A comprehensive study of oak-galls in Britain; the first volume, `Introduction & Keys', containing a long introductory chapter, which explains about galls and their inhabitants, how the book is set out and how to rear, examine and identify the inhabitants. Gall descriptions, keys to galls, gall maturity times, flight times, together with lists of insect inhabitants by gall, and the gall-hosts of the various inquilines and parasitoids, are included in this section.
Keys identify insect families; followed by detailed keys to causers, inquilines and parasitoids. Finally, a section provides keys to larval stages of the various hymenopteran genera. The keys contain, at the point where species key out, drawings relevant to the points of identification, a brief description of the sexes, a set of ratios and sizes, plus the months when they are likely to be found.
The second volume, Appendices, has complete descriptions of each of the insects, where known, including many comparative outline microscope photographs showing shapes. The appendices include much ancillary information, such as when the first of each species was reared, a summary of brief comparative facts and outline descriptions for all the insects, a glossary, and full bibliography.