Ongoing controls to protect against the tree pest oak processionary moth (Thaumetopoea processionea)

The UK Plant Health Services are currently dealing with findings of oak processionary moth (OPM) caterpillars on recently imported oak trees. To reduce the chance of further interceptions, strengthened measures on the import of most species of oak into Scotland were introduced on Tuesday 16 July 2019. Such measures have also been introduced in England, Wales and Northern Ireland.

The majority of the UK is designated as a Protected Zone for OPM meaning that the pest is known to be absent. As Scotland is part of the Protected Zone for OPM, officials are working to ensure that any interceptions are eradicated, by spraying the nest with the pesticide Deltamethrin.

Anyone who has received oak trees imported from the continent has been asked to urgently check their trees for OPM, and nurseries holding imported oak trees have also been asked to spray them as a precautionary measure to stop this pest spreading. It is vital that imported oak trees are checked and sprayed now to minimise the spread of this damaging tree pest and protect the health of our oak trees.

Spotting OPM

Further information on OPM, including pictures of caterpillars and nests can be found on the Forest Research website. If you spot OPM caterpillars or nests on your trees, please report it via the online portal Tree Alert.


If you suspect OPM, you should not attempt to touch or move infected material yourself as the nests and caterpillars can pose some risks to human health.

Further information



In Scotland, can be contacted with any OPM enquiries.