Oak Processionary Moth

Overview

The treatment and removal of Oak Processionary Moth (OPM) is a critical biosecurity and public health operation aimed at controlling this invasive pest, which poses serious risks to oak tree health, biodiversity, and human and animal health due to its toxic, allergenic caterpillar hairs.

Background:

OPM primarily affects oak trees (Quercus spp.), where larvae feed on the foliage, causing defoliation, weakening tree vitality, and making trees more vulnerable to other pests and diseases. The caterpillars possess urticating hairs, which can cause skin irritation, respiratory issues, and allergic reactions.

OPM is a notifiable pest in the UK and is subject to control measures under Plant Health legislation enforced by the Forestry Commission and Animal and Plant Health Agency (APHA).

Control and Treatment Methods:

1. Manual Nest Removal (Primary method):
   • Nests are removed by trained and licensed operatives wearing full PPE (including respirators and disposable coveralls).
   • Removal is done using pole-mounted tools or elevated platforms.
   • Nests are placed in sealed containers and incinerated off-site as hazardous waste.
   • Areas may be cordoned off during and after removal to prevent exposure.
2. Targeted Insecticide Treatment (Where approved):
   • A biopesticide such as Bacillus thuringiensis var. kurstaki (Bt) or Diflubenzuron may be applied to affected oak trees in early instar stages.
   • Spraying is performed under strict regulation, with advance notification and environmental impact controls.
   • Not typically used in sensitive ecological areas unless necessary and authorised.
3. Pheromone Trapping and Monitoring:
   • Deployed to assess spread and population density.
   • Data is used to inform regional control strategies and early intervention.

Biosecurity and Legal Compliance:

• All works are carried out under guidance from the OPM Manual (Forestry Commission) and Plant Health (Forestry) Order 2005 (as amended).
• Operatives must be licensed and trained in OPM management and health & safety procedures.
• Equipment and clothing are cleaned on-site to prevent spread.
• Access may be restricted or signage placed to inform the public.

Aftercare and Monitoring:

• Treated trees are monitored for re-infestation the following season.
• Public engagement and local authority coordination may be necessary in high-risk or urban locations.