Samuel Wendell Williston.

Manual of North American Diptera online

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have long been familiar, that the names Cecido77iyia and
Diplosis should be differently applied or abandoned.
Nor can I agree with Professor Aldrich that these changes
have been threshed out in Europe. I can find no writer
whose opinion is authoritative who has accepted them,
nor did Kieffer. On the contrary Osten Sacken, whose
opinion I value more than that of any other recent
writer, has steadily opposed not only these changes,
but the apparently unnecessary reduplication of the gen-
era, for it must be remembered that Kieffer alone has
proposed and adopted about fifty new 'genera'. Hendel,
in reply to Osten Sacken's objections, has said that gen-
era exist in nature, and that all we have to do is to
recognize them — a remarkable declaration from a nat-
uralist of the twentieth century. I suppose he would
permit 'Nature' to occasionally revise its genera a la De
Vries! While it is true that the typical species of Meigen's
genus Cecidomyia is not included in that genus as accept-
ed by Loew and in this work, but is included under
Diplosis, it is also true that rigid rules of priority can not
be extended to the works of many of the early writers. If



CECIDOMYID^.



125



they are, not a few other revolutions of a similar charac-
ter would impend, notably that of the genus Milesia, as I
have made clear in my Synopsis of the North American
Syrphidse.

In brief, the classification, or rather the nomenclature
of this family is vStill in a more or less chaotic condition,
and will be so until much more study has been given to
the insects, especially those of America and Asia. As
Aldrich has said, there is no more fertile field in all dip-
terology for thorough, exhaustive, ethologic, morpho-
logic, taxonomic and phylogenic studies than among the
Cecidomyidae. But there are many difficulties in their
study. Doubtless if Kieffer's principles of generic sub-
division are accepted, there are a host of new 'genera' to
be discovered in North America, for the permutations of
antennae, palpi and tarsi are by no means exhausted.
My advice is, however, for the non-specialist to go ver}-
slowly indeed in adding to what may prove to be an
already unnecessary confusion.

TABIvK OF GBNKRA.

(For the most part in their wider sense.)

Fourth longitudinal vein wanting. . . . Cecidomyinse.

Fourth longitudinal vein present (ocelli present) . Lestreminse.

CECIDOMYIN^.

1. First tarsal joint shorter than the following one. . . 2
First tarsal joint longer than the following one. ... 14

2. Fifth longitudinal vein not furcate, (8) . . . Spaniocera.
Fifth longitudinal vein furcate. ...... 3

3. First and third longitudinal veins approximated to the costa, dis-

tinguishable with difficulty; costa tomentose. ... 4

Third longitudinal vein distinctly separated from the first. 6

4. Fifth longitudinal vein furcate near the middle. . . 5
Fifth longitudinal vein furcate at base, giving an appearance of

two longitudinal veins. (See DD, p. 127,)



126 NORTH AMERICAN DIPTERA.

5. Proboscis much elongated, directed downward. Clinorhyncha.
Proboscis short (1) Lasioptera.

6. Antennae bead-like, the joints verticillate. ... 7
Antennae cylindrical, the joints approximated, not petiolate, pro-
vided with short, close hairs; the third vein terminates at or
beyond the tip of the wing. . . . Asphondylia.

7. The third longitudinal vein terminates in the costa before the tip

of the wing (3) , Cecidomyia.

The third vein terminates in the costa at or beyond the tip of the
wing. .....•-... 8

8. Thorax highly arched, hood-like over the head (4) . Hormomyia
Thorax only moderately arched. . . . . . . 9

9. Wings with but three longitudinal veins, the first, third and fifth. 10
Wings with apparently four longitudinal veins, that is the first,

third and, two in place of the fifth, the furcation taking place
so near the root of the wings as to give the appearance of an
additional longitudinal vein 13

10. The anterior cross-vein, that is the vein arising from the root of
the wing and connecting with the third vein nearly where it

arises from the first, is curved S-shaped 11

The anterior cross-vein is nearly straight, apparently the begin-
ning of the third vein. . . . . . . . 12

Ti. Wings very long and narrow (10). . . . Colpodia.

