How to Control Ant Infestation | Stop the March Indoors

That line of ants crossing your kitchen counter is following an invisible chemical trail back to a nest that could be in a wall void, under a slab, or outside your foundation. Spraying the ones you see kills a few workers but does almost nothing to the colony. The real fix is a layered approach that poisons the nest, blocks the next wave, and removes what’s attracting them in the first place.

Where to Start With an Active Ant Problem

The single most effective first move is placing ant baits directly beside the trail the workers are using. Baits contain a slow-acting poison mixed with a food attractant, so workers carry it back and feed the entire colony, including the queen. The University of Kentucky Entomology department confirms this as the primary control step.

Check every windowsill, baseboard, and cabinet edge where you’ve seen ants. Put the bait an inch or two off the trail itself, not on top of it. A critical detail: do not spray any cleaning product or other insecticide near the bait after you place it. The smell deters the ants, and the bait becomes useless. Let them feed undisturbed for a few days — you’ll see activity drop sharply when the poison reaches the nest.

The Full Control Sequence That Works

The sequence below follows the protocol from university extension entomologists and professional pest control guides. It covers the spreading colony problem, not just the visible scouts.

1. Seal entry points. Check door thresholds, window frames, and gaps where utility pipes and wires enter the building. A bead of caulk or weatherstripping can cut off the main highways ants use to get inside.
2. Sweep and sanitize. Wipe counters, sweep floors, and take out trash. Pet food bowls left out are a major attractant. Even a crumb on a damp sponge draws scouts.
3. Place baits. Use commercial ant baits or make your own. See the table below for ratios. Place them next to trails, not in the middle of the kitchen floor.
4. Trace the trail. Follow the ants back to their point of entry — a crack in the foundation, a gap under the door, a hole around a pipe. That point gets sealed after the bait works.
5. Treat the outdoor nest. If the trail leads outside to a mound or a crack in the sidewalk, apply a granular bait in small amounts next to the nest opening. Brands like Combat, Maxforce, Advance, Advion, and InVict are all effective for outdoor species.
6. Perimeter spray. This creates a barrier that intercepts new ants before they enter.

Natural and Eco-Friendly Remedies That Actually Help

Some readers prefer nontoxic options, especially around children, pets, or edible gardens. These methods work best for small, early-stage infestations. They are less effective on established colonies than baits, but they have their place as maintenance tools.

• Borax paste. Mix 1 tablespoon borax powder with 3 tablespoons confectioner’s sugar and enough water to make a syrup. Soak a cotton ball and place it in a shallow lid near the trail. The sweetness attracts the ants, and the borax kills them. Keep it away from pets.
• Diatomaceous earth. Sprinkle food-grade DE along baseboards and behind appliances. The microscopic sharp edges cut the ants’ exoskeleton and cause dehydration. It works slowly but leaves no chemical residue.
• Vinegar spray. Mix equal parts white vinegar and water in a spray bottle. Wipe down trails and entry points. The vinegar smell disrupts the pheromone trail, so the ants get lost and stop following the path.
• Essential oil spray. Mix 10 to 20 drops of peppermint oil with 2 cups of water and spray baseboards, windowsills, and door frames. The strong scent masks the trail and repels ants temporarily.

Best Bait Methods Compared

Note: if the infestation persists after baits, or if you’re dealing with fire ants, professional pest control is required. Consumer Reports advises against DIY methods for established infestations; Orkin’s fire ant warning states that professionals should handle those species.

What to Do When the Baits Stop Working

If ant activity returns after a month of baiting, the colony likely survived or a new one moved in. At this point, switch to a non-repellent liquid insecticide spray like Navigator SC, which ants cannot detect and carry back to the nest. Spray a 1-foot band around the foundation and spot-treat trails you can see.

Another common hidden cause is a nest inside a wall void or under a slab. Listen for rustling in baseboards on warm days, and look for fine sawdust-like frass near windows. If you suspect a wall void nest, professional treatment with foam or dust insecticide is safer and more effective than anything you can spray from a can.

When Professionals Are the Right Answer

DIY methods work for most species when you use baits correctly and seal the building. But the University of Kentucky entomologists and the Consumer Reports guide agree: fire ants and any infestation that returns after two full rounds of baiting call for a licensed pest control technician. They have access to dusts, foams, and gel baits that penetrate wall voids and sub-slab nests.

Finish With the Right Strategy

If we had to boil the whole approach into one checklist:

• Place baits on active trails first — that’s your colony killer.
• Seal cracks under doors and around pipes the same day.
• Wipe counters and remove pet food overnight.
• If the ants don’t stop after one week, apply a non-repellent perimeter spray.
• For fire ants or repeated return visits, hire a pro.

If you want a ready-to-use product and don’t want to mix your own bait, check our tested roundup of the best ant control products and sprays that actually clear the problem without guesswork.