384 



NORTH AMERICAN DIPTERA 



Family Muscidse 



Lyperosia irritans L. 



Flies of medium to small size, usually dull colored, the squama; 

 large or of medium size, hypopleural bristles absent, the second antennal 

 segment grooved above. 



Arista plumose, pubescent, bare or pectinate, eyes approximate or 

 widely separated in the males, the front rarely narrowed in both sexes; 

 frontal bristles always present, intrafrontals frecpicntly present; orbitals 

 developed but rarely in the males. Abdomen composed of four seg- 

 ments in the male, five in the female. IMale genitalia usually not promi- 

 nent but sometimes conspicuous; fifth sternal lobes sometimes promi- 

 nent. 



As here understood this family includes the Scatophagidae, Antho- 

 myidge and those Muscidse (of the Williston Manual) lacking hypopleural 

 bristles. In some cases the hypopleura is haired but there need bo no 

 question in connection with known North American genera about inter- 

 gradation with the Metopiidge. There is no means by which the Scato- 

 phagidffi can be separated from the Anthomyidae, unless tlie size of the 

 lower lobe of the squama is used, in which case the genus Anthonii/ia 

 must be associated with the Scatophagids while many of the other genera 



