Synopsis What attracts an insect to a plant is a fascinating topic but is still mostly unknown. Yet an understanding of the insect-plant relationship is essential to formulate any conceptual approach towards elucidating the subtleties and subterfuges of the functional aspect of this relationship. Do insects, for example, only damage the plants often altruistically or there is also reciprocacity between plants and insects? Given a certain amount of mutualism between insects and their plant hosts, when and how do the insects become pests? What indeed insects gain from plants and plants from insects in an equilibrium situation? These and related question are of great significance in understanding the basic of pest problems and in the evolution of the plants' natural defences against insects. The book traces the ecological basis of insect-plant mutualism, the development of plant defence against insects, and functional significance of toxic phytochemicals in the management of odyssey insects. In brief, an adduce from the ecology of insects on plants to ecological management of insect when they become pests.