Social Insects, Volume IV is the last installment of a four-volume treatise and is dedicated to the discussion on wasps and ants. Comprised of four chapters, this volume focuses on the sociality of various types of ants as their group has very diverse habits. The first chapter describes the general biology and behavior of social wasps and discusses the cyclical populations, nest associates, and communal defense of wasps. Chapter 2 introduces the broad and general overview of the biology of ants, including their behavior, food collection, and nest construction. Chapters 3 and 4 present the biology of army and fungus ants, respectively. This volume also explains how ants are defined and identified, including their colony composition and behavior. As with the previous volumes, this volume seeks to be of service to students, researchers, and scientists in various fields of research, particularly entomology, social biology, zoology, and biological science.