The hunt has been on since December 2019. The target? The Asian giant hornet, found in Washington state, with more captured into this summer. The goal was to trap a live hornet, tag it and follow it back to a nest. The efforts, until last week, had not been successful.
Then on Oct. 21, officials from the Washington State Department of Agriculture trapped live hornets and on Oct. 22, they tagged them using a new kind of tag from USDA. Following tagged hornets isn't easy. "We followed them awhile, then we lost the signal," says Sven-Erik Spichiger, managing entomologist, WSDA. "We relocated and followed the signal to a loud point about 284 years from where we released the wasp, into a heavily wooded area."
Spichiger says they were hearing a loud signal from the tracked hornet. Traditionally Asian giant hornets nest in the ground, which is likely where Spichiger was looking as he was trying to find the tracked hornet. "We had a strong signal, and at that point I heard a hornet buzz over my head, then I heard another. I took a step back and I found I was under the nest," he says. "[The hornet] had gone straight back to where she came from."
The plan was to eliminate the nest last Friday, Oct. 23, but rainy weather changed the plan. Yet plans were set to take on the nest and remove the hornets on Saturday, Oct. 24. Yet a nest located in a tree created a problem.
Getting the hornet gear needed
Spichiger says that a small percentage of AGH nests are located in trees, noting that finding this one higher up created different challenges. "We had to locate scaffolding to erect around the tree so we can work," he notes during a media conference ahead of the eradication effort.
The WSDA team already acquired the heavy neoprene ventilated suits with full face masks to wear for the operation. They knew they were going up against an insect that could sting multiple times, with a longer than average stinger that rips right through traditional beekeeper suits. The full face masks were needed because this insect can also spray venom (in rare situations when threatened) that can cause long term damage to a victim's eyes.
Washington State Department of Agriculture
NO GLUE NEEDED: Tagging a hornet isn't easy. Glue wasn't working, but it turns out dental floss tied around the body works (except in one case when a queen chewed through the floss – yes these bugs are resourceful).
With the nest opening 8 feet off the ground, the scaffolding needed to be erected the day before, so when it was time to get working the team could be ready. The nest, in a hollow of the tree, was estimated to contain about 200 hornets. Some nests can contain as many as 500 to 600 queens.
Spichiger, and colleague, Chris Looney, have had a crash course in handling AGH and the decision was made to inject foam into the nest and wrap the tree with Saran wrap to block the hole. "I've viewed several nest removal attempts," he says. "We do want to obstruct the hole so no more can get out."
How could Spichiger be sure that the opening found in the tree was the only way in and out for the hornets? "Chris Looney is sitting out in the rain right now observing the nest to make sure that's true," Spichiger says. Looney is an entomologist with WSDA, and had the task of watching the nest as preparations were being made.
Eradicate the nest, preserve hornets
The nest process included plugging the gap with foam and wrapping the tree with Saran wrap, as Spichiger says. Then the entomologists planned to vacuum out the hornets and capture them on dry ice in a container.
"When we plug the hole the hornets will work to escape," Spichiger says. "We'll be using their natural response to contain them."
Using a vacuum, the entomologists will suck the hornets out as they try to leave the nest. "We need a number of specimens for research purposes for labs across the country and other countries as well," Spichiger says.
Those sample insects can also be researched to better understand the origin of the nests and get genomic information as well to learn where the bugs came from.
After sucking out the insects, WSDA plans to drop the tree to dig into the nest to understand if they had been producing breeding cast and whether new queens that could breed for next year have left the nest.
The tree is on property near a new housing development in Blaine, Wash., and the property owner has been cooperating with WSDA.
And the result? WSDA posted a tweet (below) showing insects in containment and the phrase "Got 'em." The agency plans a press conference for later Monday, Oct. 26, offering more information. The key is that the scaffolding, heavy suits, foam, Saran wrap and a vacuum were all deployed successfully.