Uses For Diatomaceous Earth – Diatomaceous Earth For Insect Control

Uses For Diatomaceous Earth – Diatomaceous Earth For Insect Control

By: Stan V. Griep, American Rose Society Consulting Master Rosarian, Rocky Mountain District

Have you ever heard of diatomaceous earth, also known as DE? Well if not, prepare to be amazed! The uses for diatomaceous earth in the garden are great. Diatomaceous earth is a truly amazing all-natural product that can help you grow a beautiful and healthy garden.

What is Diatomaceous Earth?

Diatomaceous earth is made from fossilized water plants and is a naturally occurring siliceous sedimentary mineral compound from the remains of algae-like plants called diatoms. The plants have been part of Earth’s ecology system dating back to prehistoric times. The chalky deposits the diatoms left are called diatomite. The diatoms are mined and ground up to make a powder that has a look and feel much like talcum powder.

Diatomaceous earth is a mineral-based pesticide and its composition is approximately 3 percent magnesium, 5 percent sodium, 2 percent iron, 19 percent calcium and 33 percent silicon, along with several other trace minerals.

When using diatomaceous earth for the garden, it is extremely important to purchase only the “Food Grade” diatomaceous earth and NOT the diatomaceous earth that is and has been used for swimming pool filters for years. The diatomaceous earth used in swimming pool filters goes through a different process that changes its makeup to include a higher content of free silica. Even when applying the food grade diatomaceous earth, it is of the utmost importance to wear a dust mask so as not to inhale too much of the diatomaceous earth dust, as the dust can irritate the mucous membranes in your nose and mouth. Once the dust settles, though, it will not pose a problem to you or your pets.

What is Diatomaceous Earth Used for in the Garden?

The uses for diatomaceous earth are many but in the garden diatomaceous earth can be used as an insecticide. Diatomaceous earth works to get rid of insects such as:

  • Aphids
  • Thrips
  • Ants
  • Mites
  • Earwigs
  • Bedbugs
  • Adult Flea Beetles
  • Cockroaches
  • Snails
  • Slugs

To these insects, diatomaceous earth is a lethal dust with microscopic sharp edges that cut through their protective covering and dries them out.

One of the benefits of diatomaceous earth for insect control is that the insects have no way to build up a resistance to it, which can’t be said for many chemical control insecticides.

Diatomaceous earth will not harm the worms or any of the beneficial microorganisms in the soil.

How to Apply Diatomaceous Earth

Most places where you can purchase diatomaceous earth will have complete directions on the proper application of the product. As with any pesticide, be sure to read the label thoroughly and follow the directions thereon! The directions will include how to properly apply the diatomaceous earth (DE) both in the garden and indoors for the control of many insects as well as forming a barrier of sorts against them.

In the garden diatomaceous earth may be applied as dust with a dust applicator approved for such use; again, it is of the utmost importance to wear a dust mask during application of the diatomaceous earth in this manner and leave the mask on until you have left the dusting area. Keep pets and children clear of the dusting area until the dust has settled. When using as a dust application, you will want to cover both the top and underside of all foliage with the dust. If it rains right after the dust application, it will need to be reapplied. A great time to do the dust application is right after a light rain or in the very early morning when the dew is upon the foliage as it helps the dust to stick well to the foliage.

In my opinion, it is better to apply the product in a wettable form to avoid the airborne dust particles problem. Even then, wearing a dust mask is a garden-smart action to take. For doing the spray application of diatomaceous earth, the mix ratio is usually 1 cup of diatomaceous earth per ½ gallon (236.5 mL per 2 L) or 2 cups per gallon (473 mL per 4 L) of water. Keep the mix tank agitated or stir it often to keep the diatomaceous earth powder well mixed with the water. This mix may also be applied as a paint of sorts to trees and some shrubs.

This is truly an amazing product of nature for use in our gardens and around our homes. Don’t forget that it is the “Food Grade” of diatomaceous earth that we want for our gardens and home use.

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Diatomaceous Earth for Cats

While it's more common to use Diatomaceous Earth as flea prevention, many people have added small amounts of DE to their pet's diet. There a numerous benefits a pet can receive from a consistent dosage of DE. Pet owners who have given their pets DE have found their pet has an improved coat, appetite, metabolism, and digestion.

DE is largely made up of amorphous silica, but it also contains calcium, magnesium, titanium dioxide, gallium, sodium, and other trace minerals. Keep in mind that there are different grades of diatomaceous earth, so make sure you purchase food grade diatomaceous earth for your pet.

