The Forestry Commission is planning aerial spraying of an area of woodland near Pangbourne in West Berkshire.

A helicopter will spray the woodland twice over a seven to 14-day period. This is the time when caterpillars of the oak processionary moth (OPM), which is a risk to tree, animal and human health, are emerging from eggs in oak trees.

The product sprayed will be Bacillus thuringiensis (Bt), a bacterial agent which occurs naturally and widely in soil. Bt is very safe when used by fully qualified operators in compliance with the strict health, safety and environmental protection regulations governing its use. Natural England, the government’s advisor on the natural environment, has given authorisation for the operation.

The main, 10-hectare (25-acre) area to be treated comprises Herridge’s and Broom Copses, part of which is privately owned and part of which is public woodland managed by the Forestry Commission. Another privately owned 1ha (2.5-acre) block of trees nearby will also be treated.

If successful the operation would mark a big step forward in efforts by the Commission and West Berkshire Council to eradicate the pest from the Pangbourne area, where only three nests were found in 2012, down from several dozen the previous year.