Wings not more than three times as long as wide (2). Bpidosis

12. Joints of the antennal flagellum petiolate, in the male with two

bead-like swellings on each joint (14) . . . Diplosis.

Joints not petiolate, or at most the males with a single bead-like

swelling on each joint. ...... Dirhiza.

13. Palpi large, with the last joint elongated, anterior cross-vein

S-shaped Asynapta.

Palpi small, the last joint not or but little longer than the penulti-
mate; anterior cross-vein but little curved (13) . Winnertzia.

14. Wings with but two longitudinal veins, the finst and fifth, the lat-

ter not reaching beyond the middle of the wing (11) .

Heteropeza.
Wings with three longitudinal veins, the first, third and fifth. 15

15. Fifth vein furcate. ........ 16

Fifth vein simple, not furcate (7) . • . . . . Miastor.



CECIDOMYID^. 127

16. First and third veins approximated. {Diomyza). Lasiopteryx.
First and third veins not approximated (5) . Trichopteromyia.

LKSTRKMIN^.

1. Fourth longitudinal vein simple. ...... 2

Fourth longitudinal vein furcate; the two branches of the fifth,

when present, are divergent at base of the wing, giving the ap-
pearance of longitudinal veins . 4

2. Fifth longitudinal vein furcate near base. . Strobliella K.
Fifth longitudinal vein furcate near its middle {Joannisia K., Pe-

roniyia K., Wasmaniella K., Bryomyia K., Prionellus K.,
Aprioniis ^., Monardia 'iL.) . . . . . . 3

3. Antennae composed of from fourteen to twenty-five joints, the

joints petiolate in the male. . . . Campylorayza.

Antennae composed often (male) , or six or eight (female) joints,

the joints petiolate in neither sex. . . Micromyia.

4. The costal vein reaches to or exceeds the tip of the wing. Catocha
The costal vein does not reach the tip of the wing (9) . . 5

5. Only one vein behind the forked cell. . . . Tritozyga.
Two veins behind the forked cell (6) . . . . Lestremia.

TABIvK OF GENERIC DIVISIONS (KiefFer).

CKCIDOMYIN^.

A. First joint of tarsi shorter than the second; wings rounded at ex-
tremity; no ocelli.
B. Wings with squamae on anterior border; claws bifid.
C. First two longitudinal veins very close to the costa. ■

D. Three longitudinal veins, the first, third and fifth, the

fifth furcate near the middle.

1. Proboscis short. .... Lasioptera.

2. Proboscis elongate. . . . Clinorhyncha.
DD. Four longitudinal veins, that is the fifth is divided near

base of wing.

3. Thorax attenuated at neck. . Acorhynchus R.

4. Palpi with one joint. . . . Baldratia K.

5. Palpi with four joints. . . Choristoneura L.
CC. Third longitudinal vein, at least, remote from costa.

E. Empodia simple.

6. The third longitudinal vein terminates at or near

extremity of wing. . . . Cecidomjria.

7. The third longitudinal vein terminates at some dis-

tance before tip of wing. . . Perrisia Rond.

8. Flagellar joints with two verticils; alike in both sexes.

Macrolabis K.



128 NORTH AMERICAN DIPTERA.

KK. Empodia trifid.^

9. Antennae composed of twelve joints in both sexes.

Arnoldia K.

10. Joints of antennae more numerous in male than in fe-

male; last abdominal segment not swollen.

Dryomyia K.

11. Antennce composed of more than twelve joints; last ab-

dominal segment swollen ( 9 ) • • • Dagyneura.
BB. Anterior border of the wings without squamae; claws simple.
F. Empodia simple.

12. Palpi with four joints; antennae fourteen-jointed, verti-

cillate Scliizomyza K.

13. Palpi four-jointed; antennae fourteen-jointed, not verti-

cillate Polystepha.

14. Palpi three-jointed; costa with squamae. Cystiphora K.

15. Antennae fourteen-jointed, not verticillate; palpi with

less than four joints. . . . Asphondylia.

FF. Empodia trifid; antennae verticillate.

