The purpose of this lengthy text is to help the layman understand what is happening in the field of biological control. To this end, this reader would advise reading Chapter 13 first- and then back to the beginning. There would then be something to offset the mounting feeling from chapter 1 through 12, that the cure may be worse than the disease. Granted that pesticides are palliative -- what are the alternatives? There are the beneficial insects of the title; there are the predators (which can in turn do harm); there are birds and domestic animals, reptiles and amphibians, moles and shrews and skunks. They are enemies of the harmful insects- but not always friends of man - or gardens. There are parasites and insect diseases, which have aided in control of many posts of trees and food crops -- but they in turn have areas of danger. There are diseases due to bacteria and fungi -- and biological methods and other bacilli and fungi are brought into play to defeat them. There are other methods- the use of sexual attractants, of light traps, electro-static fields- the war goes on. Biological control is for the strategic long pull; chemical control the tactical preventive measure. And the layman is caught in a morass of terms and pressures- and had better concentrate on raising insect resistant plants. This book is perhaps for the informed layman- and the specialist.