What Are Silverfish and How to Get Rid of Them?

The short answer: Silverfish are ancient, wingless insects that feed on starch and sugar, they eat book bindings, wallpaper paste, clothing sizing, and flour. They thrive in humid environments (75–95% humidity). To control them, reduce humidity below 50%, remove food sources (cardboard, paper, glue), use diatomaceous earth or boric acid in cracks, and seal crevices. They don’t bite or spread disease, but they damage belongings.

1. Confirm it’s silverfish

• Body length 10–15 mm, flattened and tapered, silvery-grey with a metallic sheen.
• Three long bristle-like appendages at the rear, they move with a wriggling, fish-like motion.
• No wings, they are fast runners.
• Typically found in wardrobes, bookshelves, bathrooms, and basements.

2. Where do they come from?

• They come from outside or in used books, cardboard boxes, and furniture.
• They are highly dependent on humidity, they cannot survive in dry conditions.
• They feed on starch, book glue, wallpaper paste, cotton sizing, and even dried food.

3. Step 1: reduce humidity (the most effective)

• Use a dehumidifier to keep indoor relative humidity below 50%, this stops silverfish reproduction and causes dehydration.
• Ventilate bathrooms and kitchens with exhaust fans.
• Fix any leaks, silverfish need moisture to thrive.

4. Step 2: remove food sources

• Get rid of cardboard boxes, old newspapers, and paper clutter, these are feeding and hiding sites.
• Store books, documents, and important papers in sealed plastic boxes with silica gel packets.
• Wipe down shelves and baseboards to remove starch dust.
• Transfer dry foods (flour, cereal) into airtight containers.

5. Step 3: seal cracks and crevices

• Silverfish hide in tiny gaps, caulk baseboards, floor cracks, and pipe penetrations.
• Use expanding foam to seal larger voids.
• Pay attention to behind kitchen and bathroom cabinets.

6. Step 4: apply insecticides or dusts

• Sprinkle food-grade diatomaceous earth or boric acid powder into cracks, corners, and behind furniture, these are abrasive stomach poisons.
• You can also apply dinotefuran-containing household insecticide along baseboards and in hiding spots, the residual film will kill them when they crawl over it.
• Keep pets and children away from these dusts until they settle.

7. Step 5: ongoing prevention

• Keep your home dry and clean, vacuum regularly to remove dust (food source).
• Avoid storing items directly on floors, use shelving with good airflow.
• Check second-hand books and furniture before bringing them inside.

Common mistakes

• ❌ Only spraying, without humidity control, they will return.
• ❌ Leaving cardboard boxes, they love the glue and paper.
• ❌ Ignoring wall voids, they can live inside walls indefinitely.

Mini FAQ

Q: Do silverfish bite?

A: No, they are harmless to humans, but they damage paper, clothing, and wallpaper.

Q: How long do silverfish live?

A: Adults can live 2–8 years, they are slow to develop but persistent.

Q: Can I use cedar or lavender to repel them?

A: These may have slight repellent properties, but they won’t eliminate a population, focus on humidity.

Your silverfish control list

• Reduce humidity below 50%.
• Remove cardboard and paper clutter.
• Store books and papers in sealed containers.
• Seal all cracks and crevices.
• Apply DE or boric acid in cracks.
• Monitor and maintain dryness.