An agro ecosystem is characterized by a much simpler composition with regard to the number of species residing in the system and the relative simplicity of energy flows than a natural, stable ecosystem. Therefore, the agro ecosystem needs energy input to maintain its balance. The wet paddy ecosystem, although an artificial system, has a rather complex composition of biotic and non-biotic elements, providing it with relative stability. Injudicious use of pesticides, however, disturbs this balance due to the killing of natural enemies and other organisms in the rice field.