Thanks to one of the U.S. Government's tax incentives this year I'm replacing the single pane windows in my house with double pane. This will be the first winter in Northern California I'm actually at home during the day (ie not in a warm office) so I needed to do something to retain heat better. Pulling out old windows that have been in place since the 1940s has been interesting. I've found well established carpenter ant colonies and this paper wasp nest (my left foot indicates the nest size). This nest is the biggest one I've ever seen but when I googled to find out exactly what it was, I found even bigger wasp nests - many in the hands of collector Terry Prouty. His big wasp nest collection can be seen at the very interestingBugGuide.net website.