The chapters in this book were developed from some of the lectures presented at a sym­ posium at the XX International Congress of Entomology held in Florence, Italy in August 1996. The purpose of the symposium was to discuss the impact of evolving modern agricultural landscapes on the insect species, of both economic and ecological importance, that utilize that habitat. Agricultural policy, to some extent, influences the choices that farmers make and thereby the shape of the agricultural landscape. In order to move toward more sustainable agro­ ecosystems future policy makers will have to consider the history of land use, consumer demands for both environmentally sound and affordable products, and the conservation of biological diversity. I would hope the information contained in this book will help stimulate discussion about the consequences of policy decisions on our agricultural landscapes and their insect inhabitants. I thank all the speakers from the symposium and in particular those that have been able to contribute chapters to this book. There have been many delays, most due to circumstances beyond anyone's control. I would like to express my appreciation to Gloria Verhey and Patrick Dumont for taking care of the book in these final months. CHAPTER I INTERCHANGES OF INSECTS BETWEEN AGRICULTURAL AND SURROUNDING LANDSCAPES BARBARA EKBOM Department of Entomology, Swedish University of Agricultural Sciences, Uppsala, Sweden 1.