I found several of these but this is the first one I spotted. This is a stupid ladder that's always outside leaning up against the house in a corner of the deck. The rungs on the ladder are all hollow and just about every one had a nest in it. After I got the picture, I ran inside to see if we had anything I could spray them with. The only thing I could find was an old can of flying insect spray that said it was for flies and mosquitoes. Good enough and it worked. I sprayed every rung of the ladder.