200 



SCHOOL ENTOMOLOGY 



secured cheaply at any drug store. Its exact effect on the 

 parasites is not known, but it has proven effective in ridding 

 animals of them and when used as directed there have been 

 absolutely no symptoms of any injury to the animals. 



122. Horse Flies.* 

 The large black horse 

 flies or gad-flies (48) 

 are well-known pests 

 of both horses and 

 cattle, which they 

 torture with their 

 bites. Only the fe- 

 males, having piercing 

 mouth-parts, are 

 bloodsuckers, the 

 males feeding on the 

 pollen of flowers. The 

 large Black Horse Fly\ 

 is about one inch long 

 and has a wing expanse 

 of two inches. It has 

 a short broad head, 

 large eyes, a thick 

 body, a short oval 

 abdomen and large 

 powerful wings, which enable it to keep up with the swiftest 

 horse. Particularly along shady roads in woodlands these 

 flies are often so abundant as to make driving difficult. 

 The smaller Greenheads^ so called from their large green 

 eyes, are more common near the water and are well known 



* Family Tabanidce. See page 136. 

 t Tabanus atratus Fab. 

 J Tabanus lineola Fab. 



FIG. 142. The biting cattle-louse (Tri- 

 chodectcs scalaris), enlarged. (U. S. 

 Dept. Agr.) 



