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.
Here's a rather different tiny Baetid nymph. The tails are all unbanded, and the tergites all have a dark-colored anterior 2/3 and light-colored posterior 1/3. The gill veinlets are indistinct. It's probably a very early instar of some Baetis species.