336 The Diseases of Animals 



spring, forming the lumps commonly known as "war- 

 bles." When fully developed, the larvae, or "grubs," 

 work their way out through small openings in the skin, 

 drop to the ground, into which they burrow and pupate, 

 finally emerging as adult flies. 



These bot- or gad-flies of the ox cause much loss 

 to the cattle industry, not only on account of the serious 

 discomfort visited upon cattle by the adult fly in de- 

 positing her eggs, but also by the damage to hides due 

 to the presence of the openings over the "warbles." 

 "Grubby" hides are usually docked one -third in the 

 market. 



All adult bot-flies observed about cattle should be 

 killed, and, from January on, every "warble" should 

 be treated by applying turpentine to the small pore 

 or opening directly over the lump. This will kill 

 most of the warbles; the few that remain should be 

 squeezed out and destroyed, each one so treated pre- 

 venting the development of a fly. If this practice were 

 generally and carefully followed, the fly could be exter- 

 minated. The adult flies do not travel far, so that a per- 

 son, by this means, can largely rid his own cattle of this 

 pest. 



SHEEP BOT-FLY, "GRUB IN THE HEAD" 



There is a small brown fly (CEstrus ovis) , about the 

 size of the common house-fly, which in the summer and 

 fall is seen in swarms about flocks of sheep. It greatly 

 annoys the animals by depositing living larvae in the 

 nostrils. To avoid these pestiferous flies, the sheep 

 often stand with their noses close to the ground, 



