Invasive “murder hornets” found for the first time in Europe

Researchers in Spain are racing to find the nest of the first southern giant hornet found in Europe.

The insects are sometimes called “murder hornets” because they are known for killing beehives. They reach an average length of 5 cm. They are native to parts of Asia including India, China, Thailand and Vietnam.

In a study published last month in the journal Ecology and Evolution, five Spanish scientists described two separate sightings the southern giant hornet, whose scientific name is Vespa soror. Both were in the northern town of Siero in the province of Asturias: one pair was spotted in March 2022, another two in October 2023.

Researchers believe the hornets have a nest that is at least a year old.

Northern Giant Hornets – A closely related species originating in other parts of Asia – was first spotted in the United States in Washington state in late 2019. The northern and southern hornets are similar in behavior and appearance, although the former have shorter breeding seasons and produce smaller colonies and nests.

The first northern giant hornet nest found in the United States was promptly destroyed in October 2020, but a live hornet was spotted in Washington the following year.

Southern giant hornets are known to send out scouting teams to find prey colonies, and the scouts rub their bodies against beehives or nearby vegetation to signal others to join them, according to a study published in 2021. They then enter a “battle phase” in which they can take out entire hives within a few hours.

Neither northern nor southern giant hornets have been found in Europe beyond the four documented in Spain. The scientists behind the current study believe the hornets likely first arrived on a cargo ship.

Omar Sanchez, the study’s lead author and a zoologist Professor at the University of Oviedo in Spain said he expected the hornets to disrupt the balance of the local ecosystem as they aggressively preyed on native hornets, bees, butterflies, moths and flies. Long-term declines in bee populations can affect the availability of honey and disrupt pollination processes that many plants and crops rely on.

“Here in northern Spain there is another Asian hornet species called Vespa veluntina which causes severe damage to beekeeping, so the presence of another Asian hornet may increase the negative impact,” he said.

Sanchez added that researchers trying to find the nest so they can destroy it.

“It’s a little difficult because this species builds its nest underground – more than 30 meters – and so it’s not easy to find,” he said. “We’ll try.”

Researchers also looked for other hornet sightings, Sanchez said.

Sanchez and his study co-authors found and caught the four hornets after beekeepers in the area told them they had seen unusual-looking wasps. After capturing the hornets, scientists extracted DNA samples and conducted genetic testing and analysis to confirm the species.

Molly Keck, an entomologist at Texas A&M University, said the genetic study confirming the species is the first step in mitigation efforts, such as educating the public and beekeepers and alerting local authorities “so management plans, education , mapping and distribution can be carried out.”

“Most of these invasive species will invade somewhere through a port city,” she added, “so whatever quarantines and control measures are put in place, there really will be a way in which they will be discovered.”

Such processes around the world may need to be strengthened as a precautionary measure if countries want to ensure cargo is free of bugs, Keck said.

Sanchez said the discovery of southern giant hornets in Spain suggests more are likely on the way.

“It is likely that this species will be rediscovered in other places in Spain and probably in Europe in the near future,” he said.