may be ウエノヒラタカゲロウ.
I saw this at a gas station in Seattle. I've never see anything like it
yellow, small (size 20 or even 22), 3 tails, grayish wings. One of the photos shows that the brown markings on the abdomen are ridges.
Small (size 20 or smaller), grey-olive abdomen, darker thorax, apparently only 2 wings. 3 tails. Back 2 pair of legs cream colored, front legs dark. Small eyes, tails about body length.
Also a number of other species on the water. Olives of various sizes, and others.
Small (size 20) brownish body, with some lighter brown markings, esp. near end of abdomen. 2 tails, grey with dark bands. Clear wings, good-sized hind wings.
Also saw a very few sulphur mayflies in air, a couple on water, about size 20 or 22 - probably Ephemerella dorothea.
Cream cahill, size 14 - 16
Mayflies or shadflies are insects belonging to the order Ephemeroptera (from the Greek εφημερος, ephemeros = "short-lived" (literally "lasting a day" "daily" or "day-long"), πτερον, pteron = "wing", referring to the brief lifespan of adults). They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies. They are aquatic insects whose immature stage (called "naiad" or, colloquially, "nymph") usually lasts one year in fresh water. The adults are...