Who we help
OPM management for estates and large grounds
On an estate, the difficulty is scale. Hundreds of oaks, public footpaths, tenants, events and contractors mean the question is not what to do about one nest but how to run a repeatable annual programme.
Site pressures
What makes this setting different
Large oak populations
Without an inventory, inspection is inconsistent and year-on-year comparison is impossible.
Public rights of way
Footpaths and permissive access mean exposure you do not directly control, concentrated at gates, benches and car parks.
Veteran and heritage trees
The most significant oaks are often the least replaceable, so tree health matters as much as public safety.
Events and seasonal use
Weddings, shoots, festivals and camping put people beneath trees that are otherwise quiet.
Our approach
How OPM management works for estates & large grounds
Scaled to the number of oaks on site and the way people actually use the ground beneath them.
- 01Oak inventory and mapping across the holding, with a consistent tree reference system
- 02Baseline survey followed by risk classification by exposure zone
- 03Annual management programme with defined inspection windows and action thresholds
- 04Contractor and tenant briefing, including forestry and grounds operations
- 05Documented annual review carrying priority trees forward each season
The framework
The seven-step management framework
The same structure applies across sectors; the emphasis and timing change.
- Step 1
Oak Tree Inventory
Establish what you actually have: every oak, its location, approximate size and the ground use beneath it.
- Step 2
Baseline OPM Survey
A first full inspection across the inventory, recording activity, nests and feeding damage tree by tree.
- Step 3
Risk Classification
Rank trees by exposure and observed activity so attention concentrates where people and trees meet.
- Step 4
Seasonal Monitoring
Repeat inspection at the life-cycle stages that matter, with findings recorded against the same tree records.
- Step 5
Intervention Where Required
Act where exposure justifies it — exclusion, nest management or professional removal — not everywhere by default.
- Step 6
Documentation
Keep a defensible record of what was inspected, what was found, what was decided and who was informed.
- Step 7
Annual Review
Review the season, adjust priority trees and inspection timing, and carry the record forward.
Next steps
Identification and official reporting
Not sure what you've found?
Ask an OPM Expert
Send clear photographs of the tree, the caterpillars or the suspected nest and our team will give you an initial visual opinion to help you understand your next steps.
Photo identification is preliminary and may not always be conclusive. A professional site inspection or official confirmation may be required.
Think it may be OPM?
Report Suspected OPM
Suspected Oak Processionary Moth sightings should be reported through TreeAlert, the official tree pest and disease reporting service. This is an external official service and opens in a new tab.
Sending us photographs does not replace official TreeAlert reporting.
Estates & Large Grounds: common questions
Supported by
OPM Advice & Management UK is supported by Hertfordshire Pest Control, who provide the professional inspection, monitoring and nest management capability behind the advice on this site.
OPM Advice & Management UK is an independent information resource and is not part of, affiliated with or endorsed by Defra, the Forestry Commission, Forest Research or any local authority. Official organisations and resources are referenced to help visitors access authoritative information. Suspected OPM sightings should be reported through the appropriate official reporting channels.