Small black flies on the Susquehanna North Branch

[henrydavid]

Saw thousands of these last evening, I thought they looked like a small black stonefly, my friend said he thought they were caddis, but the wings were folded straight back, not "tent" like which is a dead giveaway for me with caddis. Sorry I didn't get a photo, hopefully will next time.

 

[henrydavid]

By the way, white flies came on at dark, saw quite a few Hex as well and bass were feeding on them.

 

[pcray1231]

Without a pic, its hard. But flat wings (no tent) parallel with body = stonefly. If by straight back you mean upright, then mayfly of some sort.