THE HOUSE FLY 81 



disease, some of the infected blood remains on the lancet 

 and dries there ; and when this lancet is subsequently 

 thrust through the skin of a healthy animal, it is likely 

 when withdrawn to leave behind it the infected blood of 

 the sick beast. That this species of fly is a carrier of 

 disease germs from one animal to another in this way, 

 there cannot be any doubt. Where there are plenty of 

 animals on which to feed, the Biting Stable Fly does not, 

 as a rule, gorge itself on one animal's blood. It prefers 

 to sample the blood of several, and is on this account a 

 source of graver danger than it would have been if it 

 contented itself with its fill of blood from a single beast. 



The Biting Stable Fly is commonly found in the vicinity 

 of dwellings, but it usually remains out of doors in the 

 warm sunshine, and so long as the atmosphere is balmy 

 and genial. However, at night, or when the weather is 

 chilly, or rain is falling, it seeks shelter in outhouses and 

 dwellings. It will bite a human being as readily as an 

 ox or a horse ; in fact it often specially favours the human 

 animal with its attentions, owing to his skin being so easy 

 to pierce. When reclining or moving about out of doors 

 during the summer time it is a common occurrence for 

 these flies to settle upon the bare parts of the skin. Their 

 presence is quickly made known by the sharp, painful 

 prick which they inflict. Thin clothing, such as a shirt, 

 does not deter them from biting, as the lancet can be 

 readily thrust through such material and into the tender 

 flesh beneath. 



The Biting Stable Fly, like the House Fly, breeds in 

 decaying animal and vegetable matter. Its favourite 

 breeding-places are fermenting heaps of hay, straw, and 



