Introduction

This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part considers the subsocial dung beetles, carrion beetles, and passalid beetles in an evolutionary and ecological context, stressing the significance of sexual behavior and adaptations to ephemeral food. It focuses on the remarkable nests of Australian Cerceris wasps, in which egglaying females are consistently either guards or foragers. The part shows that communal nesting evolved within Cerceris as a response to ground-dwelling nest predators. Nesting is a form of parental investment in which the parents invest time and energy in the nest, rather than in prolonged contact with the eggs and nymphs or larvae themselves. Nesting insects can gather widely scattered or ephemeral food for the later consumption by immatures, so the food resources are more diverse than those used by non-nesting subsocial insects.