispherical; face short;
eyes round or reniform, holoptic in the male; no ocelli.
Antennae scarcely longer than the head, flattened or cyl-
indrical, ten-jointed; the two basal joints differentiated,
the others closely united. Proboscis not elongated, with
small, horny labella; palpi incurvate, four-jointed; the




first joint short and the two following of equal length; the
last one longer and more slender than the preceding.
Thorax arched, without suture; the scutellum small. Ab-
domen cylindrical, composed of seven or eight segments;
genitalia concealed; legs strong and not elongated; fe-
mora broad and flat; tibiae usually with terminal spurs ;
first joint of the tarsi longer than the following and usu-
ally dilated in the male; the last joint small. Wings
large and broad, with distinct alulse, anterior veins thick-
ened, the others slender; auxiliary vein terminating in
the costa about the middle of the wing; second longi-
tudinal vein wanting, the first and third lying close to
each other; the third arising from the first rectangularly
before the end of the auxiliary vein ; anterior cross-vein
very short; fourth vein curved, forked nearly opposite
the anterior cross- vein; the forks terminating near the
tip of the wing.

Fig. 44. Siniulinvi ve7insiuin, enlarged. After Washburn.


The family Simuliidse, comprising about seventy-five
described species, is one of the best known popularly
among diptera, on account of the troublesome character
of the flies, which are scarcely less annoying than the
true mosquitoes ; they rarely exceed five or six mm. in
length, usually not more than three or four, and will be
immediately distinguished from the mosquitoes by their
thick-set appearance, their shorter legs, their shorter
proboscis, and less slender antennae. In the southern
States they are known as ' buffalo gnats' and 'turkey
gnats', and sometimes occur in almost incredible num-
bers; cattle when attacked by large numbers are driven
almost frantic, and will seek to evade them by rolling in
the dust, rushing about, or going into the water. When
the flies are numerous they will almost literally cover the
cattle, especially seeking the openings of the body, en-
tering the nostrils and the ears, the margins of the eyes,
where they will actually lie piled upon each other. When
very numerous they will produce an inflammatory fever,
frequently terminating in death. Infants have been
known to succumb to their bites. The well known Euro-
pean species is 5'. columbaczense, which during some sea-
sons in the regions of the Danube costs the death of many

The larvae are very interesting creatures ; they are
aquatic, living most frequently in mountain streams, on
stems of plants,"or stones, where they form for themselves
elongated cocoons, opened above. In the open end of
these cocoons the pupae ensconce themselves with the an-
terior part of the body naked and free, from which ex-
tend eight or sixteen very long, slender, threadlike
breathing tubes. The perfect insect escapes under water
and comes to the surface. The larvae are soft-skinned,
thickened at the extremities, with a cylindrical head,
two pairs of eye-spots ; on the first thoracic segment there



is a foot protuberance with bristly booklets ; and the end
of the abdomen has several appendages for attachment.

Fig. 45. Simuliidae. Shnulium, wing; la, Sifnulium, front tarsus;

2, genus nov., wing; 2a, id. head, front view; 2b, id. head, side view;

3, Simuliutn, antenna.

But a single genus, Simulium, has hitherto been known
in this family. What seems to be a distinct genus has
long been known to me in a single imperfect specimen
from the West Indies. The form will, I hope, be recog-
nizable from the accompanying illustrations made by me
many years since. (2, 2a, 2b). The specimen is exceed-
ingly minute, and was discovered closely applied to and
sucking the juices from the antenna of a phasmid. The
antennae and palpi are mostly wanting in the specimen.



Fig. 46, BibiocephaJa elegantula, enlarged. After Kellogg.

Moderate-sized, elongate, bare species with long legs
and broad wings. Eyes usually dichoptic in both sexes,
but occasionally holoptic in one or both sexes ; eyes of
both sexes usually bisected by a line or narrow unfacet-
ted space, with the two fields composed of larger and
smaller ommatidia (indicated by larger and smaller cor-
neal facts), in a few species the eyes bisected only in one



Sex. Yhree ocelli present. Antennae slender with from
nine to fifteen segments, clothed with short pubescence.
Mouth-parts elongate, females with slender, flattened,
elongate, saw-like mandibles, males without mandibles;
both sexes with slender elongate labrum-epipharynx,
hypopharynx, and a pair of maxillae with five-segmented
palpi; labium with a strong, elongate basal sclerite and
a pair or free, fleshy terminal lobes without pseudo-tra-
cheae, and with no palpi. Thorax with a distinct, broad-
ly interrupted transverse suture; legs moderately slender,
the hind pair much longer than the anterior ones, the
front femora of males curved in some species, tibiae with
or without spurs; empodia very small, almost rudimen-
tary, pulvilli wanting; wings broad, bare, with a mark-
edly projecting anal angle, and peculiarly different from
those of all other flies in the possession of a fine spider-
web like net- work of lines ('secondary venation') which
are the creases made by the folding of the wings in the
pupal stage.

