76 THE HOUSE-FLY 



the pupal state. The house-fly is widely 

 distributed over the world, and it sometimes 

 occurs in large numbers away from the dwell- 

 ings of man. 



The compound faceted eyes, the proboscis 

 and the complicated feet of the house-fly all 

 form instructive and interesting objects for the 

 microscope. It is now generally believed that 

 the pads on the feet do not support the fly 

 when walking on the ceiling or window-pane by 

 performing the office of suckers, but that they 

 exude a viscid fluid which enables the insect to 

 adhere to smooth surfaces. 



The bite of flies that have been feeding on 

 putrid substances is attended with danger. It 

 is well that these flies are not allowed to 

 increase indefinitely. They are subject to the 

 attacks of a white fungus, and possibly to those 

 of a tiny insect, the chelifer. 



It is hardly necessary to say that when a 

 fly assumes the perfect state it never grows 

 any larger, so that when we see small flies 

 that appear like the house-fly we must not 

 imagine they are the young of the larger ones. 



