Woodland harbouring the dangerous oak processionary moth (OPM) will be sprayed with insecticide from a helicopter for the second time, despite outcries from wildlife charities who say that aerial spraying will wipe out other harmless species.
The controversial move will see the Forestry Commission spray two sites near Pangbourne, Berkshire, where five adult male moths were found last year. This follows a first round of spraying last year, which appears to have removed nests of the moths.
The Commission have employed a number of tactics to control and eliminate the pests, however they say that aerial spraying is necessary to completely eradicate OPM from Sulham Woods in Pangbourne.
In a statement, Alison Field, Area Director for the Forestry Commission said: “Access difficulties make it almost impossible to inspect or treat them effectively from the ground, so we will use a helicopter to achieve the accuracy and degree of treatment needed.”
Spraying could threaten other species
However butterfly and moth charity Butterfly Conservation said they were ‘shocked’ by the Commission’s decision to go ahead with a second round of spraying at Pangbourne.
“Aerial spraying is a crude method of control that will cause a huge amount of damage to other wildlife and could harm several threatened butterfly species,” said Dr Martin Warren, Butterfly Conservation’s Chief Executive, who urged the Forestry Commission to rethink their strategy.
Despite assurances from the Commission that the spraying will only affect the invasive pests, Butterfly Conservation are concerned that the insecticide will also kill valued species including the White Admiral and White-letter Hairstreak butterflies.
Nick Phillips, Senior Policy Officer at the RSPB said that if the spraying did affect other insects, it would impact on any birds in the area that feed on caterpillars, including the lesser-spotted woodpecker, which is already a struggling species.
Matt Shardlaw, Chief Executive of Buglife, the Invertebrate Conservation Trust, called the decision to use spraying ‘barbaric and unacceptable’ and said “it would be cheaper, more effective and much less damaging to employ spotters to go into the wood and search for the OPM nests and treat each one individually”.
The caterpillars of the OPM cause defoliation of oak trees, which leaves them susceptible to diseases and environmental threats such as drought and flood.
OPM and the threat to human health
The caterpillars are covered in thousands of tiny hairs that contain an irritating substance called thaumetopoein which can cause skin irritation and respiratory problems. Illness can occur from physical contact with the caterpillar or its nest, however people can also become ill after interaction with airborne hairs.
“We are subject to a lot of attacks by various insects on our trees, many of which we appear not to be able to control. If the spraying will eradicate this one, then it’s a good thing,” said Lynne Jones, secretary of the Tilehurst Horticultural Society.
Not all locals have been as supportive of the move, however. Victoria Groulef, Labour’s Parliamentary candidate for Reading West that includes the affected area, said that she had been contacted by a number of Pangbourne residents who were concerned that they hadn’t been given enough information about the spraying and said that there needed to be a much bigger debate about the effects of the spraying on other wildlife, and the threat of the OPM as whole, taking the opinions of local people into account.
Foreign pest
The moth is native to central and southern Europe, but it is now making its way north across Europe, firmly establishing itself in northern France, Belgium and the Netherlands.
Of the three areas of Britain that are breeding grounds for the moth, two are in London meaning that Pangbourne is the only rural area threatened by the pest.
In its native area, the moth and its larvae has a number of natural predators including species of beetle, wasps and flies, as well as some small mammals and birds. The lack of natural predators in Britain has meant that the Forestry Commission and other concerned bodies have had to tackle the problem manually.
Pangbourne is the only area where aerial spraying will be taking place, as a decision was made by the Forestry Commission to contain the pests in London, rather than eradicate them.
The Commission insists that the second round of spraying is vital to get rid of the larvae in Pangbourne, and that Herridge’s Copse, a Site of Special Scientific Interest (SSSI) that was sprayed last year, will not be sprayed again unless new nests are found there.
More information about the Forestry Commission's treatment of OPM can be found here