This sort of thing happened to me on Memorial Day weekend. I was fishing for smallies in a local drainage and notice some mayflies coming off. Nothing rising to them, but sporatically, there were some white flies coming off. I thought they were sulphurs but when I got a closer look, they were all white. I was confused as the white fly hatch is normally a late summer thing. That, and these flies were much smaller than the normal size white flies.
I emailed a local fly shop and asked him if had seen this and what he thought they were. Turns out that they were white flyes that had the right conditions to hatch but were considered "undersized". Strange, but there it is...
It's not the heat, it's the stupidity.
What manner of jackassery will I be subjected to today?