The insect Dendroctonus micans, a bark beetle that is found in North West Europe, has for long been held, by forest entomologists, to constitute a potential threat to coniferous plantations in Great Britain, although it is not yet established here. Accordingly, in June 1964, Mr D. Bevan, the Commission’s senior forest entomologist, and Mr J.M.B. Brown, the Commission’s forest ecologist, carried out a tour through Denmark and parts of Germany and Holland, in order to assess the degree of risk. The purpose of their tour may be expressed in the form of five questions which they had constantly before them: (A) What is the present status of Dendroctonus micans in the regions visited? (B) What environmental conditions (climatic, edaphic, biotic) are of particular significance in relation to the surge of Dendroctonus breeding in Denmark, Holland and Schleswig-Holstein in the last twenty-five years ? (C) Is there a likelihood of Dendroctonus gaining a footing in Britain ? (D) Where in Britain would it find suitable habitats, should it ever gain entry? (E) What precautions can and should be taken to lessen the probability of introduction? This Bulletin presents the results of their investigations.