A sharp increase in the number of an invasive species of hornets in Britain is raising concerns that they could threaten native bee populations.

There have been 22 sightings of the so-called Asian hornet, or Vespa velutina, this year, more than in the past six years combined, according to British officials. The number of sightings, confirmed when specimens have been analyzed in a laboratory, is up from two last year, two in 2021 and one in 2020, according to British government statistics. The hornet, which is native to parts of Asia, was first detected in Britain in 2016, and its activity peaks in August and September.

It is distinct from the world’s largest hornet, Vespa mandarinia, which has been referred to as the “Asian giant hornet” or “murder hornet,” and was found in the Pacific Northwest of the United States in 2019.

Smaller than Britain’s native hornet, most Asian hornets are about an inch long and have brown thoraxes, yellow legs and black heads with orange faces. The species was first recorded in France in 2005 and is thought to have arrived in a container of pottery from China, according to the Non-Native Species Secretariat, a British organization that coordinates responses to invasive species. Since arriving in France, the population of Asian hornets has grown rapidly. As of last year, the hornets have been seen in European countries including Germany, Spain, Portugal and Italy, according to the National Bee Unit, a British agency.

Asian hornets can be devastating to ecosystems and can wipe out bee populations, including honey bee colonies, in as little as several days, Luke Whyatt, a bee farmer in Britain, said on a phone call from the island of Jersey, in the English Channel, where he is leading an Asian hornet track-and-trace training program.

“With what’s going on in the U.K. and the number of nests that have been discovered, we feel we’re going to be sooner or later inundated with nests of hornets,” Mr. Whyatt said.

Nicola Spence, the British government’s plant and bee health officer, said the government was encouraging the public to report sightings so that hornet nests could be destroyed and hornets could be prevented from posing a threat to bees and other insects.

“While the Asian hornet poses no greater risk to human health than other wasps or hornets, they can cause damage to honey bee colonies and other beneficial insects,” she said in a statement. Bees support biodiversity and agriculture, pollinating trees, flowers and crops.

Observers have noted that Asian hornets tend to hover about a foot away from the entrance to a beehive, before charging bees and forcing them to the ground. They then paralyze them and carry the bees away. By hovering, they can also force bees to stay in their hives, preventing them from being able to get food or water, said Diane Drinkwater, chair of the British Beekeepers Association.

She said that if Asian hornets grew in numbers in Britain, they could decimate honeybees and other insects. “We are quite concerned,” she said. “These hornets will eat lots of bees and deplete the colony so much that it sort of gives up.”

This week, a dozen beekeepers traveled from England to Jersey, where there are hundreds of Asian hornets, for the training program, which involves painting the backs of Asian hornets with colored markers and releasing them. Using bait, beekeepers measure how long it takes the hornets to return and use the information to locate their nests. For example, if the hornets return in four minutes, beekeepers can estimate that their nests are about 1,300 feet (400 meters) away, he said.

Mr. Whyatt, the bee farmer, described the Asian hornets as “quite docile” and said beekeepers and bee farmers could mark them without using any protective equipment. They become aggressive, however, if their nests are disturbed. “If a human stands on a nest or disturbs the nest,” he said, “then it’s possible the human is in trouble.”

Jenny Gross is a general assignment reporter. Before joining The Times, she covered British politics for The Wall Street Journal. More about Jenny Gross

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