HOUSE-FLIES 



Except that the tip of the abdomen is 

 brown with a hoary coating, there is little 

 which need be added to the characters given 

 in the key and Plate LXIX. The larvae breed in excre- 

 ment, often being abundant in human faeces. The life 

 history is completed in about three weeks. 



Both stabulans (Plate LXIX) and assimi- 

 lis are a bit larger and more robust than 

 M. domestica. The tip of the scutellum may be reddish. 

 The larvae feed on excrement and a variety of decaying 

 substances, including fungii and vegetables. M. stabulans 

 has been reared from the pupae of other insects but the 

 pupae had probably died first, as it is not likely that the 

 species is parasitic. Both species are widely distributed 

 in Europe and America, stabulans usually being the 

 commoner. 



In addition to the characters given in 

 the key and Plate LXIX, it might be said 

 that the space between the eyes is white. 

 On account of its habit of overlapping the wings when at 

 rest, it often appears narrower than domestica. The exact 

 date of its introduction from Europe is unknown. It has 

 been bred from manure, but probably only when the 

 manure contained earthworms as it has been bred from 

 these common creatures. The adults are rather sluggish 

 and have been called Cluster-flies from their habit of 

 congregating in masses, especially about the ceilings 

 of rooms. They are looking for a place to hibernate and 

 may find it in closets, behind curtains, or in other nooks. 

 When mashed, these flies are very greasy and have an 

 odor which has been described by some as like honey and 

 by others as "very disagreeable." It is even more sus- 

 ceptible to attack by a fungus (Empusa) than is M. 

 domestica. 



Like most of the Muscidae, the sexes of 



t.V 

 domestica 



Musca the House- or Disease-fly (Plate LXX) may 



be told apart by the fact that the eyes of 

 the males are nearer together than they are in the females. 



271 