The instructions below are on how to feed your cat DE.

Step 1:

You need to make sure that you are using food grade DE. Only food grade DE is safe for pets as a supplement. Other types of DE are not safe for humans or animals.

Step 2:

Your cat's size will affect the DE dosage size

Small Cats and Kittens* (2-6 ½ lbs) ½ tsp of food grade DE
Full Grown Cats (7-13 lbs) 1 tsp of food grade DE
Large Cats (>13 lbs) 1 ½ tsp of food grade DE

*If kittens are still nursing or only taking milk we recommend you hold off on adding DE to their diet until they move to solid food.

Step 3:

The type of food you are giving your cat will also affect the way to give it to them.


Gardeners are often given the advice to sprinkle diatomaceous earth ( DE ) around plants to deter pests. Unsurprisingly, we’re often asked, “What is diatomaceous earth, exactly?” Well, here’s your answer…

What Is Diatomaceous Earth?

Diatomaceous earth ( DE ) is the fossilized skeletons of microscopic single-celled aquatic organisms called diatoms. Their skeletons are made of a natural substance called silica—which makes up 26% of the Earth’s crust by weight.

Deep deposits of diatomaceous earth are mined in the western United States in places where lakes once covered the area millions of years ago.

How Does Diatomaceous Earth Deter Garden Pests?

Snugs and snails do not like to crawl over DE because the silica skeletons are very sharp—like tiny pieces of broken glass. (Slugs and snails don’t like eggshells either!) If their soft bodies do get cut, they eventually dehydrate and die. This process works on other soft bodied insects, too, including caterpillars and aphids, as well as on those with hard shells, such as beetles, fleas, cockroaches, and even bed bugs. The tiny particles of DE get into the insects’ joints, causing irritation and dehydration.

Caution: The downside to DE is that it does not discriminate between pests and beneficial insects. Ladybugs, green lacewings, butterflies, bees, and other “good guys” can also be killed by DE if they come into contact with it. For this reason, we recommend using DE with discretion on and around plants that beneficial insects may frequently visit. Avoid using it around flowers as well.

How to Use DE

  • When shopping for DE , look for the “food grade” quality. The DE used in pool filters is not effective against garden pests.
  • Sprinkle bands of DE around the plants you are trying to protect. It’s important that the ring of DE does not have any gaps for pests to sneak through.
  • If pests are eating the leaves of your plants, you can dust the leaves with DE , which should discourage further damage. However, you should avoid applying DE near the plants’ flowers, where pollinators might inadvertently come into contact with it.
  • When using DE , it’s recommended to wear eye protection and a dust mask, as the small particles can be irritating.
  • DE works best in dry conditions. It clumps together when wet, so reapply after it rains.

Is DE Safe to Use?

Even though the industry states that this product does not cause lung damage, I would still refrain from breathing it in. Remember, it might feel soft to the touch, like talcum powder, but it still is an abrasive and can cause irritation to your eyes, nose, lungs, and throat. Wear a dust mask and eye protection when handling it just to be on the safe side.

Food-grade DE is not toxic if ingested in small quantities. In fact, we probably have been eating it for years unknowingly, since it is often mixed with grain in storage to kill insects. It can also be found in toothpastes and skin care products. Some people take it a step farther and use it for treating internal parasites! However, the DE that is commonly used in pool maintenance is not edible.

DE does not harm the soil since it is made from silica, the same as sand and many rocks. It does not break down when exposed to sun. Rain can wash it into local water sources but it is non-toxic to fish and other aquatic life. It is not harmful to birds or other wildlife. It has been added to livestock feed for years.

If pests are enough of a problem that you would be tempted to resort to a chemical pesticide, give DE a try first. It is considered organic by the Organic Materials Review Institute ( OMRI ) and the National Organic Program considers it a non-synthetic and permits it use in crop production.


Different types of diatomaceous earth (DE)

Diatomaceous earth is mined all over the world from Nevada to Scotland, the Czech Republic and beyond. More important than where it comes from, however, is the quality.

Food-grade DE

To stay on the safe side of life, always opt for food-grade diatomaceous earth which contains less than 1%, or even 0.5% crystalline silica. Also, to meet safety standards, it cannot contain more than 10 mg of arsenic or 10 mg of lead.

Whether you buy it at your local health food store, or online, be sure to purchase the best quality to reap the best rewards.

