Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
July 9th was the fishiest day of the wife-oriented portion of this Montana trip. After a late-morning start, we drove the scenic highway from Philipsburg to Rock Creek and then down the valley to a spot that fished really well last year. My backpack included a Jetboil, can of Campbell's chicken noodle soup, a Mountain House meal, tea, apples, a large book about genetics, and several other unconventional amenities designed to keep everybody happy on the river for 8+ hours. It worked, I think.
The fishing was good for most places and alright for here. Nymphs were surprisingly ineffective and most fish rose to dries instead. I caught quite a few decent cutthroat and brown trout, along with one brookie, although nothing exceeded 15 inches. Rainbows remained in hiding. Lena caught a nice cutthroat, too.
I lost track of this specimen before I could get it under my microscope, but caddis expert Dave Ruiter was able to identify it from pictures as Glossosoma, with an uncertain suggestion of G. alascense as the most likely species.