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SPEC 13. A Guide to the Identification of Genera of Chironomid Pupal Exuviae Occurring in Britain and Ireland (including common genera from Northern Europe) and Their use in Monitoring Lotic and Lentic Fresh Waters

by R.S. Wilson and L.P. Ruse
Published by The Freshwater Biological Association, Ambleside, August 2005
176 pages
ISBN 978-0-900386-73-2
Price £23.00

About 600 species of non-biting or "dancing" midges occur in Britain and Ireland, with many more on the continent of Europe. They are most noticeable when the adults perform mating flights in swarms along the shores of running-water (lentic) and standing or still-water (lotic) habitats. The aquatic life-cycle of eggs, larvae and pupae usually lasts for a year or less. When adult midges emerge from their pupae the empty cast skins or pupal exuviae float on the water-surface and become part of the flotsam accumulating along strand-lines and in backwaters. In such places, pupal exuviae can be scooped-up easily with a long-handled pondnet, for subsequent identification under low magnification.

This guide provides a series of multiple-choice keys for identifying the pupal exuviae of 145 genera and more than 100 selected species of Chironomidae that have been recorded from Britain and Ireland, including some that may become added to the list as they colonise the region from Northern Europe. The guide provides a simplified introduction to the complex taxonomy of the Family Chironomidae, and is intended for use by those who are not familiar with the group. The text is generously illustrated with line-drawings of important characters used for identification. An illustrated key is also given to separate the pupal exuviae of chironomids from the cast skins of other common aquatic insects that are similar in general appearance.

All genera and species covered by the guide are allocated to one of four groups representing varying degrees of organic pollution, based on published knowledge of the ecological requirements of genera and individual species, and the authors' own extensive experience. Drs Wilson and Ruse use their Chironomid Pupal Exuvial Technique (CPET) to evaluate habitat diversity and the ecological quality of a wide variety of water-bodies, and to monitor any changes occurring in them. Their technique is comparable to others that are commonly employed in biological monitoring and assessment of water quality. CPET is summarised and briefly discussed in a special section of the text.

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