Haskell County Oklahoma Cooperative Extension Service
What are Those Huge Wasps in My Yard?
August 1, 2011
Brian Pugh, Haskell County OSU Extension Educator, Ag/4-H & CED
Over the past two weeks, this has been the most common call and office visit, so let us try to answer this question.
Description The culprit is the Cicada Killer Wasp, a giant member of the wasp family and one of our largest wasps in the US. It resembles a very large yellow jacket, but is much larger, often reaching 1 ½ to 2 inches long at maturity. The adult wasp has a rusty head and thorax, with russet colored wings and a black and yellow striped abdomen. The legless, white larvae are only found in their burrow.
Life Cycle Cicada Killer Wasps get their name because they actively search for and capture annual cicadas (also called jar flies or locusts) as food for their young. They overwinter as mature larvae in the soil, pupate in the spring, and emerge as adults in June through July. Typically, it is adult males that are noticed as they establish territories that they aggressively defend from other males. Female wasps begin excavating burrows and leave mounds of soil at the entrance. Burrows contain several cells, each of which is provisioned with one to three paralyzed cicadas and a single egg. The larvae hatches 2-3 days later and consumes the paralyzed (but still alive) cicadas. The mature larva then spins a silk cocoon and overwinters underground in its cell. There is only one generation per year.
Nature of Damage Male and female wasps are large and intimidating, but males are not capable of stinging and females will not sting unless strongly provoked. They do make unsightly mounds of soil at burrow entrances. Although these wasps are solitary, they commonly nest in groups near preferred nesting sites. These sites have sparse vegetation such as flower beds, gardens or even in sandy soil around playgrounds. This site preference is why many homeowners have witnessed these recently, coupled with the extreme drought that has made tunneling more difficult in non-irrigated areas.
Control Although these pests are not considered harmful, there digging may cause unsightly mounds of soil and their actions may be frightening to some. It is important to remember they are actually helping to keep the population of cicadas in check which feed on tree roots through the winter. In fact a female Cicada Killer might catch upwards of hundreds of cicadas in a summer, so they are beneficial in that regard. However, if control is warranted consider using a product such as an insecticide dust that can be placed in active burrows or simply squirt adults with a dishwashing soap mixture. Please call my office for more information on chemical control.
*Many of the clients who entered my office over the past few weeks had not heard of the soap spray, so I will let you in on this mixture now. Mix 4-5 tablespoons of dishwashing liquid soap (Dawn, Palmolive, etc.) with ½ to 1 gallon of water. Mix well and apply to any type of wasp preferably by using a sprayer (you can just douse them from a cup). How does it work? If you have ever seen this soap cut oil floating on water then you will understand that since the wing, leg and body joints of insects are made of complex oils and waxes the soap immobilizes them quickly. Within 1-2 minutes the insect suffocates from lack of oxygen. It also works on many other insects too.
For additional information on lawn, garden or pasture pests contact Brian Pugh at the OSU Extension Office, 967-4330.
Oklahoma State University, U.S. Department of Agriculture, State and Local Governments Cooperating: The Oklahoma Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, religion, sex, age, disability, or status as a veteran, and is an equal opportunity employer.