Island is winning the battle in controlling Asian hornets

Asian hornets are a non-native, invasive species and are an aggressive predator of many different types of insect, including honeybees. They fly into the island from France as well as other Channel Islands, and have been known to attack humans if their nests are disturbed.

Invasive non-native species policy and coordination officer Francis Russell said that the island’s Asian Hornet Strategy, which has been implemented over the last four years, was working.

‘Our strategy involves two phases,’ he said.

‘The first phase is called “Spring Queening” and runs from April to June. We split the island up into 500m spaces and set traps to try and catch as many queens as possible,’ he said, adding that a total of 20 queen hornets were caught across the Bailiwick between April and June 2022, including nine in Guernsey.

Mr Russell emphasised that this first phase was crucial to keeping numbers low because it prevented the queens building primary nests, from where worker hornets were able to fly up into higher places such as tree tops and build much bigger, more dangerous secondary nests.

‘The primary nests are only about the size of a golf ball. The secondary nests however can be up to 30cm long, and can house between 10,000 and 20,000 hornets. Therefore, it is vital that we stop the spread as much as possible in the spring,’ he said.

There had been fears that 2022 would be a bad year for hornets in Guernsey, as weather conditions in Europe were favourable for them. But to the relief of the team tasked with keeping numbers under control, numbers were quite low, with only four nests found and destroyed.

The second phase of the strategy relies on information from members of the public, and Mr Russell said he was grateful that so many people had informed his team of potential sightings.

‘We call this phase “Track Don’t Trample”. Inevitably, despite our best efforts, some queens don’t get caught in the spring, so we have to rely on suspected public sightings during the summer. We also use our own methods of setting up bait stations so that we can monitor the hornets’ general flying direction, which may then lead us to a nest.’

Of 262 reported sightings checked by the Asian hornet team in 2022, only 15 were positively identified as invasive hornets, leading Mr Russell to call it a ‘successful year’. However, he warned that islanders must stay vigilant and on the lookout for signs of hornets or their nests.

‘In terms of what to look out for, the hornets are 20-35mm in length, are a dark brown or black colour and have a distinctive orange band on their tail, as well as yellow on the ends of their legs,’ he said.

As well as the four nests in Guernsey, three secondary nests were destroyed in Alderney. No nests were found in Sark or Herm.

Since Guernsey started tracking Asian hornet in 2017, there have been 22 nests found and removed. Jersey, being closer to France, has struggled to keep hornet numbers down, with a steady rise in nests over the last five years. Last year more than 170 were found in the island.

• To find out more about Asian hornets, visit the team’s Facebook page: https://www.facebook.com/asianhornetguernsey