WALKERS at Stoke Common are being urged to watch out for dangerous caterpillars which can be a hazard to humans and animals.
The caterpillars of the oak processionary moth are pests of oak trees and have been found on the site.
OPM was first accidentally introduced to England in 2005 and is subject to a government-led programme of survey and control to minimise its spread and impact.
The caterpillars have the distinctive habit of moving about in late spring and early summer in nose-to-tail processions, from which they derive their name.
Walkers have been warned to steer clear of the caterpillars, whose hairs contain a toxin that can cause itchy skin rashes as well as eye and throat irritations.
Residents can report sightings but that the caterpillars should only be removed by pest control operators because of the health risk.
Pets, children and forestry workers who come into close contact with the caterpillars are most at risk and anyone who experiences an itchy skin rash or other allergic symptoms after being near oak trees in these areas should phone NHS111 or consult their GP.
Each caterpillar has around 62,000 hairs, which they can eject. The brown moths, which are harmless, live for only two to three days in July or August.
Action is taken to screen trees imported from Europe, but the species is established in most of Greater London and in some surrounding counties and there are restrictions on movements of oak plants from this protected zone.
The Forestry Commission and Animal & Plant Health Agency (APHA) have been working to identify infestations and spray infected trees.
Large populations can strip whole oak trees bare, leaving them more vulnerable to other pests and diseases, and to other stresses, such as drought.
Older caterpillars develop tiny hairs containing an irritating protein which on contact can cause skin rashes and eye irritations, as well as sore throats and breathing difficulties, in people and animals.
The caterpillars can shed the hairs when threatened or disturbed. The hairs can be blown by the wind and they accumulate in the caterpillars’ nests which can fall to the ground.
Signs have been erected at Stoke Common to warn visitors about the risk.