The main objective of this catalogue is to bring some uniformity into exchanges concerning forest entomology. It consists of three lists: a basic one and two supplementary. The basic list includes all species in Pests and diseases of forest plantation trees (F G Brown, 1968) occurring in Britain, to which have been added many others from both the literature and from records kept by the Entomology Branch of the Forestry Commission Research and Development Division. Besides insects the list also includes some mites and several nematodes. This list was originally designed for use within the FC Research Division as a source of valid insect names and authors together with a selected synonymy for all species with some claim to forest importance or significance. The species included show great variability in status, some being pests of economic importance, while others are of interest only. It should be noted that some synonyms may be invalid but are included because they have been used in forest literature. The two supplementary lists provide cross-references for common English names and host plants.