Centipedes & Millipedes

What it looks like

• Centipedes: flattened body, ONE pair of legs per segment, fast movers, large jaws
• Millipedes: cylindrical body, TWO pairs of legs per segment, slow, curls into a coil when disturbed
• House centipede: distinctive long-legged ghost-like appearance
• Both prefer dark damp spaces

Where you'll find it

• Damp basements, crawl spaces, and bathrooms
• Under leaf litter, mulch, and rocks outdoors
• Window wells and around foundations after rain
• Garages and storage rooms

Behavior & biology

Centipedes are predators — they hunt other insects (including silverfish and roaches) at night with venomous jaws. Millipedes are detritivores — they eat decaying plant matter. Both need moisture to survive. Mass millipede invasions happen after heavy rain when outdoor populations get displaced. House centipedes are actually beneficial indoor predators but most homeowners want them gone.

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Signs of an infestation

• Fast long-legged centipedes in basements at night
• Slow curled millipedes in window wells, garages, and around foundations
• Dead millipedes after they wander indoors and dry out

Health & property risk

House centipede bites are uncommon and mild. Millipedes don't bite but secrete a defensive chemical that can stain skin. Neither is medically significant.

How we treat it

1. 1

   Moisture reduction

   Reducing basement and crawl space humidity (dehumidifier, fix leaks) eliminates harborage. The single most effective step.

2. 2

   Perimeter treatment

   Residual insecticide in a 3-ft perimeter band, with focus on mulch beds, foundation plantings, and window wells.

3. 3

   Indoor cleanup

   Vacuum visible centipedes and millipedes; treat baseboards and basement corners with residual.

Why DIY usually fails

Run a basement dehumidifier. Move mulch and leaf litter away from the foundation. Pull stored cardboard and damp items off basement floors.

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