| Key Takeaways |
|---|
| • It kills through desiccation, not poison: Pests that contact dry diatomaceous earth die of dehydration within 12 to 24 hours, with a real population drop appearing in 5 to 7 days. • Application method depends on the area: Dry powder suits small, targeted spots, while a liquid solution of diatomaceous earth can cover larger surfaces like trees and shrubs. • Weather conditions affect timing: Apply on windless days with no rain expected for 24 to 48 hours, since moisture stops the powder from working. |
Pests are chewing on your grass, and you’re wondering how to use diatomaceous earth (DE) to get rid of them? It’s easy: Spread a thin coating of food-grade DE on your lawn on a calm, dry day, focusing on pest-infested spots.
Reapply if heavy dew or rain sets in, and repeat every 3 to 4 weeks until pests are gone.
Below, we cover how DE works, what it kills, and where it falls short. If you’d rather leave pest control to a pro, LawnStarter’s lawn treatment service connects you with the best local experts.
- What Is Diatomaceous Earth?
- How to Use Diatomaceous Earth for Pest Control
- How to Avoid Harming Pollinators
- Why Is Diatomaceous Earth Used as a Pesticide?
- Common Pests Diatomaceous Earth Might Not Kill
- Pros and Cons of Using Diatomaceous Earth as an Insect Killer
- Types of Diatomaceous Earth
- Other Uses for Food-Grade Diatomaceous Earth
- FAQs
What Is Diatomaceous Earth?
Packaged diatomaceous earth is an off-white, fine powder made of the fossilized shells of aquatic organisms called diatoms. Also referred to as DE, diatomite, Kieselgur, or Kieselguhr, it has a neutral taste, no smell, and looks like chalk or talc.
DE is a natural product you can use for eco-friendly lawn care and organic gardening (buy the OMRI-labeled products).
See Related: Natural Pest Control for Your Lawn That Works
How to Use Diatomaceous Earth for Pest Control
Here’s how to use diatomaceous earth effectively:
1. Choose Between Powder or Liquid Solution
| Dry Dusting | Wet Application | |
| Best for | Small areas, barrier rings around infested patches | Large areas, tall trees, dense shrubs |
| Application | Duster or shaker | Pumo/backpack sprayer, agitate constantly |
| Effective when | Immediately | Only after it dries (1 to 2 hours) |
| Drawback | Blows away in wind, dust inhalation | Clogs nozzles, no effect until dry |
2. Wait for the Right Weather
The best time to apply diatomaceous earth is on windless days with no rain in the forecast for 24 to 48 hours.
DE particles are fine enough to drift off target before they settle. If rain gets the powder wet, it stops working until it dries, and by then it’s usually clumped or washed away.
Wait until the evening, when pollinators are no longer active.
3. Use Only Food-Grade Diatomaceous Earth
Food-grade DE is the only type suited for pest control. It’s purified, low in crystalline silica, and safe around people, pets, and wildlife. Never use pool-grade DE in your yard.
4. Wear Protective Equipment
Food-grade DE isn’t poisonous, but the dust is abrasive. The National Pesticide Information Center (NPIC) warns that inhaling it can irritate your nose and nasal passages, with extremely large amounts causing coughing and shortness of breath. It can also irritate the eyes and dry out the skin.
Before you spread it, put on:
A dust mask
Safety glasses
Garden gloves
5. Spread Dry Diatomaceous Earth Correctly
To spread dry DE, you’ll need:
DE powder
A garden spreader or dust applicator (you can also use a flour strainer or a turkey baster)
Skip power dusters and backpack blowers when applying DE to plants. The high-velocity air turns DE into a sandblaster, says James Dill of the University of Maine Cooperative Extension in Orono, Maine.
“As it hits the plant, it’ll do the same thing to the surface of the plant it does to the insect, so it could open it up to secondary infections.”
Follow these steps:
Step 1: Look for signs of pest infestation (brown, thinned, wilted, dead grass).
