Despite their somewhat poetic name, silverfish can be a real nuisance. They are a small, wingless six-legged insect, about 3/4 of an inch long. Their solid silvery grey color looks metallic and their movements are somewhat fishlike (another name for them is "fish moths"). Silverfish (Lespisma sacchrina) are also sometimes called bristletails because of the three tail-like tendrils on their rear sections.
Despite being small and basically harmless to humans, in large numbers they can cause a fair amount of damage to textiles (including clothing, rugs and upholstery) and softer building materials. Vintage clothing and antique rugs may prove particularly vulnerable, since they're usually made of natural fibers like wool, silk or cotton. Just as moths eat wool clothing, silverfish love to munch on your old cashmere sweaters and velvet jackets. Old books or paper files might also get destroyed; silverfish eat the glue in older books. They also eat household glue and certain kinds of paint. In some cases, the presence of silverfish can exacerbate sensitivity to other allergens in the home.
A few silver fish can maintain a good insect equilibrium in the home, since silverfish eat predatory bugs, including spiders. They are also known to be cannibalistic and will eat their own dead and injured brethren. But left to breed and multiply, you may soon find you have an invasion on your hands.
6 Ways to Remove Silverfish
Once you discover you have silverfish, be prepared to take action to remove them. If you've ever had to deal with head lice or fleas in the home (and if you have small children and/or pets, you may have had to do this!), you know it's important to address it on many fronts, including cleaning all surfaces and all clothing and bedding.
You'll want to thoroughly wash all clothing and bedding. Shampoo carpets or clean area rugs. If shampooing is not practical, sprinkling with diatomaceous earth and vacuuming, followed by using cedarwood spray, may work. Vacuuming upholstered furniture, including under cushions, is also a good idea.
Sprinkle Diatomaceous Earth
Diatomaceous earth is a fine powder that contains microscopic insect exoskeletons, finely ground but with jagged edges. Once silverfish crawl over them they die. Sprinkle over rugs and floors and in corners, leave for 24 hours and vacuum. Get the food grade product, to ensure safety in case pets try to lick it up.
Trap Them in Glass
Silverfish can't climb on glass, so one method of trapping them for removal is to put tape on the outside of a glass jar containing starchy food; once they enter, they can't get out, so just put the lid on the jar and remove them from the home. Using sticky traps is also an option.
Trap Them in Paper
One makeshift silverfish trap is to roll up a newspaper and spray it with water. Silverfish will crawl into it and make a cozy home. Then after a few days discard the newspaper or burn it.
Use Boric Acid
This can be used just like diatomaceous earth; however, it can be toxic to children and pets so it's not always a desirable method.
Hire an Exterminator
Possibly a last resort, but an effective one if other methods have proven unsuccessful.
What Causes a Silverfish Infestation?
Silverfish are attracted to moist, humid areas of the home, including bathrooms, kitchens and basements, or areas near where water might get in, such as a leaking roof or window frame that is not intact. Silverfish are also attracted to dust, and to grains, and to dried meat products such as jerky and pet food. Their main food source if cellulose, a starchy sugar substance found in paper products, some fabric fibers, and in skin cells (such as dandruff). If you have stacks of old books or magazines that gather dust in your home, there's a good chance you may get silverfish. They don't like bright light and you may not see them unless you discover them at night or on a dark cloudy day. But their damage is real enough and it's important to address an infestation immediately before the destruction spreads.
How to Prevent Silverfish Infestation
There are a few good and safe ways to prevent an infestation of silverfish in the home.
One of the best modes of prevention of silverfish infestation is to make sure there is no unchecked humidity or moisture in the home. Make sure the bathroom has proper ventilation, and open windows when possible to circulate fresh air. Heated towel racks can help cut back on moisture in the air also. A dehumidifier is also a good idea. Fans to keep air flowing also help reduce humidity. Silica gel pacs placed in drawers or cupboards also help reduce moisture.
It's also important to dust and/or vacuum regularly to reduce the amount of dust that silverfish love to feed on. If you have wood floors, sweep and damp mop with an oil-based soap. Shake out your rugs regularly, outside if possible.
Cut Back on Clutter
Don't let cardboard recycling build up; silverfish are attracted to the glue. Donate some of those old books or clothes you're never going to wear again.
Seal Grain Products
Keep all grain products sealed in glass jars or ziplock bags; this includes pasta, rice, cereals and flour. Clean up food particles that fall on the floor or counter or that escape into the pantry or cupboards.
If you have gaps in any of your window frames, consider caulking to seal them. Caulking is also a good choice for any random spaces in the attic exposed to the outside where silverfish might find a way inside.
Silverfish dislike the smell of cedar, so one good natural preventive method is to make a spray using cedarwood essential oil (10 drops to 4 ounces of water, shake gently before each use) and spray in damp corners and/or in closets and near bookshelves. You can also spray down your rugs and upholstery. Another method is to drop the essential oil onto several cotton balls in an open glass container (such as a votive candle holder) and place where the scent will be diffused through the air. Bonus: cedarwood is also a good flea and tick preventive. Cedarwood shavings can also be used.
Silverfish also dislike the smell of bay leaves; crush them and tie up in muslin bags and leave in drawers, closets and corners.
How long do silverfish live?
Silverfish can live up to 8 years (how terrifying is it that there are insects that can live this long?) and can reproduce frequently in their lifetime.
“Bristletails (Silverfish and Firebrats).” Penn State Extension.
Barletta B, Di Felice G, Pini C. Biochemical and molecular biological aspects of silverfish allergens. Protein Pept Lett. 2007;14(10):970-974.
"R.E.D. Facts: Boric Acid." United States Environmental Protection Agency, Prevention, Pesticides, and Toxic Substances.