The public is being urged to keep an eye out for oak processionary moth caterpillars, a pest which damages trees and poses a health risk to people.
The warning comes at the start of the greatest risk period for the non-native species, which is predominately found in south east England having been accidentally transported from Europe in trees for planting.
The caterpillars descend oak trees in a head-to-tail processionary form, and feed on the tree’s leaves as they migrate, harming their growth and weakening the tree, leaving it vulnerable to other stresses such as drought and disease, experts said.
Oak processionary moth caterpillars and their nests of white silken webbing contain hairs that can cause itchy rashes, eye and throat irritation and should not be touched under any circumstances, they warned.
The public are also urged never to try and dispose of the nests, found in the trunk or branches of oak trees, themselves.
The warning has been issued by the Forestry Commission, which is urging the public to report any sightings of the oak processionary moth caterpillars to them.
The insect was first identified in London in 2006, and has since spread to surrounding counties in the South East.
Professor Nicola Spence, UK chief plant health officer, said: “Oak trees are an iconic and much-loved part of our British landscape.
“By reporting any sightings of the oak processionary moth to the Forestry Commission, we can all minimise the pest’s spread as well as reduce their impact on tree health.
“I would advise that members of the public living in London, the surrounding areas and Derbyshire, avoid any contact with the caterpillar and its nests, as this can cause irritation.”
People can report sightings of oak processionary moth via the TreeAlert website: https://treealert.forestresearch.gov.uk or by emailing opm@forestrycommission.gov.uk
