Carpenter Ants!
You may have noticed Carpenter Ant foragers returning to the exterior of your home. Look out for foraging trails to see what lines the ants are using. This is useful for you or us to apply baits and other materials to the active areas. Carpenter Ants are most active after dusk, so inspecting at the end of the day, or early morning will yield the best results. And always think of wood that has gotten wet in the past, such as areas with former plumbing leaks or ice dams. When examining those areas look for frass, essentially sawdust with ant parts in it, falling out from wood members.