This guidance is for landowners and site managers who have oak trees on their land, and for people who work on oak trees.
If you’re a private resident with oak trees in your garden, read Managing oak processionary moth in England.
Managing the risks from OPM
Forestry Commission leads an annual programme of work to manage OPM. The actions required under this approach will vary depending on the management zone in which your site is located.
In the established area
In the established area you must report OPM and should take a risk-based approach to managing OPM. In this area landowners are responsible for the management of OPM on their land, and it is recommended you develop a management plan which will involve assessing the risks OPM poses on your site. The OPM resource hub contains a number of tools to understand and evaluate the risks associated with OPM and to determine the appropriate risk management actions.
In the buffer zone
In the buffer zone you must report OPM and you will then be issued with a Statutory Plant Health Notice (SPHN). You must follow the instructions within the SPHN which may require you to take action. In most case support is available for treatment of trees within this zone. The SPHN document will explain what action is needed.
In the pest free area
This area is officially designated free from OPM and covers most of the country. In this area government funds an extensive programme of surveillance to monitor for OPM. Any outbreaks of OPM found in the wider environment within this area are managed by government with the objective of eradicating the outbreaks. In the pest free area, you must report OPM and you will then be issued with an SPHN. You must follow the instructions within the SPHN which will require you to take action.
Survey for OPM
If you manage oak trees, you should survey your trees for signs of OPM. Read the guide on how to identify OPM to understand what you’re looking for.
You can also use pheromone traps to survey for the presence of OPM males. Using traps can be an effective tool for identifying new areas where OPM might be spreading. This may be useful in the area outside the established area.
Pheromone traps
Funnel traps contain a synthetic chemical ‘the lure’ which mimics the sexual pheromone emitted by the female to attract a mate for breeding. This lures the male to the trap. Funnel traps are usually a plastic ‘bucket’ with the lure under the lid. Male moths attracted to the lure fall down through a funnel into the body of the trap.
Adult males are strong flyers and can travel up to 20 kilometres from the nests where they first emerge. Capturing OPM males some distance from known OPM-affected areas does not necessarily mean that OPM has spread to the area of the trap. However, if you catch a large number of adult males in a single trap or cluster of traps this may indicate a local breeding population.
Female OPMs are not strong flyers and are rarely found about 500 metres from their original nests.
You should hang the traps as high as possible – at least 10m above ground in the canopy of an oak tree. Any lower will reduce the number of moths caught. You can do this by:
- using a mobile platform (‘cherry picker’)
- climbing the tree
- throwing/catapulting a weighted line over a convenient branch, which you can tie off and use to lower and re-erect the trap when you inspect it
You may need expert help to identify the moths correctly. There are a number of other species that look similar to OPM. Contact the Forestry Commission for help.
What to do if you find OPM moths
If you trap OPM, you should:
- look for nests in all oak trees within the area of trapping
- inspect again the following year
If you find OPM nests or caterpillars, you should report it.
Public and animal health risks
If you have OPM on your oak trees, you must protect yourself, the public and animals from health risks. Read the guidance on risks to people and animals from OPM.
If your work brings you into close contact with oak trees, you should take care to protect yourself.
Site users and visitors
If you are encouraging visitors to your site, you may wish to consider actions to mitigate against public health risks such as:
- signs warning people about the presence of OPM and what to do/what not to do
- restricting access to high risk areas
- working with stakeholders, such as friends’ groups, to raise awareness
- newsletters and social media posts
- control actions, such as spraying or nest removal to reduce levels of OPM
Working on oak trees with OPM
Before starting work on trees with OPM, consider the likelihood and risk of exposure to OPM.
When you’re working in areas where OPM is known to be present:
- avoid direct contact with caterpillars and their nests
- wear long-sleeved tops and long trousers with the cuffs tucked in and consider gloves, goggles, and a balaclava to protect your head and hands
- wear a dust mask to stop hairs entering your mouth, throat, and airways
When removing nests, make sure you have the right personal protective equipment (PPE) to protect your eyes, mouth, and skin. This includes:
- face mask – filtering half mask FFP2 or FFP3 (European standard EN149: 2001), disposable, to protect against particles
- goggles – complying with European standard EN166 and either Code 4 or Code 5
- disposable spray suit – an impermeable protective suit suitable for insecticide spraying will also protect against the caterpillars’ hairs
- gloves to prevent skin contact – robust water- and chemical-resistant gloves, as used for spraying operations
- boots to prevent skin contact – water-proof and chemical-resistant rubber boots, as used for spraying operations
All these items are available from safety equipment suppliers.
Employing people exposed to OPM
If you employ people who are exposed to OPM, you have legal responsibility for your and their safety. Before you start work on the oak trees, you must:
- complete risk assessments
- identify and use control measures
- provide people with suitable PPE
- have a system for people to report defective equipment
- provide people with information and training on the health risks and control measures including skin checks
- provide suitable welfare facilities such as washing facilities
- provide a health surveillance programme
If you’re exposed to OPM at work, make sure you:
- take care of your own health at work
- follow recommended systems of work
- use the equipment provided, including the PPE
- keep equipment, such as ropes and gloves, used on OPM-infested trees separate from equipment used on other trees
- report any defects or problems with the equipment
- attend any training or instruction
- tell your employers if you have health concerns
- attend any health surveillance programme or health checks put in place
Speak to a medical professional if you have any concerns about your or anyone else’s health after working near OPM.
For more information on OPM, read guidance on how to identify and report OPM and risks to people and animals.
Management options to control or manage OPM
If you have OPM on your site, there are several management options available to tackle the risks posed by OPM. The measures available to you will be dependent on the management zone your site is in, the level of risk identified in your management plan and the wider objectives for your site.
Manage OPM: Site zonation, signage, and restricted access
In some cases, direct control action will not be appropriate, and it may be necessary to apply other measures to manage the risks associated with OPM. To manage these risks, you can:
- use signs to warn the public about the presence and risks of OPM
- use site zonation to assess the level of risk in specific areas of the site
- restrict access to high risk areas
These options will not reduce the levels or spread of OPM but will allow you to take targeted action to reduce the public and animal health risks. This is in line with the risk-based approach and is appropriate for all areas, however outside of the established area you will be subject to an SPHN which will specify action needed.
Control OPM: spraying
In the pest free area and buffer zone you will need to take action to control OPM. This may also be appropriate in the established area dependent on the approach set out in your management plan. To control the spread of OPM you can:
- spray the affected tree with insecticides
- if you have oak trees within 50m of the affected tree it is recommended you also spray those trees
To spray, use the 2 insecticides licensed for control of the larvae, or caterpillars, of OPM. These are:
- bacillus thuringiensis var kurstaki (BT)
- deltamethrin
Do not spray trees once the moths have flown – this is not effective. Only use insecticides on trees with larvae / caterpillars.
If your trees are on a site of special scientific interest (SSSI), you’ll need permission from Natural England before any work is carried out.
Control OPM: nest removal
If the nests pose a threat to public and animal health], you can remove the nests with their larvae using a vacuum cleaner or by hand.
You should use an expert to do the work. You can find businesses able to carry out this work from the:
Removing nests and larvae does not completely eradicate OPM but is considered more environmentally friendly and has little impact on other wildlife. It may be the only option if spraying is not allowed, for example if your trees are on SSSIs.
Further information about risk management options and control measures is available on the OPM hub.
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