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 would just like to use this specimen to point out that in many cases (or in all the cases I've seen), most true PMDs (Ephemerella excrucians) are not yellow, but olive (with a bit of a gold tinge).