DIPTERA 



861 



f 



Fig. 1 1 12. — A poniacc-fly. 



The pomace-flies and tlicir allies constitute the family Drosophil- 

 idoc. In tliis family the costa is microscopically broken twice, once 

 just beyond the humeral cross-vein 

 and again just before the end of vein 

 Ri ; the subcostal vein is vestigial ; the 

 arista arc ahuost invariably plu- 

 mose; the vibrissas are present; the 

 postvertical bristles are convergent; 

 and the foremost fronto-orbital 

 bristles are proclinate. 



The larvcC of most species of this 

 family, so far as is known, live in 

 deca>'ing fruit or in fungi ; a few are 

 leaf-miners; and some exotic species have been fovmd feeding on 

 other insects, Alciirodcs and Clastoptcra. 



One of the pomace-flies, Drosophila tnelanogastcr, which is easily 

 bred and which has a short life-cycle, is widely used in laboratories in 

 the study of heredity. This species has been commonly known as 

 Drosophila anipelophila; but tnelanogastcr is the older specific name. 



A monograph of this family was published by Sturtevant ('21). 



The family GEOMYZID^ is a group of small flies of which 

 nearly fifty species have been described from our fauna. In these 

 flies the postvertical bristles are convergent when present; the clypeus 

 is large, the foremost fronto-orbital bristles are directed backward; 

 and the fringe of the calyi)teres is not dense. 



The larvre of the few species of which the habits are known live 

 in the stems of plants or mine in leaves. 



The family was monographed by Melander ('13 b). 



Family AGROMYZIDvE 



of Phylomyza aquil- 



sites of the cottony-cushion scale 



This family includes small or 

 minute flies in which the costa is 

 broken only at the end of the 

 subcostal vein; the oral vibrissae 

 are present, the arista of the an- 

 tennae is closely short-pubescent, 

 the post-vertical bristles are di- 

 vergent, and the lower fronto- 

 orbital bristles are convergent. 



The genus Cryptochcctmn dif- 

 fers from the typical members of 

 this family in having the costa 

 twice broken and in that the an- 

 tennaj lack the arista. One or 

 two species of this genus have 

 been introduced into California 

 from Australia, as they are para- 



