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 is the most widespread species of Ephemerella, and also the most abundant in some places, but nobody I've talked to seemed to know what its duns looked like, and there were no pictures of its duns online or in any angling books. That mystery is solved with this male dun, which hatched from a definitively identified nymph.
This mayfly was collected from Nome Creek in Alaska on July 10th, 2011 and added to Troutnut.com by Troutnut on July 12th, 2011.