DIPTEKA OR TRUE FLIES. 



253 



ova ; each female laying as many as six batches during her life. 

 The ova hatch in from eight to tv^enty-four hours. The larvae are 

 dirty-white footless grubs, Avhich cast their .skin tvifice, and then 

 in a week they become full fed and stop feeding. When mature 

 they are about half an inch long. The skin then hardens into 

 a brown puparium case. This stage, still in the dung-heaps, 

 &c., may last three days only, depending on the weather. 

 Larvae, pupae, and flies may be found all the year round. The 

 house-fly lives by sucking up its food. They annoy us and 



Fig. 145.— Head of Stomoxiju. (Delafond.) 

 a, AntfnntL- ; 39, maxillary palp ; t, proboscis. (From Par. Dis. Ani., Fleming.) 



our animals to feed off the sweat. Numerous other species 

 of Musoidse are called house-flies, the technical differences 

 of which we cannot enter into. The house-fly is destroyed 

 wholesale by a fungus, Enipusa musca, the spores of which 

 germinate in the body, and the myoelia grow out, killing the 

 fly and fixing it, as we so often see, to the window-panes. 

 The importance of the house-fly is because it carries the germs 

 of enteric fever and suchlike. 



Another noxious fly sometimes found in houses, .stables, 



