COLUMBUS — The Asian giant hornet (Vespa mandarinia) is generating social media buzz bolstered by news feeds referring to it as the “murder hornet.” However, nothing has changed since it was found late last season in the extreme northwest corner of Washington State and the southwest corner of British Columbia, Canada.
Thus far, the giant hornet has not been confirmed anywhere else in North America, including Ohio. But this does not mean we should be complacent.
As other non-native insect pests have taught us, we must remain watchful.
Beekeepers should be particularly vigilant. Asian giant hornet is a predator of other insects and extremely aggressive toward European honey bees (Apis mellifera). In fact, beekeepers are on the front lines in monitoring for Asian giant hornet in Washington State.
The Ohio Department of Agriculture has created an Asian giant hornet reporting tool so Ohioans can provide photographs and locations of suspicious insects. Although photographs can’t serve as official confirmation, they are very helpful in making an initial identification before opening an investigation.
Here is the hotlink to the department’s Asian giant hornet online reporting portal: agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/invasive-pests/agh.
The Asian giant hornet is the world’s largest hornet with a body length of 1.5 to 2 inches and a wingspan from 1.5 to 3 inches. 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.
The hornets produce annual underground nests often taking advantage of cavities created by burrowing rodents and other animals. Their seasonal development matches that of our own North American yellowjackets (Vespula spp.) and bald-faced hornets (Dolichovespula maculata) with the nests only being used for one season.
Despite the social media hype and dubious web postings, experts consistently note that the Asian giant hornet is not particularly hostile toward humans, pets, and large animals. As with our native yellowjackets and bald-faced hornets, the Asian giant hornet generally goes about its business unless its nest is threatened.
Of course, swatting at an Asian giant hornet may also elicit a painful introduction to its 1/4-inch stinger.
As noted above, the Asian giant hornet 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, the hornets 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
For this reason, beekeepers are most likely to be the first people to observe Asian giant hornets in an area where this non-native has established a new outpost.
The two insects most commonly mistaken for Asian giant hornets are European hornets (V. crabro) and the native cicada killer wasps (Sphecius speciosus).
Cicada killers are the largest native wasp found in Ohio. Cicada killer wasps will appear much later in the season with the arrival of their namesake food item, annual dog-day cicadas (Tibicen spp.; family Cicadidae), and disappear once annual cicada activity concludes for the season.
European hornets were first found in the U.S. in New York State around 1840. Since that time, the hornets have spread to most states east of the Mississippi and a few states to the west. These hornets are impressively large, measuring 1 to 1 1/4 inches 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. Yellowjackets have black and yellow markings on the head and thorax. Technically, the non-native European hornet is the only “true hornet” found in Ohio.
European hornets construct paper nests that may look similar to the bald-faced hornet nests. However, they are most often found in hollow trees and sometimes in the walls of homes. They do not produce underground nests.
Normally, European hornets overwinter just like our native bald-faced hornets, paper wasps, and yellowjackets with only the queens that are produced this season surviving the winter.
The new queens leave the nests to seek protected overwintering sites; old nests are not re-used. However, occasionally the entire European hornet nest will survive the winter if they are sufficiently protected. Indeed, although it is rare, nests in Ohio have been observed surviving through three winters.
European hornets are reputed to be highly aggressive and their large size does make them look pretty scary. However, during past encounters with this hornet, I was able to take close-up images and move branches with hornets on them without being stung or even charged.
Still, landscapers should be cautious around these large stinging insects. Like wasps and yellowjackets, they are capable of stinging repeatedly.
The European hornets may also fly at night and are attracted to porch lights or lights shining through windows. They have been known to repeatedly charge windows at night inducing panic in homeowners.
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