Forestry Commission Oak Processionary Moth Newsletter No. 3

From the Forestry Commission, Programme Update 3 : 29 June 2020


Oak processionary moth (OPM) caterpillars are now well advanced in their development and will be at their 5 or 6th (final) instars and will soon be pupating. We are continuing to receive a large amount of public reports of OPM in the core and control zone through Treealert, email and phone calls. Apologises if there is a slight delaying in our response - we are working as quickly as we can.

Our control spray programme concluded on the 1st of June. Over 1000 sites (areas with one or more trees) were identified for treatment in the Control Zone. Over 95% of sites identified received their first sprays and 89% received their second sprays. A big thank you to our contractor resource for delivering this work during these challenging times.

Surveillance work

Our annual OPM survey began on the 1st of June and the survey teams are working on four key areas:
1) Surveying sites that were sprayed this year for reinfestation;
2) A wider environment survey looking around sites where we had interceptions in 2019. Pheromone traps will also be set up at these sites;
3) A Protected Zone survey at permanent plots across GB;
4) A defoliation survey in London and Bristol to gather evidence on the effects that OPM has on leaf cover.


We are pleased to say that this year we are working alongside specialist Observatree volunteers to monitor various oak trees around the country for OPM. This collaborative effort helps to enhance our existing knowledge of OPM populations.

OPM detected

We have discovered OPM on a very small number of trees at four sites within the OPM protected zone in Sussex, Luton and Oxfordshire. We have taken swift and appropriate action to treat the infested trees and minimise the risk of spread. This includes spraying trees in the affected areas and undertaking enhanced local surveillance. We urge everyone to be vigilant for OPM at this time of year and report any suspect findings.