Many multi-legged arthropods are often mistaken for centipedes due to their similar appearance. This article helps differentiate true centipedes from their common look-alikes by highlighting distinct characteristics for accurate identification.
Common Centipede Look-Alikes
Millipedes are frequently mistaken for centipedes. They have cylindrical bodies, move slowly, and possess two pairs of legs on most body segments.
House centipedes (Scutigera coleoptrata) are true centipedes. They have very long, slender legs and are known for their rapid, darting movements. Their yellowish-gray bodies often bear three dark longitudinal stripes.
Silverfish have flattened, teardrop-shaped bodies, silvery or grayish-blue, and are around 1/2 to 3/4 inches long. They possess two long antennae and three distinct tail-like appendages at the rear. Their movement is a wiggling, fish-like motion.
Wireworms are the larval stage of click beetles and are found in soil. These larvae have hard, segmented, cylindrical bodies that are usually yellowish to reddish-brown, resembling mealworms. They are characterized by short legs located near the head.
Sowbugs and pillbugs, both terrestrial crustaceans known as isopods, have segmented, oval bodies and numerous legs. Pillbugs are recognized for their ability to roll into a tight ball when disturbed, a defense mechanism not shared by sowbugs.
Distinguishing Features
Differentiating these multi-legged arthropods involves observing specific physical and behavioral traits. Centipedes have one pair of legs per body segment, while millipedes have two pairs on most segments. When viewed from the side, centipedes typically have a flattened body profile, whereas millipedes are more rounded and cylindrical.
Leg length and thickness also provide clues. House centipedes have exceptionally long, spindly legs, with the last pair notably longer. Millipedes and wireworms have shorter legs often tucked beneath their bodies. Silverfish have six short legs and thread-like antennae often as long as or longer than their bodies.
Movement patterns offer another way to distinguish these creatures. Centipedes, including house centipedes, are known for their rapid, darting movements. Millipedes, wireworms, and sowbugs generally move much more slowly. Pillbugs exhibit a unique behavioral cue by rolling into a defensive ball when threatened, which sowbugs do not. Silverfish are characterized by their distinctive wiggling, fish-like movement.
Are These Bugs Harmful?
Many multi-legged arthropods are largely harmless to humans and pets. Millipedes are not venomous and do not bite or sting. Some species may secrete a defensive fluid that can cause mild skin irritation or stain skin and clothing. Millipedes feed on decaying plant matter and contribute to decomposition in ecosystems.
Silverfish do not bite, sting, or transmit diseases. They are considered nuisance pests because they can damage household items like books, paper products, and clothing by feeding on starches. Wireworms, the larvae of click beetles, are agricultural pests that can damage plant roots and seedlings.
Sowbugs and pillbugs are harmless to people and pets. They do not bite, sting, or spread diseases. These crustaceans feed on decaying organic matter and might occasionally nibble on tender plant seedlings.
True centipedes, including house centipedes, are venomous and can bite, but their venom is not medically significant for humans. A house centipede bite might cause mild pain and swelling, similar to a bee sting, and they prefer to flee rather than bite. House centipedes are considered beneficial as they prey on other household pests such as spiders, silverfish, and cockroaches.