Female Baetid spinners were abundant subsurface looking for substrates to lay their eggs, and they found my waders. I'll update the ID for this picture after identifying the associated male spinner
. I caught several fish on a small brown soft-hackle fished as a crude imitation of these spinners before the fish all started taking Tricorythodes
spinners instead.In this picture: Mayfly Family Baetidae (Blue-Winged Olives).