Paddy fields are interconnected by an irrigation drainage system, and form part of a water-dependent natural ecosystem. The rice insect pest fauna in Asia is so rich that each niche in the paddy field in both the temperate and tropical zones is almost fully occupied by the same species, or by the ecological homologues of different species. Paddy fields as a semi-permanent agroecosystem of an annual crop provide a habitat for both migratory and residential pests. An increase in rice yield and its stabilization by means of high-yielding varieties have been the first priority of agricultural programs, after which the production of high-quality grain rice by cost-and labor-effective methods has been pursued. These changes were associated with a decrease in residential species, e. g. borers, while migratory pests, e. g. planthoppers, became more serious. However, the so-called BPH problems will be overcome eventually by the integrated use of selective insecticides, resistant varieties and cultural practices. Leafhoppers are an intermediate species, and remain important as virus vectors, as do planthoppers. The rise in temperature due to the greenhouse effect will have a profound influence on virus epidemiology. Since virus diseases require the most sophisticated system for integrated pest management (IPM), the systems approach will become important. In particular, the efficient utilization of local information on pest occurrence, in terms of decision-making for control, should be encouraged.