Silverfish and Firebrats | Pest ID Guide
Quick Facts About Silverfish and Firebrats
Silverfish and firebrats are small, wingless insects that wriggle like fish and hide in damp or warm corners of the home. They don’t bite or spread disease, but they feed on paper, glue, and starchy foods and can damage books, photos, and stored items.- Size: About 1/2 to 3/4 inch
- Shape: Carrot-shaped, flattened, with long antennae and three long bristles at the tail
- Silverfish: Silvery-gray scales; prefer cool, humid areas
- Firebrats: Mottled gray-brown; prefer hot areas
- Diet: Paper, glue, book bindings, wallpaper paste, cereal, flour, and natural fabrics
- Active: At night; can live for years
Silverfish vs. Firebrats
- Color: Silverfish are shiny silver; firebrats are mottled gray-brown.
- Where they live: Silverfish favor humid bathrooms, basements, and laundry rooms. Firebrats favor hot spots near furnaces, water heaters, ovens, and attics in summer.
- Control: Both respond to the same treatment, but moisture control matters most for silverfish and heat sources for firebrats.
Signs of Silverfish and Firebrats
- Insects in tubs and sinks: They often get trapped in bathtubs and sinks overnight
- Damaged paper: Irregular holes or surface grazing on books, photos, wallpaper, and cardboard
- Yellow stains: Small yellowish stains on fabrics and paper
- Pepper-like droppings: Tiny dark specks near where they feed
Where They Hide
- Bathrooms, especially around tubs, sinks, and pipes
- Basements, crawl spaces, and laundry rooms
- Near furnaces, water heaters, and boiler rooms (firebrats)
- Attics, especially in stored boxes
- Bookshelves, closets, and stored papers
- Behind baseboards and wallpaper
How to Get Rid of Silverfish and Firebrats
- Lower humidity: Use a dehumidifier, run bathroom fans, and fix leaks. Damp crawl spaces feed indoor problems; see crawl space encapsulation.
- Remove food sources: Store papers, books, and dry foods in sealed plastic containers instead of cardboard.
- Declutter: Clear stacks of paper, magazines, and boxes.
- Seal cracks: Caulk gaps around baseboards, pipes, and trim.
- Vacuum regularly: Especially in closets, corners, and along baseboards.
Professional treatment targets hiding spots with long-lasting baits and dusts. See our quarterly pest control.
Frequently Asked Questions
What do silverfish eat?
Paper, glue, book bindings, wallpaper paste, cereal, flour, and natural fabrics like cotton and linen.
Are silverfish harmful?
They don’t bite or spread disease, but they can damage books, papers, photos, and stored items.
Why do I have silverfish in my bathroom?
Silverfish thrive in humid areas. Lowering humidity and fixing leaks helps.
What’s the difference between silverfish and firebrats?
Silverfish are shiny silver and prefer humid areas. Firebrats are mottled gray-brown and prefer hot spots near furnaces and water heaters.
How do I get rid of silverfish?
Lower humidity, store paper and food in sealed containers, declutter, seal cracks, and consider professional treatment.
