Centipedes and Millipedes: They’ve Got Legs, and Know How to Use Them

House Centipede
House Centipede, courtesy Joseph Berger, Bugwood.org

“They’re creepy and they’re kooky, mysterious and spooky. . .” Like the Addams family, centipedes too are creepy — they’re even poisonous! They prompt homeowners to call a pest management professional immediately. However, they’re not dangerous. Their claws have difficulty penetrating the human skin, and when they do, it usually results in minor swelling. Their numerous long legs intimidate many people, but they are no real threat.

Similar, the multi-legged millipede looks like a worm with small legs. An old Sicilian proverb says, “We keep an eye on snakes and serpent, but we do not see the millipede.” The proverb is a warning that we should look for “hidden dangers.” However, the typical house millipede is no danger at all — just a nuisance at times.

They’ve Got Lotsa’ Legs, But Here’s The Difference

House centipedes are very common in the houses in the United States. Their bodies are flattened with striped legs. They are often found in moist basements, bathrooms, and other areas. They can also be observed rapidly crawling along the walls and scurrying away when boxes and other storage items are moved.

Millipedes are usually brown to blackish in color. They often coil up just like pill bugs or sow bugs when disturbed. Unlike the flat body of the centipede, the millipede’s body is round. They live in organic matter, such as mulch in and around the house.

Another major difference between the two is the number of legs each each has. Centipedes have one pair of legs for each of its body segments, while millipedes have two legs per body segment. The centipede has longer legs, while the worm-like millipede has shorter legs, often unnoticed until closely observed.

The Invasion

In late summer, the adults of centipedes and millipedes overwinter in garden soil. When favorable temperatures arrive, they lay eggs under the surface of the soil in clusters. When the young millipedes hatch from eggs, they start feeding on dead organic matter and live for 2 to 5 years in that immature stage. As millipedes grow up, the number of their body segments as well as leg pairs increase. In the case of centipedes, a few young ones are born with a complete set of legs and body segments and they just grow in size. Centipedes are reported to live for 2 to 3 years in the immature stage, and then they become adults; until then, they feed on a wide range of insects. Centipedes can live for almost 6 years.

Millipedes have two pair of legs per body segment.

Centipede bites cause only itching and swelling; no more than a bee sting. Other than that, centipedes and millipedes cause no harm to clothing, pets, furniture, buildings, food, or other household items. They are beneficial outdoors as they help in increasing soil fertility and aid in decomposition as well. Millipedes do not bite. Instead, they produce a defensive liquid that, when disturbed, causes irritation or burns the eyes of a predator.

Management of Centipedes and Millipedes

Management of centipedes and millipedes may become necessary when they become a nuisance as their numbers increase.

Exclusion practices help reduce the number of centipedes and millipedes inside the home. In late summer, centipedes and millipedes may enter homes in search of shelter. Therefore, caulking and sealing off entry points will help prevent them from entering. Removal of decaying / rotting material from the landscape next to the house will help keep populations down.

Non-chemical methods indoors may involve using vacuums to suck them up, or placing glue traps to catch them. Since they hide in boxes and bags, managing clutter will help prevent infestation, giving them fewer places to hide. Dehumidifiers help in that the removal of moisture in the home, making the house an environment that is less conducive to infestation.

As far a chemical management for centipedes and millipedes is concerned, there are many insecticides and pesticides available on the market which are labeled for treatment of the pests. Pyrethroids will kill centipedes and millipedes.

Reminder: always carefully read and follow label instructions when applying insecticides. Otherwise, you may be in violation of the law. A qualified professional pest management professional knows best how to apply these materials and can offer more insight on how homeowners can reduce or eliminate infestations of centipedes and millipedes.