The ground hornet, also known as the cicada killer wasp, is a large and intimidating looking insect. Although they are one of the largest types of wasps and are known for attacking and killing cicadas, ground hornets actually rarely present a danger to humans. Their sting, like that of any wasp, is painful and can cause an allergic reaction, but the cicada killer preys specifically on cicadas and has little interest in bothering humans unless bothered first. Their underground nests, however, can be irritating and unsightly when dug on your lawn. If they build their burrow in a high-traffic area, there is a greater chance that you will bother the insects and risk getting stung.