16. Palpi with one or two joints. . Rhopalomyia R.

17. Palpi with three joints. . . Oligotrophus I^at.

18. Palpi with four joints, long. . . . Janetiella K.

19. The second vein reaches the tip of the wing, palpi with

four joints Mayetiola K.

20. Palpi with four long joints. . . . Mikiola K.

21. Thorax produced over head. . . Hormomyia.
BBB. Thorax not prolonged over the head; antennae fourteen-jointed

in both sexes; in the male each joint of the flagellum with two
bead-like swellings, giving an appearance of twenty-six joints
for the antennae,
G. Claws of front tarsi bifid, or curved at right angle and enlarged
at extremity; or the empodium trifid.

22. Empodia trifid Putoniella K.

23. Verticils of antennae curved and irregular; larvae zo-

ophagous Bremia Rond.

24. Verticils regular; all the claws bifid. Dicrodiplosis K.

25. Verticils regular; hind claws not bifid; larvae mycophag-

ous Mycodiplosis R.

26. Claws simple, bent at right angles and dilated below

near extremity. . . . Octodiplosis Giard.
GG. Claws simple, bent or curved at right angles, but not en-
larged; empodia simple.

27. Three,-jointed palpi; scales of wings elongated and nar-

rowed at base Endaphis K.

28. Second longitudinal vein terminates before the tip of the

wing; larvae zoophagous. . Arthrocnodax Rbs.

29. Palpi with a single jomt. . Monarthropalpus R.

30. Palpi two-jointed, the first long and attenuated in the

middle Massalong-ia K.

31. Palpi with three joints; second joint of antennae with a

tooth Acrodiplosis K.

* I use this expression, not being certain whether or not the trifid
character is due to real pul villi. Kieffer simply begs the question by
the expression 'pelote unique,' 'pslotes trois'.



CECIDOMYDI^. 129

32. Palpi with three joints; empodia longer than claws.

Stenodiplosis Rent.

33. Palpi with four joints; empodia shorter than claws.

Oontarinia R.

34. Costal vein not interrupted after its junction with third

longitudinal vein. . . . Thecodiplosis K.

35. Male antennae with swellings alternately simple and

double; ovipositor very long. Xylodiplosis K.

36. Ovipositor not longer than body; costal vein not inter-

rupted beyond third vein; empodia one-half the length
of claws Loewiola K.

37. First two joints of flagellum not fused; empodia nearly

as long as claws. . . . Macrodiplosis K.

38. Enlargements of male antennae irregular, alternately

double and single; empodia longer than claws; first two
joints of flagellum fused. . . Harmandia K.

39. Enlargements of male flagellum irregular, alternately

double and single; empodia shorter than claws; ovipos-
tor not prominent. . . . Clinodiplosis K.

40. Wings usually spotted; larvae zoophagous.

Lestodiplosis K.

41. Joints of male flagellum alternately single and double;

costal vein interrupted after junction with third vein;

empodia longer than claws. . . . Diplosis.
BBBB. Anterior cross-vein present and curved, apparently the begin-
ning of the third vein; the longitudinal always terminate at or
beyond the tip of the wing.

42. Three longitudinal veins, the first, third and fifth; an-

terior transverse not parallel with first vein.

BryocrjTpta K.

43. Anterior cross-vein curved in form of an S (first joint of

the tarsi prolonged below at extremity) . Colpodia.

44. Anterior cross-vein not curved in form of an S; fifth

vein not furcate; palpi with two joints; claws bifid.

Oolomjda K.

45. Palpi with four joints; claws simple; empodia simple.

Holoneurus K.

46. Fifth vein furcate. ..... Dirhiza.

47. Flagellar joints petiolate; fifth vein furcate. Epidosis.

48. Ivike Epidosis, abdomen slender, Camptomyia K.

49. Fifth vein furcate at base of wing; claws simple; empo-

dia simple Ruebsaamenia K.

50. Ivike Ruebsaamema, abdomen not recurved; empodia

trifid, claws simple. . . . Clinorhytis K.

51. As in Clinorhytts\ antennae with more than fourteen

joints; empodia simple; claws bifid. Asynapta Ivw.

