BREEDING HABITS 89 



1896, and more fully subsequently. He toiiiid that they coiiM 

 be rarely induced to lay their eggs in anything hut hoisc-iiiainiie 

 and cow-dung, and that they preferred the former. The jxiiods 

 of development he found were as fc^llows : from the depo.sition of 

 the egg to the hatching of the larva about eight hours; the first 

 larval stage one day; second larval stage one day; third larval 

 stage — that is, from the second ecdysis to pupation — three days, 

 and the flies emerge five days after the pupation of the larvae, 

 thus making the whole period of development about ten days. 

 The same author, in a valuable study of the insect fauna of 

 human excrement (1900), describes experiments in which he was 

 successful in rearing M. domestica from human excrement both 

 in the form of loose faeces and in latrines. 



My own studies Avere commenced in 1905, and a short pre- 

 liminary account of some of the results were published in the 

 following year (1906). The complete account of my investiga- 

 tions on the breeding habits and development of the fly was 

 not published until 1908. 



Newstead (1907) found that horse-manure, spent hops, and 

 ashpits containing fermenting materials and old bedding, or 

 straw and paper, paper mixed with human excreta or old rags, 

 manure from rabbit hutches, all constituted permanent breeding 

 places. He also found that the following served as temporary 

 breeding places : collections of straw mixed with other vegetable 

 matter and feathers lying in a fermenting condition in open 

 spaces in poultry yards, accumulations of manure on wharves, 

 bedding in poultry pens. He was unable apparently to confirm 

 the observations made by Howard and myself as to the breeding 

 of M. domestica in human excreta. 



In my experiments, which were carried out under both arti- 

 ficial and natural conditions, the larvae of M. domestica were 

 successfully reared in, and the flies bred from, the following sub- 

 stances : horse-manure, cow-dung, fowl-dung, human excrement, 

 both as isolated faeces and in ashes containing or contaminated 

 Avith excrement, obtained from ashpits attached to privy middens, 

 and such as is sometimes tipped on to public tips. I found that 

 horse-manure is preferred by the female flies for oviposition to all 

 other substances, and that it is in this material that the gi-eat 



