Tea plant is perennial and evergreen, and leaves are stratified into 2 layers. The bush below the plucking surface is very important as a refuge for natural enemies because of minimal artificial effects. The ecosystem of tea field is the most complex and most stable among the Japanese agroecosystems. Most of the tea pests are polyphagous and complete their life cycle in tea fields Since the effects of natural enemies on the population of insect pests are pronounced even under insecticidal control because of the complexity of the ecosystems, excessive insecticide application is not recommended and conservation and utilization of indigenous natural enemies should be promoted in the control system of tea pests. A tentative IPM system for tea cultivation in Japan was proposed. In the system, both natural enemies and insecticides are used complementarily.