By Charles D. Michener. The Johns Hopkins University Press, Baltimore, Maryland. 2000. Pp. xiv + 913. £93.00 (hard cover). ISBN 0-8018-6133-0. Professor Michener, University of Kansas, is the world's leading authority on bees. His publications on bees span 65 years and include previous monographs on several aspects of bee biology, including external morphology and classification, social behaviour, biogeography and nesting. These monographs have themselves become classics in this field. Throughout this period, Michener also published over 100 papers dealing with bee taxonomy and systematics, and it is his systematic studies that are synthesized and built upon to form the body of the present volume. The book runs to over 900 pages, with the last 800 consisting of the systematic account, family by family, with illustrated keys to genera provided for each family, as well as morphological and biological synopses. These are followed by an extensive bibliography and index. The thirty-two chapters which fill the first 100 or so pages serve as an extremely effective introduction to bees, are very readable and could easily stand alone. An overview of bees is first provided, followed by a definition of what constitutes a bee, and their importance to man. Chapters on development and reproduction, social behaviour, floral relationships, nesting and parasitism are followed by detailed accounts of adult and larval morphology. The paraphyly of Sphecidae in relation to Apidae is discussed and reflected in other chapters on higher level taxonomy and classification. A couple of short chapters are devoted to fossil bees, and the relative antiquity of bee taxa, and these are followed by accounts of diversity, dispersal and biogeography. Finally, several morphological structures, in particular the sting and tongue (glossa), are discussed in relation to reduction and modification, respectively. Just preceding the bulk of the systematic account are short sections on family group names, problematic taxa, identification and, of course, keys to the families. There is little question that this volume will be generally accepted and used as the standard textbook on bee systematics for a long time to come. Controversial aspects, still not universally accepted, include the author's treatment of family group taxa. Many hymenopterists treat two families within superfamily Apoidea, Apidae (bees) and Sphecidae (sphecids). Research, much of which was undertaken by the author himself, has, however, shown that sphecoids are paraphyletic with respect to bees, which are considered to have evolved from crabronid (‘crabronine’) sphecoids. While not objecting strongly to paraphyly in classifications, the author prefers, however, to present seven families of apoids (Stenotritidae, Colletidae, Andrenidae, Halictidae, Mellitidae, Megachilidae and Apidae) and three families of sphecoids (Ampulicidae, Sphecidae and Crabronidae). While the debate will no doubt continue, it would be very useful for others if some consensus could be reached by those involved. A few final comments concern the preface, an extremely entertaining account of how Professor Michener first became involved with bees, and his encouragement from the age of fourteen by T. D. A. Cockerell and, later, P. H. Timberlake. This volume is also testament to the encouragement and support of these men and many others. Inevitably, the book is large and somewhat unwieldy, but in an effort to prevent it from being even larger, the typeface is really rather small to be read comfortably, at least by me! The line drawings and fifty-odd colour photographs are of the very high standard one would expect. This is a very different book from the similarly titled Bees of the world (O'Toole & Raw, 1991), which really is an introductory work for the general readership, and excellent in its own way. Professor Michener's monograph, while providing a superb general introduction to the bees in the first 100 pages or so, really is more of a specialist's book. However, those specialists who will find it indispensable include not only taxonomists and systematists but also insect ecologists and morphologists.