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.
This specimen resembled several others of around the same size and perhaps the same species, which were pretty common in my February sample from the upper Yakima. Unfortunately, I misplaced the specimen before I could get it under a microscope for a definitive ID.
These tiny little aquatic mites show up in my samples from time to time. This fairly large one is only about 1mm long, so these aren't relevant to trout, but it's interesting to know that they're down there, anyway.