Commercial insecticide contains chemicals that may be harmful to humans, and it can also be expensive. Wasp spray is easy to make from household items, and you won't have to worry about risking your family's health. In addition to spraying, you can prevent wasps from building nests around your house, car and play areas.
Find a plastic spray bottle that will hold enough of the homemade spray mixture for several uses. Using a permanent marker, write "wasp spray" on the side and include a list of ingredients you've selected, in case you need it for emergencies.
Remove the spray attachment from an empty plastic spray bottle. Fill the bottle half full of tap water. Squirt approximately 1/4 cup of liquid dish detergent into the bottle then add more water until it reaches the "fill" line. Another formula that works quickly is 1 tbsp. of peppermint extract and 1 tbsp. of baby shampoo, then fill the rest of the bottle with water. Replace the spray attachment. Shake the mixture carefully then let the suds settle before using. When you see a wasp or other flying insect, spray it directly with the solution. It won't harm most flowers, plants or painted surfaces.
In a mason jar, combine strong smelling roots, such as ginger, cayenne, hot peppers and horseradish. Pour boiling water over the roots and allow them to steep overnight. In a bucket with a lip, combine 2 tbsp. of liquid soap with a quart of water. Mix the root brew with the soapy water and pour into a spray bottle. Spray directly on flying insects or on outdoor areas where you want to keep them away. Leftovers of this spray will rot if left out for more than a couple of days. Freeze it if you plan to use it again.
Wasps don't care for fabric softener, so try prevention first. If they try to make nests in your mailbox or under the eaves of your house, strategically place fabric softener sheets in hidden locations. However, if they still swarm, spray them with a mixture of liquid fabric softener and water. You may also tuck fabric softener sheets around screens to provide a repellent barrier where wasps swarm.
If you don't have any of the other ingredients, squirt them with a strong shot of cheap hairspray. That will freeze them in their tracks. However, hairspray has fumes that can be harmful if inhaled.