Quick answer
Silverfish are small, wingless, silver-gray insects, mainly Lepisma saccharina, with a tapered body, two long antennae and three tail bristles, that live in damp, dark parts of homes and feed on starch, glue, paper and fabric.
They are about half an inch long, active at night and harmless to people. Damage is mostly to books, papers, wallpaper and stored dry food, and lowering humidity is the main fix.
Quick facts
The key facts about Silverfish, with sources:
Key takeaways
- Silverfish are harmless to people but chew paper, glue, starch and some fabrics.
- They need damp air, so bathrooms, basements and laundry rooms are where they live.
- Lowering humidity with fans and dehumidifiers is the most effective long-term fix.
- They live for years and can go months without food, so starving them out is slow.
- Baits rarely work; drying, cleaning and sealing do most of the work.
A very old kind of insect that loves damp rooms
Silverfish are among the simplest insects: they never grow wings, and the young look like small adults 2. Their bodies are covered in tiny shiny scales that look like a fish’s, which is how they got their name 2.
Adults are about 1/2 inch long and up to 3/4 inch, silver or pearl gray, with two long antennae and three thin tail bristles 1. That three-tailed look gives them and their relatives the name “bristletails” 5.
They hide by day and come out at night, darting away fast when disturbed 2, so most people first spot one in a bathtub, a sink or a box of old papers.
Silverfish do not bite or spread disease, and Ohio State calls them generally harmless 4. The trouble is what they eat: starch and glue in paper, book bindings, wallpaper paste and clothing starch 1.
How a silverfish lives
- Find damp shelter. They gather where it is humid and dark, often bathrooms, basements and attics 2.
- Lay eggs. UC IPM says clutches average 50 eggs (1 to 200) of silverfish and firebrats 1; UF reports silverfish clutches of seven to twelve 2. Each egg is about 1/25 inch long, so clutches are hard to spot 1.
- Hatch. Silverfish eggs hatch in about 19 to 32 days 1; UF notes under 20 days near 90°F and up to 40 days near 72°F 2.
- Grow by molting. The young molt six or seven times to reach adulthood, then keep molting through life 2.
- Feed at night. They scrape at paper and fabric rather than bite cleanly, leaving irregular holes and patches 13.
- Live for years. UC IPM puts silverfish lifespan at about 3 years 1; UF says up to four in ideal conditions 2.
Temperature sets the pace of growth, and UC IPM reports development can take up to 500 days below 50°F but as few as 60 days above 75°F 1.
Silverfish and their close relatives
| Insect | Color | Favored spot | Notes |
|---|---|---|---|
| Common silverfish (Lepisma saccharina) | Silver or pearl gray 1 | Damp, cool areas: basements, bathrooms, laundry rooms 31 | Prefers 71–90°F with high humidity 1 |
| Firebrat (Thermobia domestica) | Mottled gray or brown 1 | Hot spots near furnaces, ovens, hot water pipes 3 | Prefers spots above 90°F 4 and copes with humidity as low as 30% 1 |
| Other silverfish species | Varies | Homes in the South | Clemson notes three silverfish species and one firebrat in South Carolina 3 |
Firebrat antennae are longer than the body; silverfish antennae are about body length 5. Telling them apart tells you where to look: damp corners or the furnace room.
Example: reading the clues in a damp basement
This worked example uses published facts to show how a homeowner can reason from what they see. The basement scene is an illustration rather than a real case.
| What you find | Published fact | What it means |
|---|---|---|
| Silver insects in the basement sink at night | Silverfish are nocturnal and favor damp areas 25 | Moisture is the draw |
| Irregular holes in boxed papers on the floor | Feeding leaves irregular, unconnected holes 1 | They are feeding on the paper |
| Tiny scales and dark specks near the damage | Scales and fecal debris near damage show their presence 1 | Confirms silverfish, not mice |
| A hygrometer reads high humidity | Silverfish prefer 75–95% relative humidity 4 | Lowering humidity is the main fix |
| Lots of them | A large population usually means a long-standing infestation 3 | Expect weeks, not days, to clear |
In this case the fix starts with a dehumidifier, lifting boxes off the concrete and cleaning, not with a spray. The PNW Insect Handbook says reducing humidity often solves the problem 6.
Where you will see silverfish, and the word
In the house: bathrooms, especially shower stalls, basements, laundry rooms, attics and wall voids 12. Clemson adds stacks of old papers, magazines, books and fabric 3.
On a recurring pest control plan, check whether silverfish are covered and whether moisture fixes are part of the advice, since UC IPM ties control to humidity 1.
In libraries, museums and archives, silverfish are a known collections pest, because paper and labels are abundant 2.
Signs of silverfish
- Live insects in sinks, tubs or boxes, mostly at night 2.
- Irregular holes or scraped patches in paper, wallpaper, book bindings or fabric 13.
- Discolored pages or dark spots, which UC IPM ties to fungi that grow with their feeding damage 1.
