85 live 'murder hornets' captured from tree near Canada-U.S. border

A Washington state entomologist said discovering a nest of Asian giant hornets in the backyard tree of a home in Blaine was at first exciting, and then concerning.

"The first thing we saw was their children's play set about 20 feet from the location," said Sven-Erik Spichiger. "It was a little terrifying."

The nest of invasive insects is the first ever discovered in the U.S. and was found just south of the Peace Arch border crossing that separates South Surrey, B.C., and Blaine, Wash.

Last year, a nest of Asian giant hornets was found and destroyed in a downtown Nanaimo park on Vancouver Island.

As an invasive species with a voracious appetite for important pollinators like honey bees, "murder hornets" as they are sometimes called, are considered a major threat to apple, berry and other fruit crops in the Pacific Northwest. 

Researchers were led to the nest in Blaine after attaching tiny radio trackers to three specimens they captured live. 

Over the weekend crews wearing protective suits worked to seal the nest and insects in the tree using foam filler and shrink wrap, before vacuuming out as many individual specimens as possible. 

"When we first started vacuuming the hornets were not very upset with us and only a few were coming up,' said Spichiger. "Then we hit the side of the tree and that worked ... they came pouring out."

All 85 Asian giant hornets taken from the tree alive will now be used in research, he added.

Any individuals and larvae that remained in the tree were asphyxiated with carbon dioxide gas for 10 to 15 minutes, before expanding foam was sprayed into the nest crevice. The tree is now being removed for further examination.

"At this point we believe everything in the nest to be dead," he said. "No one was stung or even attacked by a hornet during this procedure, so from my perspective that is a huge success." 

According to Spichiger, the Washington state team has been working in close collaboration with Canadian counterparts who are also tracking the hornet. 

"[The Canadians] have traps up all along the border where we've been operating … and we are sharing capture and eradication data as it's happening," he said.

The Asian giant hornet can grow up to five centimetres long and is native to Japan, the Korean peninsula and coastal China.

Spichiger expects more nests will be found and eradicated, but because the hornets haven't been found outside of Whatcom County in Washington state, doesn't think the pest is out of control in the U.S. at this time.

"If we start finding [nests] all over the place, that's when I'll start thinking we have a problem we can't deal with," he said.