No International Congress of Entomology would now be complete without a symposium on insect life-cycles. The latest Congress, held at Vancouver, BC (Canada), in July 1988, was no exception, with a symposium on the genetics, evolution, and coordination of insect life- cycles organized by Bill Bradshaw and Valerie Brown. The present volume arose from papers contributed by most of the speakers at the symposium, together with papers from other invited authors. In editing the book, I have been assisted greatly by the other authors, particularly Bill Bradshaw, Val Brown and Fritz Taylor. All contributors agreed to referee two other chapters, a system that worked efficiently and effectively: I thank all authors for performing this task in the face of other demands on their time. I would also like to thank Philip Corbet, John Greenslade, Bryan Clarke, and Gillian Thompson of Springer for their help. Nottingham Francis Gilbert January 1990 Contents List of Contributors ………………………………………………. xiii SECTION I. Genetics of Life-Cycle Traits Introduction William E. Bradshaw …………………………………………. 3 1 Understanding the Evolution of Insect Life-Cycles: The Role of Genetic Analysis.