Parasitoid wasps are cosmopolitan, numerous and enormously diverse with probably one million or more species worldwide, most of which occur in moist tropics. The ecological importance of this group of insects is enormous although perhaps most evident in their major roles in the control of insect pest populations. In natural ecosystems they are integral in regulating populations of a vast number of insects, and therefore are key players in terrestrial food webs. Knowledge of their biology is still very poor because the current state of taxonomy is still in its infancy in many parts of the world. In this book, we provide an overview of the more than 30 families of parasitoid wasps that are found in the 11 countries in South East Asia. Particular emphasis is given to the most commonly encountered and reared, and those used as natural enemies in biological control programmes. In addition, outlines of the biology, ecology and behaviour of each family and important subfamily are presented. The current state of taxonomy in the region is summarised using distribution maps. Other chapters cover basic morphology, terminology and identification, collecting and rearing in the tropics, food web construction, and the molecular revolution in identification of difficult taxonomic groups. All groups are photographically illustrated. This book will be of value to professional entomologists, academics, entomology students and the growing body of amateur entomologists and insect photographers.