Forestry Commission
This guidance is for landowners and site managers who have oak trees on their land, and for people who work on oak trees.
If youre a private resident with oak trees in your garden, read Managing oak processionary moth (OPM) in England.
Managing the risks from OPM
OPM is regulated as a quarantine pest known to be present in GB. As a quarantine pest, it is under official control measures and cannot be introduced, moved, multiplied or released without prior authorisation.If you suspect you have found an OPM nest or caterpillars, you must report it to us immediately via TreeAlert.
Forestry Commission leads an annual programme of work to manageOPM. The actions required under this approach will vary depending on the management zone in which your site is located.
The current Great BritainOPMmanagement zones map 2024 with exclusion zoneis available to view and was updated for the start of theOPM2023 season. Alist of local authorities and wards(ODT,62.6 KB)that will fall into the buffer zone and established area is also available.
In the established area
In the established area you must reportOPMvia Tree Alert 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 several 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 via Tree Alert. 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 cases support is available for treatment of trees within this zone. The SPHN document will explain what action is needed.
In the area free from the pest
This area is officially designated free from OPM and covers most of the country. In this area, the 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 the government with the objective of eradicating the outbreaks. In the area free from the pest, you must report OPM via Tree Alert 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 guidance on how to identify OPM in Managing oak processionary moth in England to understand what youre 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.
How pheromone traps work
Funnel traps contain a synthetic chemical 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 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 lots 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 many 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
Any sightings of OPM nests or caterpillars should be reported to the Forestry Commission viaTree Alert. You can also emailopm@forestrycommission.gov.ukor phone 0300 067 4442.
Management options to control or manage OPM
In the buffer zone and area free from the pest, the government funds an extensive management programme led by the Forestry Commission. If OPM is found in these areas, it is likely that you will receive a Statutory Plant Health Notice (SPHN). This will include instructions for what you should do.
It is important that landowners, site managers or professional operators report findings of OPM within the buffer zone or area free from the pest to the Forestry Commission to enable government management to take place. If you findOPMnests or caterpillars,report it via theTree Alert online form.
In most cases the treatment of oak trees that have OPM infestation in these areas will be completed on behalf of the landowner by Forestry Commission. Professional operators should not take action on OPM findings within the buffer zone or area free from the pest without government authorisation, due to the quarantine pest status of OPM.
If you are in the established area and haveOPMon your site, there are several management options available to tackle the risks posed byOPM. The measures available to you can be selected depending on the level of risk identified in yourmanagement planand the wider objectives for your site.