Had a little hornet get in earlier. It was in a location where I couldn't easily hit it with a fly swatter, so I sprayed some wasp spray on it. Only afterwards did I read the label and find out that it was for outdoor use only. Oops...
I initially considered rubbing alcohol, but I'd have to dump it on 'em which would be a bit of a waste. I remembered I had some wasp spray, and went with that.