Centipedes-fast-moving, multi segmented arthropods up to several inches long-prey on household and garden insects. House centipedes are harmless to humans, but the bite of some other species is poisonous. They bite humans only if disturbed. You may be allergic to their venom; if you are bitten, consult a physician.
Millipedes, often mistaken for centipedes, are harmless, slow-moving arthropods with two pairs of legs per segment (centipedes have one pair). Millipedes feed on decaying organic matter. Both hide in damp places: in decaying vegetation, beneath scrap lumber, and in other debris.
To rid your house of an infestation, clear the foundation and the basement of all such hiding places. Locate your compost pile well away from the house. If the problem persists, spray infested areas with the household formulation of malathion or with diazinon or carbaryl.