322 



APPLIED ENTOMOLOGY 



hr. during warm weather but may take 2 or 3 days if the temperature 

 is low. The larvae (Fig. 342) feed on the manure or other material in 

 which they are located, for a varying number of days but probably 

 averaging about 5 days. Pupation for about the same length of time 

 follows, but many of the maggots may leave the place where they feed 

 and travel a short distance away to pupate. Thus, pupae may be found 

 in the ground around a manure pile within a foot or two. Pupation is 

 within a puparium, the fly pushing off the front end by means of its 



Fig. 340. 



-House Fly {Musca domestica L.). rather more than twice natural size. 

 duced from Hewitt: The House Fly.) 



Rc- 



FiG. 341. Fiu. 342. 



Fig. 341. — Eggs of the House Fly, much enhirged. {Original.) 

 Fig. 342. — Full-grown maggots of the House Fly, much enlarged. 



{Original.) 



ptilinum. After the emergence of the adult fly, a period of about 14 

 days elapses before egg laying begins so that the time from one of these 

 periods to the next during warm weather is about 24 days. From 7 

 to 10 generations are liable to be produced, therefore, in a long season in 

 the North or under ordinary conditions in the South, and it has been 

 calculated that the descendants of a single fly which deposits its eggs 

 the middle of April would number 5,598,720,000,000, by the middle of 

 September, if all the eggs hatched and lived to adults which reproduced 

 in their turn. Fortunately, this is not actually the case, eggs failing to 

 hatch and many larvae never reaching maturity. 



House-flies as disease carriers are of extreme importance. Crawling 

 over and feeding upon filth of any kind, their legs and bodies are hable 

 to gather the germs of various diseases, which may also be taken into the 

 flies with their food. Later, visits to houses and human food over which 



