When we bought our last house I changed a light fitting and live wasps poured out - I was freaked out, and put the fitting straight back.
A few days later I went into the attic to put some boxes up there and found a HUGE nest near the light fitting. I put my hand on it and could feel and warmth and buzz of the wasps. It was already mid summer so I just left it (there were not loose wasps in the attic - their entrance/exit was into the eves of the house).
By autumn they were gone, and we never again had a wasp issue in our house in the 10 years we lived there. I changed the light fitting the following spring.