House centipedes (Scutigera coleoptrata) do live in Arizona homes, and they’re one of the most startling but least dangerous pests you’ll encounter there. These fast-moving, long-legged arthropods are drawn indoors by moisture and prey, making Arizona’s irrigated homes an oasis in the surrounding desert. Before you reach for a shoe, it helps to know what you’re dealing with, whether it can hurt you, and how to keep it out.
What House Centipedes Look Like
House centipedes are 1 to 1.5 inches long with a yellowish-grey body marked by three dark stripes running along the top. Their most distinctive feature is their legs: long, delicate, and banded with dark rings. Those legs fan outward and give the centipede a feathery, almost eyelash-like silhouette that looks nothing like most other crawling insects. They have 15 pairs of legs, with the rear pair extending so far back that it’s easy to mistake them for antennae.
They’re also remarkably fast. House centipedes are built for speed, darting across walls and ceilings in short bursts that tend to alarm people far more than slower-moving pests do. They’re nocturnal, hiding in dark, damp spots during the day and emerging at night to hunt.
House Centipedes vs. Desert Centipedes
Arizona is also home to the giant desert centipede (Scolopendra heros), and confusing the two is common. The differences are dramatic once you know what to look for. Desert centipedes are 6 to 8 inches long, sometimes reaching up to 12 inches in warm areas. They’re heavy-bodied, typically brown or reddish-orange with dark heads, and their legs are short and stout relative to their body. House centipedes, by contrast, are small, fragile-looking, and pale.
The behavioral difference matters too. Desert centipedes are primarily outdoor creatures found under rocks and debris. They deliver a painful, medically significant bite. House centipedes are the only centipede species known to survive and reproduce entirely indoors, and their bite is far milder. If you see a small, spidery-looking centipede streaking across your bathroom floor at 2 a.m., it’s almost certainly a house centipede.
Why Arizona Homes Attract Them
This seems counterintuitive in a desert climate, but house centipedes need moisture to survive. Arizona homes create exactly the right conditions. Evaporative coolers, irrigated landscaping, bathroom humidity, and leaky pipes all generate the damp microenvironments these centipedes depend on. They seek out the coolest, most humid corners of a structure: crawl spaces, areas beneath concrete slabs, basement-level rooms, and spaces around floor drains.
They get inside through surprisingly small gaps. Common entry points include expansion cracks in concrete slabs, openings around sump pumps, gaps where pipes pass through walls, uncapped cement block walls with missing mortar, and floor drains without water traps. Once inside, they settle under cardboard boxes stored on concrete floors, in unexcavated crawl spaces, and behind fixtures in bathrooms and laundry rooms.
The other thing drawing them in is food. House centipedes are predators. They hunt cockroaches, silverfish, carpet beetle larvae, ants, bed bugs, and other small insects. If you’re seeing house centipedes regularly, it often signals that another pest population is sustaining them. In that sense, they’re a symptom as much as a problem.
Are House Centipede Bites Dangerous?
House centipedes can bite, but they rarely do, and the consequences are minor. Their front legs are modified into venom-injecting structures called forcipules, but they’re small and often can’t easily penetrate human skin. When a bite does happen, the typical result is localized pain, redness, and mild swelling that resolves within hours to a few days.
Centipede venom in general contains a mix of enzymes, serotonin, and histamine that cause pain and inflammation at the bite site. Larger centipede species (like the desert centipede) can cause more intense reactions including lingering pain, numbness, tingling, and occasionally mild systemic symptoms like headache, nausea, or dizziness. For house centipedes specifically, these broader symptoms are extremely uncommon. The clinical course is self-limited and rarely involves anything serious.
For pets, the risk is similarly low. In one documented case reported by Poison Control, a cat ate a dead house centipede and showed no symptoms at all. In another, a dog that swallowed a centipede and was stung inside its mouth drooled temporarily but recovered after drinking cool water. Pets that eat or are bitten by house centipedes generally do fine without intervention.
Their Role as Indoor Pest Control
House centipedes are genuinely effective predators of household pests. They actively hunt at night, chasing down prey with speed rather than trapping it. Their diet includes many of the insects Arizona homeowners dislike most: cockroaches, silverfish, ants, and small spiders. A single house centipede can consume multiple prey items in a night.
Some pest management professionals consider them beneficial for this reason. If you can tolerate their appearance, a few house centipedes may actually reduce other pest populations in your home. That said, large numbers of them suggest a moisture problem or a significant prey insect population that’s worth addressing on its own.
How to Keep Them Out
Because house centipedes depend on humidity, moisture control is the most effective long-term strategy. Run dehumidifiers in bathrooms, laundry rooms, and any below-grade spaces. Fix leaking pipes and faucets promptly. If you use an evaporative cooler, monitor indoor humidity levels and ventilate to prevent moisture from accumulating in enclosed areas. Outside, grade the soil around your foundation so water drains away from the building rather than pooling against it.
Sealing entry points makes a significant difference. Caulk cracks in concrete slabs, especially around plumbing penetrations. Cap open cement blocks in foundation walls and fill gaps in mortar joints. Add water traps to floor drains that connect to dry sumps, since these are a common and overlooked entry route. Repair torn window screens and add weatherstripping to exterior doors.
Reducing clutter in storage areas also helps. Cardboard boxes sitting directly on concrete floors are a favorite hiding spot. Switching to plastic storage bins with lids and elevating them on shelves removes harborage. In garages and sheds, keep stored items off the slab when possible.
If you want to create a chemical barrier, perimeter insecticide treatments applied around door frames, window casings, baseboards, and the exterior foundation line can deter centipedes from entering. For persistent problems, addressing the underlying prey population is usually more effective than targeting centipedes alone. Reducing cockroach or silverfish numbers removes the food source that’s sustaining them, and the centipedes will leave or die off on their own.