DIPTERA OF MINNESOTA. 



131 



are required for the mag-gots to mature, at which time they crawl 

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

 They remain in the pupal stage, one or two inches below the surface 

 of the ground, from four to six weeks. This upward migration of 

 the larva, and its subsequent activity, causes serious symptoms in the 

 affected animal, which occasionally result disastrously. This, how- 

 ever, according to Neumann, only occurs when the bots are quite 



Fig. 125. Sheep Gad-Fly, from a Cambridge specimen. Enlarged. Lugger. 



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 feet 

 high in the air when walking, grate their teeth and froth at the mouth. 

 This is followed by convulsions and finally death within six or eight 

 days after the appearance of the first symptoms. This fly, like most 

 allied pests, is fond of hot sunshine, and flies on warm and sunny days 

 between May and October. 



The above symptoms are sometimes wrongly ascribed to the attacks 

 of worms which cause the sickness known as "gid", or "turn sick". 

 The presence of the bot fly, however, does not cause the animal to 

 turn in a circle, as in a case of "turn-sick". The presence of the bot, 

 too, nearly always causes nasal discharges and snortings which 

 symptoms are absent in a case of "gid". 



Remedies and Means of Prevention: 



In the case of common stock destined for the market, a verv 



