The human battle with bugs has been going on for centuries, but James McWilliams says chemical insecticides came into the picture by accident. McWilliams is a fellow in the Agrarian Studies Program at Yale University and an associate professor of history at Texas State University. His new book is "American Pests: The Losing War on Insects from Colonial Times to DDT" and he was one of the featured speakers at the 2008 Aspen Ideas Festival in Aspen, Colorado.