4 HOUSEHOLD INSECTS 



and instincts, seems to be a lover of filth. Its eggs are 

 usually laid in manure, preferably in horse manure, at 

 least whenever this medium can be found. Sometimes 

 they are laid on cow manure and often on human excre- 

 ment, especially in open closets, and on other decaying 

 animal and vegetable material. A female fly may deposit 

 120 to 150 eggs at a time and as she has been observed 

 to make four deposits we must conclude that a single 

 fly is capable of laying at least 600 eggs. This will account, 

 in a measure, for the enormous number of these insects. 



The egg is a small, white object about one-twentieth 

 of an inch long and resembles in shape a grain of wheat, 



except that it is more pointed. 

 They are laid more or less in 

 clusters (Plate 1) and hatch in from 

 „ ,_ eight to t went v-f our hours or 



Fig. 2. — Maggot of house- ° ^ 



fly. (x 3i) longer, depending on the tem- 



perature. 



The maggot is whitish in color, pointed at the head end, 

 blunt at the opposite end and about one-third of an inch 

 in length when mature (Fig. 2). It is quite active and 

 can crawl with considerable facility. It grows rapidly, 

 molts three times, 1 and reaches maturity in five to seven 

 days under favorable conditions. With the third and 

 last molt the larva transforms to a pupa. 



The pupa is inclosed in the last cast skin of the maggot. 

 This skin soon turns dark brown and becomes hard and 

 dry, thus affording a protective case for the pupa, known 

 as a puparium (Fig. 3). The pupa rests quietly for five 

 to seven days or longer, at the end of which time its 

 enveloping case breaks open and the adult fly comes forth. 



1 If the casting of the last skin that serves as a puparium is counted. 



