Lots of Digger Wasps; No Asian Giant Hornets

Asian giant hornet caught in Washington, July 14, 2020
Asian giant horner.  Washington State Department of Agriculture

As expected, and after abundant publicity about Asian giant hornets in the Pacific Northwest earlier in the year, we have been busy this summer responding to reports about large wasps in Iowa.  All inquiries have been about native digger wasps, especially the cicada killer wasp.  The cicada killer wasp is a native, common, and frequently abundant large wasp that is present every summer throughout the eastern two-thirds of the U.S.  See the image and learn more in our online cicada killer wasp article

The cicada killer wasp is our largest wasp at 1.5 inches long with stripes across the abdomen and orange-colored translucent wings.  Cicada killer wasps are smaller than the Asian giant hornet (up to 2 inches for AGH).  There has been no evidence of Asian giant hornets anywhere in the U.S. outside of the previously reported individuals found in Washington.  https://agr.wa.gov/about-wsda/news-and-media-relations/news-releases?article=31413  We appreciate that Iowans are watching for this and other invasive species and encourage readers to keep those emails and images coming. 

Great golden digger wasp is black with orange legs and first abdomen segment
Gary Alpert, Harvard University, Bugwood.org

Samples of one of our other solitary, digger wasps found in Iowa were among the requests for conformation of cicada killer wasps.  The great golden digger, Sphex ichneumoneus, is smaller and more attractive than the cicada killer.  The great golden digger is 5/8 to 1 inch in length.  The slender body is black except for the first abdominal segment and legs that are orange/red.  The name comes from the golden hair on the head and thorax.

Great golden digger wasps are very active in sandy areas.  The female tunnels in the ground and provisions the burrow with crickets, grasshoppers, and katydids.  The provisions become the food consumed by the wasp's offspring. There is one generation per year.  See BugGuide for more details.

Solitary wasps are unlikely to sting and are generally not a threat.  The females have only been reported to sting if handled.  Males cannot sting but are known for their territory-protection behavior of "patrolling" along sidewalks and driveways and "dive-bombing" at people, pets, and any other large insect that enters their territory.

Cicada killers and other digger wasps are a temporary annoyance; They are not aggressive, and there is a low threat of being stung. We believe digger wasps can be safely tolerated most of the time, but if tolerance is not possible, control is the same for all of the digger wasps.  Put insecticide dust or foaming wasp and hornet aerosol spray into the burrow at night.  There is no practical control for adult wasps that are visiting flowers or passing by.

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