52. L/ike preceding, claws bifid, empodia simple; antennae

with fourteen joints. . . . Winnertzia.

53. Neuration as in Clinorhytis, second vein arises near

base. Diallactes K.



14



I30



NORTH AMERICAN DiPTERA.



HKTEROPEZIN^.

AA. 54. Two joints in the tarsi, the first shorter than the second;
no palpi; with two or three longitudinal veins.

Oligarces Mein.

55. Tarsi with three joints, the first longest; two longitudinal

veins Heteropeza.

56. Tarsi with four joints, first longer than second; three lon-

gitudinal veins; palpi with two joints. Miastor Mein.

57. Tarsi with five joints, first shorter than second; wings acu-

minate at extremity; palpi three-jointed; three longitud-
inal veins. ....... Pero Mein.

58. L/ike preceding, palpi two-jointed, third longitudinal vein

evanescent before extremity. . . . Firenia K.

59. Like Firenia; palpi single jointed. . Leptosyna K.

60. Tarsi with five joints, the first longer than second; scales

of wings long and striated. . . Lasiopteryx W.

61. Like preceding, but tarsi with four joints and neuration as

in Perrisia. Ledomyia K.

62. Like Ledomyia, but first joint of tarsi shorter than second;

fifth vein simple. . . . Brachyneura Rond.

LKSTRKMIN^.

AAA. First joint of tarsi longer than the second; fourth longitudinal
vein present.
H. Fourth vein simple; fifth furcate near its middle.

63. Flagellum in the male with twelve joints, in the female

with nine; palpi with three or four joints; claws simple.

Joannisia K.

64. Male flagellum with twelve, female with eleven, palpi with

two joints Peromyia.

65. Claws denticulate; no empodia; antennal joints long-petio-

late. ...... Wasmaniella K.

66. Claws as in Peromyia; palpi four-jointed; antennae as in

Prionellus. Bryomiya K.

67. Claws denticilate; empodia large; flagellar joints of male

antennae excentric. .... Prionellus.

68. Like Prionellus, but the claws not denticulate, and the

empodia short or rudimentary. . . Aprionus K.

69. Like Aprionus but the claws denticulated. Monardia K.

70. Antennae very short, composed of ten or eleven joints in

the male and from six to eight in the female; joints not
petiolate in either sex. . . . Micromyia R.

71. Antennae with about twelve flagellar joints in the male,

from ten to twenty-three in the female. Oampylomyza



VII. Family MYCETOPHILID^.




Fig. 39. Sciara, sp. Enlarged. After Washburn.

Mostly small, delicate, slender flies, with more or less
elongated coxae. Head small, rounded or somewhat
elongate. Eyes round, somewhat prominent; ocelli two
or three in number, when only two, placed one on each
orbital margin; rarely apparently wholly wanting; when
three in number, placed transversely in the form of a
shallow triangle. Front broad in both sexes. Antennae
elongated, curved, twelve to seventeen-jointed, the two
basal joints differentiated, the remainder cylindrical, flat-
tened, or petiolated. Proboscis rarely elongated : palpi
three or four-jointed, usually inflected, the first joint
small ; occasionally absent. Thorax more or less, some-
times highly arched, without transverse suture; metano-
tum large; scutellum small. Abdomen elongated, com-
posed of six or seven segments, cylindrical or compressed,
sometimes narrowed at the base; male genitalia project-
ing forceps-like; ovipositor pointed, usually with two
terminal lamellae. Eegs more or less elongated, the coxae

131



132 NORTH AMERICAN DIPTERA.

more or less, sometimes much elongated; femora more
or less dilated, tibiae with spurs. Wings large (wanting
in the 9 of Epidapiis)-, auxiliary vein present, though
sometimes rudimentary; second longitudinal vein want-
ing ; the third vein arises from the first usually at such
an angle that its first section (to the anterior cross- vein)
has the appearance of a cross- vein; fourth vein always,
the third* and fifth either furcate or not ; sixth vein never
furcate, sometimes rudimentary; seventh vein usually
short, often rudimentary or entirely wanting; discal and
posterior basal cells always wanting.

