There are about 10 quintillion insects in the world divided into more than 1 million known species, and some scientists believe there may be more than 30 million species. As the largest living group on earth, insects can provide us with insight into adaptation, evolution, and survival. The internationally respected third edition of Marc Klowden's standard reference for entomologists and researchers and text for insect physiology courses provides the most comprehensive analysis of the systems that make insects important contributors to our environment. Physiological Systems in Insects discusses the role of insect molecular biology, neuroendocrinology, biochemistry, and genetics in our understanding of insects. All chapters in the new edition are revised, and major revision in fast-moving areas including the Endocrine, Developmental, Behavioral, and Nervous System chapters. This new edition includes the latest details from the literature on hormone receptors, behavioral genetics, insect genomics, neural integration, and much more. Organized according to insect physiological functions, this book is fully updated with the latest and foundational research that has influenced understanding of the patterns and processes of insects, and is a valuable addition to the collection of any researcher or student working with insects. Third edition has been updated with new information in almost every chapter and new figures. It includes an extensive up-to-date bibliography in each chapter for readers who need to pursue topics in more depth. It provides a glossary of common entomological and physiological terms.