At least 3 different species of wasps construct nests in the ground in Iowa. These Digger Wasps include the cicada killer wasp, the largest wasp found in Iowa. Cicada killer wasps may be up to 2 inches long. They are black with yellow markings on the thorax and abdomen and they have rusty colored wings. The great golden digger wasp is slightly smaller. The abdomen is reddish-orange except at the tip, which is black. A third species is 1-inch long and completely black with iridescent blue wings.
The digger wasps are solitary wasps; that is, they live independently rather than in social colonies and they do not depend on other members of a colony to share in the raising of young or the maintaining of a nest. There may be several females working independently to nest in a small area and several males may be "swarming" in the vicinity.
Solitary wasps provision underground burrows with paralyzed insects that become food for their offspring. Cicada killer wasps capture annual cicadas and place them in cells located at the ends of the tunnels they have dug in the ground. Each tunnel is about the size of a quarter and extends 24 inches or more into the ground. The other two digger wasps provision their nests with grasshoppers.
The female solitary wasps have the capability to sting, but won't unless handled or threatened. Stings inflicted by solitary wasps usually are not severe but reactions vary with the individual person.
Wasps generally are beneficial and a nest in an out of the way location where it is not likely to be disturbed should be left alone. If, however, a nest is located where problems could arise, such as under a deck or near an often-used door or sidewalk, removal is justified. Ground nests of cicada killers and other digger wasps can be destroyed by placing an insecticide dust (e.g. Sevin garden dust) in and around the nest entrance during the night. The dust particles will adhere to the wasps as they come and go from the nest. Cover the nest opening with a shovelful of soil after all activity has stopped.
This article originally appeared in the 7/30/2004 issue.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on July 30, 2004. The information contained within may not be the most current and accurate depending on when it is accessed.