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.
Described by Hanson, J.F. (1943) Studies on the Plecoptera of North America, IV. Further notes on Capniidae. Bulletin of the Brooklyn Entomological Society 38, 155–163.