Following a request from the European Commission, the Panel on Plant Health was asked to deliver  a scientific opinion on a pest risk analysis for Thaumetopoea processionea L. prepared by the UK. The Panel was also asked to consider in its opinion the plant health risk of T. processionea to the whole EU territory. 

The oak processionary moth, Thaumetopoea processionea, is established in Europe and feeds primarily on deciduous oak (Quercus) species. The insect has one generation per year and overwinters as eggs laid on branches of oak trees. After emergence, the larvae feed gregariously and from the 5th instar form a communal silken nest on the tree from which they typically migrate in procession to feed. Feeding may result in partial or complete tree defoliation. From the third instar, the larvae produce urticating hairs which may cause allergic reactions in humans and animals. 

The Panel examined in detail the UK document to determine whether the evidence presented in the document supports the conclusions reached for the assessment area of the UK, including Northern Ireland and the Channel Islands. 

To consider the risks posed to the whole area of the European Community, the Panel analysed additional information obtained from a review of the literature and from consultation with experts in the EU. The Panel conducted a preliminary climatic analysis to explore the establishment in the whole EU area, based on temperature accumulation