The Growing Threat of Oak Processionary Moth (OPM)

Property managers, contractors, and residents—particularly in London and the South East—are being urged to report any sightings of Oak Processionary Moth (OPM) caterpillars to the Forestry Commission. Most importantly, do not touch them! First identified in 2006, OPM caterpillars pose a serious threat to oak trees. Their tiny hairs, also found in their nests, can cause itchy rashes, eye and throat irritation, and in some cases, breathing difficulties for both people and pets.

How the Government is Controlling the Spread

To prevent further spread, the UK Government has implemented a national control programme. The Forestry Commission, councils, and land managers conduct annual treatments to combat the pest, particularly in areas affected each spring.

What to Look Out For

• Nests: Dome or teardrop-shaped, around the size of a tennis ball. They start white but turn brown over time.
• Caterpillars: Black heads with long white hairs covering their bodies.
• Season: From May to July, the caterpillars emerge and feed on oak leaves, leaving trees vulnerable to other pests, diseases, and drought.

Reporting Sightings of OPM Caterpillars

Anyone spotting OPM caterpillars—especially in control zones monitored by the Forestry Commission—should report them immediately.
Ways to report sightings:

• TreeAlert website: Forestry Commission’s TreeAlert
• Email: opm@forestrycommission.gov.uk
• Call: 0300 067 4442

Managing Infested Trees Safely

If your trees are in an affected area, contractors spraying on behalf of the Forestry Commission will carry out the necessary work safely, while adhering to social distancing guidelines. Property owners must follow proper procedures to help stop the spread of this destructive pest.

Before Pruning or Felling Oak Trees

Building owners or property managers planning to prune or fell oak trees in affected areas should contact the Forestry Commission’s Plant Health Forestry Team for guidance on safe material removal:
Email: opm@forestrycommission.gov.uk
Call: 0300 067 4442

By staying vigilant and reporting Oak Processionary Moth sightings, we can help protect our oak trees and safeguard public health.