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.
P.S. Didn't see any the last two nights, or much of anything hatching for that matter. Friday night I pulled out the old secret weapon, a #12 Royal Wulff, and a 15-incher fell for it.