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.