Sunday, November 1, 2020

Invasion of the Murder Hornets 

They’ve been in the headlines since last December: Giant Murder Hornets Arrive in North America; Murder Hornet Nest Found in Washington State; A Sting that Can Kill.

They look and act like something out of a science fiction movie or taken straight out of a Steven King novel. They’re huge. They spit venom. And their stings can be lethal to humans.

Asian giant hornets (AGH), Vespa mandarinia, can grow to be more than two inches long. They’re the world’s largest bees. Imagine hornets the size of your thumb, with orange heads, a yellow-striped thorax, and ant-like mandibles (mouthparts used for biting, cutting, and/or holding food).

In an article written by Seth Truscott; a Public Relations and Communications Coordinator for the College of Agricultural, Human, and Natural Resource Sciences at Washington State University (WSU), Todd Murray, a WSU Extension entomologist and invasive species specialist is quoted as saying, “It’s a shockingly large hornet… a health hazard, and more importantly, a significant predator of honeybees.”

One of the key differences between bees and hornets is that bees, as a rule, can sting only once, while hornets, including AGH, may sting repeatedly, delivering several times the amount of venom of other bee species. Several times the pain, too. Combine that with the fact that, unlike other hornets, AGH have stingers that can penetrate thick clothing, including standard beekeeper suits. The insect reportedly kills dozens of people in Japan, every year, where encounters with them are not that uncommon.

As frightening as that may sound, AGH generally don’t attack people or pets, unless they feel threatened. What’s more, bees (including hornets and wasps) kill an average of 62 people a year in the United States, according to the Centers for Disease Control and Prevention (CDC).

AGH in North America

In September, 2019, a ground nest of AGH was discovered near a public footpath in Nanaimo; a city on the east coast of Vancouver Island, in British Columbia, Canada. Fortunately, authorities were able to quickly track down and destroy that nest.

Not long after that however, in December of 2019, the Washington State Department of Agriculture (WSDA) received and verified two reports of AGH in this country; near Blaine, Washington (Whatcom County).

Using a network of traps, WSDA staff, with the help of other cooperating agencies and citizen scientists, began diligently tracking sightings. The first trap-catch was made in July of this year. More recently, four hornets were captured in newer, modified traps set by WSDA entomologists. The scientists attached radio trackers to three of the captured hornets before releasing them. The trackers led them to a nest within the cavity of a tree located on private property. On Oct. 24th, the nest was successfully eradicated by technicians who used foam to seal access points in the tree trunk, before wrapping the trunk in cellophane and then vacuuming the hornets out of the nest, to be destroyed.

These encounters are commonly referred to as the first-ever AGH sightings in North America. However, although it was not highly publicized, the United States had a close call with the hornets in 2016, when an inspector with the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) flagged an express package that had arrived in San Francisco, California. APHIS Entomologist Allan Smith-Pardo, who was charged with identifying suspicious wasps or bees found in cargo or mail, identified the package as a nest of AGH; confirming that, “There were no adults in the package, but” there were “plenty of pupae and larvae.” A few were still alive. (Insect Systematics and Diversity; Oxford Press; May, 2020; page 23)

The Real Danger

Although the hazard to humans posed by the stings of AGH is real, the hornets are a much greater direct-threat to honeybee populations than to people. In late summer and fall, they enter a ferocious ‘slaughter’ or bee killing phase. A small number can completely wipe out an entire honeybee colony in a matter of hours. They literally massacre the adults; decapitating every one of them and then taking the brood; larvae, pupae, and honey; to provide food for their young.

Invasive Species

Invasive species are organisms that are able to thrive and reproduce in non-native areas to the point where they pose a risk to the existing ecological fabric. AGH, which are native to temperate and tropical forests of eastern Asia, South Asia, and Mainland Southeast Asia, including parts of Japan, China, India, South Korea, Taiwan, Pakistan, Malaysia, Thailand, Sri Lanka, and the Russian Far East, where they are also known as Japanese hornets, yak-killer hornets, and giant sparrow bees, now pose a serious threat to Washington State honeybees and the related honeybee industry. A similar hornet in Europe has reduced beehives by 30 percent and hive-honey yield by up to two-thirds. Preventing the establishment and spread of AGH in North America is critical. 

AGH are not present in New York and hopefully won’t be in the future. If you have questions about wasps or any stinging insects, you can contact your local Cornell Cooperative Extension office for advice or to submit samples for identification.


1) Asian giant hornet (Vespa mandarinia) and its most common lookalikes – Texas A&M University

2) Washington State Department of Agriculture technicians tagging an Asian giant hornet with a radio tracker – WSDA photo


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Richard Gast is a retired Extension Program Educator and has been contracted by Cornell Cooperative Extension Franklin County to continue his informative and thought provoking articles.

15 Responses

  1. Nora says:

    Thank you Mr. Richard Gast for a very informative article and I sure as hell hope they don’t come here .

    • jeep says:

      Hoping is not the answer Nora. These things are not coming to the U.S.A. from china by accident! First the China Virus, Murder Hornets, God only knows what else or what next! Its time for the World, not just the U.S.A to get real tough on china, or they will stop at nothing to for-fill their goal of world domination.

  2. Boreas says:

    I had some European Hornets in my ceiling once in CNY. They were scary enough…

  3. Pat B says:

    It would be interesting to know the shipping origin and destination of the package noted in this article containing “plenty of pupae and larvae” of the species discovered by a USDA inspector in 2016 in San Francisco.

  4. Pat B says:

    Maybe not. Did a bit of research online. They may have been shipped from Japan since they are considered a delicacy there. Maybe someone here thought it would be a good idea (not!) to have a taste from home.

    • Nora says:

      Pat B , I read the article thank you for doing the research,and yikes a delicacy , Good Lord I agree with you please keep them out of the USA

    • jeep says:

      Thanks for the research Pat B,

      They might not have come from Japan, Dr. Ueno said; they could have arrived from another country in the region.

      I’m still Betting China!

  5. John says:

    Let’s not forget that honeybees are a non-native species and are considered invasive in different places in North America. The story of travel is the story of species traveling around the globe.