FLIES THAT FREQUENT HOUSES 47 



from the pupae of the cotton-leaf worm, the gipsy moth, 

 and from pupae of certain Hymenoptera. It has also 

 been reared from masses of the larva; and pupae of the 

 imported elm leaf-beetle. The chances are that it was 

 not parasitic on these insects, but that the pupae were in 

 a decaying condition, thus acting as food for the larvae. 

 The life history of this fly is not known in detail, but 

 Taschenberg says that the life cycle occupies from five 

 to six weeks. The larva of this fly has been known to 

 pass through the alimentary tract of man. In this case 

 access was probably gained to the stomach through 

 vegetables eaten by the individual. 



The relation of this fly to the dissemination of disease 

 is not definitely known, but it is a species that should be 

 considered with suspicion until proven guiltless, at least. 

 It breeds in human excreta and is evidently attracted 

 to this material, especially when it is deposited in open 

 places. As it enters houses there is thus ample op- 

 portunity for it to pick up and convey disease-producing 

 germs. Its scientific name, stabulans, was given to it 

 before its habits were known ; but in the light of what 

 we now know of its breeding places there seems to be 

 little appropriateness in the name stable-fly. 



THE LESSER HOUSE-FLY 



Homalomyia canicularis 



In early spring, in May and June, before the house-fly 

 appears, there are often numbers of small flies frequenting 

 rooms and crawling on the window panes. Chief among 

 these is the lesser house-fly. It is considerably smaller 

 than the house-fly and by many is considered a young 



