BOT-FLIES. 



213 



ing themselves in the air with the telescopic ovipositor 

 directed downwards and forwards. When not disturbed by 

 the animal the female deposits an egg upon those parts of 

 the horse most accessible to that animal's tongue, or upon 

 the fore-limbs, knees and shanks, and this operation is re- 

 peated so that many hundreds of eggs can be found upon 

 the same animal. Horses in stables are not molested. The 

 egg, one of which is shown on a hair in the illustration, is at 

 first white, but soon becomes yellowish-white, is conical, 

 about 1.25mm. long, finely trans versely striated and provided 

 at the upper end with a peculiar cap obliquely truncated. 

 Such eggs are fastened to the hairs at their narrower end by 



Fig. 175. — Bot-fl_v of horse; male; abdomen of female, and e^ 

 larged. Original. 



Greatly en- 



means of a sticky material, which secures them so well in 

 position that they can not be removed simply by brushing, 

 as has been frequently stated. These eggs soon hatch, the 

 time varying greatly according to the climatic conditions, 

 into very active larva, w^hich, crawling over the skin, cause 

 an itching that induces the horse to lick such places. In 

 some cases the eggs themselves are removed by licking, and 

 thus reach the stomach; in other cases the very young larvae 

 crawl into the mouth, being enabled to do so by two 

 black hooks in the head, which are bent almost at right 

 angles. In this manner the larvae reach the interior of the 

 horse, where they fasten themselves to the mucous membrane 

 of the stomach. This is accomplished by means of hooks 

 found upon the head of the larvae; the head gradually sinks 



