329 



Family Opomyzidae 



Small, rather elongate flies, sometimes with pictured wings. 



Head not longer than high, the face long, often narrow; one or 

 more pairs of frontal bristles; postocellars divergent, convergent, or 

 absent; oral vibri-ssa? absent or differentiated, never strong; palpi small. 

 Presiitiiral dorsocentrals present or absent; mesopleura bare; scutellnm 

 with or without hair in addition to the bristles; preapical tibial bris- 

 tles absent. Subcosta incomplete or vestigial; anal and second basal 

 cells complete, the first vein ending before the middle of the wing. 

 Al)domen moderately long, the segments with marginal bristles; geni- 

 talia small. 



Various authors have recognized three families for this group, the 

 Anthomyzidffi and Tethinidaj in addition to the Opomyzida or Geomy- 

 zidae. Despite the differences I believe that the genera should be grouped 

 together, as otherwise there is sufficient grounds for the creation of a 

 family for each of the genera. At any rate we may safely unite the 

 Anthomyzidne and Tethinida? since both groups possess oral vibrissa. 

 However the vibrissa are weak and the characters by w^hich these groups 

 are separated from Opomyza do not appear to be important in this 

 case. 



Tlie flies occur chiefly in moist places and along the seashore. 

 Practically nothing is known about the life histories, but it is knowai 

 that species of Opomi/Z(( live in grass. 



KEY TO GENERA 



1. Oral vibrissfe differentiated; post ocellar bristles converging, though 



small - 



Oral vibrissse absent; post ocellars diverging or absent 9 



2. Presutural dorsocentrals present 3 



Presutural dorsocentrals absent 4 



3. Cheeks haired only along the lateral oral margin 6 



Cheeks with hairs over much of the surface or at least toward the eyes 7 



4. One pair of strong frontals (4, 7) Mumetopia Melander 



Two pairs of strong frontals o 



5. Posterior crossvein situated only about its length from the wing mar- 



gin (1, 12) Ischnomyia Loew 



Posterior crossvein situated almost twice its length from the wing 

 margin (6, 11 ) Anthomyza Fallen 



