House Centipede (Scutigera coleoptrata): Facts, Legs and Speed

What is a house centipede?

Centipedes are not insects. They form the class Chilopoda, a group of about 3,000 described species of predatory arthropods, and together with millipedes they belong to the myriapods, the many-legged arthropods. Every centipede has one pair of legs per body segment and a pair of venom claws just behind the head.

The house centipede belongs to the order Scutigeromorpha and the family Scutigeridae. Carl Linnaeus described it in 1758 as Scolopendra coleoptrata. In 1801 the French naturalist Jean-Baptiste Lamarck moved it to a new genus, Scutigera, a name built from Latin words meaning “shield bearer”, which refers to the plates on its back.

It is by far the most familiar member of its order in Europe and North America. Its close relatives live in warm temperate and tropical regions on every continent except Antarctica.

Appearance: stripes, long legs and big eyes

The house centipede looks very different from the flat, short-legged centipedes found under logs. Its stiff body is yellowish gray, with three dark stripes running along the back, and its legs are banded with dark rings. The back is covered by a small number of large plates, most of them spanning more than one body segment, which is why the body looks short and rigid rather than flexible.

The legs get longer toward the rear. The last pair, called the ultimate legs, can be about twice as long as the first pair and trail behind like a second set of antennae. Because the long antennae and long hind legs look so similar, it can be hard to tell which end is the head, a trick known as automimicry that may confuse predators.

Most centipedes are blind or can only tell light from dark. The house centipede is an exception: it has large faceted eyes made of many small units, similar to the compound eyes of insects, and they are sensitive to daylight and especially to ultraviolet light. Even so, it relies mainly on its long antennae, which detect touch and smell, to find prey.

Another unusual feature is how it breathes. Most centipedes have breathing holes, called spiracles, along their sides. House centipedes and their relatives instead have a single row of openings along the middle of the back.

How big and how fast is a house centipede?

An adult house centipede’s body is typically 25–35 mm (1–1.4 in) long, and larger individuals are occasionally found. With its legs and antennae included it can look 75–100 mm (3–4 in) long, which is why people often remember it as bigger than it really is. Its weight is rarely measured, but it amounts to only a fraction of a gram.

Tropical giant centipedes are far bulkier: the Amazonian giant centipede can reach about 30 cm (12 in). See How big do centipedes get? for the full range, from tiny soil centipedes to giants that catch bats.

Running speed

The house centipede is one of the fastest centipedes. It has been measured running at about 0.4 m (1.3 ft) per second, or roughly 1.4 km/h (0.9 mph). That is slow by human standards, but for an animal with a body about 3 cm long it equals roughly 10 to 15 body lengths every second.

Its leg design makes this speed possible. Because each pair of legs is slightly longer than the pair in front, the rear legs step above and outside the front ones instead of tangling with them. The house centipede typically darts forward, stops dead, then darts again, a stop-start style that makes it hard to follow by eye. It runs just as easily up walls and along ceilings.

How many legs does a house centipede have?

An adult house centipede has 15 pairs of walking legs, 30 legs in total. In front of them sits a pair of forcipules, venom claws that are really a modified pair of legs, so it has 32 leg-like limbs if these are counted.

Young house centipedes hatch with only four pairs of legs and gain more as they molt: five pairs after the first molt, then seven, nine, 11, 13 and finally 15. After reaching the full 15 pairs, they keep molting several more times as they mature. Other centipedes have far more legs, up to 191 pairs, as explained in How many legs does a centipede have?.

If a predator grabs a leg, the house centipede can shed it and run off, a defense called autotomy. Its long, thin legs break off easily, which is why house centipedes are often seen with a few legs missing.

Habitat and range

The house centipede is native to the Mediterranean region. Carried by people with goods and building materials, it has spread through much of Europe, Asia and North America, and it has also been recorded in South America. In the United States it was already common in houses by around 1900: a 1902 description by C. L. Marlatt, an entomologist at the U.S. Department of Agriculture, pictured it darting across floors and alarming the people living there.

