AbstractThis chapter describes ecological case histories for a number of species belonging to order Entomophthorales (Massospora spp., Neozygites spp., Strongwellsea castrans, Entomophthora muscae, Entomophaga grylli, Entomophthora thripidum and Conidiobolus spp.) and discusses the life cycle, taxonomy, spatial and temporal distribution, persistence, dispersal and impact of these species on host biology and behaviour which are keys to the effective exploitation in specific environments. The use of these species in pest management is discussed with particular emphasis on future opportunities.