Cicada killer wasps, which appear in sunny, open areas east of the Rocky Mountains for about a month every summer, look scary but they are docile. The males, with bodies that measure as long as 2 inches, are unable to sting or bite. Although the sting of a female wasp is painful, the mild-mannered wasps rarely sting unless you step on one or grab the wasp with bare hands. The wasps are mostly harmless, but the tunnels created by the females can disrupt the soft soil in flower beds or around play areas, patios or golf course sand traps.
Swat and kill cicada killer wasps with a lightweight swatter such as a badminton racquet. Swing quickly and you can reduce the numbers of male wasps that fly in the area, waiting to mate with female wasps as soon as they hatch in midsummer. A tennis racquet isn't quite as effective, because you can't swing the heavier racket fast enough to kill wasps in large numbers.
Plug the tunnels of female wasps with a short stick, then stomp on the stick so it is firmly placed level with the ground. Smooth the U-shaped piles of dirt left by the wasps, because the females use the piles to locate the tunnel when they return from cicada-hunting expeditions. Be persistent. If you plug holes and remove the dirt piles every morning, the females will move on and build their tunnels elsewhere.
Check each tunnel 30 to 45 minutes after plugging the hole. If you see females trying to dig back into the tunnel, hit them with a badminton racquet or step on them. Wear sturdy, closed-toe shoes to prevent stings.
Apply pesticides only if the wasps are causing significant problems and other means of control aren't effective. Use a product containing pyrethrins, or pyrethroids, which are a synthetic form of pyrethrin. The low-toxicity substances are relatively safe for humans and mammals, but they kill insects by interfering with the nervous system. Spray the entrance to the burrows and the surrounding soil at a rate of 6 ounces per 9,000 square feet.