The fastest way to eliminate ants naturally is a simple borax and sugar bait that workers carry back to the colony, poisoning nestmates and the queen within one to two days. But getting rid of ants for good requires a combination of baiting, repelling, and sealing off entry points. Here’s how to do each one effectively.
Why Killing Visible Ants Doesn’t Work
The ants marching across your kitchen counter are foragers, and they represent a tiny fraction of the colony. Spraying or squashing them does almost nothing, because the queen keeps producing replacements. Any effective strategy needs to reach the queen, which means letting workers carry something toxic back to the nest. That’s what makes baiting so much more powerful than surface-level kills.
The Borax and Sugar Bait
This is the most reliable natural method for wiping out an entire colony. Mix one part borax with three parts sugar, then add just enough water to create a syrup. For a small batch, that’s one tablespoon of borax to three tablespoons of sugar. Place small amounts of the mixture on pieces of cardboard or in shallow lids near ant trails.
Borax disrupts ant digestion slowly enough that workers survive the trip home. Once back in the nest, they share the poisoned bait with other ants through mouth-to-mouth feeding. A single contaminated worker can poison around fifty colony members, including larvae and the queen. You’ll typically see a dramatic drop in activity within 24 hours, and severe infestations can disappear completely in two days.
The ratio matters. If there’s too much borax, workers die before reaching the nest. The one-to-three ratio keeps the toxicity low enough that they survive the journey but high enough to eventually collapse the colony. When you first set the bait out, expect to see more ants, not fewer. That’s a good sign. It means foragers are recruiting nestmates to the food source, which speeds up the process.
Matching Bait to the Type of Ant
Not all ants want sugar. Argentine ants and odorous house ants (the tiny brown or black ones that smell when crushed) are attracted to sweet baits year-round. But species like thief ants and pharaoh ants prefer protein or grease. Fire ants go for oil-based baits. If your sugar-borax mixture sits untouched for a day, try mixing borax into peanut butter or a small amount of cooking oil instead. Matching the bait to what the ants actually eat is the single biggest factor in whether this works.
One note on concentration: the University of California’s pest management program recommends a 0.5 to 1% borate solution in sugar water for major infestations. Prepackaged bait stations sold in stores often contain 5.4% borate, which kills foragers too quickly for them to share with the colony. Homemade liquid baits at lower concentrations take a few more days but do far more damage to the nest.
Essential Oil Sprays as Repellents
Essential oils won’t kill a colony, but they’re useful for disrupting ant trails and keeping ants out of specific areas. Peppermint oil is the most popular option. It contains menthol, which ants find intensely irritating. Cinnamon oil works through a compound called cinnamaldehyde. Lemon oil repels ants with citral and limonene. Tea tree oil, eucalyptus oil, and lavender oil also deter ants, though peppermint and cinnamon tend to be the strongest.
To make a spray, combine about 10 drops of peppermint oil with one cup of water and a teaspoon of dish soap (the soap helps the oil mix with the water and stick to surfaces). Spray it along windowsills, doorframes, baseboards, and anywhere you’ve seen ants trailing. Reapply every few days, since the scent fades. This works well as a second line of defense after you’ve set out baits near the colony’s entry points.
Essential Oils and Pet Safety
If you have cats or dogs, be cautious with essential oils. Cats are especially vulnerable because they lack a liver enzyme needed to break down these compounds, and their grooming habits mean they’re likely to ingest anything that lands on their fur. Peppermint, cinnamon, eucalyptus, tea tree, and citrus oils are all known to cause poisoning in cats. Symptoms can include drooling, vomiting, tremors, respiratory distress, and in severe cases, liver or kidney failure.
Dogs tolerate essential oils somewhat better than cats but can still be affected, particularly by concentrated forms. If you use an essential oil spray in a home with pets, apply it only in areas your animals can’t access or lick. Never use undiluted essential oils, and avoid diffusers in rooms where pets spend time.
Diatomaceous Earth as a Barrier
Food-grade diatomaceous earth is a fine powder made from fossilized algae. It kills ants by absorbing the waxy coating on their exoskeletons, which causes them to dehydrate. Sprinkle a thin line of it across entry points, along baseboards, or around the perimeter of your home. It works best in dry environments, since moisture renders it ineffective.
The limitation is significant: diatomaceous earth kills individual ants that walk through it, but it rarely eliminates entire colonies on its own. Think of it as a physical barrier rather than a colony killer. Pair it with borax baits for a more complete approach. Avoid breathing in the dust when applying it. While food-grade diatomaceous earth isn’t toxic to humans, the fine particles can irritate your lungs.
Sealing Entry Points
Ants are persistent, and a colony will keep sending foragers as long as there’s a way inside. Follow visible ant trails backward to find where they’re entering your home. Common entry points include gaps around windows, cracks in door frames, spaces where pipes or wires pass through walls, and foundation cracks at ground level.
Seal these gaps with silicone caulk for a permanent fix. For a quick temporary seal, petroleum jelly or poster tack can plug small openings while you get the right materials. Pay attention to where countertops meet walls in kitchens and bathrooms, since these are popular ant highways. Even tiny cracks are enough. Most common household ants are only about an eighth of an inch long.
Identifying What You’re Dealing With
Knowing which ant you have helps you choose the right approach. The most common indoor invaders are small, between an eighth and three-sixteenths of an inch, and range from light brown to black. Argentine ants, odorous house ants, and pavement ants all fall into this category, and the borax-sugar bait works well against all of them.
Carpenter ants are a different situation. They’re much larger, a quarter to half an inch long, and typically black or a combination of red and black. They don’t eat wood like termites, but they hollow it out to build nests. Look for small piles of sawdust-like debris near wooden structures. If you’re finding carpenter ants, the colony may be nesting inside your walls, door frames, or window frames, and you may need professional help to locate and remove the nest before structural damage gets worse.
Removing What Attracts Them
Natural repellents and baits work much better when you also eliminate the food sources drawing ants inside. Wipe down countertops and stovetops after cooking. Store sugar, honey, and cereal in sealed containers. Don’t leave pet food bowls out overnight. Take trash out regularly, and rinse recycling before it sits in the bin. Even a thin film of juice on a countertop is a feast for a colony of Argentine ants.
Moisture matters too. Many ant species are drawn indoors by water as much as food. Fix leaky faucets, dry out sinks before bed, and check for condensation around pipes under cabinets. Pavement ants in particular tend to nest near water sources.
Borax Safety Around Kids and Pets
Borax is a naturally occurring mineral, but “natural” doesn’t mean harmless in large amounts. Keep borax baits out of reach of children and pets. Place them behind appliances, inside cabinets, or in areas only ants can access. Small covered containers with holes just large enough for ants work well. If you have toddlers or curious pets, placing baits outside near entry points rather than inside the house reduces risk while still intercepting foragers before they come indoors.