DIPTERA. 



223 



insects, as well as those which in their larval stages feed 

 upon decaying organic matter. 



Most familiar of all is the common house-fly. This lays 

 its eggs in horse-manure, each female producing ahout 

 150 eggs. In about ten to fourteen days these eggs become 

 perfect insects, so that with this rapidity of multiplication 

 it is no wonder that flies are abundant towards the end of 

 summer. Allied to this is the blow-fly which lays its eggs 

 in meat and other provisions. 



FIG. 100. Head and Proboscis of 

 blow-fly. After Kraepelin. e, egg ; 

 p, maxillary palpi. 



FIG. 101. Larva (maggot) of 

 house-fly. 



The bot-flies are parasitic in various domesticated animals. 

 These flies lay their eggs upon horses, cattle, or sheep, and 

 the larvae enter the animal and cause serious injury or even 

 death. The horse-bot larvae are taken into the stomach; 

 the ox-bot or " ox-warble " lives beneath the skin of cattle ; and 

 the sheep-bot enters the cavities connected with the nose or 

 even the horns, producing the disease known as " si 



