A full grown house centipede has a body about 1 to 1.5 inches long, but its 15 pairs of extraordinarily long, banded legs make it look much larger, giving it a total spread of 3 to 4 inches. That leggy silhouette, combined with surprising speed across walls and ceilings, is why these arthropods startle people far more than their size warrants.
Size and Appearance at Maturity
The adult house centipede has a flattened, yellowish-gray body with three dark stripes running down its back. Its most distinctive feature is those 15 pairs of legs, each pair slightly longer than the one in front of it, so the rear legs trail behind almost like a second set of antennae. The hindmost pair on a female can be nearly twice the length of the body itself. This design lets the centipede run remarkably fast, reaching speeds that few household arthropods can match.
Their long, sensitive antennae sweep the air ahead of them, picking up vibrations and chemical signals to locate prey in the dark. Large compound eyes (unusual among centipedes) give them better vision than most of their relatives. Up close, you can see the leg bands alternating between light and dark, which helps distinguish a house centipede from any other indoor arthropod.
How They Grow to Full Size
House centipedes don’t hatch with their full complement of legs. A newly hatched larva starts with just four pairs. Over the next five molts, it adds leg pairs progressively: 5, 7, 9, 11, then 13 pairs. After one more molt it reaches “adolescent” status with 15 pairs, then passes through four additional molts before it’s considered a true adult. That’s ten total molts from hatchling to maturity, a process that takes roughly three years.
This slow development means the large centipede you spot on your bathroom wall has been alive for a while. Females can survive for several years beyond reaching adulthood and may produce up to 150 offspring over a lifetime. If you’re seeing full grown individuals regularly, there’s likely an established population somewhere in the building.
Where They Live Indoors
House centipedes are extremely sensitive to moisture loss, so they gravitate toward the most humid parts of a home. Bathrooms, basements, crawl spaces, and laundry rooms are prime territory. They hide during the day in wall voids, cracks in the foundation, and behind stored boxes or clutter, then emerge at night to hunt.
That said, they aren’t confined to damp rooms. Once established, house centipedes can survive in the comparatively drier air of bedrooms, hallways, and living spaces. You’re most likely to encounter one darting across a floor or wall after dark, or when you move something that’s been sitting undisturbed for a while.
What They Eat
Full grown house centipedes are active predators. They hunt cockroaches, silverfish, carpet beetle larvae, spiders, ants, bed bugs, and other small arthropods. They use their speed to chase down prey, then subdue it with modified front legs (called forcipules) that inject venom. A single adult centipede can catch and eat multiple pests per night, which is why entomologists often describe them as beneficial.
If you have a thriving house centipede population, it almost certainly reflects an abundant food supply of other insects. The centipedes are a symptom, not the root problem.
Can They Hurt You?
House centipedes are venomous, but they pose very little risk to people. They’re classified in the order Scutigeromorpha, described in clinical literature as “fast but delicate.” Their forcipules often can’t reliably penetrate human skin, and when a bite does occur, it typically causes only mild, localized pain and redness that resolves within a few days.
To put the venom potency in perspective, researchers have estimated that the contents of roughly 1,000 venom glands would be needed to deliver a fatal dose to an average adult. A single house centipede has one gland. Severe systemic reactions like anaphylaxis have been documented with centipede bites generally, but these cases are rare and are overwhelmingly associated with large tropical species, not house centipedes. For most people, a bite is comparable to a mild bee sting without the allergic risk.
Keeping Them Out of Your Home
Because house centipedes depend on moisture, humidity control is the single most effective long-term strategy. Keeping indoor relative humidity below 50% makes your home far less hospitable. Run exhaust fans in bathrooms and kitchens, use a dehumidifier in the basement, and fix leaky pipes promptly.
Sealing entry points matters too. Caulk gaps around windows, install door sweeps on exterior doors, cover vents with fine mesh screens, and seal where utility pipes penetrate walls. Outside, keep mulch at least six inches from the foundation, clear leaf litter, and trim vegetation near exterior walls.
For direct deterrents, food-grade diatomaceous earth works mechanically rather than chemically. Sprinkled into cracks, door thresholds, and corners, it damages the centipede’s waxy outer coating and causes fatal dehydration over hours to days. It only works when dry, so skip damp areas. Peppermint oil (15 to 20 drops per cup of water) applied into cracks and along baseboards can repel centipedes for several days, though you’ll need to reapply as the scent fades. Cayenne pepper sprinkled in thin lines around entry points creates a barrier they tend to avoid.
The most sustainable approach is eliminating their food supply. A general pest management effort that reduces cockroaches, silverfish, and other prey insects will naturally drive house centipedes elsewhere. Without anything to eat, even an established population will thin out on its own.