3^2 The Two-winged Flies 



mimicry (see Chap. XV'II). Erax is a genus with many common gray and 

 black species about an inch long, with sharp-pointed tip of the abdomen. 



The third section or group of Brachycerous families includes many 

 families, in all of which the antenna^ have the first two segments small and 

 the third curiously large and club-like, and usually bearing a single con- 

 .spicuous bristle-like hair. The families of this group can be distinguished 

 by the following table: 



A. Antenna composed of three segments, the third usually large and either w-ith or 

 without a bristle or style. 

 B. Empodium pulvilliform, i.e., feet mth three little pads instead of two. 



(Snipe-flies.) Leptid.f. (in part). 

 BB. Empodium not pulvilliform, i.e., feet with two little pads and a median bristle 

 or nothing. 

 C. Radial vein four-branched. 



D. Second branch of cubital vein extending free to the margin of the 

 wing or coalesced with the first anal vein for a short distance 



(see Fig. 466) (Bee-flies.) BoMBYLllD.t. 



DD. Second branch of cubital vein joining first anal far from the 

 margin of the wing (see fig. 471). 



(Dance-flies.) Empidid.e (in part). 

 CC. Radial vein with not more than three branches. 



D. Head with a curving suture immediately above the antennae. 



(House-flies and allies.) Muscid.e. 

 DD. Head without such suture. 



E. Radial vein with a knot-shaped swelling at the point where 

 it fork.s, with a small cross-vein running back 'ust at or near 

 this swelling (Fig. 474) . . (Long-legged flies.) Dolichopodid.e. 

 EE. Wings without such characteristics. 



F. Second branch of cubital vein appearing as a cross- 

 vein or curved back towards the base of the wings 

 (Fig. 479)- 



G. Proboscis rudimentary; mouth-opening small; palpi 

 wanting; antenn;e with dorsal arista. 



(Bot-flies.) (EsTRiD.E. 

 GG. Proboscis not rudimentary^; palpi present; antenna; 

 with terminal style or arista or dorsal arista. 



Empidid.e (in part). 

 FF. Second branch of cubital vein not appearing like a 

 cross-vein. 

 G. Front with grooves or a depression beneath the 



antennae (Wasp-flies.) CoNOPiD.t. 



GG. Front convex beneath the antennae; a spurious 

 vein usually present between radius and media 

 (Fig. 479) (Flower-flies.) Svrphid.e. 



The families of flies named in the above key contain many hundreds of 

 species but few of which are at all popularly known. The bot-flies (CEstrida;), 

 house-flies, flesh-flies, bluebottles and stable-flies (Muscidw calyptrata), and 



