This “is very concerning,” said John Stoskopf Ascher, an assistant professor at the National University of Singapore’s biological sciences department. “If this many hornets and their nests are being detected then there must be a lot more of them,” he said. It “will be difficult at best to track them all down. These findings suggest that it is on a path to becoming well established.”

The hornets, native to Southern Asia, have colonized East Asia and parts of Europe including France, where they were found in 2004. Asian hornets feed on bees, interrupting pollination of plants and crops. They are different from Asian giant hornets, Vespa mandarinia, which caused a stir when they were reported in the United States in 2020.

Bees native to Britain may have a harder time fending off the Asian hornets than bees in Asia, Ascher said in an email, as the Asian honeybee, Apis cerana, “has defenses that U.K. honey bees (all Apis mellifera) lack” and because of the regions’ different climates.

The recent increase in Britain has stirred nervousness among local beekeepers.

“An establishment of the Asian Hornet in the UK will adversely impact on the viability of our beekeeping and honey industry,” the British Beekeepers Association says on its website. Of immediate concern, it said, “is that the Asian hornet preys opportunistically on a range of wild insects, and damage to pollinator communities and pollination services could be extensive.”

The Asian hornet, accidentally introduced into France in 2004 or before, has killed up to 80 percent of honeybee colonies, and overall an average of 30 percent, in areas where the species have become established, according to French researchers and the British Beekeepers Association.

From France, Asian hornets have invaded neighboring countries, including Spain, Portugal, Belgium, Italy, Germany, the Netherlands, Luxembourg and Switzerland, French researchers reported in a 2022 study.

The “national cost” of Asian hornets could reach up to 30.8 million euros, or about $34 million, due to bee colony loss, the researchers said. That amount is about 26.6 percent of honey revenue.

Scientists warn invasive pests are taking a staggering toll on society

The researchers warned that the financial cost of Asian hornets to the environment — and to the loss of the bees’ vital pollination services — would be “orders of magnitude higher.”

Honeybees — along with butterflies, birds and bats — serve as pollinators of crops key to human consumption such as apples, bananas, blueberries, strawberries, melon, peaches, potatoes, vanilla, almonds, coffee and chocolate. About 35 percent of the world’s food crops depend on animal pollinators to reproduce, according to the U.S. Agriculture Department.

Honeybees and other pollinators were already in decline because of a combination of human-caused events such as habitat destruction, widespread use of pesticides and climate change.

The British Beekeepers Association this week will host special briefings on the Asian hornets for local beekeepers. “This year Asian Hornet week takes on a new urgency,” the association said last month as it announced the briefings.

“It is vital that we stop them coming in,” Anne Rowberry, the association president, said in a video.