How to Use Boric Acid to Kill Silverfish

Lead Image
  • 1 hours
  • Beginner
  • 5-10
What You'll Need
Boric acid
Spray bottle

In many homes, silverfish can be a very problematic pest. Silverfish can exist quite happily for long periods of time with no food whatsoever, but when they find sugars or starches, they will get into them, eat them, and damage them. Additionally, silverfish will eat other items, such as books, photos, or anything else made from paper. They can even get into carpeting or furniture and eat the fibers they are constructed from. In short, a silverfish infestation is not something to take lightly. But how can you exterminate such a simple, hardy animal effectively? Luckily, it is quite possible to kill silverfish by using boric acid.

Step 1 - Mix

Boric acid is commonly used to kill pests for two reasons. First, it is effective. It can kill a wide variety of insects. Second, it is much less toxic than other chemicals used to kill pests.

Applying boric acid in an effective way involves a little bit of planning. First, heat some water on the stove. Next, stir in some boric acid. Wait for it to dissolve. Once it does, and it cools down, pour the resulting solution into your spray bottle.

Step 2 - Spray

clear spray bottle

Applying the boric acid in the best way possible to kill silverfish is important, as boric acid that is placed badly will have no effect. You can use your spray bottle on any area that you suspect gets a lot of silverfish traffic. Baseboards, surfaces connected to areas where food or paper are stored, and any area you have seen silverfish activity are all good candidates for a good spraying. Spraying under drains and behind pipes are also a good idea. Additionally, silverfish prefer dark areas. You can use this to your advantage by spraying in dark areas such as behind furniture, or under fixtures, or in closets. Areas that you spray with boric acid become very difficult for silverfish to operate in, as the acid damages their exoskeletons. However, boric acid is weak enough that it is not dangerous to humans.

If you are concerned that boric acid will cause aesthetic damage to the surfaces you spray it on, test a few drops of the solution in an inconspicuous place. Boric acid is mild enough that it should not cause any problems, but it is best to be safe.

Step 3 - Bait

You can also bait silverfish using powdered boric acid and a sugary or starchy food. Once you have a sugary or starchy food picked out — since the kind you use does not really matter, just pick any small piece of bread or cracker you have lying around — put it in a place you suspect silverfish like to go. Finally, sprinkle some boric acid powder on and around the piece of food. Any silverfish that attempt to eat the bait will have to bring themselves into contact with boric acid, which should damage them. If they survive this, they will probably eat the boric acid by mistake and die.

Putting bait in different areas is very important. It is possible for silverfish to miss your boric acid and bait completely if you leave them in a place that they do not go.