Bailiwick’s largest Asian hornet nest dissected after Sark discovery
The largest Asian hornet nest to be found in the Bailiwick has been dissected after being removed in Sark, and three more will be removed in Guernsey shortly.
But it is unclear if there are still more nests to be found in Guernsey.
Asian hornet strategy co-ordinator Francis Russell said that the team had found 14 secondary nests in Guernsey this year alone.
‘The highest previous total since the programme began in 2019 was three,’ he said.
‘We have gone from an average of two and a half to 14.’
Mr Russell believes the most likely reason for the increase in queens was this spring’s north-easterly winds, which helped the insects arrive from France.
Alderney, which is three times closer to France, had 20 nests.
‘It could have been a nest from last year we missed, but if that was the case you would expect to start seeing queens in March, not May and June,’ he said.
But it could have been due to a ‘good’ season for the hornets in France.
‘The UK has been hit this season too, and in the south they have had about 50 nests.’
He said there were still three nests in Guernsey waiting to come down – in the Vale, Le Foulon and Saints Bay – but the weather had made co-ordinating the tree surgeons and cherry pickers required difficult.
‘We hope they will all be down by Friday,’ he said.
‘The one in Saints Bay is the trickiest. It’s on a steep slope and a very spindly tree.’
‘When those three nests are down we can get a clearer picture if there are any left. Then we take stock and next year we go again.’
The Sark nest, which measured 70 centimetres from top to bottom, has now been frozen for 48 hours to kill off any hornets yet to emerge.
The team then cut it open to examine it.
The external surface provides protection and insulation from overheating, wind and rain.
The scalloped appearance is formed by concentric rings of wood pulp and saliva, laid down in coloured rings, as the workers harvest material from different sources.
Inside is a honeycomb structure made up of hundreds of hexagonal cells. The queen moves systematically across the face of the comb laying an eggs into every empty cell – around 100 eggs per day. The larvae or grubs are then fed insect protein by the workers until they are ready to pupate. They are sealed off with a white silken capping and develop into adult worker hornets after 29 days.
Around the middle of October the nests stop producing worker hornets and switch to production of males drones and virgin queens. Eventually, these queens leave the nest and mate.
A nest as large as the one in Sark could produce in excess of 750 queens, which would emerge before winter to hibernate elsewhere – something the Asian Hornet Team is working hard to avoid happening in the Bailiwick.
