FLIES FOUND IN HOUSES 21 



Hewitt says Smith obtained specimens from a hospital ward 

 at Benares and bred it from human and cow faeces. Hewitt (1910, 

 p. 353) received specimens from Aden, and Balfour (1908) in 

 Khartoum bred it from human excrement and stable refuse. 



Country files closely resembling Jionsc files. 



Though the house-fly sometimes occurs in large numbers 

 away from the dwellings of man it is probable that the flies 

 usually found under such conditions are not house-flies but 

 species closely resembling it. Writing on this subject Howard 

 (1912, p. 2) makes the following statement. "In the family 

 Tachinidae, a group composed almost entirely of species which 

 lay their eggs upon other living insects, there are many species 

 which almost precisely resemble the grey-and-black striped 

 house-fly. In the family Dexidae, of similar habits, there are 

 also many species which closely resemble the house-fly. In the 

 family Sarcophagidae, which includes most of the so-called flesh 

 flies, the species of which either live in carrion or excreta or in 

 dead insects or in putrid matter, and are occasionally parasitic, 

 as in the species which breed in the &^^ masses of grasshoppers, 

 there are also many species hardly to be distinguished from 

 Musca. There is another great family, the Anthomyidae, which 

 has many species which closely resemble the house-fly, and give 

 rise to many mistakes in identity. Then too, in the family 

 Muscidae itself there are many genera of similar habits and 

 similar appearance." He finally sums up by giving a simple 

 method of differentiating these groups. " Musca dornestica has 

 four black lines on the back of its thorax. All Sarcophagidae 

 have three such black lines. Most Tachinidae have four such 

 lines, but the Tachinidae have the bristle of the antenna smooth, 

 whereas in Mnsca dornestica this bristle is feathered. From all 

 the Anthomyidae, Musca dornestica is at once separated by the 

 bent vein near the tip of the wing. Moreover, Musca doniestlca 

 has no bristles on the abdomen except at the tip which separates 

 it from all others except some Tachinids and many Anthomyids, 

 but from these it is separated by the characters given above." 



Except certain species of the Anthomyidae, which are easily 



