It is effective when sprinkled in out-of-the-way places where insects congregate. Borax is not effective against spiders, however boric acid, from which borax is derived, does kill spiders. Indirectly, borax can reduce the spider population by eliminating the insects that make up their food source.

Will boric acid keep spiders away?

Boric acid is a better alternative than using chemicals that could be toxic to humans or their pets. This is a natural and non-toxic way to keep spiders out of the home or to exterminate them once they have made a spot in your home. It is also environmentally friendly because you will not be releasing toxic chemicals.

What insects are killed by boric acid?