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Advice about oak processionary moth

A tree affected by the mothThe oak processionary moth (Thaumetopoea processionea) is a pest that has been found in Surrey in 2017-18. It lives on oak trees and poses a risk to human and animal health.

Please note: The Forestry Commission are responsible for dealing with this pest and all sightings should be reported to them.

Do not touch the larvae or caterpillars or disturb any nests

Nor should you tread on any caterpillars on the ground as that will detach the hairs which cause health problems.

Pets are also affected and must be kept away from the nests and caterpillars.


Health risk

The caterpillar of this moth emerges in April every year and their tiny hairs contain a protein which can cause itchy skin rashes and less frequently, eye and throat irritations and breathing difficulties in people and animals. The hairs can be blown in the wind and left in their nests in and under oak trees.

  • March and April - nests should not be approached at any time.
  • May to July - this is the greatest risk period when the caterpillars are most numerous.

Health advice

If you do come into contact with the larvae or caterpillars by accident, please follow the health advice about dealing with caterpillar hairs on the NHS website. If you have an itching skin rash and/or conjunctivitis or other symptoms, contact your GP, or call NHS Direct on 111. The call is free from any phone.

There is more information about health precautions on the Forestry Commission website.

Advice for oak tree owners

Preventing the spread of oak processionary moth (OPM)

Taking action will depend in which zone of the three OPM management zones (PDF) your affected trees are in.

Government action, and government support for affected owners, depends on which one of the three OPM management zones the affected trees are in. Guidance on the zones and further information can be found in The Oak Tree Owners' OPM manual, but these are subject to change.

Survey and control in the Core Zone is the responsibility of oak tree owners. However, the Forestry Commission reserves the right to issue Statutory Plant Health Notices (SPHNs) requiring infestation removal in the Core Zone if severe infestations threaten to spread into the Control Zone. Local councils may also use their public health and safety powers to require removal.

Report any sightings immediately

First make sure you have correctly identified the species

Find out how to identify an oak processionary moth caterpillar on the Forestry Commission website.

Reporting your sighting online

If you are unable to use the form, please use one of the following contact options

  • email your report to opm@forestry.gsi.gov.uk
  • telephone it to 0300 067 4442

More information

Find out more about the oak processionary moth on the Forestry Commission website.

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