Step 2: Fill the garden duster with powder and close it tightly.
Step 3: Start spreading the powder in a thin, even layer across the affected area (plants and top of the soil), keeping the spreader about 6 inches above the ground. Too thick a layer, and insects will avoid it.
Step 4: Finish by circling the targeted area with a continuous line of DE powder. Also, apply to neighboring flower beds that show signs of infestation.
Step 5: Repeat the application weekly for a month for an extensive infestation, or every 3 to 4 weeks during pest active season to keep pests under control.
Some DE manufacturers include a spreader in the package, or you can get one online on Amazon or Walmart.
6. Spray Liquid Diatomaceous Earth
A liquid solution is easier for treating a whole lawn or large patches infested with mole crickets, beetles, or grasshoppers. You’ll need:
Diatomaceous earth powder
Water
Spray bottle (for spot treatments) or garden pump sprayer
Apply the diatomaceous earth spray in 5 steps:
Step 1: Prepare the solution. Mix 4 tablespoons of powder per 1 gallon of water in the sprayer and stir thoroughly into a muddy slurry.
Step 2: Spread the solution uniformly across the lawn. Apply a thick coat to ensure the solution reaches the soil surface, but not so much as to create runoff.
Step 3: Go around the lawn and spray the edges.
Step 4: Reapply if wind, rain, or heavy dew hits before the layer dries.
Step 5: Repeat on the same schedule as dry DE (weekly for heavy infestations, otherwise every 3 to 4 weeks).
You can find liquid sprayers online or at home improvement stores.
How to Avoid Harming Pollinators
Diatomaceous earth doesn’t distinguish between pests and beneficial insects. It kills bees, ladybugs, and butterflies the same way it kills aphids. These 4 application rules keep the damage minimal:
Treat only infested spots. Work in tight circles around chewed leaves and stems rather than broadcasting across the yard.
Apply in the evening. Bees and ladybugs stop foraging as temperatures drop and don’t return until the next day warms up, so the dust is at its densest when they’re gone.
Keep it low. Dust the soil and lower stems for slugs, grubs, earwigs, and cutworms. Pollinators mostly visit the top of the plant where the flowers are.
Skip blooms entirely. Never dust the flowers or the leaves right below them. If aphids have taken the crown of a plant, prune it instead.
Prefer something bee-safe? Beneficial nematodes target soil pests without touching pollinators.
See Related:
Why Is Diatomaceous Earth Used as a Pesticide?
Diatomaceous earth kills soft-bodied pests without the environmental trade-offs of synthetic insecticides. Insects that come into contact with it die by desiccation in a few days.
DE is high in silica, and silica works on insects in 2 ways at once:
It absorbs. As insects move through the powder, it pulls the oils and waxes out of their exoskeletons, leaving them fragile and dry.
It abrades. Its razor-sharp edges scratch through the protective outer layer, so moisture escapes faster than the insect can replace it.
“It’s like little tiny, minute grains of sand,” Dill says.
On aphids, Dill says: “When the insect comes in contact with it, it actually scars, erodes, and cuts the cuticle — the covering of the aphid — and the aphids actually dry out. They just dehydrate.”
According to the NPIC, DE is used in its pure form and as an active ingredient in over 150 registered products for use in and around buildings, farms, gardens, and pet kennels.
Common Pests Diatomaceous Earth Might Not Kill
| Pest | Why DE Falls Short | What to Do Instead |
| Slugs and snails | Mucus buffers the abrasive edges; DE mostly deters feeding rather than killing | Copper tape, slug collars, hand picking, IPM plan |
| Lawn grubs | DE kills only on contact and stays on the surface, so it rarely reaches roots where grubs feed | Beneficial nematodes on moist soil, late summer to early fall |
| Any pest in wet conditions | DE clumps when damp and loses its abrasive action | Reapply after rain or irrigation |
For any lawn pests, add preventive measures: Turn over winter mulch to expose them, till the soil in spring, and avoid evening irrigation.
