Even for those who are already familiar with mayfly larvae, this latest edition is an essential requirement for accurate and up-to-date identification, including the latest nomenclature for this important and popular group of freshwater insects. Replacing an earlier key by the same authors (published by the FBA in 1988, Sci. Publication 49), this new edition incorporates three additional species recorded in Britain since 1988 (Electrogena affinis, Caenis pseudo and C. beskidensis) as well as changes to familiar names and other recent advances in classification and taxonomy. A key to families is followed by a series of keys to identify species, illustrated by numerous line drawings that show the important key characters used for identification. These are supplemented (as in the 1988 edition) by sketches of common mayfly larvae drawn by Professor Mizzaro Wimmer and some new colour photographs of live larvae. These greatly enhance the text and will help beginners and others to familiarise themselves with the general appearance and diversity of mayflies. Apart from the keys for identification, a wealth of basic information on the ecology of mayflies is summarised in 40 pages of tables and text, plus text figures showing the life histories of most species. A final section of text covers the importance and use of mayflies for applied purposes, especially in relation to pollution and ecological assessment of aquatic environments.