I just realized the reason this summer the swallows did not nested under my window, and it wasn't my occasional smoking. A wasp colony is in progress next to their regular spot. Right underneath there is a dog swimming pool for my black lab which is full of wasps during the day, now I understand why he avoids it. Suddenly it makes sense. The colony is in a fairly high spot. I could only exterminate from the attic which is a place covered with foam insulation. I'm just not sure if the wasps are managed to eat trough all the wood yet. I will have to damage it to kill these wasps. This is a summer project I did not planned for.