5) 
In the feeding position the wings are slightly elevated, and are 
held out from the body at an angle of 60° from the abdomen; the 
legs are held out widely, and the beak, inserted beneath the skin of 
the animal, is directed almost perpendicularly (see fig. 3, c). Before 
inserting its beak the fly works its way through the hair close to the 
skin, but is able at the least sign of danger to rise instantly in flight, 
to return as quickly. The characteristic appearance of the fly is 
shown in the accompanying illustration (fig. 1). It is about half the 
size of the house fly, which it closely resembles, but is much less 
robust. 
Differing from other biting flies, the horn fly normally stays on the 
cattle night and day, and when not feeding rests on the cattle as 
already described. 
Fic. 2.—Cow-horn showing band of resting horn flies. Reduced. (From Riley and Howard.) 
The egg-laying habit of the insect was not easily discovered and is 
somewhat peculiar. The eggs are laid singly and usually upon. their 
sides upon the surface of wet dung. The moment the latter is 
dropped, a swarm of flies dart from the animal to the dung and re- 
main there a few seconds, or a minute at the most, during which 
time many eggs are deposited. Egg laying is chiefly during day- 
light, between 9 a.m. and 4 p. m., and most abundant during the 
warmer morning hours. So far as we know, they are laid upon no 
other substance, and never upon old dung. 
The larve upon hatching descend into the dung, remaining, how- 
ever, rather near the surface. When full grown they are about two- 
fifths of an inch in length and of the normal color and form of the 
related dung maggots. The puparium is formed in the ground be- 
neath the dung. The time elapsing from the egg to the adult is from 
ten to seventeen days, and there are probably seven or eight genera- 
tions annually in the latitude of Washington, with more in the South, 
[Cir.115] 
