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.
I'm just guessing Neoleptophlebia on this one. It could easily be Paraleptophlebia.
This mayfly was collected from the Neversink River in New York on September 5th, 2006 and added to Troutnut.com by Troutnut on October 3rd, 2006.