Scientists removed 98 so-called murder hornets from a nest discovered near the Canadian border in Washington state over the weekend, including 13 that were captured live in a net, the state agriculture department said.
The other 85 Asian giant hornets were vacuumed into a special container when the first nest discovered on US soil was eradicated on Saturday, the agency said.
“The eradication went very smoothly,” managing entomologist Sven Spichiger said. “This is only the start of our work to hopefully prevent the Asian giant hornet from gaining a foothold in the Pacific north-west.
“We suspect there may be more nests in Whatcom county.”
The nest was found after the state agriculture department trapped hornets and used dental floss to attach radio trackers.
Saturday’s operation began at about 5.30am, the team donning protective suits and setting up scaffolding to reach the opening of the nest, which was about 10ft up. The team stuffed dense foam padding into a crevice above and below the nest entrance and wrapped the tree with cellophane, leaving just a single opening, into which they inserted a vacuum hose to remove the hornets.
Team members used a wooden board to whack the tree, to encourage hornets to leave the nest. When the hornets stopped coming out, the team pumped carbon dioxide into the tree to kill or anesthetize any remaining insects. They then sealed the tree with spray foam, wrapped it again with cellophane, and finally placed traps nearby to catch any survivors or hornets who may have been away during the operation. The work was completed by 9am.
“We congratulate the Washington state department of agriculture for eradicating this nest,” said Osama El-Lissy, deputy administrator of the US Department of Agriculture’s plant protection and quarantine program. “Thanks to their expertise and innovation, this nest is no longer a threat to honeybees in the area.”
Entomologists will now try to determine whether the nest had begun to produce new queens. The state agriculture department will continue setting traps through at least November, in hopes of catching any more Asian giant hornets still in Whatcom county.
WSDA has been searching for nests since the first hornets were caught earlier this year. The first confirmed detection of an Asian giant hornet in Washington was made last December and the first hornet was trapped in July. Several more were subsequently caught, all in Whatcom county, in the north-western corner of the state along the Canadian border.
Asian giant hornets, an invasive pest, are the world’s largest hornet and a predator of honeybees and other insects. A small group can kill an entire honeybee hive in a matter of hours.
Asian giant hornets can deliver painful stings to people and spit venom. Despite their nickname and the hype that has stirred fears in an already bleak year, the world’s largest hornets kill at most a few dozen people a year in Asian countries, experts say probably far fewer. Hornets, wasps and bees typically found in the US kill an average of 62 people a year, the Centers for Disease Control and Prevention has said.
The real threat from Asian giant hornets, which are 2in long, is their devastating attacks on honeybees, which are already under siege from problems like mites, diseases, pesticides and loss of food.
The hornets are normally found in China, Japan, Thailand, South Korea, Vietnam and other Asian countries. Washington state and the Canadian province of British Columbia are the only places the hornets have been found in North America.