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“The Impact”: Asian Giant Hornets – 3 Separate Arrivals in 3 Years; Containment Plans from WA to B.C.

Mike McClanahan profile by Mike McClanahan

“The Impact”: Asian Giant Hornets – Three Separate Arrivals in Three Years /Containment Plans from WA to B.C.

Hornet Season in Washington

The return of hot weather means its Asian giant hornet hunting season in Washington. The state’s campaign to find and eradicate the invasive insects shifts into gear in July as the worker hornets become more active. The first specimen of the year has been located, but instead of providing actionable intelligence the find raises new questions. The race to find any Asian giant hornets that escaped eradication last year and survived the winter took a mystifying turn this month.

“A really old Asian Giant Hornet that arrived who knows how in someone’s back yard,” said Karla Salp, Washington State Department of Agriculture.

WSDA Public Engagement Specialist Karla Salp says a dead, dried out, male Asian giant hornet  was found on a lawn near an apple tree in Snohomish County, quite a ways south of the site near Custer where the nest was located last year.

“It’s about 65 miles from the Marysville detection to where the nest was in Whatcom County,” said Salp.

On top of that, it had different coloration than the specimens collected in Washington last year or Canada the year before and DNA testing confirmed it had different origins.

The hornet was reported to the agency on June 4th and retrieved by the agency June 8th. At press conference to discuss the discovery WSDA entomologist Sven Spichiger said it was too early in the year for ale Asian giant hornets to be out and about and  the slightly decayed carcass indicates the hornet died a while back, probably 2020. Based on the condition of the hornet he surmised it might have died in a protected spot before falling onto the lawn. How it got to Marysville is anybody’s guess, but one dead specimen is not enough to say there is a population in Snohomish County according to Spichiger.

However, in light of the discovery WSDA will be adding Snohomish County and King County to its Asian giant hornet trapping territory this year, in addition to preexisting plans to trap in Whatcom County. In July the agency will be putting out traps baited with pungent and sugary liquids hoping to lure any invasive hornets that might be active in the area. The agency got a lot of volunteer assistance from private citizens who put out traps last year and for 2021 WSDA is again welcoming the public to put out their own traps.

Trap or no trap, they want anyone who spots an Asian giant hornet to report it.

You can submit a photo through WSDA’s Asian Giant Hornet sightings portal, but be careful trying to snap a picture.

The hornets are packing a lot more venom than your average bee or wasp and they can sting through thick clothing, even a beekeeper suit. They species is also capable of spraying venom which can reportedly cause eye injuries.

Public interest in the spread of the invasive hornets led to a flurry of reports last year. Many of the 2020 reports were false alarms involving similar looking native species, but there were also important finds like the discovery of an Asian giant hornet queen at a residence in Bellingham. The most recent hornet discovery in Marysville was also made by an alert citizen.

New this year the Washington Department of Agriculture is imposing a hornet quarantine rule that gives the agency authority to deal with an infestation of any hornet species on private or public property and restrict access within 65 feet of a nest until it is removed. Homeowners and property owners will be allowed to access their property, but onlookers will not according to the agency. Likewise, property owners won’t be allowed to refuse WSDA access to an infestation, or refuse to allow an eradication, according to Salp.

“If any type of hornet were to be found  in this state and we know there’s a nest we would be able to come in, even on private property, and eradicate and remove that nest,” said Salp.

Meanwhile in Canada

This week we also take a look what’s happening just north of the Whatcom County line in Canada and speak with Paul van Westendorp, British Columbia’s Provincial Apiarist and lead on the Asian giant hornet issue. Even if the state’s invasive species experts are able to find and wipe out all the Asian giant hornets in Washington it won’t mean much if they’re reproducing just north of the border.

The first Asian giant hornet activity detected in North America was in the late summer/early fall of 2019 in the Canadian town of Nanaimo on Vancouver Island. Beekeepers there were able to find and eradicate that nest pretty quickly. Then in 2020 we saw a new rash of sightings in northern Washington state and on lower mainland British Columbia. A nest was found and destroyed in Whatcom County in October 2020. No nests have been found on the Canadian mainland as of June 2021. There were scattered confirmed sightings of Asian giant hornets on mainland British Columbia in the summer and fall of 2020. There were confirmed sightings in B.C. after the Washington nest eradication,  but so far no clusters of sightings in any one area. It isn’t clear if the hornets spotted in the Fraser Valley came from Washington or an undiscovered nest or nests in Canada, according to Westendorp.  The hornets are reportedly capable of flying twenty miles per day. They frequently nest in wooded, often out of the way spots.

As for how they got here, that’s anybody’s guess, but Westendorp suspects the specimens hitched a ride on international cargo.

He is concerned about the danger posed by world’s largest wasp species, to anyone who might stumble into a nest, but from an ecological standpoint he believes another invasive wasp would be a lot scarier for bees and crops than the Asian giant hornet, Vespa mandarinia. Westendorp believes it could only be a matter of time until the Asian hornet species wreaking havoc on honey bee colonies in France, Vespa velutina, winds up in North America.  In that case, the invasion would start on the East Coast and move west, per Westendorp.

“The Asian giant hornet is an apex predator. It is on top of the insect world like the polar bear of the arctic. There are only very few of them around,  even if they can establish themselves successfully,” said Paul van Westendorp, B.C. Provincial Apiarist. “Velutina in Europe and possibly going to be introduced to America on the other side of North America is a far more formidable pest because there are very large nests of thousands of individuals whose predatory behavior is far more destructive than that of the Asian giant hornet. So we really are far more concerned about velutina than of the Asian giant hornet.”

The hornets discovered in Nanaimo in 2019, were determined to be from a different lineage than the Asian giant hornets found in Whatcom County, Washington in 2020. The  June 2021 discovery of yet another Asian giant hornet specimen from a different line in Marysville- means there have been at least three unrelated introductions to the region in the last three years.  On top of that Westendorp says a specimen of  Vespa soror, another massive hornet species native to Asia, was discovered near Vancouver, Canada in May of 2019.

Asian Giant Hornets in North America – Abbreviated Timeline

  • In August-September of 2019 the first Asian giant hornet specimens were found in the Canadian town of Nanaimo on Vancouver Island, British Columbia. The nest was quickly located and destroyed.
  • In late 2019, the first Asian giant hornet ever found in the wild in the United States was discovered in Whatcom County, Washington near the Canadian border.
  • In October 2020 WSDA found and removed the first Asian giant hornet nest which was located inside a tree in the Custer area of Whatcom County.
  • There were scattered confirmed sightings of Asian giant hornets on lower mainland British Columbia in the summer and fall of 2020 before and after the Washington nest eradication, but no nests have been found on the Canadian mainland as of June 2021.
  • Early June 2021 a dead male Asian giant hornet unrelated to any of the hornets found in Canada or Washington in 2019 and 2020 was found on a lawn in Marysville, WA in Snohomish County.


Watch Nest Zero TVW’s Emmy award winning 15 minute documentary about the arrival of Asian Giant Hornets here:


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