The Forestry Commission today urged the public to report sightings of Oak Processionary Moth (OPM) caterpillars.
Oak Processionary Moth, which is a tree pest, was first identified in London in 2006 and has since spread to some surrounding counties. The caterpillars and their nests contain hairs which can cause itchy rashes, eye and throat irritations, and should not be touched under any circumstances.
The greatest risk period is May to July when the caterpillars emerge and feed before turning into adult moths.
The pest is established in London and surrounding areas although most of Britain has Pest Free Area status, meaning the pest is not known to be present in much of England.
The Forestry Commission runs an annual programme in place to tackle OPM, and works with partners to monitor, treat and research the pest, in order to slow the spread and reduce the intensity of the pest.
Andy Hall, Forestry Commission Operations Manager, said:
Trish Mannes, Deputy Director for Health Protection for Public Health England South East, endorsed the ‘don’t touch’ advice, saying:
OPM caterpillars feed on oak leaves and can make trees more vulnerable to attack by other pests and diseases, making them less able to withstand adverse weather conditions such as drought and floods. A government programme is in place to limit their spread from areas where they are present.
Since 2012, the government has invested more than £37 million in tree health research; this includes a dedicated programme of research on oaks and the pests that threaten them, such as oak processionary moth.
How to identify OPM caterpillars
- 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. They can also occasionally cause breathing difficulties in people and pets, so should not be touched under any circumstances.
- More information on how to identify OPM, including common mistaken species.