CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 253 



Larva. — ^Lives in the soil, mud or water; cylindrical, tapering, 

 2 inches long when full grown; yellowish-white with wide dark brown 

 bands at union of each two segments; prothorax with 2 lateral grooves 

 on each side; mesothorax with 4 longitudinal grooves on each side; 

 metathorax and abdominal segments like mesothorax. Carnivorous. 

 Hibernates (Fig. 159). 



Pupa.— The pupal stage lasts only a few days; i}i inches long; 

 brownish yellow; lives beneath surface of the soil. 



Fig. 158.- 



-The black gad fly. 

 {After Carman.) 



Enlarged. 



Fig. 159. — The larva or 

 grub of the black gad fly. 

 {After Carman.) 



Treatment. — ^Protect work horses with fiy-nets; smearing ears, with a 

 repellent solution composed of pine tar i gal., fish oil or crude carbolic 

 acid I qt., powdered sulphur, 2 lb. 



On the western plains horse flies are very troublesome pests. The 

 most common forms are T. septentrionalis Loew, T. illotus O. S., T. 

 hirlulus Bigot, Chrysops moerens Walk., and C.fulvaster O. S. 



