Have you spotted a long, many-legged creature crawling across your basement floor or patio and wondered whether it was a millipede or a centipede? While they may look similar at first glance, these two common household pests are very different in appearance, behavior, and the problems they can cause.
At Barnes Exterminating, we often receive calls from homeowners who aren’t sure which one they’ve found. Here’s how to tell the difference—and what to do if they’re making themselves at home.
Millipedes: The Slow-Moving Decomposers
Millipedes are often called “thousand-leggers,” although they don’t actually have 1,000 legs. Most species have between 30 and 400 legs.
How to Identify a Millipede
- Rounded, cylindrical body
- Two pairs of legs on most body segments
- Moves slowly
- Usually dark brown or black
- Rolls into a tight spiral when threatened
Millipedes are beneficial outdoors because they feed on decaying leaves, wood, and other organic matter. They help break down plant material and return nutrients to the soil.
Why Are They in Your Home?
Millipedes prefer cool, damp environments. During periods of heavy rain or drought, they may wander indoors looking for moisture. You’ll often find them in:
- Basements
- Crawl spaces
- Garages
- Bathrooms
- Around foundations
While they can become a nuisance in large numbers, millipedes do not bite, sting, or damage your home.
Centipedes: The Fast Hunters
Centipedes are predators that hunt insects and spiders. Unlike millipedes, they move quickly and can be startling to see racing across the floor.
How to Identify a Centipede
- Flat, elongated body
- One pair of legs per body segment
- Long antennae
- Fast-moving
- Legs extend outward from the sides of the body
House centipedes are among the most common species found indoors.
Are Centipedes Dangerous?
Centipedes have venomous front legs called forcipules that they use to capture prey. Although they can bite if handled, bites are uncommon and usually result in mild pain similar to a bee sting.
The good news? Centipedes help reduce populations of:
- Spiders
- Cockroaches
- Silverfish
- Ants
- Other household insects
If you’re seeing centipedes regularly, it may indicate another insect problem they’re feeding on.
Millipede vs. Centipede: Quick Comparison
| Millipedes | Centipedes |
|---|---|
| Rounded body | Flat body |
| Two pairs of legs per segment | One pair of legs per segment |
| Slow-moving | Fast-moving |
| Eat decaying organic matter | Hunt insects and spiders |
| Harmless to people | Can bite, but rarely do |
| Curl into a ball when disturbed | Run away quickly |
Why Are You Seeing Them?
Both millipedes and centipedes are attracted to moisture. Conditions that encourage them include:
- Excess moisture around the foundation
- Leaky pipes
- Damp crawl spaces
- Poor drainage
- Thick mulch against the home
- Heavy leaf litter
Keeping your home dry and reducing moisture can help discourage both pests.
How to Prevent Millipedes and Centipedes
Here are a few simple ways to reduce the chances of an infestation:
- Repair leaking faucets and pipes.
- Use a dehumidifier in damp basements or crawl spaces.
- Seal cracks and gaps around doors, windows, and the foundation.
- Keep mulch and landscaping several inches away from your home’s foundation.
- Remove piles of leaves and other organic debris.
- Reduce indoor insect populations, which serve as food for centipedes.
When to Call the Professionals
Seeing an occasional millipede or centipede isn’t unusual, especially after rainy weather. However, if you’re finding them frequently or in large numbers, there may be an underlying moisture or pest issue that needs attention.