From the preface:
"The Association’s first key to British Ephemeroptera, written by Mr D. E. Kimmins, was published in 1942 and included keys to the families and genera of nymphs. These were omitted when a new revised key to adults was published in 1954, with a second edition in 1972. A separate key to nymphs, written by Dr T. T. Macan, was published in 1961, with second and third editions in 1970 and 1979.
Some of the excellent illustrations from the earlier key to adults are included in the present publication but more illustrations have been added and the text has been completely rewritten. The section on adult ecology has been greatly expanded – some of the information coming from the authors’ own researches. The list of references has also been enlarged to contain all the more important publications known to the authors.
We have been fortunate in having two authors to revise and expand this key who have researched on various aspects of ephemeropteran natural history both independently and in collaboration. Dr Humpesch brings his experience of the taxonomy and ecology of the Ephemeroptera in continental Europe to bear on the same problems in Britain and this has enhanced the value of this revision.
Imitation of ‘duns’ and ‘spinners’ exercises the ingenuity of fly-fishermen. The trout that they attempt to entice with these imitations have often grown on a diet to which ephemeropterans have made a substantial contribution. As the second half of this handbook describes, the Ephemeroptera have fascinating life-histories and behaviour that are of much interest to entomologists and freshwater biologists. I hope that all these readers will welcome this new key in the Association’s series."