The best wasp/yellowjacket repellant for summer picnics: 2 ounces of mint extract. 2 ounces peppermint extract. 10 ounces rubbing alcohol. Pour ingredients into spray bottle and label. Spray down picnic area and play area. The mint is neurotoxic to bees and wasps. Somehow they know to stay away, but if you spray it on them directly it can also kill them.
To keep wasps from setting up a home near your front door or around your home - mix 2-3 tablespoons of Dawn dishsoap and about 2-3 cups of water. Put into a spray bottle, shake and that's it. Spray where they keep coming back to, to make a new nest. This will also kill them and drop them like a hat.