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How to identify it
- Long, cylindrical, many-segmented bodies with two pairs of legs per segment on most segments; most household millipedes are dark brown and about an inch long. Clemson describes garden millipedes as gray to brown and 1/2 to 3/4 inch long, and Kentucky says most millipedes that get indoors are around an inch. Most species have 30 to 300 legs.[1][4][2]
- Many curl up tightly or into a ball when threatened (Kentucky, Clemson), and Penn State says most curl into a spiral when they die.[2][4][1]
- Antennae are short and elbowed and most species have a rounded body, unlike a centipede's flattened body and long antennae.[2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| House centipede | Fast-running predator with one pair of very long legs per segment. Kentucky says centipedes have one pair of legs per body segment and run quickly, and Clemson that centipedes have venomous jaws while millipedes move slowly and don't bite people or pets.[2][4] |
| Wireworms (click beetle larvae) | Millipedes are sometimes called "wire worms", but true wireworms are click beetle larvae with only six legs. Penn State says they are usually dark yellow, feed on grass roots and don't crawl about on the soil surface.[1] |
Where it lives
Live under stones, leaf mold, mulch, compost, grass clippings and brick paths; migrations into window wells, basements and garages often follow cool weather or heavy rain.[1]
Biology and life cycle
They feed on decaying organic matter and can't survive long in the dry air of most buildings.[1][2][4]
Sources differ on what sets off the mass movements. Penn State says migrations often follow cooler weather or heavy rain and may be tied to mating, especially when millipedes climb trees, fences or buildings to about six feet. Clemson says garden millipedes migrate in huge numbers especially after heavy spring rains, and Kentucky says the cause is unclear.[1][4][2]
Outdoors, garden millipedes live in moist, protected spots under mulch and rocks, on trees, in tree holes and in clogged gutters. Clemson says they are most active at night and feed mainly on dead plant material, occasionally on young plants.[4]
They are part of the decomposer community that recycles organic matter, so they are useful outdoors.[4][2]
Damage and signs
Health risk
Millipedes don't bite, but many release defensive fluids when threatened. A 2019 dermatology review says these secretions can cause millipede burns: localized color changes in the skin that may come with pain or burning. A 2014 case report describes red, purple and bluish skin lesions with local pain after six hours of contact with a millipede.[4][5][6]
Control
Prevention
Remove compost, grass clipping piles and leaf mold near the foundation; plastic sheeting under gravel or mulch keeps soil damp and shields millipedes. Kentucky also suggests fixing leaks and standing water at crawl spaces, air conditioners, hose bibs, sprinklers and downspouts, and Clemson suggests dethatching, mowing closely and watering in the morning so the lawn dries before night.[1][2][4]
Keep them out
Caulk cracks in the foundation, door thresholds and windowsills, and add door sweeps or weather stripping. Clemson notes that garden millipedes climb walls easily, so they can get in up high as well as low.[2][4]
Traps and physical control
Sweep or vacuum millipedes that get inside; they die within days, so indoor treatment isn't necessary. Kentucky and Clemson agree that sweeping or vacuuming is usually all that's needed indoors.[1][2][4]
Pesticides
Pesticides only give temporary relief unless the damp habitat is fixed. Clemson says dusts such as boric acid in cracks and voids where millipedes enter can speed things up but work poorly where it's too moist, and outdoor sprays on mulch or leaf litter need enough water to get through the ground cover. Penn State says insecticide on gravel or mulch over plastic sheeting won't reach the millipedes living underneath.[4][1][2]
When to call a professional
If numbers are extremely high, Clemson suggests a licensed pest control operator, who may have better equipment and formulations.[4]
Common questions
- Should I spray inside for millipedes?
- No. Millipedes don't live more than a few days indoors; sweep them up and fix damp conditions outside. Kentucky says indoor pesticide use is rarely necessary.[1][2][4]
- Why are there so many millipedes in my house after rain?
- Heavy rain is one of the triggers for mass migrations, which Clemson says usually means a large population lives in the mulch, leaves and debris around the house. Penn State also links migrations to cooler weather.[4][1]
- Are millipedes dangerous?
- Not seriously. They don't bite, but their defensive fluid can stain or irritate skin; dermatologists describe millipede burns as localized skin discoloration that may hurt or burn.[4][5]
Sources
- Penn State Extension, “Millipedes.” extension.psu.edu/millipedes (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-645: Centipedes & Millipedes in & Around the Home.” entomology.mgcafe.uky.edu/ef645 (accessed 2026-11-11)
- iNaturalist, “Oxidus gracilis taxon page (order and family).” www.inaturalist.org/taxa/143390 (accessed 2026-11-11)
- Clemson Cooperative Extension Home and Garden Information Center, “Millipedes (HGIC 2434).” hgic.clemson.edu/factsheet/millipedes/ (accessed 2026-11-11)
- Cutis, via PubMed, “Lacy and Elston (2019), What's eating you? Millipede burns, Cutis 103(4):195-196.” pubmed.ncbi.nlm.nih.gov/31116815/ (accessed 2026-11-11)
- Revista da Sociedade Brasileira de Medicina Tropical, via PubMed, “Heeren Neto et al. (2014), Skin lesions simulating blue toe syndrome caused by prolonged contact with a millipede, Rev Soc Bras Med Trop.” pubmed.ncbi.nlm.nih.gov/24861307/ (accessed 2026-11-11)