Recent studies have shown that genetic polymorphisms play an important role in structuring the seasonal life cycles of insects, complementing an earlier emphasis on the effects of environmental factors. This book presents current ideas and recent research on insect life--cycle polymorphism in a series of carefully prepared chapters by international experts, covering the full breadth of the subject in order to give an up-to-date view of how life cycles are controlled and how they evolve. By consolidating our view of insect life--cycle polymorphism in this way, the book provides a staging point for further enquiries. The volume will be of interest to a wide variety of entomologists and other biologists interested in the control and evolution of life cycles and in understanding the extraordinarily complex ecological strategies of insects and other organisms.

This book was developed out of a symposium at the XVII International Congress of Entomology held in Hamburg, Germany, on August 21, 1984. This symposium was organized by Drs. William Bradshaw and Hugh Dingle, who subsequently asked us to edit the proceedings. The chapters represent, for the most part, papers that were read in Hamburg but have been expanded and updated. The goal of this volume is to provide a comprehensive view of current research on insect life cycles, including field and laboratory studies, broad comparisons among species or local populations, and intensive studies of single populations, as well as theoretical research. Of necessity, given the magnitude of research now being carried out on insects, some important research programs are not included, and therein lie the makings of future volumes. This volume is divided into three parts. The first part, Geographical Patterns in Insect Life Cycles, explores various applications of a comparative method that has been valuable in investigating the potential for variability in life history parameters and the relation of these parameters to important variables in the environment.

Our highly seasonal world restricts insect activity to brief portions of the year. This feature necessitates a sophisticated interpretation of seasonal changes and enactment of mechanisms for bringing development to a halt and then reinitiating it when the inimical season is past. The dormant state of diapause serves to bridge the unfavourable seasons, and its timing provides a powerful mechanism for synchronizing insect development. This book explores how seasonal signals are monitored and used by insects to enact specific molecular pathways that generate the diapause phenotype. The broad perspective offered here scales from the ecological to the molecular and thus provides a comprehensive view of this exciting and vibrant research field, offering insights on topics ranging from pest management, evolution, speciation, climate change and disease transmission, to human health, as well as analogies with other forms of invertebrate dormancy and mammalian hibernation.

This volume is an outgrowth of a Symposium entitled "Evolution of Escape in Space and Time" held at the XV International Congress of Entomology in Washington, D. C., USA in August, 1976. The choice of topic was prompted by recent advances in evolutionary ecology and the apparent suitability of insect migration and dia pause as appropriate material for evolutionary studies. In the event, that choice seems amply justified as I hope a perusal of these papers will show. These Sympos ium papers hardly cover the topic of the evolution of escape mechanisms exhaustively, and I am sure everyone will have his favorite lacuna. Some of the more obvious ones are indicated by Professor Southwood in his Concluding Remarks at the end of the book. The purpose of the Symposium, however, was not complete coverage, but rather to indicate the potential inherent in insect migration and diapause for the study of evolutionary problems. In that I think we have succeeded reasonably well. These papers are expanded and in some cases somewhat altered versions of the papers delivered in Washington. This has allowed greater coverage of the topics in question. I suggested a format of a general overview of a topic emphasizing the author's own research con tributions. In general the papers follow this outline although emphases vary. Two of the authors, Dr. Rainey and Dr. Lumme, were unable to attend the Symposium. Dr. Rainey's paper was read by Mr. Frank Walsh, but Dr.