Washington and British Columbia must be vigilant against invasive wasps, including one more “ominous” than the Asian giant hornet, a Canadian official said Wednesday.
British Columbia provincial apiculturist Paul van Westendorp said he was particularly concerned about a smaller Asian hornet, Vespa velutina, unknown in North America but a scourge in Europe.
Its predatory behavior — it prefers honey bees — and larger nests make it more dangerous, he said. “That is a far more ominous threat.”
Washington and B.C. officials talked during a video press conference about their plans to trap Asian giant hornets, the world’s largest wasps. The hornets are considered a threat to native pollinators, the ecosystem, and people and pets that unwittingly disturb nests.
The trapping season won’t begin in earnest until July, but warm spring days will bring out queens looking to create nests.
Asian giant hornets, Vespa mandarinia, were unknown in North America until 2019. Genetic tests linked a hornet found in B.C. to hornets in Japan, while those found in Whatcom County were linked to hornets in South Korea. The tests are inconclusive, but suggest separate introductions.
Washington Department of Agriculture entomologist Sven Spichiger said mated queens looking for a protective place to spend the winter probably stowed away aboard ships.
“We think that’s probably how it got here,” he said. “We believe it probably hitched a ride in some kind of commodity as a fertilized queen looking to spend the winter.”
A few months before the first Asian giant hornet detection in B.C., another Asian hornet, Vespa soror, a sister species to Vespa velutina, was found in Vancouver Harbor.
Vespa veluntina appeared in southern France in 2004 and has spread to Spain, Portugal, Belgium, Germany, Italy and the United Kingdom. According to the European Commission, the hornet’s preference for honey bees makes it a major problem for crop pollination.
“We will be prone to future introductions of these kinds of invasive species,” Westendorp said. “This is going to be an ongoing challenge.
“I think that’s where much of the focus should be at some point,” he said.
2021 trapping, tracking
All 31 Asian giant hornets detected in the U.S. so far have been in northern Whatcom County. All six hornets found in Canada have been just to the north in the Fraser Valley.
Washington tracked one live hornet back to a nest last year and eradicated about 500 hornets.
The agriculture department will hang about 1,500 traps in northern Whatcom County, Spichiger said.
The department also hopes volunteers in northwest Washington will hang traps, baited with either orange juice and rice wine or a less expensive mixture of one cup brown sugar and one cup water.
Hornets drown in the traps, but preliminary trapping helps the department pinpoint where it can find a live hornet. The department plans to again tie electronic tracking devices on live hornets and follow them to their nests.
Spichiger said entomologists plan this year to tie on devices with Kevlar thread, rather than dental floss, which proved no match last year for one Asian giant hornet.
“It’s really annoying to tie a tag onto a hornet and to watch her chew it off in a few seconds. It’s disheartening,” he said.