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 a common olive brown species according to Swisher and Richards in Selective Trout. The Stoneflies of the United States page leaves me somewhat skeptical of the identification, however.
Described by Walker, F. (1852) 1 Catalogue of the specimens of neuropterous insects in the collection of the British MuseumPart I. Phryganides-Perlides. Edward Newman, London. Available from: http://www.archive.org/details/catalogueofspeci00britrich 1-192