33 2 
The Two-winged Flies 
mimicry (see Chap. XVII). 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 antennae 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. Antennae composed of three segments, the third usually large and either with or 
without a bristle or style. 
B. Empodium pulvilliform, i.e., feet with three little pads instead of two. 
(Snipe-flies.) Leptid^e (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.) Bombyliid^e. 
DD. Second branch of cubital vein joining first anal far from the 
margin of the wing (see Pig. 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.) MuscimE. 
DD. Head without such suture. 
E. Radial vein with a knot-shaped swelling at the point where 
it forks, with a small cross-vein running back just 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; antennae with dorsal arista. 
(Bot-flies.) (EsTRimE. 
GG. Proboscis not rudimentary; palpi present; antennae 
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,e. 
GG. Front convex beneath the antennae; a spurious 
vein usually present between radius and media 
(Fig. 479).(Flower-flies.) Syrphid.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 ((Estridae), 
house-flies, flesh-flies, bluebottles and stable-flies (Muscidae calyptrata), and 
