Does Boric Acid Kill Silverfish? {Best Way To Repel Them}

Are you looking to remove silverfish from your home and prevent them from returning? Are you wondering, “Does Boric Acid Kill Silverfish?”

Will boric acid could kill and prevent them from coming back? Is it true?

Should you use diatomaceous earth instead of boric acid?  I will cover the pros and cons of both below.

Does Boric Acid Kill Silverfish?

Boric acid does a very good job at killing silverfish when they have ingested the acid. Once the acid has been ingested, it will dry the silverfish out which will kill it.

How To Use Boric Acid for Silverfish?

There are two methods that you can use to apply boric acid to kill silverfish which are

  • Boric Acid Bait Trap
  • Boric Acid Spray

WARNING : Please make sure you wear protective gloves at all time when handling boric acid.

Does Boric Acid Kill Silverfish

Boric Acid Bait Trap

You can create a bait trap which will attract the silverfish and it will poison them when they eat from it.

To create bait trap for silverfish follow these steps

  1. Cut up paper into small pieces
  2. In a pot mix one spoon of powder boric acid powder with a cup of grounded oats and a teaspoon of sugar
  3. Add the small pieces of paper into the pot
  4. Mix all ingredients well
  5. Place the baited trap near where the silverfish are

Silverfish will be attracted to the baited trap by the smell of starch in the paper, when they enter the trap the boric acid will stick to their body which will cause them to dehydrate and eventually die.

Silverfish will also spread the boric acid to other silverfish when they come in contact with them.

Boric Acid Spray

The second method is to create an acid spray which we can use to spray boric acid in the areas that we see silverfish.

To create a boric acid spray follow these steps

  1. Add 2 tbsp of boric acid and two tablespoons of sugar in to a spray bottle
  2. Add 2 cups of warm water
  3. Stir the mixture until all of the powder is dissolved
  4. Wearing protective gloves you can now apply the spray

Using this spray apply to areas where silverfish are hanging out. When the silverfish walk over the boric acid it will stick to them and cause them to dehydrate and eventually die.

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Does Boric Acid Attract Silverfish?

Boric acid will not attract silverfish on its own, to attract silverfish you will need to combine boric acid with another ingredient to attract the silverfish.

Ingredients that attract silverfish that you can add to boric acid include

  • Grounded Oats
  • Sugar
  • Paper
  • Starch
  • Honey

When adding another ingredients to boric acid you should had roughly half and half of each ingredients for the best affect.

Always wear protective gloves mixing boric acid

How Does Boric Acid Kill Silverfish?

Boric acid will kill silverfish when they have eaten it by damaging their internal systems and they will die overtime.

Silverfish are not attracted by boric acid so you will need to add something into the acid to attract the silverfish, such as sugar or grounded oats.

If silverfish have come into contact with boric acid, there is a high chance that they will spread the acid to other silverfish that they come in contact with.

How Long Does it Take Borax to Kill Silverfish?

Boric acid will kill silverfish in 1 – 2 days after they have ingested the acid. The acid will attack the silverfish internal organs which causes death.

The infected silverfish will also infect and kill any other silverfish that it comes in to contact with.

So within 2 – 5 days you should see a significant decrease in silverfish activity.

Will Diatomaceous Earth Kill Silverfish?

Diatomaceous earth is similar to boric acid in the way that it dehydrates a silver fish from the inside out. The main difference is that diatomaceous earth is a powder that can never be used wet.

You can use diatomaceous earth on silverfish and plenty of other insects. Once you sprinkle this powder and a silverfish makes contact with it, it will begin to lose moisture.

A little goes a long way with diatomaceous earth. It’s easy to sprinkle and once silverfish make contact with it, it will be killed through dehydration.

Diatomaceous Earth vs Boric Acid For Silverfish

Diatomaceous Earth is a natural insecticide which can be used in the same way as boric acid in killing silverfish.

Diatomaceous earth comes in powder form that you spread near silverfish nests.  When a silverfish walks over this powder it will stick to them and cause them to dehydrate and eventually die.

Silverfish will typically die within 48hrs of coming in contact with Diatomaceous earth powder.

Diatomaceous earth and boric acid are equally good at killing silverfish, but diatomaceous earth can be easily deployed by just simply sprinkling it on surfaces.


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jason barrett

Hello, I'm Jason. I have 8 years of experience in dealing with pests. I try to provide you the best information that'll help you to make the pest control process easy & affordable is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to