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Spring often brings ants indoors. In my time helping MD, VA, and DC homeowners, I’ve seen trails in kitchens or bathrooms turn out to be nests inside wall voids. Most ants stay where there’s moisture, food or a safe hideout. This guide shows why you see ants in walls and how to stop them.
According to the Building Science Corporation, pests find wall voids warm and humid. In walls, ants enjoy stable temps, darkness and water from plumbing. Kitchens and pantries tempt them with crumbs and grease.
Large black ants that damage wood. According to Virginia Cooperative Extension, carpenter ants hollow out damp or sound wood. You may spot sawdust-like frass near baseboards.
Small brown ants that give off a rotten-coconut smell when crushed. They nest near moisture and quickly invade kitchens.
Dark brown ants that start under slabs. They follow plumbing lines up into wall voids and create satellite nests.
Tiny yellowish ants forming “buddy” colonies in warm walls of multi-unit buildings. They need targeted baits to stop budding.
These ants seek damp, decayed wood around leaks. According to the Building Biology Institute, moisture ants often signal a rot issue rather than cause it.
Ants squeeze through gaps at sill plates, utility lines, siding joints, unsealed windows and foundation cracks.
They need wood moisture over 20%, stable temps and protected voids. Insulation doesn’t stop them—they tunnel through cellulose and fiberglass.
In the first season, a queen and a few workers stay hidden. By year three, swarmers emerge indoors Feb–April, and satellite nests expand.
Check moisture under sinks and around tubs. Try a DIY bait-tray test with honey or peanut butter every 3 feet. For more tips, see How To Keep Ants Away: Pro Techniques vs DIY Ant Control. If you spot winged ants or frass, call a pro.
Fix leaks, clear gutters and keep crawlspaces under 60% RH. Remove water-damaged wood and correct grading.
Seal cracks under 1 mm with silicone. Pack larger gaps with metal mesh then caulk. Wait 72 hours after baiting before final sealing.
Store food in tight containers. Wipe counters nightly and rinse recyclables. Lift pet bowls after feeding.
Use slow-acting baits like boric acid or indoxacarb so foragers share with the colony. Rotate sweet and protein baits if acceptance drops. Learn more from UC IPM’s baiting guide.
Inject dust formulations into voids through 1/8-inch holes. Apply non-repellent foam in carpenter ant galleries, then patch.
Licensed technicians apply non-repellent sprays around foundations and voids. This stops colonies from fissioning.
Set sticky cards or moat traps along baseboards for 8 weeks. Re-check moisture levels quarterly.
Our registered technicians start with a 78-point inspection. We perform crack-and-crevice service using EPA approved products vetted by our research team. Then we treat the perimeter with non-repellent barriers. Quarterly maintenance visits ensure protection since most products last 90 days. For local help, see Pest Control Arlington or Pest Control Bethesda.
Keep crawlspaces and attics dry with vents or dehumidifiers. Trim branches 12″ from rooflines and clean gutters. Grade soil away from the foundation. Learn more in our Ant Identification Chart: Types of Household Pests & Control.
Ants in walls trace back to food, water and shelter issues. A solid IPM plan tackles the root cause, not just the trails. Call us at 703-683-2000 or email [email protected] for an expert consultation today.
Ants look for food crumbs, moisture leaks and safe nesting spots. Wall voids offer stable temps and darkness, making them ideal.
Look for sawdust-like frass, hollow-sounding studs, faint crackling at night and small ant trails along baseboards.
Use a step-by-step IPM plan: fix leaks, seal gaps, clean up food, place slow-acting baits and follow up with non-repellent sprays.
Carpenter ants hollow out damp wood over time, creating tunnels. It’s a slow process but worth addressing before damage worsens.
Small colonies may clear in 2–4 weeks with proper baiting and exclusion. Larger or multiple nests can take 6–8 weeks.
For minor trails, DIY baiting might work. If you find frass, winged ants or structural damage, a licensed technician offers targeted treatments.
With five years of hands-on experience in the pest control industry, George Schulz is a registered technician with the Virginia Pest Management Association and a proud third-generation professional in a family business that’s been protecting homes for over 57 years. He manages and trains a team of service pros while also leading internal research efforts—recently spearheading a deep-dive review of thousands of documents on pest control materials to hand-pick the most kid and pet friendly, most effective solutions tailored specifically for homes in the DC metro area. Read his bio.
