So I was at the local Pick-N-Pull the other day, and there are always a handful of wasps flying around harassing people.
Had one land on the side of a GP I was working on. On a whim, shot him with a blast of PB Blaster. He fell down immediately, and was dead in about 30 seconds. Not a bad wasp spray for something I always carry around in my tool kit.
I've heard carb cleaner works great as well.