GAD FLIES OR BOT FLIES. 



6. First posterior cell narrowed in the margin or closed; 

 arista plumose to the tip ....... Some MUSCID^E (p. 266). 



First posterior cell very slightly or not at all narrowed ; 

 arista may be plumose, pubescent, or bare .............. 



................. . .............. ANTHOMYID^E (p. 263). 



(ESTRID.E 



These are the Gad Flies, Bot Flies, or Breeze Flies. 

 The adults are moderate or large in size; the eyes are 

 rather small and the lower part of the head is relatively 

 large. 



" One of the most interesting and injurious 

 Gastrophilus equi. 



The female horse bot fly lays from 400 to 500 eggs, all of 

 which may be placed, under favorable circumstances, 

 upon one horse. These eggs are fastened to the hairs, 

 generally of the fore legs, shoulders, or chest. A horse 

 instinctively fears this pest, and it will be seen, if in the 

 pasture, to start and strike with the fore feet, although 

 the cause of its nervousness is not visible. The adult 

 fly is brownish, more or less hairy, looking a little like a 

 small honey bee. It is most skillful in depositing its 

 yellowish eggs, 'nits' we sometimes call them, on the 

 animal's hairs. The moisture and friction which these 

 receive from the animal licking its hair cause them to 

 hatch, and further licking, occasioned possibly by the 

 irritation caused the skin by the presence of the tiny 

 larvae, carries the maggot into the mouth, whence it finds 

 its way into the horse's stomach, and there completes its 

 larval life, attached to the lining of the stomach, and 

 sometimes so abundant as to completely cover a portion 

 of it. ... The bots live in the stomach or intestine 

 eight or ten months, moulting twice during that period, 

 and naturally, when numerous, sapping the vitality of the 

 horse. They also cause great irritation by attaching 

 themselves to the lining of the small intestine and rectum. 

 In the spring these bots lose their hold and pass out with 

 droppings, working their way into the soil an inch or two, 

 or into some protected locality; each 'bot' or larva 

 changes to a pupa, lying within a pupal case, from which 



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