The family Mycetophilidae, commonly known as fun-
gus-gnats, comprises nearly a thousand described species
of small or minute flies, the best known of which are,
perhaps, the various dark-winged species of Sciara so
common about gardens. In the following description of
the immature stages I draw largely from Osten Sacken.

The larvae have a distinct horny head; horny, flat, la-
melliform mandibles; maxillae with a large coriaceous
inner lobe and a horny outside piece, with a circular in-
cision at the tip, the labium small, horny, almost rudi-
mentary; the antennae are usually small or rudimentary,
the ocelli are either wanting or seen in a small pellucid
spot below each antenna. The body is subcylindrical,
more or less elongated, fleshy, whitish or yellowish, and
composed of twelve segments. It is smooth, without
hairs or bristles, except those on the ventral side. It is
generally transparent, showing distinctly the intestinal
canal and the trachea. There are eight pairs of stigmata,
one on the first segment, and seven on the first seven ab-
dominal segments, the last two having none. The loco-
motory organs consist of more or less apparent transverse

* I am of the opinion that the so-called anterior branch of the third
vein is in reality a vestige of the second vein.



MYCETOPHILID^. 133

swellings on the underside of the ventral segments, some-
times furnished with minute bristles or spines.

The larvae present some of the most singular habits
among all diptera. They are gregarious, and live in or
upon decaying matter. Most of the species seem to pre-
fer fungus or fungoid substances, whence comes the com-
mon name of fungus-gnats applied to the mature insect.
The larvae of Sciara are found among deca\nng leaves,
in vegetable mold, in cow-dung, under the bark of dead
trees, etc.; they often live in the soil of potted plants.
The larvae are said to moult several times before pupat-
ing. The larvae of many species spin delicate webs over
the surface of fungi, and on this web they live until ready
to pupate, when they spin a dense cocoon in sheltered
spots; others live within the decaying fungi. Perhaps
the strangest habits of all are those of species of Sciara,
which are even more gregarious than other members of
this family. They have the singular propensity of stick-
ing together in dense patches, and will form processions
sometimes twelve or fourteen feet in length, and two or
three inches broad. The phenomenon has been observed
frequently both in Europe and America, but the reason
therefor is not yet well understood, though the object of
migration seems to be the search for better feeding
grounds. Because of this habit, the name of 'army worm'
has been given to them. Yet more singular is the phos-
phorescent character of the larvae of some species. The
larvae, probably of Sciophila, were observed by Hudson
to be so luminous that 'the light of a single individual
kept in a caterpillar cage may be seen streaming out of
the ventilators at a distance of several feet.'

The pupae of Mycetophilidae are free, — that is they are
not contained within the larval skin, as is so commonly
the case with diptera. They are usually smooth, with
the legs applied to the breast and venter, the antennae



134



NORTH AMERICAN-^DIPTERA.




Fig. 40. Mycetophilidae. \, Manota defecta; 1, Probolccns sin^u-
laris, head; 3, ProbolcEus singiilaris, wing; 4, Mact-ocera coficimia,
wing; 5, Ceroplatus lono^hnaniis, wing; 6, Sciara zygoneura, wing;
7, Sciara ainericana, wing; 8, Sciara, sp., antenna; 9, Platyiira ig-
nobilis, wing; 10, Sciophila dihita, wing; 11, Neoemp/ieria niacu/i-
petuiis, wing; 12, Phthinia fraudulenta, wing; 13, Neoglaphyroptera
nitens, wing; 14, Plesiasiina, sp., wing; 15, Mycetophila ijisipiens,
wing; 16, Tetragoneura sylvatica, wing (Wulp) ; 17, Dynatosonia fus-
cicornis, wing (Wulp)'.



bent around the eyes, and their remaining portion ap-
plied to the breast between the wings and the legs. The
pupae of not a few are enclosed in a cocoon of more or



MYC^TOPHILID^. 135

less density, spun by the larvae; others enclose them-
selves in earthy cases.

The study of the mature insect requires some care.
Usually a compound microscope is necessary for the de-
tection of many characters, especially of the more minute
species, and generally, when there is doubt of the iden-
tity, it is best to mount the whole insect or the most im-
portant parts under a cover glass.

