570 HOWARD 



Bouche (1834) stated that the larva lives in horse and fowl dung, 

 but does not give the length of the larval stage. Packard (1873) 

 showed that no one in this country had up to that time investi- 

 gated the habits of the house fly, and that even in Europe little 

 attention had been given to it. He bred a generation in fourteen 

 days in horse manure, finding the duration of the egg state to 

 be twenty-four hours, the larval state five to seven days, and the 

 pupal state from five to seven days. 



In the experiments made in my office in 1895 it was found 

 unexpectedly that the house fly is a rather difficult insect to rear 

 in confinement. Buzzing about everywhere and apparently 

 living with ease under the most adverse conditions, it is never- 

 theless in the warm season, when confined to a small receptacle, 

 not at all tenacious of life. The egg hatched in eight hours ; 

 the larvae lived five days, and the pupge five days ; making the 

 total time for the development of a generation ten days. This 

 was at the end of June. About 120 eggs are laid by a single 

 female, according to our observations; Porchinsky says 120 to 

 160. 



These specimens were reared in horse manure. Subsequent 

 experiments with cow manure were unsuccessful. We suc- 

 ceeded in getting only two flies to oviposit upon this substance, 

 and although their eggs hatched, all of the larvae died before 

 attaining full growth. In the same way decayed fruit was tried. 

 A single egg was laid upon a decaying blackberr}^ but this 

 was the only one which could be obtained. These facts seem 

 to indicate that horse manure is the preferred food of the adult 

 fly, and that in all probability by far the greater number of the 

 house flies in cities and towns come from horse manure. 



Taschenberg (1880) gave a good popular account of the 

 house fly, but gave the impression that the duration of a gen- 

 eration is much longer than we have indicated. He states 

 that the female lays its eggs upon a great variety of sub- 

 stances, particularly on spoiled and moist foodstuffs, decaying 

 meat, meat broth, cut melons, dead animals, in manure pits, on 

 manure heaps, and even in cuspidors and open snuff-boxes. 

 That the larvae will successfully breed in such divers substances 

 is, however, not stated by this author. 



