The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
Probably Baetis tricaudatus.
This mayfly was collected from the Touchet River in Washington on July 13th, 2011 and added to Troutnut.com by Bnewell on July 13th, 2011.