304 



NORTH AMERICAN DIPTERA. 



Fig. 119. Ephydriilte. Psilopa nigra, head; 2, Psilopa aciculaia, 

 wing. 3, Allotrichoma abdominalc, head ; 4, Parephydra facialis, 

 head; 5, Iiphydra pygmcca, head; 6, Notiphila, sp., wing; 7. Hydrina 

 nitida, head; 8, Hydrina nilida, wing; 9, Hydrcllia parva . wing; 10, 

 Ochlheroidea alia, wing; 11, Athyroglossa nitida, head. 12, Disce- 

 rn y~a dubia, head. 



deutera argcntata has a wide distribution over all of North 

 and South America, the West Indies, Hawaiian Islands, 

 etc. The flies of this species have the under surface of 

 the body of a silvery, non-wetable character, enabling 

 the insects to run about on the surface of the water. The 

 larvae doubtless live in the water, though not necessarily 

 in foul water as has been thought. 



The larvae of many forms are peculiar, resembling 



