FLIES 



473 



Warfare by " swatting " is one method of decreasing the num- 

 ber of flies ; but a single escaped fly breeds so rapidly that vic- 

 tory over the pests can be had only by removing all breeding 

 places for the young. The adult fly lays her eggs, about one 

 hundred at a time, preferably in horse manure, but she will also 



lay them in any decay- 



ing matter and even in 

 fresh meat. In order 

 to lessen the number 

 of breeding places, 

 every city should re- 

 quire livery men to 

 keep manure carefully 

 screened from flies, 

 and grocery men and 

 housewives to keep 

 garbage and refuse in 

 covered cans. Every 



FIG. 343. Eggs, maggots, and adults of the fly. 



city should do away with dump heaps and should dispose of 

 garbage in scientific ways. Every individual should see to it 

 that his home, his shop, and his office are free of breeding places. 

 Screened or covered food, yards, and pavements free from banana 

 skins, apple peelings, bits of meat, and other refuse, and clean 

 privies screened against flies ofFer no opportunities for egg 

 laying and are powerful aids in the extermination of the fly. 



The eggs of flies hatch in one day into larvae or tiny white, 

 footless maggots (Fig. 343) which worm thek way about and 

 eat greedily. As they feed and grow, their skin, which is 

 inelastic, becomes too tight for them and finally splits; the 

 growing maggot pulls itself out of its split or molted skin 

 and appears with a soft new skin. For a time the new skin 

 remains soft and elastic and the maggot grows rapidly. But in 

 time the skin hardens and becomes inelastic; it again splits 



