Why the silverfish is a primitive, paper-eating survivor that defies insect norms

Nature · Published 29 September 2026 Swipe more like this →

In short: The silverfish is a wingless, nocturnal insect that has thrived for millions of years by consuming everything from book bindings to dandruff. Despite their reputation as household pests, these metallic-scaled creatures possess remarkable biological traits, including the ability to regenerate lost body parts and continue molting long after reaching adulthood.

The silverfish, scientifically known as Lepisma saccharinum, is a primitive, wingless insect that has existed in various forms for eons. Its common name is derived from its distinctive silvery, metallic sheen and a wiggling, fish-like movement. Measuring only 7 to 10 millimeters in length, these insects are agile runners that prefer dark, moist environments with relative humidity levels between 75% and 95%. While they are cosmopolitan, found across every continent except Antarctica, they are most frequently encountered by humans in attics, basements, and libraries, where they feed on starchy materials like paper, glue, and book bindings.

What truly sets the silverfish apart from most other insects is its unusual life cycle. While many insects stop molting once they reach maturity, silverfish continue to shed their exoskeletons throughout their entire lives, which can last anywhere from two to eight years. During this time, they may undergo between 17 and 66 molts, sometimes shedding their skin as often as 30 times in a single year. They are also capable of regenerating lost antennae and terminal filaments within four weeks, a testament to their evolutionary resilience.

Their diet is equally impressive, if destructive. Silverfish possess the unique ability to digest cellulose by producing cellulase in their midgut, allowing them to consume paper, cotton, and even synthetic fabrics when food is scarce. Despite their ability to damage property and contaminate food, they do not transmit diseases to humans. Their reproductive habits are also complex, involving a three-phase courtship ritual that lasts over half an hour, culminating in the female collecting a sperm capsule deposited by the male. Though they are often viewed as pests, they remain a fascinating example of a primitive organism that has perfectly adapted to the human-built environment.

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