Half-eaten pages in your books? Chewed-through boxes in your pantry? These are signs of a silverfish infestation. Here’s how to identify, get rid of, and prevent silverfish infestations in the home.
What Are Silverfish?
The silverfish(Lepisma saccharina) is a slender, silvery insect pest found around the globe.
Siverfish are only considered a nuisance pest when they get into homes. There they are difficult to control but they are not harmful to humans nor spread disease. Instead, silverfish are known for damaging material goods, such as books, wallpaper, photos, clothing, and dry foods in the kitchen pantry.
Silverfish are particularly attracted to under-sink areas in the bathroom or kitchen, where the environment is humid and dark. They may also live in walls, closets, or crawl spaces. They remain hidden during the day, but at night, they emerge to forage for food.
A similar insect pest, the firebrat, looks and behaves much like the silverfish. Both pests can be controlled using the same techniques.
Fun Fact: The latter half of the silverfish’s Latin name, saccharina, refers to the insect’s fondness for eating materials made of polysaccharides (complex carbohydrates), such as cellulose and starch, which are found in paper products, fabrics, and foods.
How to Identify a Silverfish
Silverfish are slender, softbodies, wingless insects with long carrot-shaped bodies approximately 1/2-inch in length.
They resemble a fish due to their shiny silver, scaly bodies that taper gradually to the rear. Their bodies have no obvious segmentation, and are easily identified by the two slender antennae stemming from their heads and the three tail-like appendages on their back-ends. They are smaller and thinner than cockroaches, and a different color than the similarly-sized earwig.
Silverfish have rather stubby legs, but don’t let that fool you. They are capable of moving very, very quickly, especially when startled. This is when most people see silverfish: when the pests’ late-night feasting is interrupted and they scurry back to the dark corners of your home. Their rapid side-to-side movement resembles a swimming fish, which is said to be the source of their name.
Normally, silverfish live outdoors under rocks, bark, and leaf mold; they’ll also live in the nests of birds and ants.
In the home, silverfish are often found in bathtubs, sinks, or washbasins. Though silverfish usually stick to more humid places, they may also invade the kitchen pantry and target flour, cereals, and other grains.
Practically any material containing carbohydrates or proteins is susceptible to silverfish damage.
Bookbinding glue and wallpaper paste are common targets. Often, silverfish won’t eat all the way through a material, in which case it will look like just a thin layer has been scraped off (see photo, below).
Silverfish also feed on non-synthetic cloths, such as cotton or linen, evidenced by tiny, unconnected holes in the fabric.
Silverfish damage in a book. Photo by Micha L. Rieser/Wikimedia Commons.
Control and Prevention
How to Get Rid of Silverfish
Sticky traps, which consist of a cardboard base and a thin layer of sticky glue, can be effective at controlling small populations. Place traps in areas where silverfish activity is high. The insects will get stuck to the glue as they attempt to move across the trap. We recommend only using sticky traps that contain a pesticide in the glue, as this will prevent a trapped insect from suffering for too long needlessly.
Use dehumidifiers to dry the air in rooms where silverfish are seen, especially in the bathroom. Also ensure that under-sink areas in the kitchen and bathroom, as well as closets and cellars, are well ventilated.
Diatomaceous earth (DE)—a powder made up of tiny silica particles—can be effective. The particles act as an irritant and dehydrate insect pests as they come in contact with the powder. Spread DE around areas where silverfish have been seen, and around potential pest entry points, like cracks in the wall or furnishings.
Pyrethrin, a natural insecticide, is derived from chrysanthemum flowers and can be used to control silverfish. Its synthetic equivalent, permethrin, is generally more effective, as it does not break down as quickly when exposed to light and moisture. Warning: Both pyrethrin and permethrin are extremely toxic to cats!
There are a number of commercial pesticides that can be used to control silverfish. Always read a product’s label before use to determine that it is safe for your household.
How to Prevent Silverfish
Silverfish enjoy humid places, so making sure that under-sink areas in the kitchen and bathroom are well ventilated can be an effective deterrent. Use a dehumidifier, if necessary.
Sealing gaps and cracks in your walls and floor will cut off entry points for the pests.
The strong scents of cinnamon and cloves are said to repel silverfish. Keep small amounts of these spices in areas where you commonly see the pests to help keep them at bay.
Do not leave crumbs or food scraps out in the open, as they can attract silverfish (and other pests!).
Store precious documents and clothing in air-tight, plastic containers to keep silverfish from damaging them.
Do you have any tips for preventing or stopping silverfish infestations? Tell us in the comments below!