These wasps, despite their intimidating appearance, are really quite docile. They can fly all around you and never attack. However, we wouldn’t suggest you sit on one or try to crush one with your hands because then they may sting. Especially the females because they are known to have stingers, but the males do not have stingers. You do not have anything to fear from these Cicada Killer wasps.
Once mated, the female digs a series of underground burrows in lawns. Each burrow can have many chambers branching off in different directions. Cicada killer adults do not feed on Cicadas, they actually feed on nectar until it is time to mate. These burrows are for a female Cicada Killer wasp’s larva. Once the burrow is completed, it goes out and hunts for a Cicada. The female will sting a Cicada which only paralyzes it and then flies back with it to the burrow. It will then lay one egg on the cicada. The egg will then hatch and the larva will feed on the cicada. Even though the cicada is only paralyzed, it is very much alive! Once the larva has eaten the cicada it will pupate over the long winter and emerge in early July as a fully formed adult cicada killer.
These holes and mounds of displaced soil on the lawn surface can be unsightly and the activity following emergence can remain in the same area for some time. Once Fall emerges, core aeration and overseeding will begin to repair damage done to the lawn.
Read More: https://extension.entm.purdue.edu/publications/E-254/E-254.html