Pests in their native areas are usually managed by natural predators and parasites that help keep populations at a constant level. Problems occur when pests, but not their natural enemies, are introduced into new areas, and the pest populations increase unchecked. Biological pest control involves using the plant's natural enemies to reduce pest populations. A minimum level of the target pest will always be present. This low pest population is necessary for the biological control agent to have a continual food source after the target pest has been reduced to an acceptable level. Homeowners must be willing to accept minor levels of pest pressure. Biological controls are not the answer to all pest problems, but they may be a useful component in an effective Integrated Pest Management (IPM) program.