How to Use Diatomaceous Earth for Natural Pest Control, Both Indoors and In the Garden

If you’re interested in a more natural, less toxic approach to pest control, allow us to introduce you to the wonders of diatomaceous earth. Ideal for both indoor and outdoor use, this naturally occurring soft sedimentary rock can be a total game-changer when it comes to eradicating pests from around your home and garden, sans harsh chemicals and professional intervention.

Below, our experts break down exactly how to use diatomaceous earth and which pests it can curb, along with best practices and safety precautions when dealing with this DIY pest control method.

What Makes Diatomaceous Earth Different from Other Pest Control?

Diatomaceous earth stands out because it works mechanically, not chemically. "Most conventional pest control products rely on chemical ingredients that affect an insect’s nervous system or biological processes," entomologist Trent Frazer explains. "Diatomaceous earth, on the other hand, physically damages the insect’s outer shell." Made up of fossilized remains of tiny, aquatic organisms called diatoms, it absorbs the oils and fats from their outer layer, "effectively dehydrating and killing them," he says.

Since it contains no naturally derived or synthetic active ingredients, diatomaceous earth is not toxic to people or animals, according to James Agardy, technical and training manager at Viking Pest Control. "This makes it a good option for sensitive sites and situations where the use of traditional pesticides could be problematic," Agardy adds.

What Specific Pests Can Diatomaceous Earth Help Control?

Diatomaceous earth is surprisingly versatile when it comes to pest control. "Because it works by physically damaging the exoskeleton of insects," Frazer says, "it’s effective against a wide range of crawling pests, especially those with hard outer shells." 

Diatomaceous earth can be effective against: 

• Ants
• Bed bugs
• Cockroaches
• Fleas
• Ticks
• Silverfish
• Earwigs
• Slugs 
• Beetles 

"However, it is not effective for flying pests or rodents," says Shannon Harlow-Ellis, associate certified entomologist and technical services manager with Mosquito Joe.

Another warning to consider: Diatomaceous earth has no specificity. “In other words, it is effective against any insect, including beneficial insects such as ladybugs,” says award-winning entomologist Dr. Tracy Ellis.

How to Use Diatomaceous Earth Outdoors

To use diatomaceous earth outdoors, apply a fine layer to the perimeter of the patio or garden, paying special attention to any cracks and crevices in your walkways or patio. You can also apply it directly on plants to help control garden pests.

Considering that diatomaceous earth is a fine powder that works by dehydrating pests, it only works when it stays dry. “So the biggest thing to keep in mind outdoors is moisture control,” says Frazer. “Rain or even morning dew can reduce its effectiveness.”

How to Use Diatomaceous Earth Indoors

Diatomaceous earth can be a great low-toxicity option for targeting crawling pests, but Frazer says it’s important to use it strategically and safely. "Because diatomaceous earth works by damaging an insect’s outer shell, it needs to be placed where pests actually travel, not just where you see them," he says.

Apply thin layers behind appliances, under sinks and furniture, and along baseboards and in cracks and crevices, suggests Harlow-Ellis. "For carpet areas, diatomaceous earth can be lightly sprinkled and left for a few hours before being vacuumed," she says.

Be sure to use the powder sparingly and in areas where it won't be disturbed or create dust inhalation risks, adds Ellis.

Best Practices and Safety Precautions

Like any product, diatomaceous earth needs to be applied correctly to actually work and to stay safe for you, your family, and pets. "Just because diatomaceous earth is a natural product doesn’t mean it should be used without care," Frazer warns. 

• Always choose food-grade diatomaceous earth. Industrial-grade diatomaceous earth is harmful if inhaled, warns Harlow-Ellis. Pool-grade diatomaceous earth, for instance, has been heat-treated and can be harmful to lungs and skin, cautions Frazer, and isn’t pest control friendly.
• Protect your skin. Ellis recommends using personal protective equipment, such as dust masks and gloves, when applying diatomaceous earth. 
• Follow instructions. There are over 160 pest control products that utilize diatomaceous earth, according to Agardy. Consult the label of the specific product you are using for complete usage instructions.
• Avoid piling it up. Thick layers can actually deter pests from walking through it, Frazer warns. Stick with a thin layer of product only. 
• Reapply once moisture occurs. Diatomaceous earth loses effectiveness when wet, Ellis says, and should be reapplied after rain or heavy dew.
• Prepare your vacuum. Check the instructions on your vacuum for its use on powders, says Ellis, as some vacuum cleaners cannot handle the fine particles, and others may blow the dust everywhere. If your vacuum isn't compatible, use a damp rag for cleaning indoors. 
• Protect children and pets. Food-grade diatomaceous earth is considered generally safe for use around pets and people when used properly, but keep children and pets out of treated areas until cleanup is complete, urges Frazer.
• Don’t breathe in. Avoid inhaling the dust—even food-grade—as prolonged exposure can irritate the lungs, says Harlow-Ellis.
• Store correctly. Unused diatomaceous earth should be kept in an airtight container to maintain its effectiveness.