This suggestion came from Facebook
To keep wasps from building unwanted nests (under patio furniture, inside storage sheds, under raised garden beds, etc) fill a brown bag with paper or plastic bags or just some filler and crumple to the size of a baseball or so. Use a thumbtack to stick the bag to a corner under the furniture (where a nest might normally be built). This mimics a rival nest so the wasps won’t build one. I swear it works. I’ve been having the same brown bags under my patio furniture for years and haven’t had a single nest built…same in my little outdoor storage closet and pool storage.
Another helpful tip is suggested:
"in case you get stung by a yellow jacket, place a Copper Penny over it (make sure no stinger is left in skin). The copper stops the stinging sensation in seconds! "