Utah is home to two main types of centipedes: the common desert centipede, which lives outdoors in dry, rocky terrain, and the house centipede, which frequently moves indoors seeking moisture and prey. Neither is considered dangerous, though the larger desert species can deliver a painful bite. Here’s what to know about identifying them, understanding the risks, and keeping them out of your home.
Species You’ll Find in Utah
The most widespread outdoor species is the common desert centipede (sometimes called the multi-striped centipede). It’s tan and brown, typically 4 to 5 inches long, with a flat body and one pair of legs per segment. You’ll find it under rocks, bark, leaf litter, and other ground cover across Utah’s arid landscapes. It’s a fast, active predator that hunts insects and spiders, mostly at night.
The house centipede looks completely different. It’s smaller (usually 1 to 2 inches), yellowish-brown, and has unusually long, delicate legs that let it sprint across walls and floors at startling speed. Despite the alarm they cause, house centipedes are genuinely useful. They prey on cockroaches, silverfish, carpet beetle larvae, spiders, termites, and even bed bugs. If you’re seeing house centipedes regularly, it often signals a larger pest population they’re feeding on.
How to Tell Centipedes From Millipedes
Both show up in Utah homes and yards, and people frequently confuse them. According to Utah State University Extension, the key differences are straightforward:
- Body shape: Centipedes are flat. Millipedes are rounded.
- Legs per segment: Centipedes have one pair per segment. Millipedes have two pairs per segment.
- Color: Centipedes tend to be yellowish to brown. Millipedes are darker, typically dark brown to gray.
- Behavior: Centipedes are fast-moving predators. Millipedes are slow and feed on decaying plant material. Millipedes curl into a coil when disturbed or dead; centipedes don’t.
The distinction matters because centipedes can bite (they use venom to subdue prey), while millipedes are harmless. Millipedes may release a mild irritating fluid when handled, but they pose no real threat.
What a Centipede Bite Feels Like
Centipedes don’t technically bite. They inject venom through a pair of modified front legs called forcipules, which pierce the skin like pincers. The venom is a complex mix of compounds including serotonin and histamine, which trigger immediate pain and inflammation at the site.
Most bites from Utah’s desert centipede cause only local reactions: sudden, intense pain, swelling, redness, and sometimes a burning or throbbing sensation. Numbness, tingling, and tenderness around the puncture are common. There may be minor bleeding from the wound. These symptoms typically resolve within a few days without lasting effects.
In some cases, a bite triggers mild whole-body symptoms like headache, nausea, low fever, dizziness, or a general feeling of being unwell. These are more common with larger centipedes and usually pass on their own. Serious complications are rare but documented in medical literature. They include allergic reactions, including anaphylaxis in sensitive individuals, and in extremely rare cases, muscle tissue damage or kidney problems from venom toxicity. House centipede bites, by comparison, are weak and rarely break human skin.
First Aid for a Centipede Bite
If you’re bitten, gently wash the area with soap and water. Apply a cold, damp cloth or ice wrapped in fabric to the site for 10 to 20 minutes to reduce pain and swelling. If the bite is on your hand or foot, elevating it helps. Calamine lotion, a baking soda paste, or a low-strength hydrocortisone cream can ease discomfort if applied several times a day. Over-the-counter antihistamines reduce itching, and a standard pain reliever handles the ache.
Seek medical attention if swelling worsens over the following hours, the site shows signs of infection (increasing redness, warmth, pus), or you feel increasingly unwell. Get emergency help immediately if you experience difficulty breathing, swelling of the face or throat, hives spreading beyond the bite area, dizziness or fainting, or a rapid weak pulse. These are signs of anaphylaxis, which is rare from centipede stings but possible.
Why Centipedes Enter Utah Homes
Utah’s climate creates a specific pattern. Outdoor centipedes thrive in the warm months but seek shelter when conditions shift, whether from late-summer heat, early fall cooling, or monsoon moisture. The primary driver for indoor migration is the same everywhere: moisture. Centipedes need humid environments to survive, and Utah’s generally dry air means they gravitate toward any indoor water source.
Basements, bathrooms, laundry rooms, and crawl spaces are the most common spots. They also hide in closets, around potted plants, and under firewood stored indoors. Centipedes are strictly nocturnal, so you might have them without knowing it. You’re most likely to spot one during a late-night trip to the bathroom or when moving stored boxes in a basement.
An existing pest problem amplifies the issue. If your home has cockroaches, silverfish, spiders, or other small arthropods, centipedes follow the food. Solving the centipede problem sometimes means solving the underlying infestation they’re hunting.
Keeping Centipedes Out
Utah State University Extension recommends three core strategies: reduce moisture, seal entry points, and remove them physically when you find them.
Moisture control is the most effective long-term fix. Run a dehumidifier in your basement. Fix leaky pipes and dripping faucets. Make sure bathrooms and laundry areas ventilate properly. Outside, direct downspouts away from your foundation and avoid piling mulch, leaves, or firewood against the house. These organic materials create exactly the cool, damp habitat centipedes prefer.
Exclusion keeps them from getting inside in the first place. Caulk gaps around pipes, utility lines, and foundation cracks. Install or replace door sweeps on exterior doors. Check window screens for tears. Weather stripping around basement windows is particularly important in older Utah homes where small gaps develop over time.
When you find centipedes indoors, vacuuming is the simplest removal method. Sticky pest monitors placed along basement walls and in bathrooms help you gauge whether you have a few stragglers or a persistent population. If you’re consistently catching centipedes on monitors, that’s a signal to look harder at moisture issues or an underlying pest problem that’s sustaining them.