Oak Processionary Moth

Printer-friendly page

What is it?


Oak Processionary Moth (OPM) is a major defoliator of oak in Europe.  The larvae (caterpillars) feed on the foliage of many species of oaks, including English, Sessile and Turkey oaks (Quercus robur, Q.petraea and Q.cerris).

What harm can it do?

OPM is primarily a human health issue.The larvae (caterpillars) are covered in irritating hairs that contain a toxin and contact with these hairs, or their inhalation, can result in skin irritation and allergic reactions.  These problems are significant because oak processionary is often most abundant on urban trees, along forest edges and in amenity woodlands. See the Forestry Commission’s website for more information on signs and symptoms: https://www.forestresearch.gov.uk/tools-and-resources/pest-and-disease-resources/oak-processionary-moth-thaumetopoea-processionea/

For full details, see our Fact Sheet below.

How serious is the threat?

We have found OPM on the Alban Way near the eastern district boundary in St Albans, and so people need to be vigilant. OPM has also been recorded recently near our boundary in Welham Green and also in the neighbouring boroughs of Watford, Hertsmere and Broxbourne over the last couple of years.

What can the Council do to combat this?

We have asked tree contractors (who are most likely to come into close contact with OPM), and our network of voluntary tree wardens to be vigilant and would ask for any suspected cases to be reported as soon as possible to the Forestry Commission (who are leading on the issue) and the District Council. A number a tree contractors have, and are developing means of treating outbreaks of OPM.

Who to contact

Firstly, it is important that you do not touch the larvae or disturb the nests.  If you think you have seen OPM, its larvae or its nests you can report a sighting using Tree Alert at: https://treealert.forestry.gov.uk/

Alternatively please call: 0300 067 4442 or email: opm@forestry.gsi.gov.uk

Please also contact St Albans City & District Council, Trees and Landscape Section at: trees@stalbans.gov.uk  or call 01727 866100.

Date of last review: 29 July 2019