254 



ECONOMIC ENTOMOLOGY 



CESTRID^ (BOT FLIES) 



Common Genera and Species: 



A. Costal vein ends at tip of R4+5, M1+2 is straight not reaching the margin, 

 and cell R5 wide open; squamae small, arista bare; ovipositor elongate. — 

 Gasirophilus (Fig. 160). 

 B. Wings with spots and smoky median cross band. — G. ifitestinalis. 



Rz*3 



R-t-s 



Fig. 160. — Venation of wings of horse hot flies {Gasirophilus), 1, G. intestinalis; 

 2, G. nasalis; 3, G. hoemorrhoidalis. 



BB. Wings without spots. 



C. Posterior cross-veins (M-Cu) beyond the anterior cross-vein 

 (r-m) ; legs blackish brown. — G. hcemorrhoidalis. 

 CC. Posterior cross-vein opposite and nearer than the anterior cross- 

 vein. — G. nasalis. 

 AA. Costal vein ends at tip of M1+2; M1+2 with a bend; cell Rb much narrowed 

 or closed. 

 B. Facial grooves approximated below; cell Rs closed and petiolate. — 

 (Eslrus. 



