Sightings of Asian hornet nests double in a year

More than 30 Asian hornet nests have been found in Guernsey this season, doubling the number discovered in 2025, according to spotters.

Asian hornets are an invasive species and an aggressive predator of many types of insect, especially honey bees.

Despite the rise in sightings, the States of Guernsey said it continued to tackle the issue by "actively tracking" hornets back to their nests which are then treated with a powder-based pesticide.

Annelotte Daas-Jehan, invasive non-native species policy and co-ordination officer for the States, said: "I am surprised but not shocked because we know what's happening in other islands and many other European countries."

She added: "It is definitely concerning we are seeing an increase in the amount of hornet nests.

"But if we look on the positive side, that we have found so many and were able to treat so many means we can keep the population as low as possible."

Figures shared by the States showed a total of 44 nests were discovered from March 2026 up to now - including one nest found damaged after Storm Austen.

Seventeen nests were identified in the year up to December 2025, according to the figures.

The figures, which include both primary and secondary nests, compared with four found 2024, 19 in 2023 and four in 2022. Asian hornets were first detected in Guernsey in 2017.

Primary nests housing up to 100 insects are built by queens at the start of the season to raise a set of workers, Daas-Jehan said.

The queen then seeks a secondary location, potentially high up in a tree, or by expanding the existing nest to create a "secondary nest", which can contain up to 5,000 insects, she said.

She said nests create the greatest public health risk when they are at sites most likely to be disturbed by people such as in brambles, hedges or roof spaces.

The States said Asian hornets also posed a major threat to the island's biodiversity, with 39% of the hornets' diet being honey bees.

Daas-Jehan, who has been in post since April, said there had been a "rapid increase" in Asian hornet popuations across Europe with "pressure increasing" on authorities to act.

She said their strategy was to "flatten the curve" of the increase through a strategy of killing queens and managing nests, which she said was "doable".

"I hope that happens this year," she said.

Daas-Jehan said they were tracking queens in the spring when they come out of hibernation to look for sugar resources and "taking out" the queen could then prevent her from building a full colony.

She asked that people continue to report nest and wasp sightings to help curb the increase.

"At this time of year hornets are being spotted on flowering Fatsia japonica and camellias so if you have either of these plants in your garden or nearby please keep an eye out," she said.

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