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 Newman, E.A. (1839) On the Synonymy of the Perlites, together with brief charaters of the old and of a few new species. Art. IV. Magazine of Natural History 3, 32–37, 84–90.