(57) 



STRUCTURE, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY. 497 



sites and its relation to man, and certain of its allies which 

 frequent houses will be considered. 



II. BEEEDING HABITS OF M. DOMESTIC A. 



The development of M. domestica was first described by 

 Carl de Greer (1776) ; but, although he stated that it developed 

 in warm and humid dung, he did not give the time occupied 

 by the different developmental stages. He refers to the 

 enormous quantities of flies occurring from July to August. 

 His statement concerning their development is especially 

 interesting, as he appears to be the first investigator who 

 called attention to what I consider to be one of the most 

 important factors in the development of the fly, namely, the 

 process of fermentation occurring in the substance in which 

 development is taking place. He says (p. 76), " Les larves 

 de cette espece vivent done dans le fumier, mais uniquenient 

 dans celui qui est bien chaud et humide, ou pour mieux 

 dire qui se trouve en parfaite fermentation" (the italics 

 are mine). Since the completion of my own investigations 

 on the development, all of which indicated the importance of 

 this factor fermentation, Newstead (1. c.) has come to the 

 same conclusion. The work of Keller (1790), to which 

 reference was made in the first part of this memoir, contains 

 many interesting and careful observations on the breeding 

 habits of the " Stubeiifliege." He found that the eggs 

 hatched from twelve to twenty-four hours after deposition. 

 He reared the larvse in decaying grain where, no doubt, 

 fermentation was taking place; also in small portions of 

 meat, slices of melon, and in old broth. His observations 

 are extremely interesting, and, excluding mistakes which 

 were due to the lack of modern apparatus, his account is still 

 a valuable contribution to our knowledge of the subject. 

 Bouche (1834) describes the Iarva3 as living in horse-manure 

 and fowl-dung, especially when warm. He does not give the 

 time occupied by the earlier developmental stages, but states 

 that the pupal stage lasts from 814 days. Packard (1874) 



