August Animal - Cicada-killer Wasp

University of Nebraska - Lincoln Extension Educator Dennis Ferraro is also the resident herpetologist at the School of Natural Resources. Dennis writes timely articles on animals that you might see on your acreage in Nebraska, ranging from mammals to insects. This month Dennis covers an insect that may be seen buzzing around your property. To the right, Dennis is helping a snake (not a garter snake) shed its skin.

The Cicada-killer wasp (Sphecius speciosus) is the largest wasp species in Nebraska. The wasp is up to two inches long and boldly marked with yellow stripes on a black body. Cicada killers are most abundant during midsummer when their prey, the cicada, is active.

Cicada killers attack, sting, and carry paralyzed cicadas to underground burrows. These burrows can be found near walks, driveways, and retaining walls, and usually can be identified by the presence of fresh soil around the half-inch entrance hole. Once the paralyzed cicada has been dragged underground, the female wasp deposits an egg on it. Upon hatching, the wasp larva uses the cicada as a food source.

These wasps normally are very docile and unlikely to sting unless provoked. However, when someone walks near a Cicada-killer, the wasp may become disoriented. It will circle the person to reestablish its position, but is not attacking.  Control is rarely needed, except when nests occur in undesirable locations. If control is needed, cultural methods may work best, says Cornell University Master Beekeeper Program materials. "Since these insects nest in disturbed areas with little or no vegetation, take steps to encourage the growth of dense lawns. Place extra mulch in your flowerbeds and around shrubs to cover sandy soil."  However, if nesting activities become a problem, an infested area can be treated with an insecticide labeled for use on wasps. Be sure to wear appropriate protective clothing.

Smaller related “Digger Wasps” also may be seen this time of the year. These wasps are thin-waisted and may be black or blue in color. Digger wasps are beneficial. They appear in the morning and fly over turf in search of beetle grubs or the larvae of other insects. They generally do not sting unless handled or molested.

According to Iowa State University Department of Entomology "Wasps are generally 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, removal is justified.” Ground nests of cicada killers and other digger wasps can be destroyed by using an insecticide designed for outdoor use on wasps, following label directions. Iowa State University suggests covering the nest opening with a shovelful of soil after all activity has stopped. The image to the right shows signs of Cicada-killer wasp activity in a retaining wall.