Oak Processionary Moth


The Oak Processionary Moth (OPM) has been present as a pest in many European countries since 1995. Firstly originating from the Iberian Peninsula and spreading north through France, Belgium, Germany and Holland and is exclusively associated with oak trees. In Southern Europe, distribution of and the associated health and environmental issues associated with OPM are statistically less significant in comparison to Northern Europe. This being due to the presence of natural predators and to a lesser extent a more acclimatised niche in southern climes. Attributing dramatic global climate changes have pushed the range of OPM northwards. Without the presence of comparative natural predation an alarming amount of populations of the moth have sprung up and successfully colonised as far north as Sweden. Infestations of OPM caterpillars were first surveyed and monitored in Richmond upon Thames, London in 2006. Since then several monitoring and surveying bodies in addition to the Forestry Commission have been established to document and record the infestation.

The outbreak has reached disturbing proportions and the population of OPM has now broken out of the M25 in a number of areas, despite major and serious attempts of eradication. Slowing down the spread is now the realistic situation and avoiding outbreaks further afield in the United Kingdom. Advanced Tree Services is one of only three Forestry Commission endorsed contractors employed to tackle the pest via a number of resolutions. Our contracts include but are not restricted to; London Borough of Hammersmith and Fulham, Ealing, Merton, Epsom & Ewell, Royal Borough of Kingston upon Thames, Royal Parks and Wandsworth. Firstly though, why is it justifiable to remove the Oak Processionary Moth?

Tree Health Issues

It’s in the name; the Oak Processionary Moth. Oak trees are predominantly used as the host by the moth (Pedunculate/English oak Quercus robur, Sessile oak Quercus petraea and Turkey oak Quercus cerris mostly). Once populations of the larvae establish the emerging caterpillars strip and defoliate the tree. This reduces the trees capability to photosynthesise and repeated attacks, year on year, can place the tree under stress. This in turn can deplete the trees stored energy and natural defence systems, rendering it more vulnerable to other pests and diseases.

Health Issues

The following information is the product of direct advice and relevant research conducted by the Department of Health. The OPM is of a major health concern for several reasons. In its later stages (3rd to 6th instar growth stage) of its caterpillar development between late May and early June, the caterpillars are covered in minute hairs that contain an urticating toxin (thaumetopoein). If those hairs come into contact with the skin various persistent symptoms can occur.Oak Processionary Moth - Rash Example This includes but is not restricted to; an itchy rash, sore throats, conjunctivitis and respiratory problems and can therefore cause increased issues to those with pre-conditions. Stand alone, these symptoms are statistically non-fatal and usually predominantly leads to general uncomfortableness for up to 6 weeks after first contact (subjective). However, anaphylactic reactions are not unknown. Treatment is easily applied via the use of antihistamines despite the hairs remaining toxic for several years. If you suspect you have come into either direct or indirect contact with OPM, you should contact either NHS (111) or a General Practitioner. It is important to note that OPM has not caused any directly attributed fatalities. Animals including cats, dogs and horses can also be affected by the caterpillars irritating hairs and should be kept away from infested trees or fallen nests