Silverfish are small, wingless insects known scientifically as Lepisma saccharinum that frequently become household pests. They belong to an ancient lineage, with fossils dating back hundreds of millions of years, making them one of the oldest insect groups still alive today. The insect gets its common name from its distinct silvery-gray color and its quick, wiggling movement that resembles a fish swimming. As a common nuisance, the silverfish is primarily a scavenger, often seeking out specific conditions and materials within homes. Understanding their habits and physical characteristics is the first step toward managing their presence.
Defining Physical Traits
The size of an adult silverfish falls between a half-inch and one inch in length, excluding their long appendages. Their body shape is distinctive, often described as carrot- or tear-drop shaped, tapering noticeably from the wide head down to the abdomen. This flattened, elongated body is covered in fine scales that give the insect its characteristic metallic, silvery-gray sheen.
Silverfish possess two long, slender antennae that sometimes reach a length equal to or greater than their body. The rear end features three prominent, bristle-like filaments, known as cerci, which project backward like tails. These insects are wingless and move with a rapid, darting motion when disturbed.
Common Living Spaces
Silverfish are nocturnal creatures, meaning they are most active during the night, which often allows them to go unnoticed until an infestation is well established. Their survival is highly dependent on environmental moisture, as they require a high relative humidity, typically between 75 and 95 percent, to thrive. This preference for damp conditions dictates their primary locations within a residential structure.
They are frequently found in areas of the home where moisture tends to accumulate, such as basements, laundry rooms, and bathrooms, often hiding within cracks, crevices, and wall voids. Attics can also become favored habitats, especially if there is moisture present from leaks or poor ventilation. Outdoors, they naturally live under leaf litter, bark, and rocks, but they seek out the controlled environment of a home for consistent moisture and shelter.
Destructive Diet
The silverfish diet focuses on materials that contain polysaccharides, which include starches, cellulose, and dextrin. They are able to digest cellulose thanks to an enzyme called cellulase produced in their midgut. This specific dietary need makes common household items targets for their feeding habits.
They commonly consume paper products, such as books, cardboard boxes, and wallpaper, by eating the starchy glues and pastes found in these items. They also feed on certain natural fabrics, including cotton, linen, and silk, especially if starched. Other items in their diet include stored pantry goods like flour and cereal, dead insects, and even their own shed exoskeletons. The damage they cause appears as irregular holes, notches along edges, or light gray surface scrapings on the material.