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.
This specimen seems to be of the same species as a dun I photographed which emerged from another nymph in the same sample.
This mayfly was collected from Paradise Creek in Pennsylvania on May 29th, 2007 and added to Troutnut.com by Troutnut on June 4th, 2007.