Centipedes lack the waxy coating that protects insects from drying out, and they cannot close their breathing holes, so the house centipede needs damp, sheltered places. Outdoors it lives under large stones, in woodpiles, leaf litter, compost heaps and caves. Indoors it favors basements, garages, bathrooms and kitchens, although it can turn up in any room.

In warm climates it lives mostly outdoors. In cooler regions it depends more on buildings, where it can survive winter and spend its whole life indoors. People notice house centipedes most in spring, when warmer weather makes them active, and in autumn, when falling temperatures drive them to seek shelter.

What does the house centipede eat?

The house centipede is a predator of insects, spiders and other small invertebrates. Prey recorded for the species includes:

• Cockroaches and silverfish
• Spiders
• Termites, ants and bed bugs
• Fly larvae and other insect larvae
• Worms and small snails

It hunts mostly at night. When its antennae find prey, it either jumps onto it or sweeps its long legs around it, a technique described as “lassoing”, then stabs it with its venom claws. Because it can hold prey with its legs as well as its mouthparts, it can deal with several small insects at the same time.

House centipedes also seem to judge risk. In feeding experiments they avoided some dangerous prey and changed tactics for others: with wasps, for example, they injected venom and then backed away until it took effect. After eating, they retreat to a safe hiding place.

Behavior

House centipedes are solitary and mostly nocturnal. By day they hide in cracks, under objects or in dark corners, and at night they hunt along floors, walls and ceilings. When a light is switched on they often freeze for a moment before running for cover.

They spend time grooming, curling around to pull each leg through their venom claws and mouthparts to clean it. Their long legs and antennae are covered in sense organs, so keeping them clean helps them hunt.

Reproduction, life cycle and lifespan

Courtship takes place in the warmer months. A male and female circle each other and touch with their antennae; the male then deposits a packet of sperm, called a spermatophore, on the ground, and the female picks it up to fertilize her eggs. There is no direct mating.

Females lay their eggs in soil or damp crevices, mainly in spring. In one laboratory study of 24 house centipedes, females laid an average of 63 eggs, with a maximum of 151. The young hatch looking like tiny pale adults with only four pairs of legs and add legs at each molt.

House centipedes can start breeding in their third year and live roughly 3–7 years, depending on conditions. That is a long life for a small invertebrate, since many insects of similar size live less than a year.

Are house centipedes dangerous?

House centipedes are venomous but pose very little risk to people. They are not aggressive and run away when disturbed, so bites, strictly speaking stings from the venom claws, happen mainly when one is pressed against skin or handled. Their small claws often cannot pierce human skin at all.

When a bite does break the skin, the usual result is brief local pain and swelling, often compared with a bee sting. Allergic reactions are rare, but anyone who has a severe reaction should seek emergency medical help immediately (call 911 in the US, 112 in the EU or 999 in the UK). The full picture is in Are house centipedes dangerous?.

Predators and conservation status

Like other centipedes, house centipedes are eaten by a range of small predators, including small mammals, salamanders, birds and larger spiders. Their speed, their ability to shed legs and their venom help them escape.

The house centipede has not been assessed by the IUCN, so its Red List status is Not Evaluated. It faces no known threats as a species: people have greatly expanded its range, and it remains common in and around buildings across the Northern Hemisphere.

Myths and facts

Myth: house centipedes are insects. Insects have six legs and three body parts. The house centipede has 30 walking legs and belongs to a separate class of arthropods, just as spiders do; see spider vs insect for how insects are defined.

Myth: a house centipede is a kind of millipede. Millipedes have two pairs of legs on most body segments, move slowly and eat decaying plants. The differences are laid out in centipede vs millipede.

Myth: house centipedes run at people to attack them. When disturbed, a house centipede bolts for the nearest dark gap, which can mean under furniture or toward a person’s feet. Observers more than a century ago already concluded that it was looking for cover, not attacking.

Fact: their group is ancient. The oldest known centipede fossils, from the late Silurian period about 430 million years ago, have been identified as relatives of the house centipede.