Warning on oak processionary moth issued ahead of peak season - Forestry Commission

Public and forestry trade vigilance needed as we enter the greatest risk period for oak processionary moth (OPM).

The public are being urged to be vigilant for any sightings of oak processionary moth caterpillars, a tree pest of oak trees.

The caterpillars – predominantly found in South East England – descend down oak trees in head-to-tail procession, earning them their name. They feed on the leaves as they move which can negatively impact the oaks growth. This can weaken the tree and leave it more vulnerable to other stresses, such as diseases.

The warning has been issued today (Monday 1 June) by the Forestry Commission who are urging the public to report any sightings via the TreeAlert portal or by email to opm@forestrycommission.gov.uk, including a photo and location.

Oak processionary moth caterpillars are covered in long hairs that can cause itchy rashes, eye and throat irritation and should not be touched under any circumstances. They also form silky white nests, ranging in size from as small as a 50 pence piece up to a melon. These nests discolour over the season, appearing dirty and brown by August. The nests also contain the hairs, and similarly should not be touched. The nests can be found on the trunk or the underside of branches of oak trees. Members of the public are urged never to try and remove or dispose of the nests themselves.

Forestry Commission Oak Processionary Moth Programme Manager Dr Edward Straw said: “The warm weather in spring has led to oak processionary moth growing quicker than in previous years and we may see higher infestation levels. It is important those living and working in areas affected by oak processionary moth remain vigilant in particular.”