THE HOUSE FLY 23 



mischief, but the instant the fly speck gets dissolved in a 

 suitable substance, they are once again active, and breed 

 with astounding rapidity. A single fly speck is capable of 

 inoculating a man with enteric fever or one of a score or 

 more diseases. You may cover up your food materials 



FIG. 10 



THE HEAD OF A HOUSE FLY, seen in profile, 

 i. The large compound eye. 2. The proboscis or sucker. 

 3. The top of the head. 4. The front of the head. 



(From National Geographic Magazine, Washington, D.C. 

 Copyright 1913, by special permission,) 



with the most scrupulous care, but so long as there is a 

 single fly at large in the house, there is a danger of infection, 

 not only by microbes which harbour in fly specks, but also 

 in the following way. 



When a fly sucks up its food hurriedly, as it usually does 

 when feeding upon filth, owing to the competition of swarms 

 of other flies, each eager to get a share, it invariably wings 



