Reminder to report Oak Processionary Moth sightings

People in Greater London and neighbouring counties of Hertfordshire, Essex, Surrey, Berkshire and Buckinghamshire, are being reminded to report sightings of Oak Processionary Moth (OPM) caterpillars which could be damaging oak trees in their area.

The Forestry Commission, councils and land managers tackle the pest, which affects these specific areas in spring, with an annual control programme of tree treatment.

People should report sightings to the Forestry Commission via its Tree Alert online form here. Alternatively, people can email or call 0300 067 4442.

OPM was accidentally introduced to England in 2005. The caterpillars feed on oak leaves, which can leave the trees vulnerable to other pests and diseases and drought. Nests are typically dome or teardrop-shaped, averaging the size of a tennis ball. They are white when fresh, but soon become discoloured and brown. The caterpillars have black heads and bodies covered in long white hairs which contain proteins which can cause itchy rashes, eye and throat irritations. Less frequently, they can also cause breathing difficulties in people and pets so should not be touched.  

The greatest risk period is May to July, when the caterpillars’ emerge and feed before pupating into adult moths, but nests should not be touched at any time.

Alison Field, the Commission’s South-East England Director, said

“The public and others such as tree surgeons, forestry workers, gardeners and ground-care workers can help limit the spread and impact of this pest by reporting sightings. However, they should not try to remove the caterpillars or nests themselves. This is most safely done by specially trained and equipped pest control experts.”

Dr Deborah Turbitt, London Deputy Director for Health Protection for Public Health England, endorsed the ‘don’t touch’ advice, saying:

“We strongly advise people not to touch or approach the caterpillars or their nests because of the health risks posed by the hairs. Pets and livestock can also be affected, and should be kept away as well. The Forestry Commission website has pictures to help identify the pest. People should see a pharmacist for relief from milder skin or eye irritations following possible OPM contact, or consult a GP or NHS111 for more-serious reactions. Contact a vet if animals are seriously affected.”

Anyone pruning or felling oak trees in the affected areas should contact Forestry Commission England’s Tree Health Unit beforehand on or 0300 067 4442 for advice about safe removal of the material.

Further information is available from the Forestry Commission website here and advice about stings and bites is available on the NHS Choices website here