See Related: Lawn Grubs: How and When to Kill Them
Pros and Cons of Using Diatomaceous Earth as an Insect Killer
Pros
✓ A natural, organic pesticide safe for people, animals, fish, and the environment.
✓ It improves soil structure.
✓ It kills a wide range of pests.
✓ It is a mechanical pesticide, not a chemical one, so pests cannot develop immunity.
✓ Safe to use indoors and outdoors.
✓ Highly accessible and inexpensive.
Cons
✗ Its efficiency depends on the weather (useless when wet)
✗ It can harm pollinators if misused.
✗ DE particles can irritate the eyes, nose, and throat if exposed.
✗ You need to apply it correctly for it to work.
Types of Diatomaceous Earth
DE comes in 2 grades. Only food-grade belongs in your garden.
| Feature | Food-Grade DE | Pool-Grade DE |
| Processing | Minimally processed, purified | Calcined under high heat |
| Crystalline silica | Very low | High |
| Safe to use as a pesticide | Yes | No |
| Main use | Pest control, garden | Pool filtration |
Food-grade DE is made from freshwater diatomite and purified to remove traces of arsenic and lead. It won’t kill your grass and isn’t poisonous to people or pets, though the dust can still irritate your nose, eyes, and throat.
Can You Use Pool-grade DE for Pest Control?
No. Pool-grade DE is calcined (heated until the silica turns crystalline), which makes it a better pool filter but a serious respiratory hazard. According to OSHA, inhaling crystalline silica is linked to silicosis and other lung diseases.
Keep it out of the garden and away from pets.
Where to Buy Food-grade DE
DE is inexpensive and easy to find at garden centers or online retailers, like Home Depot, Amazon, and Lowe’s. For pest use, check the label for an EPA registration number.
Food-grade DE sold as a food additive isn’t labeled as a pesticide even though it’s the same material, and many pest-labeled products carry an OMRI listing for organic gardening.
Warning: Do not eat food-grade DE that you buy as a pesticide. Products intended for consumption are labeled separately.
Other Uses for Food-Grade Diatomaceous Earth
Around the house, DE earns its keep beyond the lawn:
Fleas indoors. Dust carpets, wait about 12 hours, then vacuum thoroughly.
Roaches and ants. Lay a fine layer along baseboards, under cabinets, and in crevices where they travel. It stays effective for as long as it is dry.
Potting mix. Coarse DE granules improve water drainage and water retention in containers.
See Related: How to Treat Fleas in Your Yard Naturally
Call a Pro to Enjoy a Green, Lush, Pest-Free Lawn
Diatomaceous earth protects your lawn from pests without polluting soil or waterways, and since insects cannot develop immunity to it, it keeps working season after season.
If you do not feel like applying diatomaceous earth, LawnStarter’s lawn treatment pros specialize in organic lawn pest control and can handle the application for you. Say goodbye to brown patches and enjoy a green, lush, pest-free lawn without harming your local environment.
FAQs
Pest insects that get dry diatomaceous earth on their bodies die of desiccation in 12 to 24 hours. A significant change in pest population typically appears after 5 to 7 days.
Diatomaceous earth kills arthropods: insects, spiders, and mites with a waxy exoskeleton (exterior skeleton) that it can abrade and dry out. That covers fleas, ants, earwigs, cockroaches, ticks, squash bugs, and Japanese beetles, among others.
Accidental exposure to food-grade diatomaceous earth during gardening is not toxic to children or pets. But the dust can still irritate the eyes, nose, and throat, so keep kids and pets away during application.
LawnStarter participates in the Amazon Services LLC Associates Program, an affiliate advertising program. LawnStarter earns revenue from products promoted in this article.
Main Image: Diatomaceous earth handwritten on a napkin beside a measuring spoon, powder, and a glass mixed with water. Photo Credit: MarekPhotoDesign.com / Adobe Stock
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