When we had carpenter ants we had a couple people out and ended using this company that sprays some stuff called Termidor. I went to his web site which linked to a national web site - http://www.ipconetwork.org/ that lists places that use this stuff in different states. (I'm in Washington) This stuff worked great and was good because they didn't have to drill holes to shoot into or behind our siding (which is the "new LP" and I was afraid to mess with our siding at all).
