The national press generated a lot of buzz about “Murder Hornets”, spurring a flurry of interest and confusion about where the Asian giant hornet has been reported, and what it actually looks like in comparison to local hornets, bees, yellowjackets, wasps, and flies.

August updates:

Insect pest species often arrive quietly and might go unnoticed until they become established and begin impacting local agriculture or forests. When you’re the largest hornet species in the world, however, you’re going to immediately be recognized as an out-of-towner.

That’s exactly what happened near Blaine, Wash., when a resident alerted the Washington Department of Agriculture about the appearance of an unwelcome new invasive insect, the Asian giant hornet.

What is it?

The Asian giant hornet, Vespa mandarinia, is a large, extotic hornet that has only recently been reported in the US. They establish annual below-ground nests, and are usually dormant through the winter. You’re most likely to encounter an Asian giant hornet in the spring and summer months, when workers are out foraging and virgins queens mate and disperse to establish new nests. Asian giant hornets can forage for long distances, and they prey on a variety of other insects, including honeybees.

How will it impact Oregon?

The Washington State Department of Agriculture quickly issued an alert after confirming reports of the Asian giant hornet near Blaine and Bellingham, Wash. Their quick action was driven by concern for the potential devastating impact that Asian giant hornets can have on the honeybee industry, pollination services, and crop production in the Pacific Northwest. In Europe, where the Asian giant hornet is already an invasive pest, they have shown that they can attack and quickly destroy honeybee hives.

What does it look like?

It’s menacing appearance and painful sting have earned the Asian giant hornet some fearsome nicknames throughout its indigenous range, including yak-killer hornet, the commander wasp and the tiger head bee. Asian giant hornets are very distinctive looking, and not just because of their impressive size (workers are over 1.5 inches in length, and queens can be closer to 2 inches!). Adults have solid yellow-orange heads with large dark eyes, and a striped abdomen punctuated with a serious looking stinger.

Asian giant hornets

Asian giant hornets have distinct orange heads and large dark eyes. Photo © LiCheng-Shih / Flickr CC

Asian giant hornet eating a large insect

Asian giant hornet eating a large insect. Photo © Joe Carey CC

Asian giant hornet scale

Asian giant hornets are large! Workers can be about 1.5 inches in length, queens are even larger! Photo © Yasunori Koide CC

Pinned Asian giant hornet

A pinned Asian giant hornet gives a sense of scale. They’re big! Photo © bcinvasives.ca

Where is it?

The Asian giant hornet was first reported on Vancouver Island BC in August 2019. Later that year, in December, the first confirmed reports of the introduced hornet in the US came from Blaine and Bellingham, Wash., near the US-Canadian border.

Where did it come from?

Exotic insects arrive in the US in a variety of ways. One possibility is that the hornets were “stowaways” in cargo or ballast material on a ship that crossed the Pacific from eastern Asia, where they are native. A single mated female can make the journey and then establish a colony in a new country.

What should you do?

Early detection and quick action is our best defense. If you see what you think is an Asian giant hornet, try to get a photo of it and send it to the OSU Insect ID Clinic, which offers free identification services. The best way to confirm is if you have a (dead) specimen you could send us. Warning: Asian giant hornets are not interested in people, but they will attack (sting!) if disturbed.

OSU Plant Clinic
Department of Botany & Plant Pathology
bpp.oregonstate.edu/plant-clinic