In America, as elsewhere, but little study has been
given to this family, and hence there are doubtless not
a few genera that have hitherto escaped detection. The
following table has been for the most part compiled from
V. d. Wulp, Winnertz and Schiner, and compared with
representatives of nearly all the genera.

TABLE OF GENERA.

1. Coxae moderately long; anterior cross-vein in the same right line

with the second section of the third vein; the fifth vein forked

near base of wing Sciarinse.

Coxae much elongated; anterior cross-vein distinctly angulated
from the second section of the third vein. ... 2

2. Only the distal part of the forks of the fourth vein visible. . 3
Fourth vein visible in its whole extent, the anterior fork rarely in-
complete proximally. . . . . . . . • 4

3. Proboscis short; palpi three-jointed; ocelli distinct (1) . Manota.
Proboscis much elongated; no palpi; ocelli indistinct or absent

(2, 3) Probolseus.

4. Origin of fourth vein from the fifth, near base of wing; sixth vein

more or less indistinct. ....... 5

Origin of fourth vein opposite or beyond the origin of the third;
sixth vein usually distinct. ...... 6

5. Third longitudinal vein furcate, its anterior branch* usually so near

its origin and so transverse in position that it resembles a super-
numerary cross-vein; three ocelli present. Sciophilinse.
Third longitudinal vein not furcate. . . MycetophilinsB.

* In reality the second longitudinal vein.



136



NORTH AMERICAN DIPTKRA.



6. Third longitudinal vein not furcate. . . . Diadocidia.
Third longitudinal vein furcate. ...... 7

7. Anterior branch of third vein long, terminating in the costa.

Mycetobiinse.

Anterior branch of the third vein short, more transverse, usually

ending in the first vein. ....... 8

8. The prsefurca of the fourth vein arises from the third vein beyond

the anterior cross-vein, i. e. the cross-vein is really wanting and

the third and fourth veins are coalesceut for a short distance. 9

The fourth vein continuous in nearly the same line from the fork

to its origin from the fifth; cross-vein distinct. Bolitophila.

9. Antennae short and thick-set, often flattened. . Ceroplatinse.
Antennse exceedingly long and slender, longer than the body (4).

Macrocera.

SCIOPHILIN^l^.

1. Anterior cross-vein more than twice the length of the basal section

of the third vein, forming apparently the beginning of the

third vein (16) Tetragoneura.

Anterior cross-vein shorter or but little longer than the first sec-
tion of the third vein, and forming a distinct angle with the
second section. ......... 2

2. The costal vein terminates at the tip of the third vein (10).

Sciophila.

The costal vein continues a short distance beyond the tip of the

third vein. .......... 3

3. Fork of the fourth vein short petiolate, the prefurca shorter than

the anterior cross-vein. . - . . • Lasiosoma.
Prefurca of fourth vein much longer than the anterior cross-vein. 4

4. Proximal end of the posterior furcation (fifth vein) before or op-

posite the anterior cross-vein (11). . . Neoempheria.
Proximal end of the posterior furcation beyond the anterior cross-
vein Polylepta.

MYCETOBIIN^.
I. Auxiliary vein complete; the anterior branch of the third vein arises
at a point where the third vein and the anterior cross-vein unite.

Mycetobia.
Auxiliary vein rudimentary, not terminating in the costa; furca-
tion of third vein petiolate. ...... 2



MYCKTOPHILID^.



137



2. F'urcation of third vein more proximad than that of the fourth.

Ditomyia.
Furcation of fourth vein more proximad than that of the third (14)

Plesiastina.
CKROPIvATin;i5.

1. Face and proboscis prolonged, snout-iike. . Asindulum.
Face and proboscis not produced. . . . . . . 2

2. Antennse shorter than the head and thorax, flattened; palpi short

(5) Ceroplatus.

Antennae more elongate, cylindrical; palpi moderately long (9).

Platyura.
MYCETOPHILIN^.

1. Three ocelli present. . . . . . . . . 4

Two ocelli, one situated near the margin of each eye. . . 2

2. The costal vein is continued beyond the tip of the third vein.



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