56 
IMPORTANT AND FAMILIAR INSECTS 
are eaten by nighthawks, martins, bats, and dragon flies. 
Certain diseases caused by plants attack the adults and kill 
them in great numbers. (See Chapter XXIII.) 
The number of mosquitoes can be greatly reduced by 
destroying their natural breeding places in old rain barrels, 
watering troughs, boxes that may hold water, pails, eaves 
troughs, and sink holes. The larger breeding places are 
sluggish streams and swamps. Draining these is the most 
effective method of preventing mosquitoes from laying their 
eggs in such localities. When this is not possible, the surface 
of the water may be covered with kerosene, which kills 
the larvae by preventing them from getting oxygen from 
the air. Frequent applications of oil greatly reduce the 
number of mosquitoes. 
36. The House-fly. — Because of its filthy habits of 
breeding and living and because it comes to the dining room 
and kitchen crawling over the food, the house-fly has come 
to be recognized as a dangerous disease carrier. 
37. Life History. — Each female lays from one hundred to 
one hundred and sixty eggs in stable filth or other refuse. The 
eggs hatch in a day or so into legless larvae. In five to seven 
days, depending on the temperature and the food supply, the 
larvae are full grown. They then pupate for another five to 
seven days. At the end of this time the adults emerge as 
mature flies ready to lay eggs for another generation. This 
continues until cold weather puts an end to their activities. 
Enough generations are produced every year so that a 
single female in the spring could have a million descend¬ 
ants by October if numerous enemies did not make this 
impossible. 
38. Methods of Control. — Every one should support the 
“ swat the fly ” campaign and help reduce the number of 
flies. The few house-flies that survive the winter are re¬ 
sponsible for the millions that swarm about in the summer. 
Their numbers may be reduced by several methods: 
