I have a nest of yellowjackets (the not very aggressive european kind) that is just below my flat roof. I would normally just leave them, but I have no way of getting to the yard without passing by the nest at a distance of about a foot. Currently, this does not seem to make them swarm yet (though I can get hit by one as the swoop down a bit before entering the nest).
I'd like to get rid of them without using poison (the yellowjacket poison I can get in the stores here is a neurotoxin that also kills cats and there are a lot of cats in the neighborhood and they love that flat roof).
The nest itself is hidden. I can only see the entry points. Damage to the roof or walls is not a big issue (the entire building needs to be replaced in the next few years anyway).