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 male nymph is probably in its final instar. The wing pads are extremely black and the large turbinate eyes are very apparent inside the nymph's head.
This mayfly was collected from the Bois Brule River in Wisconsin on June 9th, 2005 and added to Troutnut.com by Troutnut on May 26th, 2006.