Oak Processionary Moth (Thaumetopoea processionea, OPM), a native of southern and central Europe, was first found in trees in the west and south west of London in summer 2006, and has been breeding in oak trees in several locations across five London Boroughs in the area. A small new outbreak was confirmed in Pangbourne, Berkshire in 2010, and we are monitoring areas of Leeds and Sheffield, where evidence of OPM introductions has also been found.
The caterpillars - the larval stage of the moth's life cycle - pose two problems. They severely defoliate oak trees by feeding on the leaves and, from the third instar, they have tiny hairs which are sharp, barbed and contain a toxin called thaumetopoein that can cause irritation and allergic reactions. Further information including Q&As can be found on the Forest Research website.
Oak processionary moth and its caterpillars can be easily mistaken for other, native moth species, so Forest Research has published a guide to distinguishing the different species.
In June 2007, in response to reports of tree damage, the Forestry Commission launched a Contingency Plan and produced a Pest Alert Poster (updated and re-issued each year since).
The Forestry Commission, working with Defra, Royal Botanic Gardens Kew, the Health Protection Agency London, and Ealing and Richmond Upon Thames Borough Councils formed an Outbreak Management Team and agreed an Action Plan, which was put in place in June 2007. The aim of the action plan was to determine the extent of the infestation with a view to developing a strategy to reduce or eliminate the caterpillars soon after the eggs hatched in spring 2008, before the species spreads out of London and becomes permanently established in Britain.
Brent, Hounslow and Hammersmith & Fulham Borough Councils and the Royal Parks have since joined the OMT.
Surveys of the affected London Boroughs have been carried out each spring and summer since the outbreak was first discovered in 2006, and the larvae and nests found have been removed. Details of the action taken are contained in the following survey and control reports:
2007 Survey Report.
2008 Survey and Control Report.
2009 Survey and Control Report.
2010 Survey and Control report
Following the findings of the 2007 survey a formal request was made to the European Commission to consider designating Great Britain as an EU 'protected zone' with measures to prevent further accidental introductions, which we considered necessary for eradication attempts to succeed. Pending a final Decision, we put in place temporary emergency measures by amending the Plant Health (Forestry) Order 2005 (SI2008/644). This came into force on 31 March 2008, and requires that all oak trees coming from another Member State must have a plant passport confirming that the plants have been grown in a nursery where the moth is not present and which has been free of symptoms for the last complete growing season.
On 23 March 2010, in preparation for the continuing eradication programme in 2010, the Forestry Commission met a number of key owners and managers of sites based in the area around the Royal Botanic Gardens, Kew to update on progress so far and to outline the plans for action this year. Presentations were given by Roddie Burgess, Forestry Commission (a general overview, including year-on-year results), Nigel Straw, Forest Research (lifecycle and controls) and Olivier le Polain, Health Protection Agency (implications for human health). To view the presentations:
FC,
FR,
HPA.
Report of the meeting (Updated 20 April 2010)
The Outbreak Management Team has met regularly since formation, and its minutes are available at the following links:
Guidance on surveying, treatment of larvae and nest removal has been published by the Tree Health Division of Forest Research.
Further information about the discovery on 4 August 2010 of one small OPM nest on an infested tree in Sheffield.
