My house had these every 3 feet.

[Baron]

What are these and how does affect trout. My house is 1/4-1/2 Mile from the river.

Learning is slow but I am learning.

 

[redietz]

They're sulfurs, one of the most widespread mayflies in the midalantic region. They didn't necessarily come from a river; a small brook is enough to have them. Still, the purpose of mayflies having duns instead of just hatching and immediately laying eggs is to spread the populations to new waters, so they could also possibly be from the river.

If you don't already know, mayflies hatch from nymphs into duns (winged sub-adults), fly off somewhere, shed their skins again to become spinners (full adults), fly back to the river, lay their eggs and die.

The insect in your photo is a male dun. You can that because the males have much larger eyes than the female, and the wings on spinners are clear.

The hatch is sure to get fish feeding.

 

[Baron]

Thanks Bob. So they're all gone now. I guess they were drying and when dry they flew. This hatch is nothing like some of the caddis hatches I've seen on the Lehigh but maybe one every 3-5' and I assume that the skins also present were also from them "hatching."
Last night at the lake in the Poconos I saw very large insects at dark. Some appeared to be co-joined and were skimming the surface. If they had been tied flies they would have been size 8-12.
Its pretty exciting to notice these things for the first time and not regard them as pests. They were of course always there but now that I Flyfisher I'm beginning to notice them.