What Causes Silverfish Infestations in Boise?

Silverfish are small, fast-moving insects that prefer dark, damp, undisturbed areas. In Boise and across the Treasure Valley, they’re commonly found in bathrooms, basements, laundry rooms, and storage spaces where humidity and clutter create ideal conditions.

Silverfish don’t bite or spread disease, but they can damage books, photos, wallpaper, clothing, and other items made from paper or natural fibers. Understanding what attracts them is the first step to getting rid of them.

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What Do Silverfish Look Like?

Silverfish get their name from their fish-like shape and silvery sheen. They’re often noticed darting across floors or walls when lights are turned on.

• Size: About 1/2 to 3/4 inch long (not counting antennae and tail-like appendages)
• Shape: Long, flattened, and tapered toward the rear, with three “tail” bristles
• Color: Silvery-gray to blue-gray, sometimes metallic
• Movement: Very quick and wriggling—often compared to a small fish darting through water

Silverfish are nocturnal. They hide during the day in cracks and tight spaces, then come out at night to search for food.

What Do Silverfish Eat in Your Home?

Silverfish feed on materials that contain starches, sugars, and proteins. Inside a home, common food sources include:

• Books, magazines, paper stacks, and cardboard boxes
• Wallpaper and wallpaper paste (glues)
• Stored papers, photos, and important documents
• Natural fabrics like cotton, linen, silk, and wool
• Starchy pantry items (flour, cereal, pasta), especially if spilled or loosely stored
• Dead insects and organic debris in undisturbed areas

This is why silverfish are often discovered in long-term storage areas, closets, bookshelves, and boxes that haven’t been moved in a while.

What Causes Silverfish Infestations in Boise Homes?

Boise may have dry summers, but indoor moisture can build up year-round in certain rooms and hidden spaces. Silverfish take advantage of that combination of humidity, shelter, and stored materials.

1. High Humidity and Moisture

Silverfish thrive in damp environments. Moisture-related causes often include:

• Bathrooms with weak ventilation or no exhaust fan
• Basements or crawlspaces with condensation or dampness
• Leaky pipes, fixtures, or appliances
• Laundry rooms and utility areas with steam and poor airflow

Consistent humidity supports silverfish development and makes it easier for populations to grow in hidden areas.

2. Clutter and Long-Term Storage

Undisturbed storage creates perfect hiding spots and food access:

• Cardboard boxes stacked in basements, closets, or garages
• Piles of magazines, newspapers, or stored documents
• Stored clothing and linens that aren’t checked regularly

The darker, tighter, and more undisturbed the space, the more attractive it is for silverfish to hide, feed, and reproduce.

3. Easy Entry Points

Silverfish can get into Boise homes through:

• Gaps around doors, windows, and foundation cracks
• Utility penetrations and vents without proper screening
• Cardboard boxes, used furniture, or stored items brought indoors

4. Older or Poorly Ventilated Areas

Older homes—or spaces with limited airflow (some basements, interior bathrooms, attics, and storage rooms)—tend to hold moisture longer and often have more cracks and crevices. That combination can make silverfish problems more likely if conditions aren’t managed.

Are Silverfish Infestations Harmful?

Silverfish are not known to bite or transmit disease to people or pets. However, they can still cause real problems when populations build up.

• Damage to belongings: Grazing on paper, photos, wallpaper, stored files, and natural fabrics can leave irregular holes or surface scraping.
• Damage to finishes: Wallpaper, book bindings, and stored materials can be marked or degraded over time.
• Nuisance factor: Frequent sightings in sinks, tubs, closets, or along baseboards can be frustrating and unsettling.

Ignoring a silverfish issue can lead to ongoing damage—especially in libraries, closets, and long-term storage areas.

How to Help Prevent Silverfish in Boise Homes

Preventing silverfish is mostly about controlling moisture and removing easy food and hiding places.

1. Reduce Indoor Humidity

• Run exhaust fans during and after showers.
• Use a dehumidifier in damp basements or laundry areas if needed.
• Fix plumbing leaks, dripping faucets, and “sweating” pipes.
• Improve airflow in closets, storage rooms, and under-sink areas.

2. Protect and Organize Stored Items

• Store documents, photos, and memorabilia in sealed plastic containers instead of cardboard.
• Keep seasonal clothing and linens in tightly sealed bins or garment bags.
• Rotate or check storage areas periodically so spaces don’t stay undisturbed for long periods.

3. Seal Cracks and Crevices

• Seal gaps around baseboards, trim, and pipe/wire penetrations.
• Caulk cracks around window and door frames.
• Inspect foundation and siding for openings that lead into wall voids.

4. Clean Regularly in High-Risk Areas

• Vacuum along baseboards, in closets, under furniture, and in storage rooms.
• Clean up food spills and crumbs promptly, especially in kitchens and pantries.
• Remove or recycle old cardboard, paper stacks, and magazines you don’t need.

How to Get Rid of Silverfish Once They’re Inside

If you’re regularly seeing silverfish in bathrooms, basements, or storage areas, you may already have an established population in hidden harborages.

1. Identify and Clean Source Areas

• Prioritize damp rooms (bathrooms, basements, laundry rooms) and cluttered storage spaces.
• Move items away from walls so you can inspect and clean behind them.
• Vacuum thoroughly, including corners, seams, and cracks.

2. Use Traps and Targeted Products Carefully

Sticky traps designed for silverfish can help monitor and reduce activity when placed along walls, behind furniture, and near suspected hiding spots.

Always follow label directions and safety instructions—especially around children and pets. If you’re unsure what’s appropriate for your home, a professional can recommend safe and effective options.

3. Focus on Long-Term Prevention

Even after activity drops, silverfish can return if conditions stay favorable. Long-term control depends on:

• Keeping humidity under control
• Storing items in sealed containers
• Sealing cracks and reducing clutter

4. When to Call a Professional

If you’re still seeing silverfish after moisture control, decluttering, and basic traps—or if you’re worried about damage to books, archives, or stored items—professional help can be the fastest path to lasting control.

A local pest control team can:

• Identify where silverfish are harboring and what’s attracting them
• Recommend moisture and structural corrections
• Apply targeted treatments in cracks, crevices, and hidden areas where silverfish live

If you’re struggling with silverfish in Boise, Nampa, Meridian, or surrounding Treasure Valley communities, you can contact a local Pestcom service location to discuss inspection and treatment options.

Frequently Asked Questions

Why do I see silverfish mostly in bathrooms and basements?

Bathrooms and basements often have higher humidity, less natural light, and more cracks and crevices—exactly what silverfish prefer. Leaks, condensation, and poor ventilation make these areas especially attractive.

Can silverfish damage my belongings?

Yes. Silverfish can feed on paper, cardboard, glue, fabrics, and some food products. Over time, they can damage books, documents, wallpaper, clothing, and stored items.

Are silverfish harmful to people or pets?

Silverfish are not known to bite or spread disease. They’re considered a nuisance pest because of the damage they can cause and their unsettling presence in homes.

Do I need professional pest control for silverfish?

Occasional sightings may improve with moisture control, cleaning, and sealing. But if you’re seeing silverfish regularly, noticing damage, or aren’t sure where they’re coming from, professional pest control can provide a more thorough and longer-lasting solution.