Oak Processionary Moth

Oak Processionary Moth Caterpillar

Oak Processionary Moth (OPM) Caterpillar is a tree pest which was accidentally introduced to a site in west London in 2005 through imported tree stock.  Despite an extensive programme of control, OPM has unfortunately spread from its initial outbreak area to include many Greater London boroughs as well as Surrey and the Home Counties. 

OPM has been managed on Wimbledon and Putney Commons since 2011 and whilst numbers remained very low for a few years, survey teams are now finding an increasing number each year. 


Keep your distance

The caterpillars are a potential threat to the health of oak trees, people and animals and we advise that visitors to the Commons take particular care to ensure that contact with the caterpillars and their nests is avoided. 

The caterpillars are covered in thousands of tiny hairs which contain an irritating substance called thaumetopoein and it is important that no skin contact is made with the caterpillars or nests as this can result in skin rashes and, less commonly, sore throats or breathing difficulties.

As the nests are not confined to specific areas, we do suggest that children and pets are kept away from the Oak trees and possible contact with the nests.


What should you do if you find some OPM caterpillars?

The advice from the Forestry Commission is to not approach or touch the nests or caterpillars and, in particular, keep children and pets away from the Oak trees.  If you are able, do please keep a note of the location and advise the Ranger's Office by telephone - 020 8788 7655 or by e-mail

OPM survey teams are continuing to work on the Commons and our fully trained staff will begin nest removal in late June once the caterpillars have started to pupate and form nests.

Find out more about Oak Processionary Moth on the Forestry Commission Website