158 MISC. PUBLICATION 631, U. S. DEPT. OF AGRICULTURE 



The Family PIOPHILIDAE 



This family includes some rather slender flies, usually 5 mm. or less 

 in length and mainly of a glossy black color. The antenna is short in 

 most species, the third segment being oval, with the arista arising near 

 its base; the eyes are round; the occiput convex and prominent. Vi- 

 brissae are present ; the postvertical bristles are divergent ; the fronto- 

 orbitals are rather weak, with not more than two pairs developed. 

 Vein sc is complete ; the second basal and the discal cells are separated. 

 The legs and abdomen are never strongly bristled. The family is re- 

 lated to the Sepsidae, but may be distinguished by the lack of the 

 small, but evident, postspiracular bristles that characterize that 

 family. 



Only one species is of known medical importance. 



The Genus PIOPHILA Fallen 



The antennae are short, the first and second segments being shorter 

 in their combined length than the third ; the arista is bare. Only one 

 clorsocentral bristle, the prescutellar one, is present. Vein m 1+2 

 parallels r 4+5 beyond the posterior cross vein; the anterior cross vein 

 reaches the discal cell slightly beyond its middle, and anterior to its 

 apical third. The abdomen shows five pregenital segments. 



PIOPHILA CASEI (Linnaeus) 



The Cheese Skipper 



Recognition Characters. — Adult : This is a black fly 2.5-4 mm. in length, 

 with the lower part of the head, the antennae, and parts of the legs yellow. The 



Figure 94. — Piophila casei, adult female. 



ocellar bristles are small, widely distant, and located opposite the front ocellus ; 

 the fronto-orbitals are undeveloped. The cheeks are prominent and distinctly 

 more than half the eye height. The mesonotum is scabrous; in the center it 



