This book is a timely compilation of synthesized information on behaviourally fascinating and economically important mites. The book gives much attention to fundamental aspects of eriophyoid anatomy, behaviour, ecology and even systematics, as bases for understanding the ways of life of eriophyoid mites and their effects on host plants; in turn, this will lead to developing the most appropriate means of regulating mites as detrimental or beneficial organisms. It presents new views intended to stimulate interest in eriophyoids and their enemies, and it points to areas where further research is needed. This book is intended for extension workers, experts of acarology and plant protection as well as students, teachers and researchers. It stimulates readers to critically test the view presented and aimes ultimately toward environmentally safe, sustainable and economically efficient means of regulating detrimental and beneficial eriophyoid mites.