The Forestry Commission updated operational zones and boundaries in a bid to manage the spread of oak processionary moth (OPM) this month.

The OPM season begins in March when the caterpillars can start to emerge. To coincide with this, the Forestry Commission has made changes to the three operational boundaries of the management zones.

These management zones are: Area designated free from the pest, Buffer Zone, and Established Area, and they will be implemented to continue to help to restrict the spread of the pest, the commission said.

The Forestry Commission warned that 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 – like drought and floods.

The commission warned that the greatest human and animal health risk period is from May to July, as this is when the caterpillars emerge and feed before pupating into adult moths.

Commenting on the implementation of the updated operational zones to manage the spread of OPM, project manager Andrew Hoppit 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.”

Hoppit urged the public to report any OPM sighting to the Forestry Commission via its TreeAlert portal.

Oak Processionary Moth

The OPM was first identified in England in 2006 and 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, the Forestry Commission said.

A UK government programme to manage OPM has been in place since 2010 to control its spread and reduce pest prevalence, undertaken by the Forestry Commission.

Landowners, the public and trade are urged to remain vigilant for sightings of the pest.