62 



NORTH AMERICAN DIPTERA 



The larvffi live in swift water, clinging to the rocks or stream 

 bed by a series of ventral suckers, pupation taking place in the stream. 

 The immature stages are even more easily identified than the adults. 

 The latest revision of the family is contained in Williston's Manual 

 of North American Diptcra, 3rd edition. 



KEY TO GENERA 



1. An incomplete longitudinal vein between the fourth and fifth longi- 



tudinals (1) 3 



No incomplete vein between these veins (2) 2 



2. Proboscis long; palpi but little developed (2, 5) Paltostoma Schiner 



Proboscis not longer than the vertical diameter of the head; palpi well 



developed, four-segmented Kelloggina Williston 



3. Second basal cell closed apically 4 



Second basal cell open apically (1) Blepharicera Macquart 



4. Second longitudinal vein branched, the branch either simulating a cross- 



vein near the base of the second vein, or elongate 5 



Second vein not branched (3) Philorus Kellogg 



5. Pleura pilose or haired (4) *Bibiocephala Osten Sacken 



Pleura bare Agathon Roder 



* Bibionus Curian is a synonym but the two species upon which the genera were based 

 are distinct. 



Blephariceridai. — 1 . Blepharicera ; 

 cephala; 5, Paltostoma argyrocincta. 



Paltostoma ; 



Philorus; 4, Bibio- 



