Getting rid of an ant infestation comes down to one principle: kill the colony, not just the ants you can see. Only about 20% of an ant colony ever leaves the nest, so squishing visible ants or spraying them barely dents the population. The most reliable approach combines baiting to destroy the colony from the inside, cutting off food and water sources, and sealing entry points to prevent reinvasion.
Identify What You’re Dealing With
Not all ant problems are equal, and knowing which species you have helps you choose the right bait and understand the stakes. The most common indoor invaders are odorous house ants, pavement ants, and carpenter ants.
Odorous house ants are tiny (about 1/8 inch), black, and give off a rotten smell when crushed. They love sugary foods and nest under sinks, appliances, or along your home’s foundation. These are the classic “kitchen ant.”
Pavement ants are similar in size, reddish-brown to black, and eat both sugary and greasy foods. You’ll often see small mounds of excavated soil in sidewalk cracks or along your foundation. They frequently nest under concrete slabs and enter through cracks in the floor.
Carpenter ants are the ones that demand urgency. They’re noticeably larger, black (or black with a red head), and they chew tunnels into wood to build their nests. They don’t eat the wood, but the structural damage is real. Signs include piles of fiber-like debris that looks like pencil shavings (called frass), and in mature infestations, you can actually hear rustling or gnawing sounds inside walls. Carpenter ants prefer wood with moisture problems, so their presence often signals a leak or ventilation issue you also need to fix.
Why Baiting Works Better Than Spraying
Your instinct might be to grab an ant spray and blast every trail you see. That approach kills on contact but creates a bigger problem: it scatters the colony, potentially splitting it into multiple new nests, and makes the infestation harder to eliminate. You end up spraying more often while the colony keeps growing underground or inside your walls.
Baiting takes a completely different approach. Worker ants find the bait, carry small portions back to the nest, and feed it mouth-to-mouth to other workers, larvae, and most importantly, the queen. When the queen dies, the colony collapses. Bait products are designed to be slow-acting so foragers have time to make the return trip before dying. This is why you’ll keep seeing ants for a week or more after placing bait. That’s a sign it’s working, not a sign it’s failing.
Expect 7 to 10 days before ant activity drops significantly. During that time, resist the urge to spray the trails or wipe them away. Those foragers are your delivery system.
How to Set Up Bait Effectively
Place bait stations along the trails you’ve observed and near entry points like windowsills, baseboards, and under sinks. You don’t need to put bait directly in the ants’ path. They’re excellent at finding food and will locate it on their own. Less obvious spots like behind outlet covers, inner areas of windowsills, or near crawlspace openings also work well and keep bait away from kids and pets.
Match your bait to the species. Odorous house ants go for sweet, sugary baits. Pavement ants eat both sweet and greasy foods, so a protein-based or combination bait may work better. Carpenter ants prefer sugary and protein-rich foods. If you’re not sure what species you have, set out both sweet and protein-based bait and see which one the ants prefer. If they ignore one type, switch to the other.
One common mistake is putting out too little bait or removing it too soon. Keep bait stations fresh and available until you see no ant activity for at least a few days.
Cut Off Food and Water
Baiting works best when it’s the most attractive food source around. That means eliminating the competition. Wipe down countertops and stovetops daily, especially of sticky residues and crumbs. Store sugar, honey, and open cereals in sealed containers. Don’t leave pet food bowls out overnight. Take out garbage regularly and use bins with tight lids.
Water matters just as much as food. Fix dripping faucets, dry out areas under sinks, and address any standing water in basements or crawlspaces. Carpenter ants in particular are drawn to moisture-damaged wood, so a persistent leak can be the root cause of the entire infestation.
Seal Entry Points
Ants are small enough to enter through cracks you might not notice. Inspect your foundation, window frames, door thresholds, and anywhere utility lines or pipes enter the house. Seal gaps with caulk or weatherstripping. Homes built on concrete slabs are especially vulnerable because ants nest under the slab and come up through cracks, heating ducts, and utility openings.
Outside, trim tree branches and shrubs that touch or overhang your roofline. These act as highways for ants to bypass your foundation entirely. Move firewood piles well away from the house, since carpenter ants readily nest in stacked logs and lumber.
When Natural Repellents Help (and When They Don’t)
Vinegar, cinnamon oil, and peppermint oil can disrupt the pheromone trails ants use to navigate. A study published in the International Journal of Scientific and Research Publications found that cinnamon oil at 20% concentration significantly repelled ants. The catch is that essential oils evaporate quickly, so a single application won’t solve anything. During peak ant season, you’d need to reapply daily, then weekly once activity slows.
These repellents can be useful as a supplement, especially for keeping ants out of a specific area like a pantry shelf. But they don’t kill the colony. If you rely on repellents alone, the ants will simply find another route. Use them alongside baiting and sanitation, not instead of those steps.
Safety Around Kids and Pets
Most commercial ant baits use insecticides at very low concentrations, and unintentional exposures generally pose little toxicity risk. Enclosed bait stations are specifically designed to let ants in while keeping children and pets out. Still, a toddler who tastes ant bait might develop nausea and vomiting, and skin or eye contact can cause irritation.
Place bait stations in areas children and pets can’t easily reach: behind appliances, inside cabinets, within wall voids accessed through outlet covers. Don’t pry open enclosed bait stations. Wash your hands after handling any bait product, and store unused bait in its original packaging. If a child does get into ant bait, rinse their mouth and any skin that contacted the product, and watch for vomiting, diarrhea, or a skin rash.
Carpenter Ants Need Extra Attention
If you’re finding piles of wood shavings mixed with insect parts, hearing faint rustling in your walls, or spotting large black ants (or red-and-black ones) inside your home during winter, you likely have a carpenter ant colony nesting in your structure. The frass they produce looks distinct from termite damage: coarse, fibrous debris rather than fine powder, often with a dark appearance that signals decaying wood underneath.
Baiting still works for carpenter ants, but finding and addressing the moisture source is just as important. A colony won’t establish itself in dry, sound wood. Check around bathrooms, kitchens, rooflines, and anywhere you’ve had past leaks. For large or established colonies causing structural damage, professional treatment is worth the cost, since the nest may be deep inside a wall, crawlspace, or even a living tree near your house.