Dr. Walker and Dr. Corbet make a signal contribution in gathering together all available information on the dragonflies of Canada and Alaska. The order as a whole and the zygoptera are covered. The treatment is not confined to taxonomy and geographical distribution, but includes data on habitats, seasons of adult life, and brief notes on habits when these are available.

Dr. Walker makes a signal contribution in gathering together all available information on the dragonflies of Canada and Alaska. The order as a whole and the zygoptera are covered. The treatment is not confined to taxonomy and geographical distribution, but includes data on habitats, seasons of adult life, and brief notes on habits when these are available.

Dr. Walker and Dr. Corbet make a signal contribution in gathering together all available information on the dragonflies of Canada and Alaska.

Written in language that is accessible to the sports fisherman and the naturalist and with over 1,000 original illustrations, the book includes features such as coverage of all insect families and genera important to fly fishing; comphrensive treatment of the biology of all life stages of aquatic insects including terrestrial as well as aquatic stages; special chapters on shore dwelling insects, insects associated with aquatic vascular plants, residents of tree holes and plant cups, aquatic arachnids and freshwater crustaceans.

Dragonflies (Odonata), represented by over 6000 known species, are unique insects. In more than one feature they differ, at the very first glance, from all other insect superorders including their nearest allies, the mayflies (Ephemeropteroidea). The Zygoptera and Anisoptera, on the other hand, are the dominant groups. Being voracious predators in both immature (aquatic) and adult (aerial) stages they are important elements of all, except the drier (or high alpine) environments in temperate and tropical regions, occupying a position at the apex of the food chain of invertebrate life. Many dragonfly species are tested biological control agents for several disease-transmitting vector mosquitoes, especially Aedes species. They are also ideal organisms to be used as indicators of water pollution and contamination. Many species serve as intermediate hosts of fluke parasites of birds, and thus are important in the transmission of parasitic diseases, especially of domestic poultry and wild ducks. Because of their unique morphology and physiology, dragonflies are used extensively in the study of many biological phenomena. All these subjects are discussed in this unique book comprising twenty three articles written by expert odonatologists from different parts of the world. The book is written in a lucid and comprehensible language, and will likely be useful to both the professional and amateur alike.

Dr. Walker makes a signal contribution in gathering together all available information on the dragonflies of Canada and Alaska. The order as a whole and the zygoptera are covered. The treatment is not confined to taxonomy and geographical distribution, but includes data on habitats, seasons of adult life, and brief notes on habits when these are available.

This monograph is the first of its kind devoted entirely to the dragonfly nymphs of North America north of Mexico, the focus being accurate identification of the 330 species of Anisoptera that occur in the region. Nymphal external morphology is described and illustrated in detail, and all terms needed to navigate the dichotomous keys are defined. Species are tabulated with references that provide the most detailed, accurate descriptions for each; species that are inadequately described are so indicated. The key separating the seven families in the region contains several new characters. The families are then covered separately: Aeshnidae (13 genera), Gomphidae (17 genera), Petaluridae (2 genera), Cordulegastridae (2 genera), Macromiidae (2 genera), Corduliidae (7 genera), and Libellulidae (29 genera). Each family is further characterized, followed by a generic key. A drawing of the habitus and diagnostic details for each genus are provided, along with additional diagnostic remarks and notes on habitat and life cycle; for each genus, a map shows its geographic distribution in North America. Full-grown nymphs of all known species of each genus are keyed and diagnosed; characters that apply to earlier instars are noted. Morphological variation in character states was analyzed in order to assess the reliability of previously utilized characters and to discover new characters. Most of the characters used to distinguish all levels of taxa are illustrated; a total of 702 figures, comprising 1,800 original drawings, along with selected photographs where necessary for clarity, accompany the keys. Measurements of total length, head width, and other variables for each species are provided in tables. Difficulties with past keys and descriptions, including errors, omissions and other shortcomings, are addressed. The importance of nymph characters in helping solve generic and specific distinctions and their role in phylogenetic studies is emphasized. Methods for collecting, rearing, and preserving dragonfly nymphs and exuviae are presented. The final chapter discusses research opportunities on North American Anisoptera nymphs, including taxonomic needs, studies on structure and function, life history and microhabitat, water quality indices and conservation efforts. The habitus drawings of all genera are arranged according to family in five plates (Appendix I); although the book is intended as a lab manual, these plates conveniently allow for comparison based on nymph shape making field identification to genus possible in many cases. Appendix II contains a brief history of dragonfly nymph studies in North America. A glossary and an index to scientific names are included.