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What Are Silverfish?

Silverfish are primitive pests that can destroy your books, clothing, and more. Here’s how to identify and prevent these pests from infesting your home.

Author Icon Written by Brenda Woods Updated 03/26/2024

If you’ve spotted holes in your favorite books, yellow stains on your clothing, or small pellets on a newspaper, you may have a silverfish problem. These primitive pests, named for their shimmery silver bodies and fishlike movements, feast on paper, clothing, and upholstery. Nocturnal, nimble, and quick-moving, silverfish can be difficult to eradicate on your own.

That’s where professional pest control companies come in. The best pest control companies can eliminate silverfish infestations and help to stop them from returning.


How To Identify Silverfish

Silverfish are ancient insects. According to the University of Florida entomology school, silverfish are some of the simplest and least evolved species. Unlike many insects, they can live for up to four years and even go an entire year without food.

These pests are shiny silver or gray and have slender, flattened, tear-shaped bodies, bristlelike tails, and threadlike antennae. They grow to be between 1/2 and 1 inch long. Silverfish continue to molt as adults, shedding their skins and leaving scales behind. These pests have no wings but are extremely fast climbers and crawlers.
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Silverfish aren’t known to be harmful to humans. They don’t bite and there’s no scientific evidence that they are poisonous or carry disease. However, their molted skins can trigger allergic reactions.
Silverfish are drawn to moisture and often infest in damp, dark places like bathrooms, laundry rooms, basements, attics, and garages. They prefer room-temperature areas with 70%–90% humidity.
Silverfish feed on carbohydrates, with a preference for sugar and starch. Unfortunately, that means their destructive feeding habits spell damage to clothing, books, newspapers, wallpaper, insulation, cardboard, tissue, envelopes, and food like oats and cereal. Silverfish can survive for weeks without water and up to a year without food.
Telltale signs include visible silverfish scurrying into cracks and crevices at night, holes in papers, yellow stains on clothing or upholstery, and small, pepperlike pellets of feces.

As with most pests, the best offense is a good defense. There are several measures you can take to help prevent a silverfish infestation, with moisture prevention being key. Following these steps will make your home less hospitable to these nuisances.
Reduce food sources: Store dry goods such as cereals, oats, grains, flour, and pasta in tightly sealed containers.
Purchase dehumidifiers: Set them up in damp places like basements to limit the moisture that attracts silverfish.
Repair pipes and drains: Leaks can lead to excess moisture, which will attract silverfish.
Seal entry points: Using caulk, seal up any cracks in your foundation, walls, and ceilings along with behind baseboards and windows.
Vacuum: Go over your carpets and upholstery thoroughly with a vacuum to make sure that there are no crumbs to attract silverfish.
Clean gutters: Keeping your gutters clean will help make sure that water drains away from your house instead of collecting and creating a damp environment.
Move anything stored against your home: Items stored against your home can make it easier for silverfish to climb into your home through vents, pipes, and window or door frames.
Clean your shingles: Clean and seal your shingles to prevent access by silverfish.
Remove moldy wood: If you have any moldy wood, either repair or get rid of it.
Store books and magazines carefully: Avoid storing paper in moist, humid areas that silverfish seek out, like basements and garages. If you must store paper, keep it in airtight plastic or metal containers.

How To Get Rid of Silverfish

Most of the time, preventive measures are successful at keeping silverfish numbers low. If you decide to use insecticide, choose a product that’s safe for indoor use and follow the manufacturer’s instructions carefully. Note that pyrethrins, the active ingredient in most aerosol pesticides including bug bombs, won’t work against silverfish. Boric acid dust is more effective, and Japanese cedar oil has also been found to repel silverfish.

The best way to get rid of a large silverfish infestation is by hiring a professional pest control company. Traps only kill the individual silverfish that come across them, and it’s difficult to apply insecticides well enough to treat a full infestation. To effectively eliminate silverfish, you must get rid of all of the pests and their eggs and keep them from returning. Experienced pest control specialists can create an effective treatment plan.


FAQ About Silverfish

Is it bad to have silverfish?

Silverfish won’t cause people any harm but can damage books, upholstery, clothing, wallpaper, and insulation.

Why do you get silverfish?

Silverfish may come into your home in search of moisture and food. Highly humid areas in your house like your basement, laundry room, or bathroom are attractive to silverfish.

How do you get rid of silverfish?

You can try using boric acid dust or silverfish traps. However, these methods are insufficient for large infestations. In that case, consider calling a pest control company.

Are silverfish a sign of a dirty house?

Silverfish aren’t necessarily the sign of a dirty house, though they’re more likely to inhabit homes that have food and crumbs out and excessive paper clutter.


Our Rating Methodology

The This Old House Reviews Team backs up our pest control recommendations with a detailed rating methodology that we use to objectively score each provider. We review pest control plans, navigate the provider website, speak with customer service representatives by phone and online chat (if available), request quotes, and analyze customer reviews for each provider. We then score the provider against our review standards for plans and services, reputation and customer responses, customer service offerings, workmanship guarantees, financing, and availability to arrive at a final score on a 5-point rating scale.

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