Many spiders are not harmful to humans or animals.

Diatomaceous Earth as a Pesticide for Spiders

by Marylee Gowans

The mere thought of spiders lurking in and around homes can make people’s skin crawl. Called arachnophobia, the fear of spiders is one of the most common phobias that people suffer from. Pesticides designed to kill spiders are readily available; however, many of these products contain harsh chemicals that leave lingering residue behind. Instead, use diatomaceous earth to safely control unwanted spiders.


Spiders may appear terrifying but are actually beneficial in many ways. These predatory insects prey on undesirable insects in your garden and recycle decaying and dead plant debris. Spiders are also pollinators and act as a food source for birds. Even though most common spiders found inside and outside the home are harmless, most people don’t want these eight-legged creatures creeping around their home.

Diatomaceous Earth

Diatomaceous earth -- also called DE -- is a fine powder made from diatom fossils, which are a member of the algae family. This powder has sharp edges that rip through the larval stage of insects and damage the protective coating of adult insects. DE is relatively safe for humans and pets but can cause eye, lung and skin irritation if you're not properly protected while applying the dust. Furthermore, ensure you use natural food-grade DE and not the diatomaceous earth used in pool filtration systems, which is toxic to humans and animals.


Diatomaceous earth works by drying out the spiders that crawl through the dust. DE can be sprinkled around the inside and outside of the home to control these creepy crawly insects. When using DE, wear a dust mask to prevent breathing in the dust, and rubber gloves and safety goggles. Apply a light dusting to outdoor and indoor areas where spiders are present. These areas should include around home foundations, windows, doors, patios and flowerbeds. Don’t forget to sprinkle diatomaceous earth in cracks and crevices inside your home. Not only will DE control spiders, it will also kill fleas and cockroaches that crawl through the dust.


Implementing proper spider repelling techniques will go a long way toward keeping spiders out of your home. Regularly removing cobwebs from the corners of rooms and sweeping windowsills and other dark areas where spiders can lurk will drive spiders out of your home. Sealing gaps and cracks around doors, windows and foundation, and ensuring doors and window screens have no holes in them will prevent spiders from entering your home. When you find a benign spider inside your home, refrain from killing it and instead capture it by placing a jar over top of the spider, carefully sliding a piece of paper under the jar opening and releasing it unharmed outside.

About the Author

Marylee Gowans has written about gardening for both online and print publications. She attended the University of Akron, graduating with a Master of Fine Arts in creative writing. In 2009, she received master gardener certification from the Master Gardeners of Summit County, Ohio.

Photo Credits

  • Comstock Images/Comstock/Getty Images