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How to identify it
- Shiny silver or pearl gray and soft-bodied, slender and wingless. Size: UC IPM says about 1/2 inch (up to 3/4 inch), and Clemson and Ohio State give 1/2 to 3/4 inch and 1/3 to 3/4 inch.[1][4][5]
- The body tapers from front to rear and ends in three long, thin tail-like appendages; two long antennae point forward.[1][5]
- Delicate, dustlike scales left around damaged items are a good sign silverfish or firebrats are the culprits.[1]
- Young silverfish look like small, white adults; they have no scales until after several molts.[1][6][4]
Look-alikes
Where it lives
Indoors, silverfish live in damp, warm places such as laundry rooms, basements and bathrooms (around 71 to 90°F with high humidity); large numbers can invade new homes from surrounding wild areas or arrive in lumber and wallboard.[1]
Biology and life cycle
Egg counts differ by source. UC IPM says eggs are laid in clutches averaging 50 (anywhere from 1 to 200), in crevices, on cloth or in food and dust. Clemson and Ohio State say a female lays about 100 eggs in her lifetime, singly or a few at a time, and Penn State says more than 50 offspring.[1][4][5][6]
Egg hatching time also varies: UC IPM gives about 19 to 32 days, Penn State 19 to 43 days depending on temperature, Clemson three to six weeks and Ohio State two to eight weeks.[1][6][4][5]
Lifespan: UC IPM says about 3 years, Penn State at least two to three years, and Clemson and Ohio State two to eight years. Unlike most insects they keep molting as adults; UC IPM counts 45 to 60 stages.[1][6][4][5]
They can go months without food, according to UC IPM and Ohio State, and Penn State says they live for weeks without food and water but more than 300 days if water is available. By day they gather in a central hiding place.[1][5][6]
Populations grow slowly, so a large one usually means a long-standing infestation. Silverfish usually arrive in food, books, papers, starched clothing and furniture.[4][5]
If they fall into a sink or tub they can't climb the slippery sides, which is why they're often found there; they don't come up through the drain.[1][5]
Damage and signs
- Weak jaws scrape rather than bite, leaving irregular, unconnected holes and grazed patches on paper and fabric, sometimes with fungal discoloration.[1][4][6]
- Foods and materials attacked include cereals, flour and pasta, paper with glue or paste, wallpaper, book bindings, photographs, starched clothing, cotton, linen and rayon. Penn State notes that given a choice they prefer high-protein items such as dried beef and dead insects.[1][5][6]
Health risk
Silverfish are a damage and nuisance pest; their harm is to paper, fabrics and stored dry foods.[1][6]
Control
Prevention
Keep basements, laundry rooms and bathrooms clean and dry; repair leaks and use dehumidifiers or fans, since silverfish need a lot of moisture.[1][5][4]
Sources differ on how warm silverfish like it. UC IPM describes damp laundry rooms at 71 to 90°F, while NC State, Clemson, Ohio State and Penn State say silverfish prefer cool, damp places; firebrats are the ones that seek heat, above 90°F.[1][2][4][5][6]
Keep them out
Patch holes and gaps around pipes and conduits.[1][6]
Sanitation
Clean routinely to remove dust and debris, periodically go through closets and stored items, and keep dry foods in tight-lidded containers.[1][4][5]
Traps and physical control
Monitor with sticky traps, or small glass jars wrapped on the outside with masking tape: insects climb the tape, fall in and can't climb out.[1][5][2]
Pesticides
Insecticides aren't needed for light infestations and won't work without fixing moisture and food sources. For heavy infestations, crack-and-crevice sprays or dusts such as silica gel with pyrethrin or diatomaceous earth can be used. Ohio State and Clemson say results can take 10 to 14 days, since insects in wall voids have to come out and contact the treatment.[1][5][4]
On baits the sources disagree: UC IPM says baits aren't very successful because silverfish tend not to feed on them, while NC State says a few boric acid baits used in museums work well in homes when used properly.[1][2]
More from NC State Extension
Indoors, silverfish turn up in damp spots such as bathrooms and basements and on bookshelves or in storage areas holding rarely used items, while firebrats favor hot places.[2]
Common questions
- Why do I find silverfish in my bathtub?
- They fall in while foraging and can't climb the slippery sides; they don't come up through the drain.[1]
- Do silverfish damage books?
- Yes. They graze on paper, glue and bindings, leaving irregular holes and scraped areas.[1]
- How long do silverfish live?
- Years. UC IPM says about 3 years; Clemson and Ohio State say two to eight years.[1][4][5]
- Does a lot of silverfish mean a new infestation?
- Usually the opposite. Clemson and Ohio State say populations build slowly, so a large one usually means they have been there a long time.[4][5]
Sources
- University of California Statewide IPM Program, “Pest Notes: Silverfish and Firebrats, Publication 7475 (December 2009).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnsilverfish.pdf (accessed 2026-11-11)
- NC State Extension, “Silverfish and Firebrats.” content.ces.ncsu.edu/silverfish-and-firebrats (accessed 2026-11-11)
- iNaturalist, “Lepisma saccharinum taxon page (order and family).” www.inaturalist.org/taxa/1445691 (accessed 2026-11-11)
- Clemson Cooperative Extension Home & Garden Information Center, “Silverfish & Firebrats (HGIC 2443).” hgic.clemson.edu/factsheet/silverfish-firebrats/ (accessed 2026-11-11)
- Ohio State University Extension (Ohioline), “Silverfish and Firebrats (ENT-64).” ohioline.osu.edu/factsheet/ENT-64 (accessed 2026-11-11)
- Penn State Extension, “Bristletails (Silverfish and Firebrats).” extension.psu.edu/bristletails-silverfish-and-firebrats (accessed 2026-11-11)