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've never seen this strange coloration on any Ephemerella subvaria nymph in a book before, but it's similar to several other specimens I collected on the same outing, including a smaller one that I photographed. They were outnumbered by the "normal" Ephemerella subvaria nymphs in the sample.
This mayfly was collected from Salmon Creek in New York on March 29th, 2006 and added to Troutnut.com by Troutnut on April 7th, 2006.