The most effective natural way to get rid of ants inside your home is a homemade bait made from boric acid and sugar, which worker ants carry back to the colony and share until the queen dies. But bait alone won’t solve the problem permanently. You also need to erase the scent trails that guide ants through your house and seal the entry points they’re using. Here’s how to do all three.
Figure Out What You’re Dealing With
Most indoor ants are tiny, dark brown or black, and roughly an eighth of an inch long. These are typically odorous house ants (crush one and you’ll notice a strong, unpleasant smell) or pavement ants, which nest under foundations and patios. Both species are nuisance pests looking for food and water. The natural methods below work well against them.
If you’re seeing larger ants, a quarter inch or bigger, that are black, red, or both, you may have carpenter ants. They tunnel into wood to build nests, and piles of fine wood shavings near baseboards or window frames are a telltale sign. Carpenter ants can cause real structural damage, so they warrant professional treatment rather than a DIY approach.
Homemade Borax Bait: The Colony Killer
Spraying ants on sight only kills the ones you can see. A colony can contain thousands more, including a queen that keeps producing replacements. Bait works differently: the concentration of poison is low enough that foraging ants survive long enough to carry it back to the nest and feed it to the rest of the colony, including the queen.
The University of Hawaiʻi’s College of Tropical Agriculture recommends this liquid bait recipe:
- 1 teaspoon boric acid powder
- 3 tablespoons white sugar
- 1¾ cups warm distilled or bottled water (not tap)
Stir until everything dissolves completely. Soak cotton balls in the solution and place them in shallow dishes or jar lids along the ant trails you’ve spotted. You’ll likely see ant activity increase at first as more workers discover the bait. That’s a good sign. Allow ants to feed on the bait stations for up to one or even two months before expecting the colony to collapse. Replace the cotton balls every few days to keep the bait fresh.
Safety Around Kids and Pets
Boric acid is considered low in toxicity for adults, but the picture changes for small children and animals. Lethal doses for infants can be under 5 grams, and even small ingestions have caused vomiting, diarrhea, and seizures in babies. Dogs appear more sensitive than other animals, and young or elderly pets face higher risk. Symptoms of ingestion in pets include excessive drooling, vomiting (sometimes blue-green), diarrhea, and loss of appetite.
Place bait stations inside sealed containers with small entry holes that ants can access but children and pets cannot. The underside of a heavy appliance or inside a cabinet along the back wall are good locations. If you have crawling infants or curious pets and can’t keep bait out of reach, skip this method and focus on the alternatives below.
Diatomaceous Earth for Dry Areas
Food-grade diatomaceous earth is a powder made from fossilized algae. Under a microscope, the particles look like broken glass. When ants walk through it, the sharp edges cut through their waxy outer coating and the powder absorbs their body moisture, causing them to dehydrate and die.
Apply a thin, even line of food-grade diatomaceous earth along baseboards, window sills, wall cracks, and any other gaps where ants are entering. It only works when dry, so skip bathrooms and areas under sinks where it’ll clump from moisture. Wear a dust mask during application. The powder isn’t toxic if swallowed in small amounts, but inhaling it can irritate your lungs. Reapply after vacuuming or if it gets wet.
Diatomaceous earth kills individual ants that walk through it, but it won’t eliminate a colony the way bait does. Think of it as a complement to baiting, not a replacement.
Erase the Scent Trails
Ants navigate by following pheromone trails, invisible chemical paths laid down by scouts that say “food this way.” Even after you remove the food source, those trails persist and keep drawing ants back to the same spots. Wiping down surfaces with a solution of equal parts white vinegar and water disrupts these chemical markers. Spray it along baseboards, countertops, and windowsills, then wipe with a clean cloth.
Dish soap mixed with water works similarly, dissolving the scent compounds that keep the trail active. Either solution is safe on most surfaces and costs almost nothing. Reapply daily until you stop seeing new ants.
Tea Tree Oil as a Barrier
Among essential oils, tea tree oil stands out as a legitimate ant repellent. In lab testing against fire ants, zero ants crossed a tea tree oil barrier across five separate trials, making it the most effective oil tested. Its active compound disrupts ant behavior on contact.
Mix 10 to 15 drops of tea tree oil into a cup of water in a spray bottle and apply it around door frames, window edges, and any cracks where ants are entering. The smell is strong but fades for humans within an hour or two. Reapply every few days. Like vinegar, this is a deterrent, not a colony killer. It works best as a perimeter defense while your bait stations do the deeper work.
Skip Coffee Grounds and Cinnamon
You’ll find plenty of recommendations online for sprinkling coffee grounds or cinnamon on ant trails. The evidence for both is poor. In controlled testing, ants initially avoided coffee grounds but within a day simply pushed them aside or made new entrances around them. An entomologist at Texas AgriLife Extension tested coffee grounds on fire ant mounds and found zero effect on colony activity compared to untreated mounds. Cinnamon, whether powdered, in stick form, or as essential oil, has similarly failed to repel common indoor species like pharaoh ants in real-world kitchen tests. These remedies aren’t worth your time when options like boric acid bait and tea tree oil actually work.
Cut Off Food, Water, and Entry Points
No natural remedy will keep ants away permanently if your home keeps inviting them in. Ants are searching for two things: food and moisture. Removing both is the single most important long-term step.
Wipe down counters and stovetops after every meal, not just at the end of the day. Rinse dishes immediately rather than stacking them in the sink. Store dry goods like sugar, cereal, and flour in airtight containers. Keep trash cans sealed with tight-fitting lids. If you have pets, pick up food bowls between feedings and rinse them to remove scent residue.
Moisture matters just as much as food. Check under sinks, around toilets, and near your water heater for slow drips or condensation. Fix leaks promptly. Outside, move sprinkler heads away from your foundation so water doesn’t pool against the slab, and trim back plants or mulch that trap moisture directly against exterior walls. Both create a damp bridge ants follow straight to entry points.
Finally, seal the gaps. Walk your home’s perimeter and look for openings where utility lines, pipes, and cables enter the structure. Inside, check along baseboards, behind appliances, and around window frames. Use silicone caulk to fill cracks and gaps, starting at ground level where ants travel most. Install door sweeps on any exterior door where daylight is visible at the bottom, and replace torn window screens.
Putting It All Together
The most reliable approach combines several of these methods at once. Set out boric acid bait stations along active trails to kill the colony over the next few weeks. Apply diatomaceous earth in dry crevices and entry points. Wipe down surfaces daily with a vinegar or soap solution to erase pheromone trails. Use tea tree oil as a barrier spray at doors and windows. And maintain strict kitchen hygiene so there’s nothing left for ants to find. Most indoor ant problems resolve within two to four weeks using this layered strategy, though larger or well-established colonies can take up to two months to fully collapse.