o. Petiole of the first forked cell (R_2) more than a third the length of the cell. Mississippi valley. A. WALKERI
oo. Petiole of the first forked cell a third the length of the cell. Md. A. BARBERI
nn. Wings spotted.
o. Front margin of the wings with a patch of whitish and yellow scales at a point about two-thirds or three-fourths of the way from base to apex of wing.
p. Veins of the wing with many broad obovate outstanding scales; thorax with a black dot near the middle of each side. W. I. A. GRABHAMI*
pp. The outstanding scales of the wings rather narrow, lanceolate.
q. Scales of the last vein of the wings white, those at each end black; R_{4+5} black scaled, the extreme apex white scaled. Widely distributed north and south (fig.
131). A. PUNCTIPENNIS
A dark variety from Pennsylvania has been named A. PERPLEXENS.
qq. Scales of the last vein of the wing white, those at its apex black; R_{4+5} white scaled and with two patches of black scales. South and the tropics. A. FRANCISCa.n.u.s and PSEUDOPUNCTIPENNIS*
oo. Front margin of the wings wholly black scaled.
p. Last (a.n.a.l) vein of the wings white scaled with three patches of black scales (fig. 132). New Jersey to Texas. A. CRUCIANS*
pp. Last vein of the wings wholly black scaled.
q. Widely distributed north and south (fig. 130), (= MACULIPENNIS). A.
QUADRIMACULATUS*
qq. Distributed from Rocky Mountains westward. A. OCCIDENTALIS
kk. Scutellum distinctly trilobed.
l. Cell R_2 less than half as long as its petiole; thorax with metallic blue scales; median lobe of the scutellum not tuberculate; few small species which are not common. URANOTaeNIA Arrib.
ll. Cell R_2 nearly or quite as long as its petiole, or otherwise distinct.
m. Femora with erect outstanding scales; occiput broad and exposed. Large species. P.
CILIATA. P. HOWARDI PSOROPHORA R. D.
mm. Femora without erect scales.
n. Clypeus bearing several scales or hairs, scutellum with broad scales only; back of head with broad scales; scales along the sides of the mesonotum narrow; some or the claws toothed; thorax marked with a pair of silvery scaled curved stripes; legs black with white bands at the bases of some of the segments (fig. 134). Yellow Fever mosquito. AEDES (= STEGOMYIA) CALOPUS.
nn. With another combination of characters.
Numerous species of mosquitoes belonging to several closely related genera, widely distributed over the country. (_Culex_, _Aedes_, _Ochlerotatus_, etc.). CULEX in the wide sense.
ii. Metanotum with setae. _Wyeomyia_ (found in the United States); and related tropic genera.
bb. Antennae composed of three segments with a differentiated style or bristle; third segment sometimes complex or annulate, in which case the empodium is usually developed like the pulvilli, i.e., pad-like (fig. 161 g).
c. Empodium developed pad-like (pulvilliform) i.e., three nearly equal membranous appendages on the underside of the claw (fig.
161g).
d. Squamae, head, and eyes large; occiput flattened or concave; third segment of the antennae with four to eight annuli or segments, proboscis adapted for piercing; body with fine hairs, never with bristles; middle tibia with two spurs; wing venation as figured (fig. 163f); marginal vein encompa.s.ses the entire wing. Horse flies, greenheads, deer flies, gad flies TABANIDae[I]
e. Hind tibia with spurs at tip; ocelli usually present (PANGONINae)
f. Third joint of the antennae with seven or eight segments; proboscis usually prolonged.
g. Each section the third antennal segment branched. Central American species, _P. festae_. _Pityocera_ G. T.
gg. Sections of the third antennal segment not branched.
h. Upper corner of the eyes in the female terminating in an acute angle; wings of both s.e.xes dark anteriorly.
_G. chrysocoma_, a species from the eastern states.
_Goniops_ Ald.
hh. Upper corner of the eye in the female not so terminating; wings nearly uniform in color, or hyaline.
i. Proboscis scarcely extending beyond the palpi; front of the female wide; much wider below than above. S.
W. States. _Apatolestes_ Will.
ii. Proboscis extending beyond the palpi.
j. Wing with cell M_3 closed. Tropic America. (= _Diclisa_) _Scione_ Wlk.
jj. Cell M_3 open; ocelli present or absent. Two or three eastern species; many south and west PANGONIA Rdi.
ff. Third segment of the antenna with five divisions; ocelli present.
g. First and second segments of the antenna short, the second only half as long as the first, three western species. SILVIUS Rdi.
gg. First and second segments of the antenna long, the second distinctly over half as long as the first. Deer flies. Many species, widely distributed. CHRYSOPS Meig.
ee. Hind tibia without spurs; ocelli absent.
f. Third segment of antenna with four divisions, no tooth or angulation; wings marked with rings and circles of darker coloring; front of the female very wide. Widely distributed. _H. americana_, _H. punctulata_. HaeMATOPOTA Meig.
ff. Third segment of the antenna with five divisions (fig.
161b).
g. Third segment of the antenna not furnished with a tooth or distinct angular projection.
h. Body covered with metallic scales; front of female of normal width; front and middle tibiae greatly dilated.
_L. lepidota_. _Lepidoselaga_ Macq.
hh. Body without metallic scales; antennae not very long, the third segment not cylindrical, not situated on a projecting tubercle; front of the female narrow.
South. _D. ferrugatus._ (= _Diabasis_) _Diachlorus_ O.
S.