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.

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.

Treatment Options

Before treating OPM, the first step is to look for infestations and confirm the presence of caterpillars. If found, there are a variety of treatments available for affected trees, including:

Biological control
Biological control is a method of keeping pests below damaging levels using natural enemies (such as Bacillus thuringiensis) and usually involves an active human role in the process.
Insect growth regulator
Insect growth regulator is a chemical that inhibits the life cycle of the insect.
Synthetic insecticides
Synthetic insecticides are botanical pesticides based upon plant extracts that are used to manage pests.

Removal of OPM caterpillars or larval nests is another method to control the spread of this pest. Caution must be taken when coming in contact as there are many risks to human health.

Below is a table that shows the recommended treatment options for the life-cycle stages of development of the oak processionary moth. The table sets out the life cycle of OPM. Note that the timings of the various stages are approximate, reflecting seasonal and local variation. In some years, S1 may appear in mid-April and S4 by the first week of May.

S = Life cycle stage. Timing can be heavily influenced by prevailing climatic conditions. The table provides an estimation and should be used only as a guide.

Next Steps

Bartlett Tree Experts is the only company that offers a full-range of treatments for oak processionary moth, including bio-control, systemic tree injections, and electrostatic spraying.

Learn more about OPM from Bartlett.

Make an appointment with a local service company near you using the Bartlett Tree Experts appointment scheduler. Bartlett covers most areas in the UK that are affected by OPM, including the entire Greater London area. If your property is outside of the Bartlett coverage area, additional resources will be provided to help you find a qualified expert.