I kept finding wasps in my basement. After a little investigation I found that they were getting into the basement through loose caulking on the central AC pipes going into the house. My very first thought was to plug the hole! DON'T DO IT! If you have a nest already in your home the wasps will find other entry points as a way to get to their Queen in the nest. Once that happens you have no control and they will end up in your walls with multiple entry and exit points. I called an exterminator and he found their nest up in a corner of the basement beside the AC pipes and UNDER insulation. You couldn't see it as it was hidden. He sprayed and then put on a bee suit and got rid of the nest. The spray they use is 10 times more powerful than what you can buy in the store like Raid. The exterminator's spray also coats the wasps body with insecticide to further reduce any stragglers still coming from the outside to the nest. He said to wait a couple of days and then plug the hole as he was sure there were no other nests.