Silverfish (Firebrat)

Photo of a firebrat, a type of silverfish
Scientific Name
Lepisma saccharina, Thermobia domestica, and other species
Lepismatidae (silverfish) in the order Zygentoma (or Thysanura) (silverfish)

Silverfish have elongated, flattened bodies that are usually covered with scales. They lack wings and have long antennae with many segments. At the abdomen tip are 3 appendages that look like antennae or “tails,” and the eyes are small, compound, and on opposite sides of the head. They run quickly on their six legs. Two species are most common.

  • The common silverfish (Lepisma saccharina) is silvery, tapered toward the tail, about ½ inch long, and lacks stripes, bars, or other markings.
  • The firebrat (Thermobia domestica) is shorter and stouter, not as tapered at the abdomen tip, is more yellowish, with brown bands and spots above. As its name implies, it prefers warm areas.

Similar species: Bristletails (in the order Microcoryphia) are cylindrical (not flattened), with an arched or humped thorax, usually darker and mottled, with large eyes that touch (not on opposite sides of the head). They live outdoors under bark or stones or in leaf litter (never in houses) and move by jumping.

Length (not including appendages): about ½ inch (varies with species and age).
Where To Find
image of Silverfish Firebrat Distribution Map
Statewide. There are about 14 species in the silverfish family in North America.
Commonly seen on walls or in basements, attics, closets, kitchens, and garages. They avoid light and hide in cracks, behind baseboards, and similar places. They need moist or humid places. The common silverfish prefers damp, cool areas; the firebrat prefers warm places, such as near furnaces, fireplaces, and warm pipes. Most of us know silverfish from finding them in our homes, but some species are found outdoors in garden mulch, under bark, in caves, and near the foundations of buildings.
The most well-known types of silverfish are fond of foods with a high starch content, including certain types of paper, many dried grains and other starchy or sugary foods, starched clothing, wallpaper paste, and glued book bindings — this explains why they can be so common in houses. Outdoors, silverfish chew on decaying plant material, algae, moss, lichens, and other organic materials.
Common silverfish and firebrats are indoor pests, damaging paper, books, wallpaper, fabrics, and foodstuffs. They do not transmit disease, however. Some other silverfish species live outdoors and cannot be considered problematic.
Life Cycle
After an elaborate mating ritual, female silverfish lay eggs in protected crevices. Silverfish represent an ancestral insect group with a simple life cycle. The hatchlings look like the adults, only whitish and much smaller. They go through several molts as they grow but never gain wings (much less pupate). After becoming sexually mature, they usually undergo additional molts each year. In some species, individuals can live for 8 years and molt dozens of times.
The common silverfish is a pest of human habitations worldwide. Control usually begins with reducing moisture and humidity, sealing cracks, and removing stacks of papers, undisturbed fabrics, and long-stored or spilled foods. If the infestation is bad, consult a professional exterminator.
Silverfish are eaten by house centipedes, earwigs, and spiders. They and their relatives the bristletails represent some of the most ancestral (primitive) insects and some of the first animals to walk on land. Their fossils date to 400 million years ago — about twice as long ago as the dinosaurs.
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Similar Species
About Land Invertebrates in Missouri
Invertebrates are animals without backbones, including earthworms, slugs, snails, and arthropods. Arthropods—invertebrates with “jointed legs” — are a group of invertebrates that includes crayfish, shrimp, millipedes, centipedes, mites, spiders, and insects. There may be as many as 10 million species of insects alive on earth today, and they probably constitute more than 90 percent all animal species.