What Are Silverfish?

Silverfish (Lepisma saccharina) are small, wingless insects named for their silvery, fish-like appearance and wriggling movement. Adults grow 12–19 mm long and have three tail-like appendages at the rear. They are nocturnal, fast-moving, and tend to hide in dark, damp areas — making them easy to miss until a population is well established.

Signs of a Silverfish Problem

• Live insects: Spotted at night in bathrooms, basements, kitchens, or closets.
• Feeding damage: Irregular holes or yellow staining on paper, books, wallpaper, and clothing containing natural fibres (cotton, linen, silk).
• Frass (droppings): Tiny black pepper-like specks near feeding sites.
• Shed skins: Small, translucent husks left behind as they moult.

Step 1 — Monitoring with Sticky Traps

Before treating, confirm activity levels and locate hotspots. Place sticky glue traps flat against walls in:

• Under sinks and around plumbing
• Along baseboards in bathrooms and basements
• Inside closets, behind bookshelves, and near electrical panels
• Along the perimeter of the garage or storage room

Check traps every 3–5 days. Areas with the most catches indicate where to focus treatment. Sticky traps also provide ongoing population monitoring after treatment.

Step 2 — Reduce Moisture (Critical First Step)

Silverfish cannot thrive without humidity. Reducing moisture is one of the most effective long-term controls:

• Fix leaking pipes and dripping faucets immediately.
• Run a dehumidifier in basements and crawl spaces — aim for below 50% relative humidity.
• Ensure bathroom exhaust fans are vented to the outside and used during and after showers.
• Seal cracks around pipes where moisture can accumulate.
• Store firewood, cardboard boxes, and paper materials away from the home or in sealed plastic bins.

Step 3 — Diatomaceous Earth (DE)

Food-grade diatomaceous earth is a popular, low-toxicity option safe for use around people and pets when applied correctly. It works by physically damaging the insect's exoskeleton, causing dehydration.

How to apply:

• Apply a thin, barely visible layer — a heavy pile is less effective and more likely to be avoided.
• Dust along baseboards, behind appliances, inside wall voids (via electrical outlets if accessible), under sinks, and in crawl spaces.
• Reapply after vacuuming, cleaning, or if the treated area gets wet, as moisture reduces effectiveness.
• Wear a dust mask during application to avoid inhaling the fine powder.

Step 4 — Residual Insecticide Treatments

For more persistent or widespread infestations, residual insecticide sprays and dusts can be applied to cracks, voids, and entry points. Products available in Canada and commonly used for silverfish control include pyrethrin-based sprays and boric acid dusts.

Safe application tips:

• Always read and follow the label — it's the law in Canada.
• Apply to cracks and crevices, not open surfaces, to minimize unnecessary exposure.
• Keep children and pets out of treated areas until dry.
• Never apply near food preparation surfaces unless the label explicitly permits it.
• Store all products in their original containers, out of reach of children.

Apartment-Specific Considerations

In multi-unit buildings, silverfish can travel through shared walls, plumbing chases, and electrical conduits. If you're a renter:

• Notify your property manager or building superintendent — treatment is most effective when coordinated across units.
• Seal gaps around plumbing under sinks and around baseboards with caulk.
• Sticky traps are an ideal first step since they require no landlord approval and generate no fumes.
• Follow up with DE along perimeter baseboards for ongoing control.

Products Available in Canada

Not all pest control products sold internationally are registered for use in Canada. Health Canada's Pest Management Regulatory Agency (PMRA) regulates which products can be sold and used here. Look for products with a valid PCP (Pest Control Products) registration number on the label — this confirms the product is approved for use in Canada.

Browse our selection of silverfish control products sourced for Canadian homeowners:

→ Shop Silverfish Control Products

When to Call a Professional

Consider contacting a licensed pest management professional if:

• You've been treating for 4–6 weeks without a noticeable reduction in trap catches.
• Activity appears in multiple rooms or floors simultaneously.
• You suspect a large hidden infestation in wall voids or subfloor areas.
• You're dealing with a multi-unit property where coordination is needed across suites.
• You have concerns about using pesticide products safely in your specific situation.

A licensed technician can perform a thorough inspection, apply prescription-strength products not available to consumers, and help identify the moisture or structural conditions driving the problem.

Summary: Your Silverfish Control Checklist

• ☐ Place sticky traps to confirm activity and find hotspots
• ☐ Fix leaks and lower humidity below 50%
• ☐ Apply diatomaceous earth to baseboards, voids, and harborage areas
• ☐ Use a Canada-registered residual product for persistent populations
• ☐ Seal cracks around pipes, baseboards, and entry points
• ☐ Store paper, cardboard, and fabric in sealed plastic bins
• ☐ Monitor traps ongoing to track population trends
• ☐ Call a pro if results plateau after 4–6 weeks