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Giant Asian Hornets in the US

In 2019, a new invasive insect dubbed the “Murder Hornet” was spotted in the United States. They are more commonly known as Asian giant hornets (Vespa mandarinia), and are the largest species of hornet in the world. The queens can be almost 5 cm long (nearly 2 inches) and they nest almost exclusively underground. This species is native to temperate and tropical east Asia and far east Russia where they live in low mountainous regions and forests, completely avoiding plains. A New York Times article about the 2019 detection of these hornets in the Pacific Northwest set off a social media frenzy.

May contain: wasp, hornet, andrena, insect, invertebrate, animal, bee, and honey bee

Asian giant hornets feed mostly on other insects, tree sap, and occasionally prey on eusocial insects, like honey bees or other hornets, raiding their colonies for young larvae or honey stores. The giant hornets invade a honey bee hive and start indiscriminately killing the bees inside – cutting the heads off with strong mouthparts. The European honeybees that we raise in the United States have no defense against this – their stings are too weak to penetrate the shells of the wasps, and because of this very few giant hornets are needed to completely decimate an entire hive. Because humans raise bees in such high numbers, it’s become a simple matter for them to increasingly attack and feed off honey bee colonies.  For humans, these hornets are also known to have a very painful and venomous sting.

The initial sightings of this species were in British Columbia, Canada in 2019, but scientists have also found individual Asian giant hornets in Washington state, which could suggest they are becoming established. Agricultural organizations concerned about their potential to threaten honeybee populations are working hard to find and eradicate them with the help of local beekeeping associations. So far, every discovery has been limited to Canada and Washington state, and no Asian giant hornets have been found in California.


Page last reviewed: July 21, 2021

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