Pine processionary moth is a serious pest of pine trees in southern Europe. The moth larvae (caterpillars) feed on pine needles and defoliate trees, which reduces tree growth and timber production. Large numbers of larvae can cause severe damage – weakening the trees sufficiently to make them vulnerable to other pests and diseases and, in some cases, leading to tree death. Since the 1990s the moth has been expanding its distribution in Europe and it can now be found breeding as far north as Paris in France. Although not present in the UK, the favourable climate and presence of suitable host trees in the south of Britain suggests that the pine processionary moth might be able to establish breeding populations in southern parts of England.