FLIES FOUND IN HOUSES 



29 



Wings. Clear. The end of the 4th longitudinal vein is bent up, but not so sharply 

 as in the house- fly, so that its termination is distinctly separated from that of the 

 vein above it. Squama opaque, white. Halteres rather long and partly covered 

 by the squamae. 



Legs. Black. Pulvilli rather marked. 



Abdomen. Grey, and without ochraceous-buff patches, but spotted with clove brown, 

 the spots being usually more conspicuous in the ? . There are three conspicuous 

 spots, one median and two lateral, on the second and third segments, and one 

 median spot on the fourth. 



This fly is very widel)' distributed, being found in Europe, 

 North, Central and South America, and parts of Asia and Africa. 

 It is an outdoor fly which loves the sun, and may often be seen 

 resting on doors, paling, etc., exposed to its full glare. Both 

 sexes suck blood and attack both men and animals. It is very 

 common in stables and cow sheds, and is not infrequently found 

 in country houses in the summer and autumn, especially in wet 

 weather, but is not attracted to food. Although it frequents 

 stable manure, it is probably not an important agent in dis- 

 tributing the organisms of intestinal diseases. 



The egg is like that of the house-fly and is i mm. in length. The eggs are usually 

 laid in irregular heaps, and the average number deposited is about sixty. 



The ia7-vie are very like those of the house-fly, but can be distinguished "by the 

 plates on the posterior end of the body bearing respiratory apertures being much 

 smaller and circular (instead of the inner side of each plate being straight), and from 

 four to six times as far apart, with the openings straight instead of sinuous." 



ThQ piipn is chestnut brown, barrel shaped, with the front end somewhat pointed ; 

 " precisely similar in general appearance to pupa of M. doniestica, but can be 

 distinguished by size and distance between posterior respiratory plates of larva which 

 are still visible' (Austen, 1909). 



The eggs hatch out in two to three days, and the larvse, 

 which usually live on horse manure, are full-fed in fourteen to 

 twenty-one days under favourable conditions. According to 

 Newstead the absence of excessive moisture and the admission of 

 a little light materially retard development, which then extends 

 over a period of thirty-one to seventy-eight days. The pupal 

 stage lasts nine to thirteen days. The development of this 

 species is therefore slower than that of the house-fly. Newstead 

 is of opinion that the winter is passed chiefly in the pupal 

 condition. 



