422, THE HORSE GAD-FLY. 



blood. This they suck in at a small longitudinal 

 aperture, situated between the hooks. 



From their slowness of growth, and the very small 

 quantity of food they require, it has been found 

 extremely difficult to destroy th?m by any medicine 

 or poison that could be thrown into, the stomach. 

 They are, however, not now considered so injurious 

 to horses as they formerly were, and therefore the 

 difficulty of their extirpation seems not a matter of 

 so much consequence as people have imagined. 



The mode pursued by the parent fly to obtain 

 for its young a situation in the stomach of the horse 

 is very singular:— The female, when the time for 

 laying her eggs is at hand, approaches on wing 

 that part of the horse where she intends to deposit 

 the egg y with her body nearly upright ; and her tail, 

 which is lengthened out for the purpose, bent in- 

 wards : she scarcely appears to settle, but merely 

 touches the hair, with the egg held out on the pro- 

 jected point of the abdomen. The egg adheres by 

 means of a glutinous liquor secreted with it. She 

 then leaves the horse, goes to a small distance, and 

 prepares a second egg ; then, poising herself before 

 the part, deposits this in the same way. The liquor 

 dries, and the egg becomes firmly glued to the 

 hair : this is repeated by various flies, till 400 or 

 500 eggs are sometimes laid on one horse. 



The inside of the knee is the part on which these 

 flies principally deposit their eggs ; and next to this 

 they fix them on the sides, and the back part of the 

 shoulder: but always in places that are liable to be 

 licked by the tongue. When these eggs have re-* 



