Washington’s hunt for the Asian giant hornet had a breakthrough this month followed by heartbreak.
On Oct. 5, a resident was able to catch a live specimen of the invasive species and it was turned over to officials with the Washington state Department of Agriculture. Hoping to follow the live hornet back to its nest, researchers used dental floss to tie a tiny radio transponder to the hornet.
The electronic backpack – size large hornet – was designed to send two signals per second with the same Bluetooth technology that allows drivers to remotely open their cars. Anyone can track the hornets after they download an app for their cell phones.
“It worked like a charm,” said Sven-Erik Spichiger, the department’s managing entomologist.
And then it didn’t.
Trackers followed as the hornet flew Oct. 7 from where it was released on an apple tree. The female hornet flew in a spiral pattern high into the air to get her bearings. It then took off, followed by researchers and neighbors using their cell phones.
The hornet then landed in a tree. It took off and landed in another tree. Then she landed near the ground in heavy vegetation that included blackberries. After 10 minutes in a single location and raising hopes she was at a nest, she took off and was lost, Spichiger said.
“I was extremely impressed with how well the technology worked for us,” Spichiger said. “We have a basic idea of what direction she flew as a result of this. Just using every tool at our disposal and accepting the help from the beekeeping community and the general public is the pathway to victory, if you will.”
Since Asian giant hornets – called murder hornets by some – were first found in northwest Washington in 2019, a total of 18 of the 2-inch-long hornets have been confirmed to be killed or captured, all in Whatcom County. The last confirmed sighting of the hornet which somehow came here from Japan or South Korea, occurred on Oct. 9 south of Blaine.
That 18 count does not include several other reported sightings that have yet to be confirmed and a handful of other confirmed specimens just north of the border with Canada, Spichiger said.
“I am very optimistic that we are only really seeing hits in a couple areas … in Whatcom County,” he said. “We expected it was going to be far worse than this. I was afraid that we might have to be focusing on the entire western half of the state. It looks like we really are concentrated in one area, which does give us a fighting chance.”
Vikram Iyer, a final year doctoral student of electrical and computer engineering at the University of Washington, explained that the electronic device on the hornet works the same as radio-tracking devices used for larger animals but on a much smaller scale.
As a result of that tiny scale, the devices have limited range and battery life. The transponder tied to the hornet in question only had a usable life of about 12 hours.
In addition to sending radio signals, the tiny packs include temperature sensors that could help researchers locate nests, which typically are hotter inside than the outside air.
“The antennas are like lenses focused to a particular direction,” Iyer said. “We can see how strong the signal from the transponder on the hornet is and determine which direction it is flying.”
But again, the technology has range and time limits. The transponder can send a trackable signal for about a 100 feet in an open field, but that range drops to 20 to 30 feet in forested areas because the radio signal has so many obstacles.
The bad news is that Asian giant hornets tend to nest underground in forested areas, Spichiger said.
“There is quite a bit of forested area in the areas that we are working and it’s a very difficult process,” he said. “We believe the tagging is just going to get better and better. I believe we’ve narrowed one (nest) down to the east of Blaine, and I believe we are probably going to find that in the next few weeks.”
Based on traps and sightings, researchers believe they are dealing with only two or three nests at this time.
“Having the ability with anybody with a cell phone can assist us is actually a huge asset,” Spichiger said. “It’s kind of a toss up: You have two people wandering around with a very strong tracker or a hundred people assisting you with one that maybe doesn’t carry as far.”
The focus of the hunt now centers on beekeepers. Asian giant hornets tend to mostly eat carbohydrates. The hornet they tracked had slurped down strawberry jam before its release. But as they near the breeding season, the hornets switch and seek out protein to feed the brood that will become next year’s hornets.
One of their favorite targets are beehives. The hornets attack and literally bite the heads off thousands of honeybees so they can get the bee larvae to feed to the future hornets.
In 2019, the state had two confirmed honeybee massacres late in October. The state has a hotline set up for beekeepers to report any hornet activity, because researchers want to race there, tag hornets and then follow them back to their nests, Spichiger said.
“Unfortunately, we lost the signal but we were very happy with how it worked,” he said. “We are pretty sure this is going to lead us right where we need to go. We are gong to try everything until we can to find the nests and get rid of them.”
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