The Cosmic Watchdog

A species of enormous hornets has found its way to Europe for the first time. 

The southern giant hornet (Vespa soror) is native to a broad swath of tropical Asia, but four of the immense insects were recently discovered in Spain, researchers report November 9 in Ecology and Evolution. If the supersize sojourners manage to establish populations on the continent, they could threaten humans, honeybees and other animals.

The discovery is “a little worrying” says Phil Lester, an entomologist at the Victoria University of Wellington in New Zealand. V. soror is “a known aggressive honeybee eater. It’s going to attack an awful lot of things,” says Lester, including other wasps, insects and even small vertebrates like geckos. “So if it gets established and abundant, it could be a real issue.”

Beekeepers in northern Spain tipped off University of Oviedo zoologist Omar Sánchez and his colleagues in early 2022 about unusual, yellow-headed wasps they’d been seeing. Thinking the insects might be a rare color variant of either invasive yellow-legged hornets or another, native species, the researchers set out traps to capture them. In March 2022 and October 2023, they ensnared four of the hornets. The team examined the dead hornets, comparing their DNA and physical features to those of known species. 

The hornets’ genes and unmistakable alternating black, brown and yellow coloration suggested they were southern giant hornets. A ferocious predator, V. soror is one of the largest known hornets, with workers measuring over 3 centimeters long, roughly the length of a battery. Until now, they’d only been identified outside of their native Asia once — a single sighting in Canada in 2019. 

Sánchez and his team suspect the hornets were introduced as hibernating stowaways in shipments to the region, a method that is thought to have previously led to the introductions of yellow-legged and northern giant hornets far from their native habitats. The northern giant hornet (Vespa mandarinia), a close relative of V. soror, was introduced in British Columbia, Canada, and Washington state in 2019, though it has been seemingly eradicated (SN: 7/27/22). 

It’s unclear if V. soror has established a foothold in Spain. But the fact that hornets were caught a second time in 2023 may mean at least one young queen reared in 2022 survived to start a new colony, the researchers suggest.

Much like its northern cousins, V. soror is notorious for slaughtering honeybees by the hive, making its introduction a threat to the beekeeping industry in Europe. Even for humans, “this is an insect whose sting can be very painful and long-lasting,” says Sánchez.

Sánchez and his team are now searching for colonies. Time may be of the essence while the population is still low, says Lester. “Now is the absolute time to get onto this and try and kill it.”