The larvae are curious, flattened, slug-like creatures,
legless, but provided with six suckers arranged in a me-
dial longitudinal row on the venter (one sucker for each
of the six parts separated by constrictions of the body,
of which the anterior part is composed of the fused head
and thoracic segments, and the posterior part of the
fused last two abdominal segments, the other four
parts representing each a single abdominal segment).
The larvae live in swiftly running, shallow, clear and
highly aerated water (mountain brooks) clinging by the
suckers to the smooth surface of boulders or the rock bed
of the stream. The pupae are even more extraordinarily
shaped, being flat below and flatly convex above with
strongly chitinized, dorsal body-wall smooth and shining
black or blackish brown, with a pair of projecting pro-
thoracic dorsal respiratory horns or 'books', each com-



pcsed of four flattened leaves, two of them delicate
tracheal gills and the other two protecting chitinized
plates. The pupae are fastened by three pairs of pads on
the fiat venter to the rock-bed or boulders in the swift
stream and are nonmobile.

The delicate adults are to be found, usually only rare-
ly, despite the oft-time abundance of larvae and pupae,
clinging to rocks projecting from the stream or to stream-
side cliffs or foliage. The females are predaceous and
may be seen flitting about capturing small flies, especial-
ly Chironomidae, which they lacerate with their saw-like
mandibles and knife-like maxillae in order to suck or lap
up the blood. The males are rarely found. A few spe-
cies are known as yet only in the larval and pupal stages.
The egg-laying habits are unknown.

The family Blepharoceridae was established by Loew
in i860 to include a half dozen species, which could not
well be located in any of the existing families. Since
that time the number in the family has been increased to
about twenty known forms included in nine genera, of
which three genera, represented by eight species, are
found in the United States. Our species are recorded

Fig. 47. Blepharoceridae. i, Blepharocera, wing, showing second-
ary venation (Comstock) ; 2, Paltostonia schineri, vnng; 3, Phtlorus,
wing (Kellogg); 4, Bibiocephala, wing (Kellogg).


from Canada, New York, Colorado, New Mexico, Idaho,
Utah and California. The foreign species are found in
Europe, Asia, South America and certain Mediterranean

The family is readily divisible into two groups, of
which one, characterized by the absence in its members
of a short, incomplete vein near the posterior margin of
the wing, includes six genera, nearly all of which are
represented by a single species, and none of them occur-
ring in North America, north of Mexico. The remaining
known species are grouped according to the latest revis-
ion of the family (Kellogg, 1903) into three genera rep-
resented in Europe by about six species and in America

by eight.


1. No inccmplete vein running into hind border of the wing [Apisto-

7nyia, Corsica; Hannnatorhina, Ceylon; Kelloggina, Brazil;
Curnpira, Brazil; Hapalothrix, IS^Viroye.) . Proboscis: elongated;
hind tibiae with spurs; eyes entire, not bisected (2) .

An incomplete vein near the posterior margin of the wing. . 2

2. Second longitudinal vein with an anterior branch; a cross- vein con-

necting the fourth and fifth veins, that is, the second basal cell
complete. Anterior branch of second vein and the second and
third veins all separating at a common point or close together

(4). . • • Bibiocephala.

Second longitudinal vein simple, without branch. ... 3

3. No cross-vein connecting the fourth and fifth veins, that is, the

second basal cell incomplete (1) . . . Blepharocera.

A cross-vein connecting the fourth and fifth veins, the second basal

cell complete (3) Philorus.


I. Eyes of female contiguous, of male separated by-broad space; length

not over six millimeters ostensackeni.

Eyes of both sexes separated by a narrow space; length not less
than seven mi'llimeters. . . . , . " . 2



2. Ungues slender and rather long. .... tenuipes.
Ungues stout and shorter. jordani.


1. Eyes contiguous; anterior branch of second vein running into vein

near margin of wing ; eyes bisected ; front femora of male

strongly curved. , grandis.

