258 THE HOUSE FLY DISEASE CARRIER 



ticular species are not known, but its relatives feed in 

 the earlier stages on decaying vegetable matter, dead 

 insects, snails, etc. The species in question possibly- 

 fed upon decaying vegetation in the neighborhood of 

 the houses in which it was collected. 



THE WINDOW FLIES (Scenopinus fenestralis L.) 



Comstock has applied the term window flies to the 

 little flies of the family Scenopinid?e. The term, how- 

 ever, does not apply to all of them ; but the best-known 



Fig. 35. Scenopinus fenestralis; a, adult; b, pupa; c, larva; 

 d, eggs ; enlarged. (Original.) 



species, namely, Scenopimts fenestralis, is not uncom- 

 monly found upon windows both in this country and 

 in Europe. These flies are usually black and rather 

 smooth, S. fenestralis being about one quarter of an 



