220 



SHEEP GAD-FLY. 



detected, hence few persons have ever seen it, and judging 

 from the fact that it is not represented in most of the larger 

 collections in this country even entomologists have not fre- 

 quently observed it. Fig. 181 was made by J. W. Folsom 

 from a specimen in the Cambridge museum. It resembles a 

 very large house-fly; the upper parts of the head and thorax 

 are of a dull-yellow color and are covered with little elevat- 

 ed, round, black spots and still smaller brown specks. The 

 five-jointed abdomen is velvety and variegated with brown 

 and yellow colors; the feet are brow^n; the swollen underside 

 of the head is white; the eyes are purplish-brown; three e3^e- 

 lets are found upon the top of the head, and two very min- 



Fig. 180. — Sheep Gad-fl3'; u, adult; h, larva; r, pupariutn. After Braiier. 



ute feelers in front. As the fly possesses no mouth it can 

 take no food; and it is only active during the warmer days 

 of summer, when it attempts to deposit the young larvee in 

 the nostrils of sheep. Of course these larvge come from eggs 

 that were already hatched in the oviduct. Both sexes are 

 nearlj^ of the same size, measuring from 10 to 12mm. in 

 length. 



This parasite is found throughout Europe, Asia, Africa, 

 and the Americas. Very likely it was introduced into the 

 United States with the earliest flocks of sheep; more recently 

 it has been introduced into Chili. 



The Sheep Gad-flj^ flies only during dry and warm 



