Silverfish and Firebrats: Identification and Control Guide
By the Clark Pest Entomology Team
Last updated: October 2026
Quick answer: Silverfish and firebrats are slender wingless insects with three tail-like appendages, and they look almost identical. What separates them is where they live. Silverfish want damp rooms. Firebrats want hot dry ones. Pick the guide that matches where you found yours.
Which one did you find?
Silverfish
Shiny silver or pearl gray. Check bathrooms, basements, laundry rooms, closets and bookcases. If the room is damp, this is probably your insect.
Firebrats
Shiny but mottled gray or brown. Check near ovens, water heaters, fireplaces and hot water pipes, plus attics in summer. Firebrats chase heat.
What's the difference between a silverfish and a firebrat?
Color and location do most of the work. Both run about half an inch, with soft bodies, no wings, a pair of long antennae up front and three thin filaments trailing off the back end. Here's where they split.
| Trait | Silverfish | Firebrat |
|---|
| Color | Shiny silver or pearl gray | Shiny, mottled gray or brown |
| Size | About half an inch, up to three quarters | About half an inch |
| Temperature it wants | About 71 to 90 degrees F | Above 90 degrees F, best at 98 to 102 |
| Humidity | Needs damp air, above 75 percent when it's warmer | Handles dry air, down to 30 percent |
| Where in the building | Laundry rooms, basements, bathrooms, closets, bookcases | Ovens, heating units, fireplaces, hot water pipes, attics in summer, furnaces in winter |
| Lifespan | About 3 years | About 2 years |
| Scientific name | Lepisma saccharina | Thermobia domestica |
Both species keep molting their whole lives, running through 45 to 60 developmental stages. Somewhere warm, a firebrat reaches adulthood in about 40 to 60 days and a silverfish in about 60. Cold slows both of them down a lot.
What do they damage?
Starch, paper and glue. Their usual targets are dry foods like cereal and flour and pasta and pet food, plus paper with glue or paste on it, wallpaper sizing, book bindings, starched clothing, household dust, dead insects and some fungi. Either one can go months without eating.
The damage has a look you can learn. Their jaws are weak, so they scrape the surface of paper instead of chewing through it. Feeding usually starts in one spot and spreads outward as irregular holes that don't connect to each other. Fungi growing alongside the feeding often leave pages discolored. Shed scales near a damaged book or box are another sign.
How do you get rid of silverfish and firebrats?
- Find out which rooms they're using. Sticky traps or taped glass jars in corners and along edges will tell you.
- Dry the room out, because for silverfish this is the step that matters most. Patch the openings around pipes, fix leaks and run a dehumidifier or a fan in closed spaces.
- Keep the damp rooms clean, especially basements and laundry rooms and shower stalls. Clear dust and debris regularly, and empty out closets, cabinets and storage bins.
- Take away the food and the hiding places. Shift stored books and papers around now and then, and move dry food into containers that actually seal.
- Save insecticide for a real infestation. When it's warranted, treatment goes into cracks, crevices and voids rather than across open surfaces. Baits generally don't work on these insects, and foggers aren't recommended.
- Watch the two to three week window. If nothing has improved by then, they're coming from a hiding place nobody has treated yet. Find that spot and deal with the water feeding it.
Clark's Expert Insight
Where you see one of these is usually not where it lives. Both species travel along plumbing and slip through openings in walls and floors between levels, which is exactly why they end up stranded in a bathtub or a sink. UC IPM puts a clock on it worth remembering: if treatment hasn't worked inside two to three weeks, the population is sitting in a harborage nobody found. Chase the moisture for silverfish and the heat source for firebrats. Treat there, not where you saw the bug.
Frequently Asked Questions About Silverfish and Firebrats
Do silverfish bite?
No. Silverfish and firebrats have very weak jaws that scrape surfaces rather than bite, and they aren't a biting risk to people or pets. What they damage is food, paper, books and starched fabric, not you.
What bug looks like a silverfish?
A firebrat, nearly every time. The two are close relatives with the same slender shape, the same two long antennae and the same three tail-like appendages. Color is the fastest tell, since silverfish are shiny silver or pearl gray and firebrats are mottled gray or brown. Where you found it helps too, because firebrats stick to hot dry spots near ovens and water heaters while silverfish want damp rooms. Our firebrat guide puts them side by side.
What does silverfish damage look like?
Look for irregular holes that don't connect to one another, and scraped surfaces on paper instead of clean chewed edges. Feeding tends to start in one area and spread. Pages often end up discolored from fungi growing along with the feeding, and you may find shed scales near whatever got damaged.
Are silverfish harmful?
Not to people directly, since they don't bite or sting. They're a damage and contamination problem instead. Silverfish and firebrats feed on stored dry foods, paper, book bindings, wallpaper paste and starched clothing, so a population nobody treats works its way through pantry goods and books and stored fabric.
Found them in your pantry or your books?
A licensed Clark technician can confirm which species you've got, trace it back to the moisture or heat keeping it alive and treat the harborage instead of the sighting. Clark has protected homes and businesses in California and Northwestern Nevada since 1950.
Call 1-800-882-0374 or request service online.
Find help with your silverfish and firebrat problems. Find your local Clark Pest Control branch here.