Book excerpt: One of the principal aims in writing this book pertains to the increasing impact of human influence on natural habitats in recent years, more notably to the loss of habitat quality. Increased urbanization, considerable reduction in natural forest areas, changing ecology of fresh water ecosystems, lakes and wet lands, besides changing microhabitats, have had their impact on insect populations. A wide range of responses exist among several species of insects living in these changing environments, more especially landscape dynamics creating a shifting mosaic of habitats. Sudden changes in the extent or quality of habitat tend to influence the behaviour, reproduction and survival of individuals. In very rare cases the existence of a particular species depends on the presence of some other species, not to mention of the extinction of food chains. As such, a basic understanding of the nature of habitat loss and fragmentation and their impact on insect species dynamics become important. Numerous questions are raised about patterns and timing of the evolution of insect-plant association which are essential for an understanding as to ``why the world is the world as it is today''. In this effort several specialists on diverse aspects have generously rendered assistance through providing literature and photographs and while appreciating their generosity, we would like to thank them individually for all the assistance rendered without which the production of this volume would be impossible.