DEET damages all kinds of stuff. I was using some at a buddy's cookout once, and it was some "industrial strength" that they used. (They are telephone linemen in IL and get to meet all the bugs in their line of work) It ate the paint of the Adirondack chair I was sitting in and left my forearms dark green with paint. It also does a number on the screens of my depth finders on my boat... Evil stuff, but good for keeping off evil bugs...