Residents are being warned by Three Rivers District Council about a harmful caterpillar which could be in local parks.

The Oak Processionary Moth can usually be found on oak trees and are dangerous to humans and pets.

If touched, they can cause rashes, difficulty breathing and a sore or itchy throat due to the hairs on the insect.

According to the Blue Cross, they are poisonous to dogs and cats. If they touch one they can suffer with excessive drooling or conjunctivitis as well as other symptoms.

You can spot them by their grey bodies, black heads and long white hairs, with their nests being a teardrop or dome-like shape.

Three Rivers District Council and the Forestry Commission are working to control the animal, so it does not pose a large risk to residents.

Cllr Chris Lloyd, Lead Member for Leisure, added: “I urge anyone who spots these OPM caterpillars to help reduce the impact they have on human health by reporting any sightings.”

If you see any, they can be reported to the Forestry Commission using its Tree Alert online reporting form at, emailing, or calling 0300 067 4442.