House Centipedes

Summary

House centipedes are common inhabitants of homes and other buildings. While they are fast and have long legs, which may frighten some people, they are harmless. House centipedes feed on small arthropods, including pest insects, so their presence in large numbers may indicate another underlying pest issue.

Classifications

Common name: House centipede

Species: Scutigera coleoptrata (Linnaeus, 1758)

Family: Scutigeridae (House centipedes)

Order: Scutigeromorpha (House centipedes and kin)

Class: Chilopoda (Centipedes)

Description

Adult house centipedes have 15 pair of legs with the last pair (on adult females) nearly twice the length of the body, which is one to one and one-half inches in length (Figure 1). This gives the centipede an overall appearance of being from three to four inches in length (including legs and antennae). The legs are banded light and dark, and the body is a dirty yellow with three longitudinal, dark stripes.

Figure 1. Adult house centipede. Photograph by Mario Bassini via iNaturalist, used under a CC BY 4.0 license.

Newly hatched larvae (which are rarely seen) have four pair of legs. During the next five larval molts, the centipedes will have 5, 7, 9, 11 and 13 pairs of legs (Figure 2). On the next molt the centipede is considered an adolescent and will have 15 legs during each of the next four molts, after which it becomes an adult.

Figure 2. Immature house centipede. Notice the small size and 9 pairs of legs. Photograph by Steve Jacobs, Penn State.

Distribution

House centipedes are native to the Mediterranean region but were accidentally introduced into the southern United States. They were first recorded in Pennsylvania in 1849 and are now widespread throughout the country and the world.

House centipedes do not survive winters outdoors in Pennsylvania, but readily reproduce in heated structures. During the summer, they can sometimes be found outdoors in areas near buildings.

Life History and Behavior

There are six larval instars or molts, and four post-larval instars before the centipedes reach maturity. Females have been known to survive for several years and produce up to 150 young. During the daytime, the centipedes inhabit dark, damp locations in the home and come out at night to forage for prey.

House centipedes feed on silverfish, firebrats, carpet beetle larvae, cockroaches, spiders, and other small arthropods. If house centipedes are seen frequently, this indicates that some prey arthropod is in abundance, and may signify a greater problem than the presence of the centipedes (Figure 3).

Figure 3. House centipede feeding on a cockroach. A large house centipede population may indicate an underlying pest problem. Photograph by mourad-harzallah via iNaturalist, used under a CC BY 4.0 license.

Locations within structures that have been known to provide safe harborage for house centipedes include:

• Beneath concrete slabs - the centipedes enter the house through expansion cracks, around sump pump openings, or other breaks in slab integrity;
• Inside cement block walls - the centipedes can enter through uncapped blocks, missing mortar between blocks, and around pipes where they pass through the walls;
• In floor drains without water traps - especially those drains that are connected to dry sumps;
• Under and in cardboard boxes that are stored on slabs;
• In any damp, cool location, such as unexcavated areas (crawl spaces) under the house.

Management

Modify the Habit

Reduction in the centipede food source is the first step in managing a house centipede population. Determine what other types of arthropods, in your house, are providing a meal for the centipedes by distributing 'sticky insect traps', also called monitors, around the house. These monitors (and the service for identifying the specimens) can be obtained through a pest control company.

Harborage reduction is the second most important management tactic. With appropriate fillers, fill or seal cracks and crevices in concrete slabs and block walls. Seal the covers to sump pumps with screen and caulk. Install window screen in basement floor drains to prevent centipedes from entering from dry sumps.

Reduce the humidity by utilizing dehumidifiers. Grade the soil around the building to facilitate water movement away from the foundation.

Pesticides

Insecticides that are effective for centipedes and labeled for use in the home are formulated as either emulsifiable concentrates or wettable powders that are mixed with water for application as a spray, or as dusts.

Dusts are either boric acid or diatomaceous earth - both which are inorganic insecticides and have very low risk to mammals.

Sprays that are available for homeowner use include many of the synthetic pyrethroids such as cyfluthrin, deltamethrin, lambda-cyhalothrin, cypermethrin, permethrin or tralomethrin

Sprays or dusts should be applied to sites where centipedes are suspected such as cracks and crevices in concrete slabs, block walls, etc.

Warning

Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

Original article by Steve Jacobs (2013), reviewed by Michael Skvarla (2023)