In addition to being critical components of terrestrial ecosystems, insects provide excellent model systems for understanding evolutionary ecology. Because insects are abundant, small, and relatively easy to rear, they are ideal for both field and laboratory experiments. Drawing on the Royal Entomological Society's 22nd international symposium (2003) topics include: speciation and adaptation; life history, phenotype plasticity and genetics; sexual selection and reproductive biology; insect-plant interactions; insect-natural enemy interactions; and social insects.