Keep an eye out for Oak Processionary Moth caterpillars

Oak Processionary Caterpillar

The Oak Processionary Moth (OPM) is a non-native pest species which is harmful to people and animals and has now reached Dacorum.

The hairs from the caterpillars and nests of the species can cause painful skin, eye and throat infections in both people and animals. The moth itself is not harmful.

Our Trees and Woodlands Officers are putting up safety notices on any affected public trees in the borough.

Although currently there have only been a couple of reported cases, we're asking residents to be vigilant - especially with curious young children who may be exploring trees this summer. The caterpillars and nests are only likely to be found on oak trees.

Please ensure that if these caterpillars or nests are discovered that you do not touch or go near them. If you, your child or your pet are affected, please see a doctor or vet immediately.

Cllr Alan Anderson, Dacorum Borough Council's Portfolio Holder for Environmental Services, says: "We're working with the Forestry Commission to control the spread of this harmful species. If you discover an OPM nest or caterpillar, we ask that you ‘spot it, avoid it, report it’.”

If there is no warning sign pinned on the tree and you find a caterpillar or nest, please report it on the Forest Research website so that it can be officially logged and safely exterminated.

Please do not attempt to exterminate a nest or caterpillar yourself. This is important both for your own safety, and in case the species you have found is harmless and not OPM.

For more information about the moth and caterpillars, visit the Forest Research OPM web page.

For local advice about publicly managed trees, please email

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