Centipedes are recognizable arthropods characterized by their long, segmented bodies and a single pair of legs extending from nearly every segment. These creatures are swift, predatory hunters that rely on speed and venom to capture their prey. Centipedes are often confused with several other common arthropods due to their elongated shape and many legs. Distinguishing a true centipede from its look-alikes requires a closer look at body structure, movement, and feeding habits. This inspection helps clearly identify the most common segmented creatures found in homes and gardens.
The Primary Imposter: Millipedes
The most frequent source of confusion comes from millipedes, which belong to a separate class of arthropods called Diplopoda. The primary physical difference is the number of legs on each body section. Centipedes have one pair of legs per segment, while millipedes have two pairs of legs on most segments. This occurs because two body segments are fused together during development, resulting in a double-legged appearance.
This structural difference affects their shape and movement. Millipedes have a more cylindrical, rounded body compared to the centipede’s flatter form. Millipedes are noticeably slower than centipedes, moving with a rhythmic, wave-like gait that helps them burrow through soil and leaf litter. Centipedes, by contrast, are built for speed and quick turns to chase down prey.
The two creatures also differ entirely in their diet and defense strategies. Millipedes are primarily detritivores, meaning they feed on decaying plant matter, which makes them beneficial for soil nutrient cycling. They are not predators and do not possess venomous fangs. When threatened, a millipede curls its body into a tight spiral to protect its softer underside, and some species release a foul-smelling, noxious fluid as a chemical defense.
The Confusing Fast Runner: House Centipedes
The house centipede (Scutigera coleoptrata) is a true centipede, but its distinct appearance makes it a unique identification challenge often mistaken for a spider or an entirely different type of bug. Its body is relatively small, usually measuring between one and one and a half inches in length. The creature appears much larger, however, due to its fifteen pairs of extremely long, spindly legs that increase in length toward the rear.
These legs are typically banded with light and dark stripes, contributing to a startling, almost hairy, appearance as the animal runs. The house centipede is one of the fastest arthropods, capable of moving up to 0.4 meters per second across floors and walls. This speed, combined with its nocturnal habits, makes a sudden sighting particularly unnerving for homeowners.
The creature is often found indoors in dark, damp environments such as basements, crawl spaces, and bathrooms because it lacks a waxy cuticle and requires high humidity. Despite its frightening look, the house centipede is actually a beneficial presence in a home. It is an active predator that hunts common household pests, including silverfish, carpet beetle larvae, cockroaches, and spiders. It uses a pair of modified legs on its first body segment, called forcipules, to inject venom into its prey.
Minor Look-Alikes and Garden Pests
Several smaller, segmented arthropods found in garden environments are occasionally mistaken for miniature centipedes. One such group is the Symphylans, commonly known as garden centipedes. These creatures are very small, typically ranging from two to ten millimeters in length, and are whitish or translucent in color.
Symphylans lack eyes and possess six to twelve pairs of legs. They are considered pests because they feed on the delicate new root growth of plants, especially seedlings. They move quickly through the soil’s existing burrows.
Another group, the terrestrial Isopods, includes pillbugs and sowbugs, which are sometimes confused with centipedes due to their segmented bodies. Isopods are crustaceans, not insects, and have a distinctive, flattened oval body shape with seven pairs of legs. They are slow-moving detritivores that feed on decaying organic matter. Pillbugs have the unique ability to roll themselves completely into a defensive ball, and unlike centipedes, isopods are not predatory and pose no threat to humans.