Centipedes (class Chilopoda) are common arthropods often discovered scurrying away when a rock or piece of wood is overturned. Gardeners often debate whether these fast-moving, many-legged creatures are beneficial or harmful to their plants. Understanding the centipede’s primary role as a predator is necessary to determine its value in the outdoor landscape. This clarification is important because centipedes are frequently mistaken for their less aggressive, plant-eating relatives, the millipedes.
Identifying Centipedes Versus Millipedes
Centipedes and millipedes are often confused, but they belong to different classes of arthropods with distinct characteristics. The most telling difference is the number of legs per body segment. Centipedes have one pair of legs extending from each segment, while millipedes have two pairs on most segments, giving them a denser appearance. Centipedes also have a flatter body shape, allowing them to squeeze into tight crevices while hunting.
In contrast, millipedes feature a more rounded, cylindrical body, making them look worm-like. Movement is a strong indicator of their differences. Centipedes are known for their speed and agility, moving quickly to pursue prey. Millipedes are much slower, often moving with a wave-like motion, and prefer to curl into a tight spiral when disturbed. This behavior reflects their diets: centipedes are active hunters, while millipedes are slow-moving detritivores that feast on decaying plant matter.
Pest Control: Why Centipedes Benefit the Garden
Centipedes are predominantly carnivorous generalist predators, making them valuable allies in natural garden pest control. They actively hunt and consume a wide variety of soft-bodied garden pests and their larvae, helping to keep populations in check. Their predatory diet includes soil-dwelling mites, insect larvae, small spiders, slugs, and snails.
Centipedes use a modified first pair of legs, called forcipules, located behind the head, to inject venom into their prey, quickly incapacitating it. Since centipedes do not feed on live plant tissue, they pose no threat to garden vegetables, flowers, or herbs. Their presence signifies a functioning ecosystem where natural biological controls manage potential pest outbreaks. By reducing harmful insects, centipedes lessen the need for chemical interventions, supporting a healthier, more balanced environment.
When Centipedes Become a Concern
While centipedes are beneficial outside, they become a concern when they move indoors, often suggesting an underlying issue. Centipedes enter homes seeking food or moisture, meaning their presence may indicate an existing population of household pests like ants, silverfish, or cockroaches. They are also drawn to dark, damp areas such as basements, crawl spaces, and bathrooms, especially when outdoor conditions become too dry or cold.
The primary risk to humans is a defensive bite, delivered through their venom-injecting forcipules. Although the venom is potent enough for insect prey, it rarely causes serious harm to humans. Symptoms are typically limited to localized pain, redness, and swelling, comparable to a mild bee sting. Larger species, like the Giant Desert Centipede, can deliver a more painful bite, but most house centipedes are too small to puncture human skin easily. Managing indoor centipedes involves reducing moisture, sealing foundation cracks, and addressing the pest population providing their food source.