Boxes, paper, insulation, and damp spaces are likely to attract silverfish.

My downstairs neighbors have been remodeling their condo, and my place has been overrun with silverfish. I’m desperate to get rid of them, but I don’t want to use toxic chemicals. Help! -Tina

Silverfish (Lespisma sacchrina) are nocturnal members of the insect order Thysanura that thrive in high humidity and warm temperatures. They can move very fast, making them hard to see, and live on a diet that includes starchy foods, paper, and fabric.

While they don’t bite, silverfish are a creepy nuisance that can be destructive to your belongings. The best way to get rid of silverfish is to attack them at the source; however, in your case it sounds like the source is going to be impossible to find! The good news is, you don’t have to reach for the highly toxic sprays; in fact, some of the less-toxic options are the most effective! Here are some things to try:

• Boric Acid: This is the most popular product for silverfish control, and compared to other products, boric acid is quite low on the toxicity scale. In fact, it has historically been used as a cleaning product. You can purchase boric acid powder to sprinkle in areas where silverfish are active. You can also find boric acid in ready-to-use products such as baits, wafers, and traps. Roach Ridd and Dekko Silverfish Paks are examples of products made with boric acid.
• Diatomaceous Earth: The tiny silicate shells of microscopic sea diatoms are lethal to many insects, penetrating their exoskeletons and dehydrating them. Sprinkle diatomaceous earth in crevices, but make sure pets and children cannot get close enough to breathe it.
• Pyrethrin: This is a chemical pesticide, but because it’s made from the seeds of the pyrethrum plant, it’s biodegradable and considered less toxic than others. It’s the active ingredient in many flea and tick pet collars. While no pesticide is completely safe, this might be a more attractive option than a harsher chemical. You can find pyrethrin sprays and powders at most garden centers, and you would apply it only in crevices and areas where the silverfish are active.
• Jar Traps: Make your own silverfish trap by covering the outside of a glass jar with masking tape (to help the critters crawl in), then put crackers or something starchy in the bottom of the jar as bait. The silverfish crawl in, but they can’t get out.

DIY silverfish control:

• Sticky traps: Make a paste of flour, water, and boric acid. Coat index cards with the paste, allow it to dry, and use as sticky traps.
• Baits: Sprinkle boric acid on and around a cracker, and place it as poison bait. Be sure to put it out of reach of children or pets! You can also do this with diatomaceous earth.
• Crevice sprays: Make a 5% solution of boric acid in water. Use a spray bottle or turkey baster to inject the spray into cracks and crevices. You can also spray the powder directly. This puts the treatment where you need it and reduces your exposure to the chemical.

Be sure to target:

• Boxes and file cabinets
• Insulation
• Baseboards
• Behind appliances
• Cabinet tops
• Light fixtures and behind electrical outlets
• Behind siding and within walls
• Holes where water pipes enter walls

To make your home less inviting to silverfish:

• Fix Damp Spots: Leaky pipes, water condensation, damp basements, and humidity provide an attractive environment for silverfish.
• Eliminate Food Sources : Silverfish eat starches and sugars found in paper, glue, book bindings, insulation, and cardboard boxes, and they usually hang out pretty close to their food source. Use airtight plastic storage bins for paper, and get rid of anything that you find full of silverfish.
• Vacuum Crevices: Silverfish hide and lay their eggs in cracks and crevices. Dispose of the vacuum cleaner bag in the trash outside so they can’t crawl out again.

Further Information

• Silverfish (AgriLIFE Extension, Texas A&M)
• How to Get Rid of Silverfish (howtogetridofstuff.com)
• Boric Acid (Al’s Home Improvement Center)
• Boric Acid, Borates, Borax (beyondpesticides.org)

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