Using Borax for Silverfish Control: A Homeowner’s Guide
If you're looking for an effective, affordable, and time-tested way to eliminate silverfish, borax might be the answer. Often found in laundry aisles and cleaning supplies, borax (sodium borate) is a natural mineral compound that doubles as a powerful pest control agent. You’ll learn how borax works, how to use it safely, and why it’s such a popular silverfish remedy among homeowners.
What Is Borax?
Borax is a naturally occurring mineral composed of sodium, boron, oxygen, and water. It’s commonly used as a cleaning agent, laundry booster, and insecticide. Borax kills insects by damaging their digestive and nervous systems after they ingest it, and it also dries out their exoskeletons.
Unlike synthetic pesticides, borax is considered low-toxicity when handled properly, making it a popular DIY pest control option.
How Borax Kills Silverfish
- Silverfish are attracted to starchy or sugary bait mixed with borax.
- Once consumed, borax interferes with their metabolism and causes dehydration.
- They also absorb borax through their bodies if they crawl over it repeatedly.
It’s a slow-acting but reliable way to reduce populations over time without the mess or smell of sprays.
How to Use Borax Safely
- Always keep borax away from children and pets
- Wear gloves while handling or applying
- Use in cracks, crevices, and out-of-reach areas
- Avoid contact with food preparation surfaces
Although it’s natural, borax should be treated with care especially in homes with small kids or animals.
DIY Borax Trap Recipes
1. Sugar and Borax Bait
- Mix 1 part borax with 3 parts sugar
- Sprinkle in shallow lids or bottle caps
- Place near baseboards, under sinks, and in closets
2. Borax and Flour Paste
- Mix equal parts borax and flour with a few drops of water
- Roll into small balls or smear in corners and cracks
- Replace every few weeks for best results
3. Dry Powder Application
- Sprinkle pure borax lightly behind baseboards, appliances, or inside wall voids
- Vacuum excess after 7–10 days and reapply if needed
Where to Apply Borax
- Behind toilets and under bathroom cabinets
- Inside kitchen cupboards and pantry corners
- Along baseboards, window sills, and floor cracks
- In closets and dark storage areas
- Under appliances and furniture
Target areas where you’ve seen silverfish activity or signs like shed skins, droppings, or paper damage.
How Long Does It Take to Work?
Borax isn’t instant, it can take a few days to several weeks to reduce a silverfish population, depending on infestation size and placement. You should begin to see fewer sightings after the first week.
Be patient and reapply as needed. Combine with sticky traps and moisture control for best results.
Precautions and When to Avoid Borax
- Don’t use near pet food or toys
- Keep out of reach of children
- Avoid overuse in high-traffic areas
- Use gloves and wash hands after handling
If you prefer a gentler approach, essential oils and herbal repellents are good alternatives.
Borax is one of the most effective natural tools in the fight against silverfish. It’s affordable, easy to use, and works quietly behind the scenes to control infestations. By combining borax traps with moisture control and routine cleaning, you can make your home far less welcoming to these persistent pests.
If you would like to focus on room-specific strategies, read our other blog posts starting with how to get rid of silverfish in bathrooms and kitchens.