326 INSECTS ATTACKING STOCK AND POULTRY 



The Sheep Bot-Fly, Sheep Gad-Fly, " Grub in the Read," 

 " False Gid." This bot-fly ((Estrus ovis Linn.) is dull yellow in 

 color, looks a little like a large house-fly, and has no mouth. It 

 places its living young in the nostrils of sheep, the egg having been 

 hatched in the body of the parent. The attempts of the female 

 fly to reach this point drive the poor animals frantic. They lie 

 down, bury their noses in the dust, throw dust in the air, huddle 

 together, etc. This fly, like most allied pests, is fond of hot sun- 

 shine, and flies on warm and sunny days between May and October 

 (Fig. 330). The young larva, once in the nose, works its way 

 upward, occasionally gaining lodgement in the frontal sinuses 

 cavities between plates of bone over the eyes. Ten months are 



FIG. 330. Sheep gad-fly: a, adult; b, larva; on right, puparium. (After Brauer.) 



required for the maggots to mature, at which time they crawl 

 back to near the anterior opening of the nose and are sneezed out. 

 They remain hi the pupal stage, one or two inches below the sur- 

 face of the ground, from four to six weeks. 



Injury. The adult flies pester the animals as above described. 

 The upward migration of the larva in an animal's head and its 

 activity cause serious symptoms in the affected animal. These 

 occasionally result disastrously. This, however, according to 

 Neumann, occurs only when the bots are quite numerous in the 

 animal, and are well advanced in their development early in the 

 season. Animals seriously affected lose their appetite, become 

 emaciated, discharge thick mucous matter from the nose, some- 

 times throw their heads back, or, hanging their heads, lift their 



