This book synthesizes the extensive research on the species diversity of Ichneumonidae, offering a comprehensive overview of their host records and biological information in the Middle East and globally. It serves as an invaluable reference for entomologists, researchers in insect systematics, and professionals in agricultural biocontrol. With its detailed examination of ichneumonids, this book is also a crucial resource for those involved in crop protection and Integrated Pest Management. Comprising 38 chapters, of which 35 of them are dedicated to a specific ichneumonid subfamily, the book provides introductory data on biology, worldwide distribution, and interrelationships among subfamilies. It meticulously lists over 2300 ichneumonid species across 35 subfamilies, complete with host records and new findings for Middle Eastern countries. This structured approach allows readers to gain a deep understanding of each subfamily's ecological role and significance. Drawing on the latest global research, this book transcends regional boundaries, making it a must-read for anyone interested in insect systematics and agricultural biocontrol. This book will also be of great value to all those working in crop protection (especially biological control) and Integrated Pest Management.