My yard seems to be a bit of a magnet for paper wasps (South African Paper Wasp - Polistes marginalis) with about three or four nests all around the house. I know a couple of Geocachers who would be able to tell you all about the fact that unlike honey bees that only sting once, the paper wasp can inflict multiple stings. The nest is built by a queen who lays the first eggs. As these hatch and grow up the females join the queen on building onto and tending the nest. Usually they are very docile but they will attack if threatened. Or perceived to be threatened like when I passed a nest the other day with the lawnmower and they decided to shoo me away. Bang bang bang, two on the arm and one on the neck.