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Does Borax Kill Spiders?

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Borax, also known as sodium borate, is a soft, light, colorless crystalline mineral that is commonly used in various household and industrial applications. But one particular use that has sparked curiosity among homeowners is its effectiveness in killing spiders. In this comprehensive article, we’ll explore whether Borax does indeed kill spiders and delve into other alternatives for effective spider control.


Borax, also known as sodium borate, does not directly kill spiders. However, it can indirectly control them by eliminating their food sources, such as roaches, ants, and termites. For a more direct solution, consider using boric acid, a derivative of Borax, which is toxic to spiders.

Borax and Spiders: The Connection

While Borax itself isn’t directly effective against spiders, it can indirectly affect them by eliminating their primary food sources – insects like roaches, ants, and termites. By eradicating these pests, spiders may either starve to death or be forced to abandon their habitat in search of food.

However, it’s important to note that Boric acid, a derivative of Borax, can directly kill spiders due to its toxic properties. While it’s generally harmless to humans, it poses a significant threat to spiders.

The Impact of Borax on Different Spider Types

Borax’s effectiveness can vary depending on the type of spider. While it indirectly affects all spiders by eliminating their food sources, it’s not a reliable spider repellent or killer. Boric acid, on the other hand, is highly toxic to spiders and can be used to control them directly.

Safety and Environmental Considerations

Borax is registered as a pesticide with the Environmental Protection Agency (EPA) and is generally considered safe for humans and the environment. However, it’s not entirely a “green” chemical, and its mining and refining process can leave a significant environmental footprint. It’s crucial to use it responsibly and follow the recommended guidelines to ensure safety for humans, pets, and the environment.

How to Use Borax for Spider Control

To use Borax for spider control, sprinkle it in areas infested by insects that spiders feed on. However, for a more direct approach, use boric acid instead. Other natural spider control methods include using white vinegar, baking soda, and essential oils like peppermint, which are known to repel spiders.

Risks and Disadvantages

While Borax can control spiders indirectly, it comes with certain risks and disadvantages. It can be harmful if ingested in large quantities and may not be effective against all types of spiders. Additionally, it’s not a completely “green” chemical and requires careful application to prevent potential harm to people and pets.

Alternatives to Borax

If you’re looking for alternatives to Borax, consider natural methods like white vinegar spray, diatomaceous earth, baking soda, essential oils, cinnamon, lemon peel, and vinegar. Remember, not every method will work with every spider, and it may take some trial and error to find the most effective solution for your situation.

Preventing Spiders from Entering Your Home

Preventing spiders from entering your home is the best form of spider control. Use natural repellents, seal cracks and gaps, maintain cleanliness, trim back plants, install screens, use yellow bug lights, remove webs regularly, and use DIY spider repellents.

In conclusion, while Borax does not directly kill spiders, it can indirectly control them by eliminating their food sources. However, for more direct control, consider using boric acid or other natural alternatives. Remember to use these substances responsibly and always prioritize prevention over control.

Frequently Asked Questions

What is the difference between Borax and Boric Acid?

Borax and Boric Acid are both boron compounds, and while they are related, they are not the same. Borax is a mineral that is mined directly from the ground. Boric acid is produced when borax is reacted with an acid like hydrochloric acid.

Can I use Borax or Boric Acid around my pets for spider control?

While Borax and Boric Acid are generally considered safe for use around humans, they can be harmful to pets if ingested in large quantities. It’s important to apply these substances in areas where pets cannot access them.

Can Borax or Boric Acid harm plants?

Borax can be harmful to plants if used in large quantities, as it can cause the soil to become too alkaline. Boric acid, on the other hand, is typically safe for plants and can even be used as a fertilizer in small amounts.

How often should I apply Borax or Boric Acid for effective spider control?

The frequency of application will depend on the severity of the infestation. It’s best to start with a single application and monitor the area for signs of improvement or the need for additional treatment.

Where can I buy Borax or Boric Acid?

Borax and Boric Acid are commonly found in most grocery stores, home improvement stores, or online. Always remember to read and follow the instructions on the label for safe and effective use.

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