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.
I have no experience with important fishing to this species, but it is probably the Baetisca species that Ernest Schwiebert discussed in Nymphs as locally abundant on one stretch of a Catskill river.
PRohlfsen on May 11, 2007May 11th, 2007, 6:09 am EDT
I was fishing the Vermillion River in Minnesota south of the metro area and found a nymph similar to the Armored Mayfly Nymph. It did appear to be much more green in color. It was moving through a really muddy part of the stream, which I found interesting.