Eyes separated by a narrow or broad space, in both males and fe-
males; fore femora of male straight. . " . . . . 2

2. Eyes in both sexes bisected. ..,..,. 3
Eyes of male bisected, of female not bisected; anterior branch of

second vein running into the first very soon, making a triangle
in which the anterior branch forms the shorter side. doanei.

3. Eyes of male separated widely; of female narrowly; anterior branch

of second vein running into first vein very soon, forming a

nearly equilateral triangle elegantula.

Eyes of both male and female separated narrowly; anterior branch
of second vein running into first about one-third the distance
from origin of second to tip of first vein. . comstocki.

Philorus is represented by but two known species in America, viz:
yosemite and ancilla, and by one species in Europe, bilohata Loew; of
the two American forms, P. ancilla has the eyes contiguous (in the
female at least) , while the eyes of P. yosemite are separated by a broad
front (in the male at least) .

Paltostoma is known by a single described species from the West
Indies, and another from Brazil; one or the other or possibly a third
is known also from Central America. P. schineri will be recognized
from the generic characters and the figure.


Small, obscurely reddish yellow, bare flies of peculiar
appearance. Head small, round; holoptic in both sexes;
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, appar-
ently consisting of a small first joint, an oval second
joint and a terminal arista; the second joint and the arista
are, however, complex, composed of ten or eleven seg-
ments, the last of which terminates in a bristle. Thorax
strongly convex, robust, without transverse suture, some-
what impressed before the scutellum. Scutellum rather
large, obtusely three cornered; metanotum arched. Ab-
domen narrower than the thorax, cylindrical, composed
of seven segments; male genitalia thick, the basal piece
swollen, bladder-like; ovipositor with broad, rounded
lamellae. Legs simple, comparatively short; coxae not
elongated ; tibiae without spurs ; tarsi moderately long ;
the front pair about as long as the tibiae, the penultimate
joint short; claws small; empodia vestigial. Wings

Fig. 48. Wing of Orphnephila.

longer than the abdomen; auxiliary vein short, termin-
ating in the costa ; second longitudinal vein sinuous;




third and fourth veins not furcate; anal angle rounded;
basal cell short.

But three or four species of this singular family are
known, and of them even, as far as-I am aware, the larval
habits are yet unknown. The known American species
belong to one genus, Orphnephila Haliday; a second
genus has been proposed by Mik. The small fly is found
on the banks of streams.


Head nearly hemispherical ; eyes rounded, holoptic or
dichoptic in the male; broadly separated by the front in
the female; ocelli present. Antennae about as long as
the thorax, composed of sixteen joints, cylindrical, the
two basal joints distinctly differentiated; those of the
flagellum closely united, short-haired, gradually decreas-
ing in size toward the end. Proboscis moderately prom-
inent, with small labella ; palpi long, four-jointed; the
second joint longer and broader than the others. Thorax
convex, without transverse suture ; scutellum semicircu-
lar, short and broad; metanotum strongly developed.
Abdomen flattened cylindrical, composed of seven seg-
ments; genitalia concealed or nearly so. Legs slender,
without spines; the coxae, especially the front pair, more
or less elongated; metatarsi elongated; tibiae with or
without spurs; empodia pad-like, the pulvilli absent.
Wings large, in rest lying flat upon the abdomen; aux-
iliary vein present; second and third veins not furcate;

Fig. 49. Rhyphus.

Fig. 50. Olbiogaster.

discal cell complete (fig. 49^); five posterior cells and
two complete basal cells present; anal cell not narrowed
in the margin.

But very few species of this family are known, belong-
ing to but three genera. The typical genus Rhyphus con-




tains a number of species of wide distribution. The
genus Olbiogaster is known from two or three species
hitherto recorded only from Mexico and the West Indies.
' It differs from Rhyphus in the structure of the head (eyes
separated by a broad front in both sexes, and occiput but
very little developed), of the antennae (scapus short, fia-
gellum of male filiform, etc.), of the thorax and abdo-
men, as also in the venation.' (Osten Sacken.)

The larvae of Rhyphus are worm-like, legless, naked,
more or less transparent, with snake-like movements;
there are two, short, fleshy points at the posterior end.

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Online LibrarySamuel Wendell WillistonManual of North American Diptera → online text (page 10 of 25)