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Millipedes are common arthropods found in damp locations where they feed on decaying organic matter. Millipedes are are beneficial as “recyclers” as they break down decaying organic matter. Millipedes are not harmful; they cannot bite or sting and they do not attack people, property, possessions or pets.

Millipedes live outdoors or in damp locations such as greenhouses and hide during the day under leaves, needles and dead plant debris, or in cracks and crevices. They are most active at night when the humidity is higher or when dew is present.

Millipedes have an elongated, worm-like body with two pairs of short legs on the underside of almost every body segment. The common millipede is approximately 1 inch long with a hard, rounded, cylindrical body that is brown to blackish in color. They have short, inconspicuous legs and they usually coil into a spiral when handled or disturbed and when dead.

The garden or greenhouse millipede (also called flat-backed millipede) is often abundant in greenhouses (as the name implies) but is also found in potted houseplants and may live outdoors in damp areas. The garden millipede is different from the more common millipedes by being moderately flattened from top to bottom and lighter colored. The legs are fairly prominent. Flat-backed millipedes have small “flanges” or ridges along the sides of each body segment.

Life cycle of millipedes

Millipedes spend the winter as adults, hiding in protected locations.  Eggs are laid in the soil or under decaying organic matter.  Young millipedes that hatch from eggs resemble small, shorter versions of adult millipedes. The immature millipedes grow gradually in size, adding segments and legs as they mature.

Growth and development occurs in damp areas with decaying organic matter.  Millipedes can not reproduce indoors. All millipedes found inside wandered in by mistake.

Damage caused by millipedes

Millipedes are harmless; they do not feed upon building structures or furnishings and they cannot bite or sting.  However, millipedes can be annoying as accidental invaders in houses and other buildings when they migrate into buildings over night. Millipedes are usually found in the garage, basement or lowest level although they may wander into other parts of the house.  Millipedes in greenhouses, gardens and potted plants may be annoying but do not feed on the plants unless the plant is already damaged or decayed.