- Shed scales and tiny dark fecal specks often collect near damaged items 1.
- Damage to starchy dry foods such as flour, cereal and pasta 1.
Skip the bug bomb
UC IPM does not recommend foggers for silverfish 1. If you use any dust or spray, follow the label and keep oil-based sprays away from motors and flames. Keep products away from children and pets. Should a silverfish spray or dust get on someone, call Poison Help at 1-800-222-1222.
What each control step does well
Works well
- Dehumidifiers and fans drop humidity below what silverfish can tolerate 1.
- Cleaning and vacuuming remove the dust, debris and crumbs that silverfish feed on 1.
- Sealing gaps around pipes and fixing leaks removes hiding spots and water 1.
- Labeled dusts in cracks and voids work when applied in a thin layer to dry areas 1.
Why silverfish are slow to clear
Silverfish are hardy enough to go months without eating: UC IPM says several months 1, and UF reports up to a year 2, so removing food alone will not clear them quickly.
They live a long time and hide in wall voids, which slows treatment. Ohio State and Clemson both say chemical control may take 10 to 14 days, because insects in voids must come out and touch the treatment 43.
If the moisture stays, they come back, and UC IPM notes that if control has not worked in 2 to 3 weeks, pests are likely coming from untreated hiding places 1.
What drives the cost of silverfish control
We do not list prices, because most of the cost of beating silverfish is moisture work: a dehumidifier, fixing plumbing leaks, better bathroom ventilation or improving a damp basement, and that work also helps against other moisture pests.
If you hire a pest company, the price depends on how many rooms are treated, whether wall voids need treatment and whether it is a one-time visit or part of a plan. Our recurring plan tool compares the options, and the pest control cost guide explains quotes.
A step-by-step silverfish plan
- Identify. Confirm silverfish or firebrats, so you know whether to look in damp or hot spots 3.
- Monitor. Set sticky traps in corners and along edges, or a glass jar wrapped in masking tape on the outside 1. The PNW Insect Handbook suggests baiting the jar with a little dry oatmeal 6.
- Dry the space. Run dehumidifiers and fans, and fix any plumbing leaks that keep the room damp 1.
- Clean and declutter. Vacuum, clear old papers and fabrics, and store dry food in tight-lidded containers 13.
- Seal. Close gaps around pipes and cracks and crevices 13.
- Treat if needed. For heavy infestations, a professional may apply labeled products to cracks, crevices and voids 3.
Clemson suggests considering a professional when the infestation is extensive or keeps returning after these steps 3.
Keeping silverfish from coming back
- Keep basements, laundry rooms and bathrooms clean and dry 1.
- Do not store cardboard boxes directly on concrete floors 6.
- Store books, photos and papers in sealed plastic bins in dry rooms.
- Keep flour, cereal and other dry foods in tight-lidded containers 1.
- Vacuum closets, shelves and storage areas regularly to remove dust and debris 1.
Humidity is the lever
Ohio State says silverfish prefer 75 to 95 percent relative humidity 4. UC IPM says dehumidifiers and fans can drop humidity to levels they cannot tolerate 1.
Our page on moisture control for pest prevention explains how humidity draws many pests, and the pest risk checklist covers the rest of the house.
When to call a professional
Call when silverfish keep showing up after a few weeks of drying and cleaning, when they are damaging valuable papers or books, or when they seem to come from wall voids.
Call a plumber or contractor for the moisture source: leaks, poor bathroom ventilation or a wet basement.
Rules that apply
Federal (EPA, FIFRA). Any spray or dust used must be EPA-registered and applied as its label says, and Clemson stresses reading and following labels 3.
No special silverfish rules. Our sources do not name any federal or state rule specific to silverfish, although the pest companies that treat them are licensed by the state; see pest control licensing and our pesticide safety guide.
Silverfish vs other small household pests
| Pest | Look | Main damage | Main draw |
|---|---|---|---|
| Silverfish | Silver, scaly, three tail bristles 1 | Paper, glue, starch, fabric 1 | High humidity 4 |
| Firebrat | Mottled gray-brown, three tails 1 | Same as silverfish 3 | Heat above 90°F 4 |
| Cockroach | No scales or three tail bristles | See the cockroach page | See the cockroach page |
| Termite worker | No scales or tail bristles | Structural wood | See the termite page |
See our pages on the cockroach and the subterranean termite if what you found does not fit silverfish, and our pest identifier can help you narrow it down.
Common silverfish myths
- Myth Silverfish bite people.
- Reality Ohio State calls them generally harmless; they feed on starch and paper 4.
- Myth They mean the house is dirty.
- Reality They follow moisture, so damp basements and bathrooms draw them in clean homes too 1.
- Myth Bait will wipe them out.
- Reality UC IPM says baits are generally unsuccessful 1.
- Myth A bug bomb will clear them.
- Reality Foggers are not recommended, because the fog does not reach insects hiding in voids 1.
