Silverfish in Your SLC Home: Causes, Signs, and What to Do

Silverfish are one of the most under-reported pests in Salt Lake City. They're not dangerous, they don't bite, and they don't spread disease — but they're deeply unsettling to find in your bathroom at midnight, and they can damage books, wallpaper, and stored linens. If you're finding them in your Salt Lake home, there's a specific reason.

Why silverfish love Salt Lake basements

Salt Lake City is a dry climate, but our basements aren't. Older Avenues brick, Sugar House bungalows, and 1950s ranches through Murray and Holladay all tend to hold humidity in below-grade spaces. Silverfish thrive at humidity above 75%, and they eat starches — book bindings, wallpaper paste, cardboard boxes, cereal packaging, natural fibers.

If you're seeing silverfish, you almost certainly have a humidity issue in that room. Fixing the moisture is more than half the job.

Where you'll find them

• Basement bathrooms and utility rooms.
• Behind baseboards in older brick homes.
• Inside cardboard storage boxes, especially old books, tax paperwork, and photo albums.
• Around water heaters and washing machines.

What actually works

• A dehumidifier in the affected basement or bathroom. Aim for 45–55% relative humidity.
• Move stored paper and books out of cardboard and into sealed plastic bins.
• Seal cracks along baseboards and around pipe penetrations.
• Fix the moisture source — leaking water heater fittings, poorly vented bathrooms, or damp crawlspaces are the usual culprits.

When a professional helps

If you're seeing silverfish in multiple rooms, in the kitchen, or on upper floors, the population has been growing for a while and typically warrants a professional treatment. A licensed local exterminator will treat harborage areas directly and often package silverfish work with a broader spider-and-ant program for a small incremental cost.

Call the referral line and we'll connect you with a residential pest professional who serves your Salt Lake neighborhood.