Thousands of ermine moth larvae colonies cover cliffs

EERIE scenes of massive cobwebs draped on Alderney's cliff-top undergrowth may look like the work of giant spiders – in fact they are the work of hundreds of moths.

Thousands of ermine moth larvae are feeding and pupating on blackthorn, hawthorn and cherry trees on southern cliffs of the island. Walkers can see them close to the Impot site and near Alderney Wildlife Trust's Woodland bunker.

The tiny larvae have wreathed their favourite food source in cobwebs, spun to protect them as they feed before wrapping themselves in cocoons.

Through the webbing passers-by can just make out the greyish, black-spotted larvae.

AWT's terrestrial ecologist Paul Griffin said the unusually large number of larvae was probably due to the late onset of summer.

It is not often that they form colonies in this number, but it is happening in a few places this year.

'Everything has happened later because of the cold and long winter.

'That could mean that fewer of them have been eaten by natural predators like birds and bats because those animals were late breeding.

'So the pressure on them at the egg and larva stage has been decreased.'

The infestations have also occurred in Guildford and Essex, but are the first reported in the Channel Islands.

Unlike other moths with similar feeding habits, such as the brown-tail moth, the ermine moth does not destroy the trees it populates and generally chooses different sites to feed on and lay eggs each year. Nor do the larvae produce hairs irritating to humans.

Mr Griffin said: 'The adults will emerge as a small, bright white, black-spotted moth with a wingspan of no more than two-and-half centimetres.

'Keep an eye out for ermines congregating around light sources from late June to October.'