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.
My experiences with grasshoppers have taught me three lessons valuable in fishing them: the gentle twitch of the fly, bouncing the fly off bankside grass, and dapping or swimming the fly on a short line. All of these tricks are suggest of the natural in the water.