This book provides an accessible and richly illustrated reference guide to the Darwin wasp tribes Pimplini and Theroniini (Hymenoptera: Ichneumonidae). It includes 25 species, each represented by both male and female specimens. Dichotomous keys to both sexes are provided, organized by genus, followed by individual species accounts featuring diagnostic photographs and biological notes, including known host associations. To support accurate identification, the book includes all currently known British species, along with a selection of extralimital (non-British) species. These are presented for both comparative purposes and in recognition of their potential to appear in Britain in the future. Designed to assist both newcomers to ichneumonids and more experienced entomologists, the guide features high-resolution photographs throughout, standard dichotomous keys to species and supplementary flowchart-style keys illustrating variation within the tribe Pimplini, helping users to identify species with clarity and confidence.