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.
I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing this one.
Cubitus: The cubitus (denoted Cu) is the fifth major longitudinal wing vein in insects, located behind the media. In caddisflies, its anterior branch Cu1 arises from a point on the media near or at its base, and the posterior branch Cu2 arises separately from the base of the wing. The anterior branch Cu1 is subdivided into two branches Cu1a and Cu1b, while the posterior Cu2 is unbranched. In the forewing, the tip of Cu2 curves backward to the wing edge at a slightly inflexed point called the arculus.
These other words reference the same concept: vein Cu, Cu vein, Cu, vein Cu1, Cu1 vein, Cu1, vein Cu2, Cu2 vein, Cu2, vein Cu1a, Cu1a vein, Cu1a, vein Cu1b, Cu1b vein, Cu1b.
