Diatomaceous Earth for Ants: Complete DIY Guide

Whether they’re pestering you at a picnic, messing with plants in your garden, or stealing crumbs in your kitchen, ants can be a major nuisance. They may play a valuable role in nature, but a little goes a long way — especially around your home and property.

Strategies abound for removing unwanted ants, from squashing them frantically with your boot to coating your lawn in harsh chemical pesticides. If you need something more practical than the former and more natural than the latter, you could do worse than working with inexpensive, effective, and easy-to-use Diatomaceous Earth.

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What is Diatomaceous Earth?

Diatomaceous Earth (that’s die·a·toe·may·shus, but we can just say DE for short) is a naturally occurring substance used for a range of home care and pest control purposes. The first deposit of this fine white powder was discovered in Germany around 1836, and its use as a pesticide began in 1960.

The fancy name comes from diatoms, a type of unicellular microalgae living in bodies of water all over the world. These diatoms’ skeletons, made of silica, accumulate in the sediment when they die and create deep deposits of DE. Much of the Earth’s oxygen — about 20% — comes courtesy of diatoms, so they were already carrying their fair share of Earth’s weight before we started using their fossils for pest control.

Being a natural mineral, DE doesn’t expire or lose its effectiveness over time. Simply keep it clean and dry and it will do you good (and insects bad) for thousands of years.

Safe, Natural, and Organic Pest Control

What sets Diatomaceous Earth apart from other pesticides is the fact that it works mechanically, not chemically. It’s a natural mineral that contains no harmful chemicals and is certified organic by OMRI, the Organic Materials Review Institute (with some exceptions for artificially treated variations).

DE isn’t toxic to humans or animals, and only kills insects because of their small size and vulnerable exoskeletons. In fact, most DE you can buy is classified as “food-grade,” which means that, yes, you can eat the stuff.

In fact, you probably have — it’s used as an ingredient in thousands of foods, medicines, and hygiene products like toothpaste. It also happens to be an important component of dynamite, but hopefully you aren’t eating too much of that.

Does Diatomaceous Earth Kill Ants?

Yes, Diatomaceous Earth kills ants — though its efficacy may vary between different species. It also kills insects and arachnids like ticks, mites, spiders, bedbugs, and even scorpions. The common factor between these creatures is their exoskeleton; you’ll have to use a different product to control, say, rodents.

Diatomaceous earth can be used to get rid of black house ants, as well as helping to get rid of carpenter ants from your home.

How Does Diatomaceous Earth Work?

Despite being a mouthful for humans, Diatomaceous Earth isn’t consumed by the insects it kills. Rather, its microscopic mechanical makeup is coarse, porous, sharp, and deadly.

DE sticks to insects’ oily exoskeletons like burrs, cutting through the cuticle and absorbing the fats and moisture within. The insect slowly dries out and dies of dehydration.

Because this is a physical process, not a chemical one, there’s no way for ants or other insects to develop resistance.

DE’s lethality only functions on a microscopic scale: to humans and animals, DE is a harmless white powder that feels soft to the touch. It is only to tiny insects like ants that DE becomes a beach of razor-sharp sand (beach sand, in fact, is also made of silica, so you can imagine this somewhat literally).

How to Get Rid of Ants with Diatomaceous Earth

Diatomaceous Earth is effective for ridding ants both inside and outside your home, and is most often applied simply by sprinkling it by hand. But it doesn’t have to be: because DE is so safe and versatile, it can be applied however is most convenient for the situation: with a flour sifter, turkey baster, salt shaker, paint brush, mixed with water in a spray bottle, or whatever else you can imagine.

However you choose to work with DE, take care when doing so. Though the substance itself is perfectly harmless, it’s a fine powder that, like all fine powders, can be an irritant to the skin, eyes, and lungs. It’s wise to wear a dust mask and gloves while handling it, just to be safe.

Also be aware that you should only ever use food-grade DE for pest control purposes, as other grades (like pool-grade) can be hazardous to humans as well as ants.

Indoor Application Guide

That it can be used safely indoors is one of DE’s key advantages over chemical pesticides: it does no harm to pets, children, or most furniture. Simply be careful when spreading DE over wood or other scratchable surfaces, and keep the powder well away from computer fans.

Start by figuring out where to apply the powder: near cracks where ants have entered your home, in areas they congregate, directly along their trails, or anywhere you want them to avoid. You may need to follow a few ants to get a better sense for where they’re coming from.

Then, sprinkle a thin layer of DE around the areas and ant trails you’ve identified. If you want to be extra thorough, It doesn’t hurt to do the same along baseboards, window sills, and other potential entry points, even if you haven’t seen ants there before. And if you see a  group of ants you want to target directly, go for it! Just dust the congregation with DE and draw a perimeter around them with powder.

Wait a day or two and check around the areas you treated. If your ants have persisted or found new trails to avoid the DE, reapply as needed.

Cleaning Up Indoors

With the ants gone, you have to take some special care to clean up the DE and ensure the treatment sticks. If you can, vacuum up the powder with a shop vac — your home vacuum’s filter may get clogged by DE, which can damage the motor. If you must use a home vacuum, clean the filter a few times as you go.

You can also use a mop or wet towel to soak up the remaining DE. Though a slightly more tedious process, this will help prevent the dry powder from dusting up in the air.

Finally, when the powder’s cleaned up, wash all surfaces where ants gathered to remove any lingering pheromones (which, if left alone, can attract more ants).

Outdoor Application Guide

DE is just as effective outside the home as in, and may help prevent ant infestations from migrating indoors. Spreading the powder 6-12 inches out from doorways, cracks in the foundation, and plants in your garden is a quick and simple measure you can take to be proactive.

There’s a caveat to be aware of when applying DE outdoors: moisture. Diatomaceous Earth only works when dry, so there’s no use spreading it around if the week’s forecast calls for rain.

However, this property is not without its usefulness: because diatomaceous earth will become effective again when it dries out, it can be applied wet in the form of a spray. This is especially helpful outdoors, as you can spray exposed areas with a DE solution instead of sprinkling powder that might just blow away. When the spray dries, the DE sticks and works just as good as new.

(The magic ratio, if you mix this spray yourself, is four tablespoons of DE to one gallon of water. Don’t be shy when applying: the thicker the coating, the more effective the dried DE).

If you are sprinkling powder, its best to avoid damp areas that may dilute the DE in addition to temporarily neutering its pest-killing powers. It’s worth noting that ants congregating near water may be more difficult to kill for this reason.

No matter how you apply DE outdoors, you’ll want to reapply frequently — weekly at the most — to account for natural scattering to the winds and rain.

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How Effective is Diatomaceous Earth at Killing Ants?

Diatomaceous Earth might take several days to fully handle an infestation, and its overall efficacy will depend on the size and species of ant, the wetness of the soil, the temperature and humidity, and other factors. In general, DE takes about 16 hours to kill red ants, and black ants are a little hardier — they last about 24 hours.

As with many things in life, sticking to it is the key to success. If you keep a close eye on the infestation and regularly reapply DE to control it, your ants will have relocated to that great anthill in the sky before you know it.


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