Commercial insecticides contain chemicals that may be harmful to humans, and they 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.
Basic wasp spray
Remove the spray attachment from an empty plastic spray bottle. Fill the bottle half full of tap water. Squirt approximately 50 ml (1/4 cup) of washing-up liquid into the bottle then add more water until it reaches the "fill" line. Another formula that works quickly is 15 ml (1 tbsp) of peppermint extract and 15 ml (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 bubbles 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.
Larger outdoor areas
Combine strong smelling roots, such as ginger, cayenne, hot peppers and horseradish in a large glass jar. Pour boiling water over the roots and allow them to brew overnight. In a bucket with a lip, combine 30 ml (2 tbsp) of washing-up liquid with 1 litre (1 quart) of water. Mix the 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.
Wasp invasion prevention
Wasps don't like fabric softener, so try prevention first. If they try to make nests 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 doors and windows to provide a repellent barrier in the areas where wasps swarm. If you spot a wasp nest, contact your local council's pest control department.
If you don't have any of the other ingredients, squirt wasps with a strong shot of cheap hairspray. This will freeze them in their tracks. However, hairspray contains fumes that can be harmful if inhaled.