Oak Processionary Moth

Oak Processionary Moth (OPM) identified within the London Borough of Bexley

Oak Processionary Moth caterpillar

What is Oak Processionary Moth (OPM)?

Oak Processionary Moth is a non-native insect originating from Southern Europe and has been in the UK for approximately 12 years. 

How will it affect me?

The caterpillars of this moth primarily live and feed on Oak leaves, but they can also be found on the ground around an infected tree. The caterpillars are easily identifiable as they move together as a group in a column, head to tail in a procession - hence their name Oak ‘Processionary’ Moth.

rash from Oak Processionary Moth caterpillar

Although the adult moths are harmless, the hairs of their caterpillars contain a strong irritant. Contact with these hairs can cause severe irritation with skin rashes, less commonly: sore throats; breathing difficulties; and eye problems.

Both people and animals can be affected by touching the caterpillars, their nests, or if windblown hairs make contact with the skin. The greatest risk period is May to July, but the hairs from the caterpillar can be present on old nests and could be blown or touched at any time of year.

How it affects the trees

The caterpillars’ preference for a diet of oak leaves means a large infestation can strip a tree bare which reduces its ability to capture sunlight and make food. A healthy Oak can regrow its leaves in a few weeks. However, over time, these attacks may reduce an Oak’s tolerance to stresses such as drought, floods and other pests and diseases.

Public London Borough of Bexley sites where the Forestry Commission has identified OPM - as of June 2018

Public open spaces (including allotments) Public highways
Danson Park (2018) Watery Lane (2018)
East Wickham Open Space (2018) Danson Road (2019)
Monks Farm allotment (2018) Portland Avenue (2019)
Sidcup Place (2018) Carlton Road (2019)
Lesnes Abbey Woods (2019)  
Lamorbey Park (the glade) (2019)  
Holly Hill open space (2019)  
Franks Park (2019)  
Footscray Meadow (2019)  

Please note: OPM may be present in any site with Oak trees.

infected tree

What action is being taken and when?

Advanced Tree Services Ltd will spray known infected trees on Council and private land with a contact insecticide between April and June on behalf of the Forestry Commission. The technicians will remove the caterpillar’s nests on the Council’s land later in the year. The contact insecticide spraying will commence from Monday 30 April 2018.

Areas being treated will be signposted and there is no risk to people or animals from the treatment process.

Whilst the Forestry Commission undertakes these necessary works, the London Borough of Bexley will assist and also work to minimise the impact on access for visitors and local residents to Bexley’s Parks and Open Spaces.

The mowing of grass beneath Oak trees will be stopping on sites affected by OPM, this is to reduce the potential for contact with the caterpillars by discouraging sitting or standing beneath the trees.

Action update - 22 June 2018

tree spraying

Insecticide treatment has been completed, and the nest removal phase is currently being carried out at the sites listed above by qualified contractors.

We expect the removal of the nests to take place between mid-June and the end of August.

Advanced Tree Services Ltd can be contacted on:

Telephone: 01483 210066
Email: office@atstrees.co.uk 
Website: Advanced Tree Services Ltd 
Address: The Depot, Pixham Lane, Dorking RH4 1PH

For further information please visit Forest Research.