Once again, the ringing song of cicadas can be heard in trees throughout South Dakota. Although cicadas aren’t much of a concern, their arrival indicates that it’s time for cicada killers to be active as well. Each year, we receive numerous reports of large scary wasps that are terrorizing home owners. The wasps in question are cicada killers. Although they are formidable in size, they are actually one of the more docile insects observed during the summer.
Our advice to anyone who has these large wasps is to leave them alone. They are not aggressive, except for the occasional male cicada killer who may display territorial behaviors around a nest. Even during these displays, the male is simply using its size and buzzing noise to scare away potential invaders. Even if the male cicada wanted to sting you, it couldn’t as he lacks a stinger entirely!
The adult cicada killer wasps can vary in size from 1.5 to 2 inches in length, which makes them one of the largest wasps encountered in South Dakota. The cicada killer adults have a reddish-brown thorax (area directly behind the head) and black abdomen with yellow banded markings (Figure 1). These wasps are often observed hovering close to the ground near mounds of excavated soil. The mounds are created when the female wasps dig tunnels in areas of bare dry or sandy soil to create a nest. Cicada killer wasps can often be seen in groups near garages, patios, sidewalks, retaining walls, and playgrounds.
Figure 1. Cicada killer wasp. Courtesy: Amanda Bachmann
Cicada killers are solitary wasps, which means the females dig nests and provision their eggs alone (Figure 2). However, there are often multiple wasps using the same area of suitable habitat in a yard. The female cicada killers hunt cicadas and other large insects near their selected nesting site. Once prey is caught, the wasp paralyzes it using her stinger and carries it back to her nest. She will then lay an egg on the prey and bury it. When the egg hatches, the larva will consume the prey, spin a cocoon, and overwinter in the soil. With suitable environmental conditions, new adult cicada killer wasps will emerge from the same area during the following year.
Figure 2. Cicada killer wasp digging a hole in a lawn. Courtesy: Adam Varenhorst
No Need to Manage
As mentioned, we receive many questions regarding the management of cicada killer wasps. A lot of these cases are the result of people feeling threatened by having large wasps in their yard. In other cases, it’s because the excavated soil around nests appears to be destroying property. Although they do cause minor disturbances in lawns and gardens, these wasps are benign. Cicada killer wasps may look deadly, but in reality, they are rarely aggressive towards humans or pets. For the most part, the only time cicada killers respond to human activity is when the males are patrolling an area and may buzz around passing people or pets. If cicada killers are nesting in an undesirable location, the long-term solution is to amend the habitat in that area (e.g., replanting grass, mulching, etc.). As long as an area remains bare, with loose or sandy soil, it has an increased chance of being utilized by subsequent generations of cicada killer wasps.
Figure 3. Cicada killer nest located in dry grass near a driveway. Courtesy: Adam Varenhorst