Control of insect pests and weeds by their natural enemies offers a proven, feasible, safe, ecological method to pesticidal control. In this concise and fascinating account, Paul DeBach and David Rosen trace the historical background of biological control and examine in detail some of the most famous examples of the discovery of natural enemies and their implementation as active successful biological controls. The book has been thoroughly updated to incorporate recent studies, projects and developments on all aspects of biological control. Conclusions reached, however, remain the same; more biological control is needed - alone and as the mainstay of integrated pest management programmes - if there is to be a diminished use of toxic chemicals which are more expensive, less effective and most importantly, damaging to the environment. This is a second edition of the highly successful book published in 1974 under the same title.