We are currently receiving a large number of reports of native caterpillars and defoliation of oak trees. Some caterpillars that are mistaken for OPM include: Brown-tail moth, Ermine Moth and Tortrix Moth and need not be reported to the Forestry Commission. Although OPM is a defoliator of oak trees there are many other Lepidoptera species that also feed on oak trees, especially in spring when species all become abundant at the same time. It appears that oak defoliation is particularly noticeable this year.

Now is a good time to familiarise yourself with caterpillar species that could be mistaken for OPM. Please see the Forest Research webpage and poster to help you identify similar looking species.  

With previous weather conditions holding back the development of OPM but now improving we are starting to receive reports of OPM. The photo below was taken in the OPM core zone in London on the 7^th of June and indicates that OPM is now visible and moving through its life stages. This is a reminder to not approach or touch the caterpillars but please do report all OPM sightings to us via the online portal Tree Alert www.forestresearch.gov.uk/treealert.  Alternatively, you can send in your reports to opm@forestrycommission.gov.uk.

Many thanks to all those who attended the two OPM awareness events last week. Both events were very well attended and we hope you found them useful. We are proposing to hold an end of season workshop on 6^th October, there will be further details later in the year.

Carcelia iliaca is a parasitoid that is associated with OPM. It parasitises older, almost full-grown OPM larvae inside or outside OPM nests. This survey season we are actively recording the presence of C.iliaca on infested sites. Additionally, we are working closely with Newcastle University who will be carrying out field research on a handful of sites to take biopsies of OPM caterpillars to detect whether OPM caterpillars are carrying parasites. Please see this link on how to identify this parasitoid and please do report any sighting to us via OPM@forestrycommission.gov.uk. 

Please continue to report OPM sightings via the contact information below.  

If you’re new to OPM, please note that we have an OPM manual on our website with guidance on surveillance, identification and managing OPM. You can find it at www.forestresearch.gov.uk/opm.  

The Forestry Commission has a suite of communication resources which partners are welcome to use. PDF versions of posters, leaflets and banners available under ‘Further information resources’ at the bottom of the OPM webpage at:  www.forestresearch.gov.uk/opm.  

Please send us information on your OPM activity so that we can provide up-to-date and comprehensive OPM reports, including developments outside Defra/FC-funded work. Email your updates to opm@forestrycommission.gov.uk  

OPM Control Programme

opm@forestrycommission.gov.uk

Tel: 0300 067 4442

www.forestresearch.gov.uk/opm