Oak Processionary Moth warning to the public

Welwyn Hatfield Borough Council has been notified by the Forestry Commission that evidence of the Oak Processionary Moth (OPM) has been found at Northaw Great Wood, near Cuffley. OPM caterpillars are pests which can be a hazard to the health of oak trees, people and animals.

oak moth

The Forestry Commission contractors will inspect, and if necessary, manually remove and dispose of the live and newly formed OPM nests in infested oak trees by 20 August.

The pests can cause itchy rashes, eye and throat irritations, and should not be touched under any circumstances. Visitors to the site should take extra care when walking in the woods and are advised to not touch or go near caterpillars or nests. If they do come into contact with the caterpillars, they should call NHS 111.

Durk Reyner, Head of Environment at WHBC, said:


"We would like to reassure the public that as long as the Oak Processionary Moths are left alone, there is no danger to the public.

"However, it would be helpful if visitors reported any sightings to the Forestry Commission via its Tree Alert online form (https://treealert.forestresearch.gov.uk /). Reports help inform the management and treatment programme and enables the Forestry Commission to slow the spread of this pest."


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 and crawl in large groups, nose-to-tail, forming long lines on or around oak trees.

The public can also report sightings by email to opm@forestrycommission.gov.uk or over the phone: 0300 067 4442.