We have been plagued lately with wasps, I keep finding 10 - 20 dead and groggy ones in the garage when I come home from work. I thought they must of been in the flat roof space, but couldn't see any milling around.
The Mrs spotted the buggers on saturday up in the eaves of the house (the same side as the garage) all around a small hole in the brick work (they are nesting in either the cavity, or even worse the loft). I pi55ed them off a few times with plain old fly / wasp killer in preparation for sunday (I headed in with a can of nest destroyer)
Basically, you sneak up to the nest, spray the foam all over them, AND RUN LIKE HELL !!
I still think all I did was pi55 them off, but I must of got a few.