ANIMALS AS DISEASE CARRIERS 



397 



to be taken into man's body with the food. The only use 



that the house fly serves is that of a scavenger, helping to 



decompose decaying organic matter. If the body of a fly 



is viewed under the microscope, it will be 



seen to be well fitted for carrying germs. 



Its legs and feet are covered with hairs; and 



its head and proboscis are also very rough. 



It has two compound eyes which enable it 



to see in all directions, making escape from 



its enemies easy. 



The life history of a house fly should be 

 known in order that we may be able to 

 destroy it most effectively. It deposits its 

 eggs in garbage cans or in decaying matter 

 about barns and other outbuildings or even MAGNIFIED 

 in decaying logs in the woods. In a day or FOOT OF A 

 so the eggs hatch and the larva eats the ma- 

 terial in which it lives. The larva has no legs, how it i 

 but can move slowly by twisting and bending ted for carry- 

 its body. It is white in color, and in about mg s erms - 



five to seven days grows to 

 maturity, when it is about 

 a half inch in length. When 

 the larva stops eating, a 

 brown coating is formed over 

 its body and it is then in the 

 LIFE HISTORY OF THE HOUSE FLY pupa stage. It does not take 

 (a) Adult. (b) Eggs (c) The any f ood while m this CQn _ 

 larva or grub stage, (a) The pupa. ... 



dition, but the six legs and 



the wings, head, and eyes are developed. It takes from five 

 to seven days for it to change from the pupa to the adult 

 state. At the end of the pupa stage the fly comes out 

 a full grown adult. Flies vary in size, but this variation 



HouSE FLY 

 w 



