The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
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.