How climate shapes a silverfish problem
Silverfish follow indoor humidity more than outdoor climate, so in humid regions, basements, crawl spaces and bathrooms stay damp much of the year, which favors them. Clemson notes three silverfish species and a firebrat in South Carolina alone 3.
In dry or heated rooms, firebrats can still thrive near furnaces and hot water pipes 31. The local variable is your home’s humidity, so a cheap hygrometer is the best local test.
When it matters to you, and what to do next
Match the response to what you see: for one silverfish in a tub, dry the room and watch.
If you see several a week or find paper damage, measure humidity, dry the space and set traps.
If they are still there after 2 to 3 weeks of drying and cleaning, or valuable items are at risk, call a professional.
Protect what matters most first: photos, documents and books go into sealed bins in a dry room, and then you can fix the moisture.
Quick decision guide
A single sighting calls for drying the room and watching. Regular sightings call for a dehumidifier, cleaning and traps. With no change in 2 to 3 weeks, bring in a professional, and if they cluster near the furnace, think firebrat.
Questions about Silverfish
Are silverfish harmful to humans?
No, silverfish are not known to harm people, and Ohio State Extension calls them generally harmless; they do not bite or spread disease. The harm is to belongings: they feed on paper, book bindings, wallpaper paste, clothing starch and some fabrics, and can get into dry foods such as flour and cereal.
What attracts silverfish to a house?
Moisture attracts silverfish most, and Ohio State says they prefer 75 to 95 percent relative humidity, and UC IPM says they need a lot of moisture. Damp basements, bathrooms and laundry rooms, plus food such as paper, glue, starch and dry goods, make a home attractive to them.
What do silverfish eat?
Silverfish eat starch, sugar and protein in many forms, and UC IPM lists dry foods, paper with glue or paste, wallpaper sizing, book bindings, clothing starch, dust, dead insects and some fungi. UF notes they prefer glazed paper, which is coated with starch, and also eat linen, silk and cotton.
How long do silverfish live?
Silverfish live for years, which is unusual for a household insect. UC IPM puts their lifespan at about 3 years, UF reports up to four years in ideal conditions, and Ohio State says adults may live two to eight years. They also keep molting as adults, sometimes dozens of times.
Do silverfish mean I have a moisture problem?
Usually, yes, because silverfish need humid air, so regular sightings point to damp rooms, leaks or poor ventilation. UC IPM says dehumidifiers and fans can lower humidity below what they can tolerate. The PNW Insect Handbook says reducing humidity often solves the problem on its own.
How do I get rid of silverfish naturally?
The most effective non-chemical steps are drying the space, cleaning and sealing, so run dehumidifiers and fans, fix leaks, vacuum dust and debris, clear old papers and store dry foods in sealed containers. Sticky traps or a tape-wrapped glass jar can catch and monitor them, and these steps address the cause, not just the insects.
Can silverfish live without food?
Yes, silverfish can survive long periods without food: UC IPM says several months, and UF reports up to an entire year, which is why simply removing food rarely clears an infestation quickly. Lowering humidity works faster, because they need moisture more than they need a steady meal.
What is the difference between silverfish and firebrats?
Silverfish are silver-gray and like damp, cooler areas, while firebrats are mottled gray or brown and like hot places.
Clemson says firebrats live near ovens, furnaces and hot water pipes, while Ohio State says firebrats favor spots above 90°F, and UC IPM says they cope with humidity as low as 30 percent, and Maine notes firebrat antennae are longer than the body.
Why do I find silverfish in the bathtub?
Silverfish are drawn to damp bathrooms and often fall into tubs and sinks while foraging at night.
Bathrooms are among the damp spots UC IPM names as their favorites, so a silverfish in the tub is a sign the room stays humid.
Better ventilation, a bathroom fan and fixing leaks reduce how often you see them.
Sources
- UC Statewide IPM Program, Pest Notes: Silverfish and Firebrats (Publication 7475), retrieved .
- UF/IFAS Extension, Silverfish, Lepisma saccharina (EENY-705 / IN1211), retrieved .
- Clemson Cooperative Extension HGIC, Silverfish & Firebrats (HGIC 2443), retrieved .
- Ohio State University Extension, Silverfish and Firebrats (ENT-64), retrieved .
- Maine Department of Agriculture, Conservation and Forestry, Silverfish and Firebrat, retrieved .
- Pacific Northwest Insect Management Handbook, Silverfish (Lepisma saccharina), retrieved .
Expert review
Written by the HyrePest Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Biology, conditions, food, damage and control follow UC IPM Pest Notes 7475, UF/IFAS EENY-705, Clemson HGIC 2443, Ohio State ENT-64, Maine DACF and the PNW Insect Management Handbook, attributed to each.
Where sources differ (egg clutch size, lifespan), both figures are given. The bar chart plots UC IPM’s published development times. No prices or application rates are given.
Suggest a correction. We fix errors and say what changed.