Diatomaceous Earth For Cockroaches: The Ultimate Guide

What is Diatomaceous Earth?

Diatomaceous earth is a naturally occurring sedimentary rock.

It consists of fossilized remains from small, aquatic organisms called diatoms.

Diatoms are primarily made of a natural substance called silica.

The silica in Diatomaceous earth is useful to us in many ways.

For instance, we use Diatomaceous earth to treat high cholesterol levels and improve skin, nails, teeth, bones, and hair.

While diatomaceous earth is safe for humans, it kills insects by destroying their exoskeletons.

You can rub them on your pet to fight fleas, ticks, and lice.

More importantly, it is very effective at eliminating cockroaches.

How Does Diatomaceous Earth Work Against Roaches?

Close-up of Diatomaceous earth on a wooden surface

Diatomaceous earth kills insects by destroying their exoskeletons.

This happens in two steps.

First, DE absorbs the oily and waxy outer cuticle layer found on a cockroaches exoskeleton.

Second, once the outer layer is destroyed, cockroaches lose water and die from dehydration.

Although to humans DE is just like any other powder, to insect, it has microscopic, razor-sharp edges.

Two things determine how effective DE is on insects.

First, cockroaches must make contact with DE for it to work.

This can happen if cockroaches walk through DE or other cockroaches transferring DE from their bodies onto other cockroaches.

Second, DE must be dry for it to remain effective on cockroaches.

To ensure that insects make contact with DE place it in common hiding places.

Also, it is important that you only apply a thin layer, barely visible to the human eye.

If the layer of DE is too thick, cockroaches will avoid it.

How Effective is Diatomaceous Earth?

When roaches get in contact with DE, they don’t die right away.

Don’t worry, this is a good thing.
When roaches return to their hiding spots, they spread the DE to the rest of the population.

The powder then gets transferred to other cockroaches and kills them as well.

This horizontal transfer allows DE to have a 100% mortality rate on roaches.

Demacreous earth can eliminate 60% of roaches in your home within 24 hours, 80% within 48 hours, and at one week, 100% mortality rate.

How to Use Diatomaceous Earth?

Step 1: Clean and Dry.

Clean before applying the DE.

Then give the area a few minutes to dry.

Remember, DE needs to be dry to be effective.

If your attic, basement, or bathroom are humid, use fans to minimize moisture before applying DE.

Step 2: Spread a thin layer where roaches live and travel.

Next, spread a thin layer of the DE dust on spots where the roaches live and travel.

Cockroaches will avoid thick layers of DE.

You’ll want to spread some anywhere food is available.

Common places to target include under, on the side, and behind appliances and cabinets. 

If it’s not too humid, spread some under your bathroom sink and closets.

Step 3: Apply dust in Hard to Reach Areas.

Using a duster bottle, apply DE to hard to reach areas such as crevices and cracks.

Common places to target are wall voids, crevices between cabinets, and under floorboards and cabinets.

You’ll also want to apply a thin layer inside outlets and gaps around wiring.

If there are any cracks on your walls or floors, roaches are likely hiding there.

When spraying DE, remember to wear a mask and goggles to avoid irritation.

Step 4: Apply DE Outside.

Finally, spread a thin layer of DE outside.

A great place to start is around your home.

Look for any entry points and apply DE inside.

Even if cockroaches make it past DE, they won’t make it very far once they are inside.

You can also use DE to prevent outdoor roaches from infesting your yard and garden.

Common places to target are your garden soil, lawn, shrubs, flower paths, and around trees.

Do not worry, DE won’t damage your landscaping!

But remember, DE is only effective when it’s dry. So only do this treatment on dry days.

Step 5: Repeat This Process.

How often you should reapply depends on how many roaches you’re dealing with.

In general, you’ll need to apply DE about once a week for a full month to achieve the best results.

Reapply DE outdoors if it rains or becomes too humid.

Is DE Safe for Pets?

While DE powder is safe to rub on pets, you should prevent them from ingesting it.

Ingesting DE can cause minor irritation to the repertory tract for pets.

If ingested in large amounts once or gradually, DE can cause more severe problems.

It’s best to store DE in a secure location away from your pets.

Is DE Safe for Humans?

Food-grade diatomaceous earth is safe for humans to consume.

They can pass through your digestive system unchanged and does not enter the bloodstream.

That said, be careful not to inhale DE.

Just like any dust, inhaling DE dust can irritate your lungs.

But the silica found in DE makes it especially harmful.

Inhaling crystalline silica can scar your lungs (silicosis) and cause inflammation.

Silicosis is common in miners. It caused approximately 46,000 deaths in the community in 2013 alone.

Although food-grade DE contains less than 2% crystalline silica, long-term inhalation can still damage your lungs.

If a substantial amount is inhaled, people may cough and have shortness of breath.

The silica on DE can also irritate the skin and eyes.

Will Diatomaceous Earth Kill Roaches and Their Eggs?

Diatomaceous earth can’t kill roach eggs, but it can kill juveniles (nymphs) as soon as they hatch.

The hard shell of a cockroach egg protects them from any damage that DE can cause. 

If there is DE surrounding the roach egg when it hatches the soft shelled nymphs will be exposed to the DE.

Theses Nymphs will die quickly because they have no exoskeleton to protect them from the DE. 

Can You Use Too Much DE?

Too much DE could scare the roaches away, making it ineffective.

Cockroaches will avoid thick layers of DE. 

It will also cause roaches to spread into other areas of your house without DE.

For best results, only use a thin layer of DE to kill roaches.

What Insects Can DE Kill?

Diatomaceous earth can kill most bugs.

This includes roaches, ants, ticks, fleas, slugs, bed bugs, beetles, centipedes, spiders, etc.

How long does diatomaceous earth take to kill roaches?

While diatomaceous earth is not an instant solution, you should start to see results within two weeks. 

For best results, reapply DE about once a week for a full month. 

Remember that the roaches do not die from DE instantly.

So you may not see the dead roaches lying around. 

That said, you should be able to see less of them gradually.

What Kind of Diatomaceous Earth Is Best for Bed Bugs?

Any DE available on the market can kill all bugs, including bed bugs.

If you are worried about safety, I suggest getting a “food grade” DE to air on the side of caution.

Is It Safe to Sleep in a Room That Had Diatomaceous Earth Applied?


While you want to wear a mask when applying DE dust, DE dust settles within seconds of application.

As such, you shouldn’t have to worry about sleeping if you’ve applied it to your bedroom.

Does Diatomaceous Earth Still Work When It’s Wet?

Diatomaceous earth does not work when it’s wet.

That said, it will work again once dry if not washed away by water.

Which is Better Diatomaceous Earth Or Boric Acid?

Both Diatomaceous Earth and Boric Acid are effective natural ways to kill roaches.

But Boric has some advantages over DE in that it doesn’t need to be dry to be effective.

Keep in mind that both products require that roaches get in direct contact with them for either to be effective.

For the most effective approach at eliminating cockroaches use on of these dusts along with gel bait, insect growth regulators, and an insecticide spray. 

Can I Vacuum Up Diatomaceous Earth?

Yes, you can vacuum diatomaceous earth.

It’s best to only use a vacuum with a HEPA filter or a wet/dry vac.

DE is a fine powder, which means it could get through cheaper vacuum filters and ruin your vacuum’s motor over time.

Can Diatomaceous Earth Be Used Outside?

Yes, you can use diatomaceous earth outside.

But, it’s effect won’t last as long outside as it does inside.

That’s primarily because DE needs to be in dry environments.

If it gets too humid outside or starts raining, DE will stop working.

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