If your lawn or garden seems to be infested with ground wasps, look for the source of the wasps so you can effectively control the insects and keep your home and yard free from the risk of painful stings. Because wasps are beneficial predatory insects in the sense that they feed on other pests such as caterpillars and crickets, use pest control to eliminate wasps only if they are very close to high traffic areas of the garden or yard.
Look for ground wasp nests in June, when the colonies have already established their nests but are still small and easy to exterminate. Locate the nest by looking for small piles of dirt in the yard that have an entrance about the size of your finger, or for larger holes leading to small animal burrows that have been taken over by wasps.
Mark the entrances to nests during the day using small flags or plastic knives placed in the ground about a foot away from the actual entrance.
Pour a solution of 10% soap and 90% water into the marked nest entrances after nightfall. Ground wasps are less active at night, so your risk of being stung is reduced.
Check for wasp activity the following day. If you still see wasps, look for any nests you may have missed. Pour the soap and water solution into the entrance holes of all nests every three days until you no longer see any ground wasp activity.
Apply a lawn-safe insecticide to the nest entrance if the soap and water solution is not effective. Choose a carbaryl or chlorpyrifos dust if available, or a carbaryl, acephate or diazinon liquid concentrate.
Fill the entrance to the nest when you are sure all the ground wasps have been exterminated.
Reduce the possibility of ground wasps returning by keeping your lawn free of fallen fruit or food waste, standing water or hummingbird feeders, all of which may attract wasps.
Freezing temperatures will kill the entire colony of ground wasps, so if you discover a ground wasp nest in the late fall in an area that freezes, don't worry about exterminating it.
Use only insecticides that will not harm your lawn plants. Many insecticides used for hanging wasp nests are not safe to use on your lawn. Even when using lawn-safe insecticides, keep pets away from the treated areas around nest entrances.