I don't know where they're coming from, but I've killed 6 wasps inside my house in the last month. Most of the time, they fly in and try to land on the light fixture by my desk. The first time, I was really worried about hitting the bulbs and ruining them. Now, my aim has gotten good enough to kill them without ever hitting the bulbs themselves.

For those that care, the foreground of this one was all digital. The background was hand drawn and inked, then colored in Illustrator.