Silverfish and centipedes are frequently confused household pests, yet they represent two fundamentally different groups of arthropods. Both are multi-legged invertebrates that thrive in damp, dark environments and move rapidly when disturbed. Understanding their distinct classifications and physical traits is the clearest way to correctly identify the one you encounter.
Defining the Creatures
Silverfish are classified into the Class Insecta, making them true insects belonging to the Order Zygentoma. Their body is divided into three distinct sections: the head, thorax, and abdomen. They are considered primitive insects because they are wingless. Centipedes belong to the Class Chilopoda, within the Subphylum Myriapoda, which also includes millipedes. The centipede’s body is elongated and consists of many flattened, repeating segments.
Key Physical Distinctions
The most immediate difference is the number of legs. A silverfish has only six legs, characteristic of all insects, concentrated near the head of its teardrop-shaped body. A centipede, by contrast, has a single pair of legs on nearly every body segment, often resulting in 15 or more pairs. Silverfish are covered in tiny, silvery-gray scales that give them a metallic sheen and a fish-like movement. Centipedes are typically yellowish-brown and have a long, visibly flattened, segmented body.
Another major distinction lies in their appendages. Silverfish possess three long, bristle-like filaments extending from the rear of their abdomen. Centipedes have two long antennae on their head, and the first pair of legs is modified into sharp, claw-like structures called forcipules. These forcipules are used to inject venom into prey. The silverfish lacks any venomous apparatus and is not capable of biting humans.
Household Impact and Behavior
The two organisms exhibit entirely different behaviors inside a home, primarily due to their feeding habits. Silverfish are scavengers with a diet rich in starches and carbohydrates, feeding on household items like paper, book bindings, wallpaper glue, and certain fabrics. Their presence is associated with property damage, leaving behind small holes, notches, and yellowish stains on materials. They are slow-moving and nocturnal, preferring to hide in high-humidity areas like bathrooms, basements, and attics.
Centipedes are active, nocturnal predators known for their fast, darting movements. They hunt and consume other small arthropods, including spiders, cockroaches, and even silverfish. While they possess venom, a bite to a human is rare and typically results in localized pain comparable to a bee sting. Centipedes are attracted to homes because the presence of other insects provides a reliable food source in a damp, sheltered environment.