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In late summer, early fall, Asian giant hornets go into “slaughter mode” to feed growing embryos.

The state Department of Agriculture is asking people to be on the watch for Asian giant hornets this time of year.

Agriculture staff eradicated an Asian giant hornet nest near Blaine on Wednesday, Aug. 25, after a resident reported an Asian giant hornet attacking a wasp nest Aug. 11 near Blaine. Biologists captured the giant hornet along with two others, tagged them with tiny radios and tracked one to this nest a quarter-mile away.
 The nest was in the base of a dead alder tree in rural Whatcom County, about 1 mile east of Blaine and about 2 miles from a nest that officials eradicated last October. 

Nest eradication

WSDA staff began last week's eradication of the second nest near Blaine by vacuuming 113 worker hornets from the nest and caught 67 more hornets in the area with nets.

Then the team removed decayed wood at the nest’s entrance to reveal that hornets had excavated the interior and built a nest with nine layers of comb that held had about 1,500 hornets in various stages of development. The portion of the tree with the nest sent to Washington State University Extension in Bellingham for further analysis.

The first nest found in the U.S. was eradicated in October 2020 and is called Nest Zero. It had 76 newly emerging queens inside plus more than 100 suspected queens still developing.

In late summer and early fall, Asian giant hornets go into “slaughter mode” to feed growing embryos. By early winter, the new queens disperse to shelter in the ground and form new nests.

“While we are glad to have found and eradicated this nest so early in the season, this detection proves how important public reporting continues to be,” WSDA managing entomologist Sven Spichiger said. “We expect there are more nests out there and, like this one, we hope to find them before they can produce new queens. Your report may be the one that leads us to a nest.”

In June, a "slightly dried out, dead specimen" of the hornet was discovered on a lawn in Marysville.

“When it comes to preventing and stopping a new invasive species, we all have a role to play and this is a great example,” said Justin Bush, executive coordinator of the Washington Invasive Species Council.

Destructive invaders

The Washington Invasive Species Council lists the Asian giant hornet as a priority species to eradicate because it poses a serious threat to Washington honeybees and the honeybee industry. A similar hornet in Europe has reduced beehives by 30% and up to two-thirds of the honey yield.

In the TVW documentary video Nest Zero, the state's public affairs network reported that the first Asian giant hornets in the area were sighted August 2019 in Nanaimo on Vancouver Island, B.C., and a nest was eradicated. Another was found in White Rock that November on the mainland near the Canadian border. A month later, they were reported in Whatcom County — the first in the U.S.

Since then, WSDA has been working with local, state and federal partners to stop the hornets from getting a foothold here.

“The first detection of Asian giant hornet in the entire United States was made by an aware member of the public. Every other detection since has been made by everyday citizens,” Bush said. “Being aware of new plants and animals or changes in your community and then letting the experts know if something seems like a problem can save thousands, if not millions of dollars, in damages.”

Asian giant hornets, Vespa mandarinia, are an invasive species that normally range from India through Southeast Asia to Japan. They are the world’s largest hornet being about 2 inches long with a 3-inch wingspan.

They prey on honeybees and other insects, especially in late summer and early fall. A small group of these hornets can attack honeybee colonies en masse, resulting in the complete destruction of a healthy colony in a matter of hours, helping them to earn the nickname "murder hornet.” An attack leaves piles of decapitated honey bees in front of the hive.

They don’t usually bother people or pets, but if provoked, Asian giant hornets can sting multiple times and have powerful venom that can inflict serious injury or even death.

You can help

WSDA continues to trap for Asian giant hornets through November. People who would like to set their own traps can find instructions on WSDA’s website. Those who suspect they have seen an Asian giant hornet should take a photograph if possible.

Report suspected Asian giant hornet sightings and learn more at agr.wa.gov/hornets.

Contact reporter Peggy Wendel at pwendel@scnews.com or 360-416-2189.

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