268 



SYSTEMATIC ZOOLOGY. 



Among the former are those forms which feed upon other 

 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 about 



FIG. 86. Head and proboscis of FIG. 87. Larva (maggot) of house- 

 blow-fly. After Kraepelin. e, eye; fly. 

 p, maxillary palpi. 



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. 



The bot-flies are parasitic in various domesticated ani- 

 mals. 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 



