The Forestry Commission is today (8 March) updating the operational zones and boundaries to manage the spread of Oak Processionary Moth (OPM).
OPM caterpillars and their nests contain hairs which can cause itchy rashes, eye and throat irritations, and should not be touched under any circumstances. OPM caterpillars feed on oak leaves and can increase trees' vulnerability to attack by other pests and diseases, making them less able to withstand adverse weather conditions, such as drought and floods. The greatest human and animal health risk period is May to July when the caterpillars emerge and feed before pupating into adult moths.
As The OPM season begins in March when the caterpillars can start to emerge. To coincide with this, changes to the three operational boundaries of the management zones - Area designated free from the pest, Buffer Zone, and Established Area - will be implemented to continue to help to restrict the spread of the pest.
In response to government surveillance in 2022, the Established Area in which OPM is established, and the Buffer Zone in which an annual programme of OPM management led by the Forestry Commission takes place, will be expanded. This will be implemented to limit the spread of OPM into the rest of the UK which is designated free from the pest.
Trade and local authorities should check the updated zones and boundaries on GOV.UK and the OPM resource hub to establish which zone they are in from 08 March 2023 onwards.
Andrew Hoppit, Oak Processionary Moth Project Manager, said:
Oak processionary moth larvae can cause significant damage to oak trees and pose a risk to human and animal health. These new measures are designed to minimise the spread and impact of the pest and protect our precious oak trees, as part of our wider tree health protection regime.
Any sightings should be reported to the Forestry Commission via our TreeAlert portal
First identified in England 2006, the pest is now present in London and surrounding counties. OPM management varies across England to reflect the known distribution of the pest and to protect uninfected areas. A Government programme to manage OPM has been in place since 2012 to control its spread and reduce pest prevalence, undertaken by the Forestry Commission.
Landowners, the public, and trade are urged to remain vigilant for the pest and report any sightings to the Forestry Commission via our TreeAlert portal, by emailing
