The oak processionary moth (OPM), Thaumetopoea processionea, is not known to exist in the United States but may pose a serious threat to oaks and other trees if introduced. The larvae of this high-consequence defoliator strip trees bare of leaves, making them vulnerable to other pests, diseases, and environmental stressors.

Oak processionary moth (Thaumetopoea processionea, OPM) is a native of southern Europe accidentally introduced into Britain in 2005 due to the trade of live plants.

The outbreak was contained within London for some years however, they are now moving remorselessly outwards into the Home Counties. The OPM caterpillars feed on oak leaves and cause significant damage to the integrity of the tree.

The oak processionary moth (Thaumetopoea processionea, OPM) has been spreading into the north for years. One of the main reasons is the decline in late frosts, since the moth thrives in warmer temperatures. Oak processionary, treatment for this caterpillar This well-known oak tree parasite is a caterpillar that devours the leaves, until it gathers to form a nest that looks like a spider web. The scientific name is Thaumetopoea processionea and it’s also called oak processionary moth. In July, the Department of Agriculture Food and the Marine’s (DAFM) Horticulture and Plant Health division reported the first interception of Thaumetopea processionea, commonly known as the Oak Processionary Moth (OPM) in a trader notice.

The caterpillars have distinctive long white hairs emerging from reddish warts along their bodies, a single dark stripe down their backs and a whitish line along each side. Their hairs are irritating and can cause skin problems, conjunctivitis, respiratory congestions and asthma in humans, wildlife and pets. Contact with dead larvae, cocoons, nests and debris-infected oak trees can cause dermatitis and other symptoms.

Effective treatment includes cutting out, vacuuming or burning of nests during the day when most caterpillars are in the nest. Chemical applications can also be effective.

Treatment of Oak processionary moth, or OPM, should only be carried out by an appropriately trained professional.

What to do if you see a nest?

‘SPOT IT, AVOID IT, REPORT IT’

DO NOT:

• Touch or approach OPM nests or caterpillars
• Let children or animals touch or approach nests or caterpillars
• Try and remove nests of caterpillars yourself

DO:

• Immediately call Maydencroft. We will be able to confirm and remove infestation or point you in the right direction for additional help.
• Report the sighting to the Forestry Commission Tree Alert System (forestry.gov.uk/treealert).
• Keep a safe distance from the tree and other trees in the vicinity and encourage others to follow suit.

If you think you have spotted OPM you should firstly report any sightings to the Forestry Commission using their Tree Alert tool available from www.forestry.gov.uk/treealert or by email to opm@forestry.gsi.gov.uk. They can then keep track of the outbreak.

Processionary Moth Ireland

Secondly, please do not try to remove the caterpillars or nests yourself. They need to be removed by an Arborist who has had the correct training and has the necessary equipment require. The nests must also be disposed of properly to avoid the pest spreading.