
This wasp, which I am pretty sure is a
bald-faced hornet, was swimming in a trap made of a container of acetic acid when I came upon it and saved its life. The trap has three different lures designed to attract social wasps. I was using these traps to catch yellow jacket queens in the spring before they established nests. My tests showed that one of these three was best at catching the wasps I was after, so from now on I'll use that lure exclusively. The acetic acid lure caught no queens, several workers, and an amazing amount of non-target organisms: non-pest wasps, moths, crane flies, spiders, earwigs, and so on.
The trap I used is labeled for catching bald-faced hornets, but I'm not interested in catching them. They usually build their nests high out of reach of humans (as opposed to yellow jackets and European paper wasps which build nests in harm's way more often than not) and they are the only species I know of that actually preys on yellow jackets. (That's a very close kinship between predator and prey, by the way, the equivalent of Homo sapiens eating that little hominid in Indonesia, or a bullfrog eating a green frog.)
So when I saw her swimming in vinegar, waiting for the acid to clog her spiracles and drown her, I dumped out the trap and let this wasp dry out and get on with her life. Pest control isn't all about the killing.