Biological control is the intentional manipulation of natural enemies by man for the purpose of controlling pests. Biological control of aquatic weeds is especially attractive because rivers and lakes are sensitive ecosystems important to wildlife and human health.
Conservation is the preservation and maintenance of the natural eneimies that occur in an area.
Reducing insecticide use and providing flowers as nectar sources for wasps that need this food are examples of the conservation method of biological control. Augmentation is the periodic release of natural enemies that do not naturally occur in sufficient numbers to provide pest control. In Texas, because the problems are exotic species importation of host-specific enemies has been necessary for the success of biological control of aquatic weeds. Importation of natural enemies into areas where they do not occur is sometimes called classical biological control and is the method most commonly used in biological control of aquatic weeds. Natural enemies from the native range of the pest are identified, collected, imported, reared and released.