What I believe you are seeing are
Backswimmers or
Water Striders.
They both "skate" across the surface, although the backswimmers will occasionally dive under the surface. They are consumed often by fish like bulegills, carp, bass, and trout, but a few hits on the surface and they get out of there.
They will congregate in areas where the fish are not, simply because they have to do so in order to be undisturbed, but they often do not "know" fish are present until they lose a few and have to move on.
I hope I hepled!