Feed-grade DE

Not so long ago, feed-grade was the thing to buy for livestock and pets. The silica content varied, as did the origin of the diatomaceous earth, making it suitable perhaps for the garden, less so for human consumption. But your pets, chickens, dogs, horses and donkeys deserve the very best, so set the standard and deliver them food-grade DE.

Pool-grade DE

This grade of diatomaceous earth is ineffective for eliminating insects (natural insecticide) as it is treated with very high heat by a process called calcination. This process turns the silicon dioxide into crystalline silica – which is toxic to both humans and animals!

It is often used to filter out impurities in water, and while it has industrial uses, it should not be used in the home or garden.

Only purchase food-grade diatomaceous earth from reputable sources.


Natural diatomaceous earth comes from crumbled sedimentary rock that contains the fossilized bones of organisms called phytoplankton. Although it is not toxic to humans, dogs or cats, the product can cause irritation or damage to lungs and nasal passages if it's inhaled. Another kind of diatomaceous earth that is used in swimming pool filters contains crystals of silica and can cause severe damage to people and pets, so avoid that type completely in your garden.

Diatomaceous earth is most effective when the soil or area where you spread it is dry. Wet soil or rain will dissipate the powder and allow it to soak into the soil rather than sitting on the top of the soil where insects will run into it. Apply the powder during a dry day, and reapply it after a rainfall or a heavy dew.

Diatomaceous earth kills many different insects, including ants, aphids, centipedes, cutworms, crickets, Japanese beetles, millipedes, slugs, snails, sow bugs and squashbugs.


Use Only Food Grade Diatomaceous Earth (DE)

There are different grades of diatomaceous earth but many of them contain added chemicals. To use it at home, on animals, or to take internally, it’s important you only use the food-grade diatomaceous earth.

The FDA has rated food-grade diatomaceous earth as ‘Generally Recognized as Safe’ (GRAS), specifically when it is used as filter aids in food processing.

Here are some of the health benefits and uses of food-grade diatomaceous earth:


​Benefits of Using Diatomaceous Earth in the Organic Garden

Diatomaceous earth, also called diatomite or simply "D.E.", is a chalk-like substance that’s a naturally occurring substance mined from lake beds. It consists of fossilized diatoms, which are a type of single-celled planktonic algae that lived in oceans and freshwater lakes years ago. There are several benefits for using diatomaceous earth in an organic garden, including eliminating the need for chemical pesticides.

Aphid Control

Aphids are rice-sized green pests that feed on plant juices by piercing young plant parts and sucking the sap. This will stunt plant growth and reduce yield. Dust aphid-infested plants with the diatomaceous powder or mix it with water and spray on plants with a sprayer.

Ant Killer

Ants indirectly destroy garden plants through the use of aphids. Ants “farm” aphids by carrying them to new plants and protecting them from predators. The ants then “milk” the honeydew from aphids in return.

Dust garden plants and ant hills with diatomaceous earth to get rid of them.

Organic Pest Control

Diatomaceous earth is a safe, non-toxic way to control pests in the garden. It’s effective against all insect pests that crawl on plants because contact with the powder is extremely dehydrating.

Water plants, then dust with the powder. The moisture will help the powder stick to plants better.

Slug Away

Slugs are nocturnal pests that like to feed on garden plants under the cloak of darkness.

Protect tender plants by creating acircle of diatomaceous earth around plants. When the soft body of a slug comes in contact with the powder, the sharp particles inflict tiny cuts on the skin and they quickly dehydrate.

Fly Deterrent

Flies are an annoyance to gardeners, but they can easily be kept away with an application of diatomaceous earth.

Sprinkle the powdery organic product liberally on all plants and on the ground. Flies tend to avoid treated areas.

Maggot-Free Compost

Fresh manure and compost piles can house the larvae of many types of flies. While maggots aren’t harmful, the resulting flies are a source of aggravation.

To keep the compost pile maggot-free, just sprinkle diatomaceous earth all over it.

Reduce Rodent Population

Rats, moles, mice, and rabbits often do great damage to your garden, but can be deterred from visiting the garden with the use of diatomaceous earth.

Add a few drops of the essential oil of lemon or peppermint (rodents hate both scents) to the powder, then sprinkle it around the garden perimeter. This highly porous substance absorbs the oil and retains the scent for several weeks.


Watch the video: How to Use Diatomaceous Earth for Tomatoes