HORSE BOT FLY. 



65 



fleshy tubercles; also the maggots of this family of 

 Flies live ■within some part of the animal that is 

 attaclved. Prof. Westwood notes three principal 

 diflerences in their habits : — Some live in tumours 

 beneath the skin; some attack the cavities of the 



Fig. 50. — Horse Bot Fly, 1, male ; 2, female ; 3, maggot ; 4, chrysalis, 

 nat. size, after Bracy Clark. 



head, which are reached through the nostrils ; and 

 some are gastric in their attack, by the maggots being 

 introduced into the stomach. 



These Flies belong to the family of the Q^stridce ; 

 and the kind we are about to notice (the Gastropliilus 

 equi, or Horse Bot Fly, see figure above), are about 

 the size of a house Fly, or rather larger, and are 

 somewhat gaily coloured with yellowish and dark 

 markings, and very hairy. 



In the case of this Horse Bot Fly, the female hardly 

 touches the animal, but, whilst lightly flying to and 

 fro, places the eggs on the hairs, until the very nu- 

 merous supply are laid. These are fixed by a kind of 

 sticky moisture on the shoulder, or on the mane, 

 inside the knee, or on any other part selected. The 

 maggot forms within the egg, and when it is ready to 



F 



