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.
With limited weekends remaining for fishing before October gets really busy, my wife and I braved the smoke to float the Yakima Canyon from mile 20 down to Red's. We found very few steadily rising fish, just small ones sipping Baetid duns in a couple of spots, and picked up some rainbows up to 14" on miscellaneous attractor dries and nymphs. I've never seen so many deer along the canyon, perhaps a consequence of the fire burning out much of the adjacent habitat and feed a few weeks ago.
I did a fairly poor job of budgeting our time, stopping at every likely-looking seam early in the float and then having to blow through some of the best water in a rush to reach the landing before it was too dark to see. That's what I get for not learning the river yet. There were some nicer fish feeding at dusk and I missed a couple strikes, but I didn't have time to stick around and keep working on them.