60 THE INSECT WORLD. 



carried away with the excrementitious matter. It traverses, mixed 

 with the excrementary bolus, the whole length of the intestinal canal, 

 leaves it by the anal orifice, and on touching the ground at once 

 seeks a suitable place to go through the last but one of its 

 metamorphoses. 



The skin then gets thick, hardens, and becomes black. All the 

 organs of the animal are composed of a whitish amorphous pulp, 

 which soon assumes its destined form, and the insect becomes perfect. 



\ * / 



4S- Bot-fly (CEstrus b 



It then lifts a lid at the anterior part of its cocoon, emerges, dries its 

 wings, and flies off. . 



The Bot-fly (CEstrus bovis, Fig. 45) has a very hairy body, large 

 head, the face and forehead covered with light yellow hair, the eyes 

 brown, and the antennae black. The thorax is yellow, barred with 

 black ; the abdomen of a greyish white at the base, covered with 

 black hair on the third segment, and the remainder of an orange 

 yellow ; the wings are smoky brown. 



As soon as the cattle are attacked, they may be seen, their heads 

 and necks extended, their tails trembling, and held in a line with the 

 body, to rush to the nearest river or pond, while such as are not 

 attacked disperse (PLATE II.). It is asserted that the buzzing alone of 



