Millipede

What it does

Millipedes are slow-moving, harmless scavengers that curl into a tight spiral when threatened and may secrete a defensive fluid. They are nocturnal and moisture-dependent, staying in damp soil and litter. In fall or during heavy rains, or conversely during drought, large numbers may migrate and wander into homes, though they cannot survive long in dry interiors.

Where it lives

They live in moist, organic-rich places: under mulch, leaf litter, logs, stones, and in garden soil and compost. Indoors they appear in damp basements, garages, and around ground-level door thresholds after migrating in, usually dying quickly once inside. Millipedes are found nationwide wherever there is decaying plant matter and moisture. Though grouped here as an insect, a millipede is actually a many-legged arthropod, not a true insect.

How it breeds

Females lay clusters of dozens to hundreds of eggs in the soil. The young hatch with only a few segments and legs, adding more with each molt as they grow, and can take one to several years to mature. Millipedes are relatively long-lived and continue the cycle in moist outdoor habitats.

What it eats

Millipedes are detritivores, feeding on decaying leaves, wood, and other organic matter, which makes them beneficial recyclers in soil and compost. They occasionally nibble tender seedling roots or soft, damaged plants, but they do not eat structural wood, stored food, or fabrics in the home.

Identification

Millipedes have long, rounded, cylindrical bodies with many segments, each bearing two pairs of legs, giving a dense fringe of short legs and a slow, wave-like crawl. Most household invaders are brown to black and 1 to 1.5 inches, though some native species are larger. Curling into a coil when disturbed is a key identifying trait that separates them from centipedes.

Signs of an infestation

• Slow, cylindrical many-legged bugs that curl into a spiral
• Large numbers appearing indoors after heavy rain or in fall
• Dead millipedes accumulating near doors, garages, or basements
• Live ones found under mulch, logs, or flowerpots outdoors
• A faint odor from their defensive secretion when crushed

Prevention tips

• Move mulch, leaf litter, and debris away from the foundation
• Improve drainage and reduce moisture around the home's perimeter
• Seal gaps under doors and around the foundation and vents
• Use weatherstripping and door sweeps at ground level
• Water lawns in the morning so soil dries before nightfall

Professional solutions

Millipedes rarely require professional control, since indoor ones die quickly and the fix is habitat and moisture reduction outdoors. For repeated mass invasions, a perimeter barrier treatment around the foundation during migration periods helps, and a pest professional can apply an exterior treatment and advise on drainage and harborage reduction to prevent future waves.