R.W. Merritt, K.W. Cummins, and M.B. Berg, eds.
Kendall/Hunt Publishing Company, Dubuque, IA
2008; 1158 pp.
ISBN 978-0-7575-5049-2
Price $124.95 (spiral-bound)

Merritt, Cummins, and Berg have generated another tremendous contribution to the study of aquatic insects. The fourth edition of An Introduction to the Aquatic Insects of North America provides the same ecological background and identification keys we’ve come to expect from past editions, with the addition of new color photographs, expanded coverage, updated keys, additional references, and a supplemental digital key (CD) to the major orders of insects found in aquatic and semi-aquatic habitats.

Martin Berg has joined the already successful editorial team of Richard Merritt and Ken Cummins in producing this expanded and improved edition of what is arguably the most widely used taxonomic guide to aquatic insects in North America. This new edition sells for $124.95 directly from Kendall Hunt Publishing, making it very affordable for such a comprehensive treatment.

As with previous editions, this volume is designed as a guide to aquatic and semi-aquatic insects in North American habitats. The book is organized into 26 chapters and is spirally bound, making it easy to use on a crowded lab bench. The book begins with an introduction to the study of aquatic insects and citations to major taxonomic and ecological works. The book then goes on to introduce basic morphological features of immatures and adults and strengths and weaknesses of sampling methods; both of these chapters are accompanied by well-labeled illustrations. A large table of sampling methods appropriate for different habitats is provided, with references cited for each method. Factors introducing bias to different sampling methods are also discussed here. A separate chapter (Chapter 4) discusses different adaptations for respiration among the aquatic insect orders and how osmoregulation is linked with the effects of toxicants on respiration. A large chapter covers habitat, life history, secondary production, and behavioral adaptations of each group, but excellent tables summarizing these characteristics for representative genera and species within each order help the reader immensely. The ecological groupings of aquatic insects (e.g., functional feeding groups, modes of habitat use, trophic relationships, and energetics) and their distribution in aquatic habitats are discussed at length; phylogenetic relationships are treated separately in Chapter 8. The usefulness of aquatic insects in biological monitoring programs is discussed, and monitoring endpoints that range from biochemical to ecosystem levels of organization are presented within the context of different monitoring objectives. A list of citations which detail monitoring designs, sampling protocols, and laboratory procedures is provided.

Taxonomic treatments begin with a key to the orders of immatures and adults. The key works well, but illustrations of key characters are spread throughout the book, so be prepared to do a lot of page turning. In addition, it would be useful to have page numbers next to each order name to speed transition from this general key to the more specific treatments in later chapters. Subsequent chapters (10-26) are authored by specialists of each order. Most of these chapters each cover a single order of insects. However, the Megaloptera and Neuroptera keys are presented together in Chapter 16. The Trichoptera families and genera are split into two chapters (17 and 18), and Tipulidae (23), Culicidae (24), Simuliidae (25), and Chironomidae (26) are broken out in separate chapters from the rest of the Diptera (22). Keys to the pupae are also provided for the Trichoptera and Diptera in their respective chapters. Regional taxonomic literature is cited for families in each order and ecological attributes and regional tolerance values to organic pollution are provided for each genus in tabular format at the end of each chapter. A glossary of terms, a large bibliography, and an index follow the taxonomic treatments.

Several significant changes have been introduced to the fourth edition. The size of the volume has increased from 862 to 1158 pages and the number of contributing authors has increased from 42 to 45. A healthy addition of 243 color photographs provides the reader with reference images of each insect order. These pictures are placed toward the beginning of the book and are grouped by order in chapter sequence. Representative specimens of each order are provided with the family and genus labeled below each picture. While these color plates are a welcome addition, they might be more strategically placed within their respective order chapters. Taxonomic treatments of the Ephemeroptera and Coleoptera have been revised. Regional tolerance values to organic pollution have been added in each chapter. The index has increased in size from 14 pages in the third edition to 20 pages in the fourth edition, and more than 800 morphological terms are included in the glossary with cross references to figures in the text where the characters are displayed. I have always found the taxonomic citations to be extremely helpful for finding regional literature on identification. More than 1000 additional references (nearly 6000 in all) have been added to the fourth edition. Individual citations are both numbered and arranged alphabetically to facilitate easy searching.

Included with this edition is a digital interactive key to the orders of larvae, pupae, and adults, produced by Ralph Holzenthal, Aysha Prather, and Stephen Marshall. Provided on a CD inside the cover and through a Web site at the University of Minnesota, this key offers many outstanding features useful to the beginner. The user interacts with the key by choosing among several alternative morphological states. There is no fixed starting point. The possible identification choices narrow automatically as the user progresses through each of several morphological features. "Best features" can be targeted for each specimen as you progress through the key. Well-labeled drawings are offered for comparison. Selected taxa with atypical characteristics within their respective orders may throw the user off. However, the key is easy to use and highly interactive, and the illustrations are terrific. This is a great addition to the book.

Reviews of an early printing were critical, as many mistakes in labeling and keys were found. Some of these mistakes remain in the corrected printing. For example, the Coleoptera family key to larvae ends on a couplet that doesn’t exist. I also found that some genera had been omitted from the ecological attributes tables of their respective chapters (e.g. Mayatrichia: Hydroptilidae). Some citations to regional identification literature are without references in the bibliography. Some of the keys refer to illustrations that are many pages from the couplet of reference and not all diagnostic characters are clearly delineated with arrows and labels.

Overall, this new edition represents a tremendous effort and continues to stand alone as a comprehensive introduction to the ecology and taxonomy of aquatic insects. The amount of information compiled and number of references cited is really mind-boggling. The new features of this book improve its utility for the insect enthusiast and aquatic scientist. Given the resources available in the book, the price is very reasonable even for students.

Nels H. Troelstrup, Jr.
Department of Biology & Microbiology
South Dakota State University
Brookings, SD
E-mail: Nels.Troelstrup@sdstate.edu
American Entomologist
Vol. 55, No.4, Winter 2009