MOSQUITOES AND FLIES 



tic pest to people that live indoors, is intimately associated 

 with the stable. Its favorite breeding place is the manure 

 pile. Here the female fly lays her eggs (B), and here the 

 larvae, or maggots (C), live until they are ready for trans- 

 formation. It is estimated that fully ninety-five per 

 cent of our house flies have been bred in horse manure. 

 A few may come from garbage cans, or from heaps of 

 vegetable refuse, but such sources of fly infestation are 

 comparatively unimportant. Measures of fly control are 

 directed chiefly to preventing the access of flies to stable 

 manure and the destruction of maggots living in it. 



The eggs of the house fly (Fig. 182 B) are small, white, 

 elongate-oval objects, about one twenty-fifth of an inch 

 in length, each slightly curved on one side and concave on 

 the other. The female fly begins to lay eggs in about ten 

 days after having transformed to the adult form, and she 

 deposits from 75 to 150 eggs at a single laying. She re- 

 peats the laying, however, at intervals during her short 

 productive period of about twenty days, and in all may 

 deposit over 2,000 eggs. Each egg hatches in twenty-four 

 hours or less. 



The larva of the house fly, in common with that of many 

 other related flies, is a particularly wormlike creature, and 

 is commonly called a maggot (Fig. 182 D). Its slender 

 white body is segmented, but, in external appearance, it 

 is legless and headless. On a flat area at the rear end of 

 the body are located two large spiracles (PSp), which 

 the novice might mistake for eyes. The tapering end of 

 the body is the head end, but the true head of the maggot 

 is withdrawn entirely into the body. From the aperture 

 where the head has disappeared, which serves the maggot 

 as a mouth, two clawlike hooks project (mh), and these 

 hooks are both jaws and grasping organs to the maggot. 

 The larva sheds its skin twice during the active part of its 

 life, which is very short, usually only two or three weeks. 

 Then it crawls off to a secluded place, generally in the earth 

 beneath its manure pile, where it enters a resting condi- 



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