Centipede vs Millipede: Legs, Speed, Diet and Danger

Key differences at a glance

Centipedes and millipedes are both myriapods, many-legged arthropods with a head and a long, segmented trunk. Neither is an insect. Yet the two classes have lived separate lives for more than 400 million years and have evolved very different bodies and habits.

Centipedes (class Chilopoda) number about 3,000 described species. Millipedes (class Diplopoda) are far more diverse, with about 12,000 described species. The table at the top of this page summarizes the main differences; the sections below explain each one, using the house centipede and the giant African millipede as familiar examples.

Legs: one pair per segment or two?

Every centipede has one pair of legs on each leg-bearing segment, from 15 to 191 pairs depending on the species. The house centipede has 15 pairs, or 30 legs. See How many legs does a centipede have? for the details.

Most of a millipede’s body rings carry two pairs of legs, because each ring forms from two segments fused together. That is where the name Diplopoda, meaning “double feet”, comes from. Most species have between a few dozen and a few hundred legs; the giant African millipede has roughly 250 or more, and the record holder has 1,306. The full story is in How many legs does a millipede have?.

The legs also look different. Centipede legs are long and stick out from the sides of the body, while millipede legs are short and sit underneath it, so that from above a millipede can seem to glide on a rippling fringe.

Body shape and speed

Most centipedes have a flattened body, ideal for slipping into narrow cracks and under bark. Long, threadlike antennae sweep the ground ahead. Their long legs make them fast: the house centipede can run at about 0.4 m (1.3 ft) per second, roughly 10 to 15 times its own body length every second.

Most millipedes have a rounded, tube-shaped body made of hard rings strengthened with calcium salts. Their antennae are short and elbowed, and their many short legs push together in waves. This gives strength rather than speed, letting a millipede bulldoze through soil and leaf litter. A few groups, such as the flat-backed millipedes, have side flanges that make them look flatter, but they still have two pairs of legs per ring.

Diet: hunters vs recyclers

Centipedes are predators. They eat insects, spiders, earthworms, fly larvae and other small animals, and the largest tropical species also kill frogs, lizards, mice and even bats. A centipede finds prey with its antennae and kills it with venom.

Millipedes are detritivores. They eat fallen leaves that have started to rot, soft decaying wood and other dead plant matter, along with the fungi and bacteria growing on it. In doing so they break down plant material and return nutrients to the soil. Learn more in What do millipedes eat?.

Defense: venom claws vs chemical weapons

A centipede’s main weapon is a pair of venom claws, called forcipules, curving forward under the head. They are the first pair of body legs changed into pincers, each with a venom gland inside, and they exist only in centipedes. Centipedes use them to kill prey and to defend themselves. Many also run away fast, shed a seized leg, or raise their spiny last legs in a threat display.

Millipedes cannot bite in self-defense. Instead they curl into a tight coil or ball, protecting their soft legs inside a shield of hard rings. Many species also release defensive fluids from pores along the sides. Depending on the species these contain benzoquinones, which sting and stain the skin brown, or small amounts of hydrogen cyanide. Some birds and mammals still eat millipedes, but many predators avoid them.

Which one can hurt people?

Centipedes can bite, but most species are too small to cause more than brief pain. The house centipede’s small claws often cannot pierce skin, and a successful bite usually feels like a bee sting. Large tropical centipedes of the genus Scolopendra are a different matter: their bites are very painful and cause swelling. Deaths are extremely rare. The details are in Are house centipedes dangerous?.

Millipedes cannot bite or sting, and they are not dangerous unless handled roughly. Their defensive fluids can irritate and stain the skin and are harmful if they get into the eyes or mouth. With either animal, the safest approach is not to pick it up with bare hands. Anyone who has a severe reaction should seek emergency medical help immediately (911 in the US, 112 in the EU, 999 in the UK).

Lifespan and life cycle

Both groups live longer than most insects of their size. Centipedes typically live several years: about 3–7 years in the house centipede, up to 5–6 years in the brown centipede, and more than a decade in the giant desert centipede. Millipedes live from about one year to around ten, depending on the species; the giant African millipede is usually given about 7–10 years, mostly from captive animals.

Neither group mates the way insects do. A male centipede deposits a sperm packet on the ground or on a small silk pad for the female to pick up. A male millipede transfers sperm with special modified legs called gonopods.

Young millipedes typically hatch with just three pairs of legs and add segments at each molt. Some centipedes, such as the house centipede, also start with few legs and add more, while giant and soil centipedes hatch with their full set, often guarded by a mother curled around her eggs.

Where they overlap and how to tell them apart

Centipedes and millipedes often share the same damp hiding places, under logs, stones and leaf litter, and both come out mainly at night. They need humid places because neither has the waxy coating that protects insects from drying out.

To tell them apart in the garden, watch how the animal reacts when its cover is lifted. A centipede usually runs for shelter at once. A millipede usually freezes, curls into a coil or keeps plodding along slowly. If you can see the underside, one pair of legs per segment means centipede, and two pairs means millipede.