Quick signs of ants in winter

Ants in winter almost always mean the colony is inside your home, nesting near heat or moisture. Look for these signs:

• Live ants on unseasonably warm days or near heat sources (radiators, appliances).
• Nighttime sightings in kitchens or bathrooms as ants forage for water and sweets.
• Consistent trails along baseboards, plumbing lines, or heating pipes.
• Small piles of sawdust-like debris (frass), sometimes with insect parts—strong clue for carpenter ants.
• Faint rustling or tapping sounds in walls when rooms are warm; frass may appear after you gently tap wood.
• Discarded wings on windowsills or in basements; ants’ front wings are larger than the hind wings.
• Tiny “pinholes” or slit openings in wood with frass below, especially near window/door frames.
• Ants emerging from outlets, light fixtures, or gaps around pipes (they use voids to travel).
• Activity clustered around leaks, damp wood, or insulation (moisture attracts and softens wood).

Where to check and how to confirm

• Inspect warm, moist zones: under sink cabinets, dishwasher edges, bathrooms, laundry areas, boiler rooms, and attics near vents.
• Follow any trail to find entry points at gaps around plumbing, wiring, window frames, and sill plates.
• Differentiate from termites: ants have a narrow “waist” and bent (elbowed) antennae; termites have straight bodies and equal-length wings.
• Look for repeat frass piles and recurring winged ants indoors—both indicate an indoor nest, commonly carpenter ants.
• Capture a few ants on clear tape for identification if you need expert confirmation.

Use slow-acting ant baits (both sweet and greasy), not sprays. Place them along ant trails and entry points, remove food and moisture, seal gaps, and monitor for 1–2 weeks. If you see large black ants or sawdust indoors in winter, call a pro (possible carpenter ants).

Quick steps that work in winter

• Vacuum visible ants, then deploy bait stations; let ants carry bait home. Expect results in 3–14 days.
• Offer two bait types: sugar-based (e.g., liquid sugar/borax) and protein/grease (e.g., peanut butter/borax).
• Place baits on trails, under sinks, behind appliances, near door frames and baseboards; keep from kids/pets.
• Avoid repellent sprays, bleach, or vinegar near baits; clean with mild soapy water only after trails shift.

Stop them coming inside

• Seal cracks and gaps with caulk; add weatherstripping and door sweeps; repair screens.
• Fix leaks, insulate sweating pipes, and run a dehumidifier (target 40–50% humidity).
• Store food airtight; wipe crumbs and sticky spots; manage pet food; keep trash sealed and dry.
• Trim branches touching the house; keep firewood off ground and away from walls.

Carpenter ants and when to call a pro

• Signs: large black ants active indoors in winter, piles of sawdust-like “frass,” rustling in walls, soft wood.
• These indicate an indoor nest; professional treatment (non-repellent insecticides and void dusting) is best.
• If baiting doesn’t cut activity within 2 weeks, or you find winged ants indoors, schedule an inspection.
• Until service, continue baiting, reduce moisture, and seal access points.