The fight against ‘murder hornets’: Kevlar thread to tie on trackers, thick foam suits to prevent stings

An Asian giant hornet that was tagged by the Washington State Department of Agriculture flies through the air with a bent radio tracker antenna. (WSDA Photo)

The entomologists and researchers leading the fight against Asian giant hornets in Washington state have made some tweaks to the tech they’re using to tag, track and hopefully eliminate the invasive species.

In a press conference last week, Sven-Erik Spichiger, managing entomologist at the WSDA, detailed what was different this year as a new nest of so-called “murder hornets” was located and eradicated.

To start with, WSDA has moved to a slightly different radio tracker, produced by a different company. The tiny tech is tied to the hornets, which are then followed by WSDA workers carrying receivers. Last year, when another nest was located near Blaine, Wash., WSDA was tying the trackers on using dental floss, and the hornets seemed to be able to chew through that material.

“We have switched to Kevlar thread this year,” Spichiger said, noting that three hornets were captured and tagged this year. “The last hornet, the one that led us back to the nest, didn’t even seem phased.” He said workers were “able to recapture the hornet later after the discovery of the nest and deactivate the tag and maybe get to use it again.”

The use of radio technology was first explained last fall when some device insight and guidance was sought from a researcher at the University of Washington.

Spichiger said scientists are chilling the captured hornets as little as possible. Once a hornet is netted, it is chilled down for about 10 minutes, tagged and released. The tough part is keeping up.

“The tracking event was as difficult as one might think when you’re trying to follow something that flies very quickly through Himalayan blackberry,” Spichiger said, adding that new receivers this year are also lighter and easier to carry through heavy brush.

One signal was lost altogether. WSDA has been working very close to the Canadian border and they think they lost the signal as they were pointing north. They shared the radio tag frequency and worked with counterparts in British Columbia who did some tracking on the Canadian side of the border. But the tag was never recovered or relocated.

A WSDA worker poses with the Asian giant hornet nest located inside a tree in rural northwest Washington state. (WSDA Photo)

The removal of the nest from a rotten alder tree took place on Aug. 25, and proved to be a bit different from the eradication last October.

“I will say this: this nest was a little more aggressive than the nest we encountered in 2020,” Spichiger said. “In general [the hornets] were more interested in what we were doing, whereas the nest in 2020 they barely paid us any mind.”

Spichiger said warmer temperatures could have contributed to the hornets’ aggression — and he was thankful that safety gear did its job.

“A few of us who were working very tight in the area were approached by the hornets and they did actually attempt to sting us this time,” he said. “But we’re all very happy to say that our hornet suits worked very well and no injuries were sustained.”

Spichiger said the hornets “bounced right off of our lovely suits,” which he described as 1/4-inch-thick soft foam covered by a white mesh netting. The hornet stingers are unable to penetrate the foam.

“They can get a little warm,” Spichiger said of the bee suits. “They are fairly uncomfortable, but it’s gotta be more comfortable than being stung, so we’re always happy to make that tradeoff.”

A queen Asian giant hornet is shown on a nest built inside a tree in Whatcom County, Wash. (WSDA Photo)

Spichiger shared some numbers related to what was inside the nest of nine combs: 292 eggs, 422 larvae, 563 cap cells (hornets that are about to be produced), 195 workers vacuumed or netted, no males, one queen. That totals 1,473 individual life stages which is almost three times the size of the nest last year, which had approximately 500 life stages.

Spichiger and WSDA offered up a few more nuggets from this year’s hornet work:

  • Officials will be testing the genetics from several specimens to see if the nest is related to the one that was eradicated last year.
  • Spichiger was not sure why the nest was bigger than the previous nest. He said the environment appears to be strongly suited to the development of the hornets, and perhaps the weather was a little more favorable this year. Data so far does not suggest additional nests, but he said, “We’ll keep hanging our traps out.”
  • WSDA will need to see three years of negative survey data, and three years of no reports of hornets before they can consider the hornets eradicated. But biologically speaking, Spichiger said there are large portions of remote and overgrown land that scientists just can’t get to, so it could be a number of years before the state can declare the hornets 100% confidently eradicated.
  • A subset of the new nest hornets will be kept alive to try to develop new attractants for traps.
  • A property owner did observe Asian giant hornets attacking and carrying off single honeybees that were foraging on her sunflowers.

Watch last week’s full press conference here:

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