Diptera 293 



11. 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, scutel- 

 lum 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, A edes, 

 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 empo- 



dium 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 claws (fig. i6ig). 



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. i63f); marginal vein encompasses the entire wing. Horse 



flies, greenheads, deer flies, gad flies 



e. Hind tibia with spurs at tip; ocelli usually present 



f. Third joint of the antennae with seven or eight segments; probo- 



cis usually prolonged, 

 g. Each section the the third antennal segment branched. Central 



American species, P. festa 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 sexes dark anteriorly. G. chrysocoma, 



a species from the eastern states Goniops Aid. 



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. 



*This table to the North American genera of the Tabanidae is adapted from one given by 

 Miss Ricardo. 



