Centipedes and millipedes are frequently confused because both have long bodies and many legs. Despite their similar appearance, they behave very differently.

Neither generally wants to live in the middle of your living room. When they appear indoors, environmental conditions outside — particularly moisture — are often involved.

Centipedes

Centipedes have one pair of legs per body segment and are predators.

They feed on insects, spiders, and other small creatures.

House centipedes are especially recognizable because of their unusually long legs and remarkable speed.

They often appear in basements, bathrooms, crawl spaces, or other damp locations.

Millipedes

Millipedes have two pairs of legs on many body segments and feed mainly on decaying organic material.

They are usually slower than centipedes and often curl into a tight coil when disturbed.

Outdoors, millipedes thrive in mulch, leaves, compost, damp soil, and decaying vegetation.

Why Do They Come Inside?

Periods of heavy rain can drive both pests from saturated soil and outdoor hiding places.

Hot, dry conditions may also push them toward buildings in search of moisture.

They can enter through door gaps, cracks, foundation openings, garage doors, and other small spaces.

Are They Dangerous?

Most encounters are more startling than dangerous.

House centipedes can bite if handled, but bites are uncommon.

Millipedes generally do not bite, although some can release defensive substances that may irritate skin.

Avoid handling unfamiliar species directly.

Why Do I Suddenly Have Dozens of Millipedes?

Mass migrations occasionally occur when weather conditions change.

A homeowner may suddenly find millipedes covering a porch, foundation, garage, or basement floor.

The source is usually outdoors rather than an indoor breeding population.

Reducing moisture and organic debris near the foundation can help.

What Can Homeowners Do?

Keep leaves, heavy mulch, and decaying vegetation from accumulating directly against the structure.

Correct drainage problems and leaking exterior faucets.

Seal obvious openings around doors, foundations, and utilities.

Indoors, address excessive humidity in basements and crawl spaces.

When Should You Call a Professional?

If centipedes or millipedes appear repeatedly or in large numbers, Underworld Pest Control can help determine where they are entering and what conditions are supporting them.

Heavy centipede activity may also indicate plenty of other insects are present for them to eat.

The many-legged visitor may not always be the main problem — sometimes it is simply the pest that makes another problem visible.