How to recognise it
Caterpillars move head to tail in nose-to-tail processions on oak trunks and branches, usually between May and July. They build white silken nests on the trunk or in branch forks, which later turn brown and look like a dirty teardrop. Other harmless caterpillars are often mistaken for OPM, so a clear photograph taken from a safe distance is the sensible first step.
- Do not touch nests or caterpillars, and keep children and pets away.
- Report suspected sightings via the Forestry Commission TreeAlert portal.
- Nest removal is specialist work requiring respiratory protection and controlled disposal.
If you have oaks on your property
Check trunks and lower branches in early summer, particularly on oaks that have recently been planted or moved. Trees imported as semi-mature stock are the usual route for introductions. If you find a nest, keep people and animals away from beneath the tree and take advice before any work — normal pruning around an active nest can spread the hairs.
How James David Forestry Ltd can help
James David Forestry Ltd works across Liverpool, Merseyside, Wirral, Ormskirk and Lancashire. We assess the actual tree, access and surroundings before recommending work. Clear photographs can be useful for initial guidance, but some questions need a site visit and we will not diagnose a dangerous or diseased tree from website information alone.
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