Oak processionary moth manual: what its 12 parts cover

This page reports what the official source says. It is not legal advice: ask the office named here. It describes the manual hosted by Forest Research. It gives no steps for spraying or nest removal and names no products or rates: the manual and the Health and Safety Executive carry those. Each part is described from its own page, all read on October 9, 2026. The insect itself is on the oak processionary moth profile, and the zone and legal status table is on the regulated status page. Abbreviation: OPM is oak processionary moth.

Who the manual is for

Part 1 says the manual is written for owners and managers of oak trees that are or could be affected by OPM, from a garden with one or two oaks to parks, woodland and streets. It says control depends on landowners, government and local authorities working together, and that the advice reflects the strategy agreed between Forestry Commission England and local authorities. Its stated focus is to prevent or limit outward spread and to minimise the population and its impacts where the pest is present. Several parts also speak directly to tree surgeons, forestry workers and their employers.

The 12 parts

Part	What it covers
1. Introduction and contents	Purpose, the audience above, the strategy it reflects and the list of the other 11 parts.
2. Public and animal health advice	How the irritating hairs reach people and animals, symptoms, the May to July period of greatest risk, and a list of what the manual advises people and pet and livestock owners to do and avoid. It is aimed at owners and the public.
3. Management zones	The three zones: the established area in the south east of England, the buffer zone with an annual programme of surveillance and control led by the Forestry Commission, and the area free from the pest, which covers other parts of the United Kingdom. It says boundaries can be updated annually and points to the maps and the lists of local authorities and wards on GOV.UK.
4. Biology and life cycle	Susceptible oaks in descending order, the one-generation year, the six caterpillar stages and when the hairs begin. The profile page already sets this out and it is not repeated here.
5. Surveying trees and timing of control measures	When and how each stage can be looked for: egg masses in winter, spent nests, young caterpillars from late March to May. It says surveys can be done any time of year by anyone with reasonable eyesight, and that treatment timing depends on the caterpillar stage and the zone.
6. Chemical control of larvae	The two pesticides the manual says are licensed for larvae, the difference in who they suit by caterpillar stage, a pointer to the HSE for approvals, and a health note that one of the two is highly toxic to bees and aquatic life. It says special restrictions apply in Sites of Special Scientific Interest and that spraying tall oaks should be done only by properly qualified and trained operators.
7. Manual removal of nests and larvae	Removal by vacuum equipment or by hand, who the manual says should do it, timing, and waste. It opens with the hazard: nests hold thousands of shed hairs that remain a hazard for a year or more. Nest material is classed as hazardous waste.
8. Occupational health	The hair effects, the workers named at greatest risk and the employer and employee duties. See the section below.
9. Pheromone trapping	Traps as a way to survey for adult males, not to control. It describes two trap types, the height the manual gives for hanging them, the Forestry Commission's programme in the buffer zone and the 10 kilometres round it from mid-July to early September, and how far males and females travel.
10. Other work on oak trees	Pruning, felling, pollarding and tree surgery in affected areas: the two added risks, hairs and spreading the pest on removed material, a reminder to check for a Tree Preservation Order and Conservation Area rules with the council, and what to do on finding OPM mid-job.
11. Handling oak in OPM areas: good practice guide	A guide for contractors and site managers on risk assessment, visual checks before work, reporting, and rules on moving oak material. See the section below.
12. Pictures	Photographs of caterpillars in processions and feeding clusters, nests of different ages and shapes, and the moth.

Part 8 and part 7: hairs, health and employer duties

Part 8 says the caterpillars carry thousands of minute irritating hairs, which contain a substance called thaumetopoein, and that contact can cause itching rashes, eye complaints and breathing difficulties, and in very rare cases severe allergic reactions. It says repeated exposure can make symptoms worse and that hairs persist in nests and the environment for a year or more. It names forestry workers and tree surgeons at greatest risk, with arborists, landscapers, gardeners and ground-care staff at heightened risk. It lists as employer duties risk assessments, control measures, suitable protective equipment, training including skin checks, welfare facilities and a health surveillance programme, and names these laws: the Control of Substances Hazardous to Health Regulations 2002, the Management of Health and Safety Regulations 1999, RIDDOR 1995 and the Personal Protective Equipment at Work Regulations 1992.

Part 11: moving oak material and reporting

Part 11 says any person responsible for tree-work sites within affected areas must follow its guidance. It says contractors in affected areas should have a specific risk or COSHH assessment for OPM, and that a tree with spent nests is treated as infested, because the females that left them are highly likely to have laid eggs high in the canopy. It says greater vigilance is needed in March, April and May, when small caterpillars are hard to spot. On reporting, it states that a person is legally required to inform the Forestry Commission immediately on seeing evidence of OPM in any tree, even after work has started, through TreeAlert or by the team's published contact details, with photographs that do not risk contact with the hairs. It says making a dangerous tree safe takes priority.

The rules in part 11 on material include these. Oak material under 10 cm in diameter must not leave the affected area unless absolutely necessary. If it must, the Forestry Commission OPM team is to be consulted first, material under 10 cm is chipped on site and taken to an approved incinerator, and it travels in an enclosed vehicle that is washed down afterwards. Larger material carries less risk but the manual presumes it is handled the same way. Reporting offices for the United Kingdom are on the report a pest in the United Kingdom page.

Text on the United Kingdom is adapted from Forest Research and contains public sector information licensed under the Open Government Licence v3.0.