The fourth edition of this excellent identification guide to aquatic insects in New Zealand has been updated with the latest information, making it an essential resource as the demand for river surveys and water quality studies continues to grow. Since the third edition was published five years ago, there have been great advances in our knowledge of New Zealand's aquatic insects. This edition includes information from several new publications about the systematics of New Zealand aquatic insects. More than 80 new titles have been added to the reference list and cited in the text; this serves both to document taxonomic changes and to guide the reader to the expanding literature on the aquatic insects of NZ. The book provides keys to enable insects to be identified to the family or genus level. Notes on distribution, habitat, and problems likely to be encountered with identification are included, along with full references, glossary of terms, and an index of taxa, common names, and general subjects. This is a joint publication venture of the Entomological Society of New Zealand (Inc.) and the New Zealand Freshwater Sciences Society.