The function of spider egg sacs in relation to parasitoids and predators,with special reference to the Australian fauna

The function of spider egg sacs is analysed as structures to reduce or prevent mortality by parasitoids and predators. The host relationships of the groups concerned are documented, with special reference to the Australian fauna. Many new records are presented and the biology of each group is discussed. Information presented supports the hypothesis that egg sacs are an effective barrier against scavenging predators (generalists), while coevolution between spiders and their specialized (highly adapted) parasitoids and predators is responsible for the specificity displayed by the latter two groups and the structural diversity evident of egg sacs.