A recent announcement by the Washington Department of Agriculture has put the Asian Giant Hornet (AGH) (Vespa mandarinia) back in the news. A dead male hornet was submitted by a homeowner located in the state of Washington just outside the geographical locations of the original detections in 2019 and 2020.
However, all detections in the U.S. continue to be confined to the extreme northwest corner of the state of Washington. Thus far, AGH has not been confirmed in Ohio or anywhere else in North America.
This does not mean we should be complacent. AGH did not fly from Asia to southwestern Canada or northwest Washington State. As other non-native insect pests have taught us, we must remain vigilant.
What to Do:
1. Take Pictures.
If you suspect that you have found AGH in Ohio, take pictures! The old adage “a picture is worth a thousand words” applies.
2. Send the Pictures.
The Ohio Department of Agriculture (ODA) created an easy-to-use Ohio Asian Giant Hornet [Online] Reporting Tool so Ohioans can provide photographs and locations of suspicious insects. Beekeepers should be particularly vigilant. AGH is a predator of other insects and extremely aggressive towards European honey bees (Apis mellifera). In fact, beekeepers are on the front lines in monitoring for AGH in Washington State.
Here is the hotlink to the ODA Asian Giant Hornet Online Portal:
The Asian Giant Hornet (AGH)
AGH is the world's largest hornet with a body length of 1.5 – 2" and a wingspan from 1.5 – 3". Two of its most notable features are its large orange or orangish-yellow head and distinct orangish-yellow and reddish-brown bands on its abdomen.
AGH produce annual nests in hollow trees or underground often taking advantage of cavities created by burrowing rodents and other animals. Their seasonal development matches that of our own yellowjackets (Vespula spp. and Dolichovespula spp.). Fertilized queens leave the nests in the fall to seek protected overwintering quarters. They emerge in the spring to find suitable nesting sites where they initiate new colonies.
Despite social media and various web postings tagging AGH as the “murder hornet,” experts consistently note that AGH is not particularly hostile towards humans, pets, and large animals. As with our native stinging insects, AGH generally goes about its business unless its nest is threatened. Of course, swatting at an AGH may also elicit a painful introduction to its 1/4" stinger.
As noted above, AGH is an extremely aggressive predator of European honey bees. It will mass-attack honey bee hives and quickly dispatch the workers primarily by clipping off their heads. They then rip out the honey bee larvae and pupae, fly back to their underground nests and feed the mellifera meat morsels to their young.
This discriminating taste for honey bees is a two-edged sword. On one hand, AGH can be highly destructive by quickly devastating honey bee hives. On the other hand, their strong preference for honey bee meat means beehives are highly effective in revealing undetected AGH populations. For this reason, beekeepers are most likely to be the first people to observe AGH in an area where this non-native has established a new outpost.
Mistaken Identities: And the Survey Says!
Ohio is home to several native and non-native hornets and wasps. Although the ODA’s online AGH Reporting Tool wasn’t meant to serve as a survey, the data from reports submitted in 2020 illuminated the range of insects that were mistaken for AGH. This serendipitous information is important for informing our educational efforts.
Colette Gabriel (ODA Division of Plant Health) reviews the reports submitted to the AGH Reporting Tool. She identifies the subjects in the photos and when needed, calls upon resources to seek additional help with identifications. Her work remains critical to the overall effort to monitor for AGH.
There were 436 reports submitted to the AGH Online Portal in 2020. 51 images were of such poor quality, they could not be identified and 47 submissions did include images. The insect images submitted as a possible AGH are shown below as percentages of the total number of images.
Almost 52% of the insects mistaken for AGH were European Hornets (Vespa crabro). This is understandable given the hornet's large size; they measure 1 to 1 1/4" in length. Their black and yellow markings on their abdomen make them look like yellowjackets on steroids; however, their head and thorax have distinct chestnut-colored markings. Their heads look nothing like AGH and they lack the distinctive banding found on the AGH abdomen.
The ODA data also revealed that European Hornets appear to be more common in the northeast part of Ohio. Although pictures were submitted from throughout Ohio, the highest numbers came from the northeast part of the state.
Below are pictures of other insects found in Ohio that were submitted to the ODA portal as a possible AGH.