Oak Processionary - a black week for conservation

On Tuesday of this week, the Forestry Commission carried out aerial spraying of a Site of Special Scientific Interest near Pangbourne in Berkshire with the insecticide Bacillus thuringiensis (Bt) in order to eliminate the Oak Processionary moth.

Why? The Oak Processionary is found in continental Europe and is thought to have been accidentally introduced into Britain in 2006 on imported trees. In Europe it occasionally causes defoliation of oak trees and the hairy caterpillars can induce an adverse reaction in some people. However, there are plenty of native moths that can cause defoliation (I have seen it several times where the 'culprits' have been Mottled Umber and Scarce Umber and the Green Oak Tortrix is well know for causing defoliation). So what about the health issues? The native Brown-tail moth causes the same problems and some people also suffer adverse reactions to a wide range of bites and stings. Do we hear of mass health problems in Europe within the Oak Processionary's native range? Of course not. People there are educated to avoid contact with the caterpillars, just as we are educated not to touch Stinging Nettles.

So has there been an outcry from conservation organisations about the aerial spraying of a broad-spectrum insecticide in an SSSI? Butterfly Conservation have criticised the action (see http://www.guardian.co.uk/environment/2013/may/06/pest-caterpillars-helicopter-blitz-insecticide ) but the local Wildlife Trust report that it is taking place on their web site without any comment and the RSPB appear to be silent on the matter. Why should the RSPB care? Because the use of Bt will kill all the caterpillars that insectivorous birds need to feed their young at the moment. What about Natural England? You should be astonished (but probably aren't if you know how useless they are these days) to hear that they voted IN FAVOUR of aerial spraying of an SSSI!

Aside from the damage caused to the Lepidoptera communities within this SSSI and the knock-on effect on everything that feeds on them, why do I object to the spraying? Firstly, because the caterpillars are gregarious and live in obvious nests which can be located and sprayed individually, as has been done throughout London. Secondly, the whole exercise is pointless! The response to finding Oak Processionary in London was too weak and too slow and even the Forestry Commission admit that the situation is now out of control in London. So if they've lost the battle in London and the moth continues to spread as rapidly as it has done, how long before it is back in Pangbourne (and everywhere else in southern England).

It is a sad indictment of conservation in Britain today that such activities can take place on our most important wildlife sites will hardly a murmour of opposition.