Asian hornets on the rise: Number of sightings almost double in a year

17 April 2025

Nearly 8,000 Asian hornets have been spotted in gardens across Belgium this year, according to data from waarnemingen.be. The figure has almost doubled compared to the same period last year.

Every spring, the Asian hornet queen emerges from hibernation to build a new nest. So far this year, volunteers using the ObsIdentify app have reported 7,873 sightings. Between January and April last year, only 4,490 were recorded.

ObsIdentify, an initiative supported by organisations such as Natuurpunt, has around 1 million users in Belgium.

"Because of the mild winter, they've emerged stronger"

"This year the hornets came out of hibernation more than a month earlier," says Dominique Soete of Vespa-Watch, the national reporting platform.

"Because of the mild winter, they've emerged stronger and with more body mass. A queen usually weighs about half a gram, but this year I've caught specimens weighing 0.6grams. The stronger the queen, the more likely she is to successfully build a nest. Even so, it is estimated that more than 90 per cent of emerging queens die before settling."

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Originally from Southeast Asia, the Asian hornet has been making a rapid and worrying advance across Europe since the mid-2000s. It was first detected in France in 2004 - probably via cargo from China to the port of Bordeaux - and has since spread elsewhere in Europe, including Spain, Portugal, Italy, Germany, the Netherlands and the UK.

Voracious predator

The species is a voracious predator of other insects, particularly honey bees, solitary bees and wasps. A single colony can kill thousands of bees in a day. In regions with high nest densities, the pressure on pollinator populations is considerable, with potential impacts on agriculture and ecosystems.

The Asian hornet is listed as a species of Union concern under the EU's Invasive Alien Species Regulation, which requires member states to monitor and control its spread. However, coordination between countries often lags behind the hornet's rapid spread.

^{An Asian hornet stalks a beehive © PHOTO MIGUEL RIOPA / AFP}

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