66 



NORTH AMERICAN DIPTERA 



KEY TO GENERA 



1. Third vein forked 3 



Third vein simple 2 



2. Petiole of the second and third veins setulose above . . . Eusimulium Roubaud 

 Petiole of the second and third veins bare (1) Simulium Latreille 



3. Fifth vein not forked (3) Parasimulium Malloch 



Fifth vein forked (2) Prosimulium Roubaud 



Simuliidse. — 1, Simulium; 2, Prosimulium; 

 3, Parasimulium 



