How do I keep ants out of my house?

Keeping ants out comes down to two things: give them no reason to come in, and make it hard for them to get in. There is no reason to wipe out ants in their natural habitat; the goal is to keep them from infesting the house.^[1] That is mostly housekeeping and small repairs, not pesticides, and it lasts. Done properly, sanitation and maintenance can be a permanent fix to an ant problem.^[1]

Take away the food

Ants come indoors to forage. A crumb-free kitchen gives the scouts nothing to report.

• Store food in sealed containers, not cardboard boxes, in clean, dry areas, and keep food containers off the floor.^[1] Sugar and honey can go in the refrigerator.^[5]
• Clean up crumbs and spills, especially sweet liquids like soda.^[5]
• Remove garbage from the house promptly, and clean recyclables with soapy water and store them outside if you can.^[1] Regularly empty and wash garbage cans and recycling bins.^[5]
• Pick up pet bowls between meals. Fire ants like greasy and oily foods, especially cat and dog foods, so keep pet food out of their reach.^[7]
• Keep clutter to a minimum.^[1]

Take away the water

Kitchens, bathrooms, spots near leaky pipes and the space under sinks give ants a dependable water source.^[1] Fix dripping faucets and leaks under sinks and around toilets, and wipe up standing water around the dish rack and the tub. Carpenter ants are drawn to water in a different way, by nesting in wood that has stayed wet. Replace water-damaged wood, because carpenter ants nest in wet wood.^[6] Whether carpenter ants are a sign of water damage explains where to look.

Close the ways in

Ants follow edges, pipes and wires, so the gaps worth sealing are usually where something passes through a wall.

• Caulk holes and cracks ants can use as a way in, and weather-strip around windows and doors.^[1]
• Seal areas where plumbing, cable or electrical lines enter the house.^[6] Caulk around the outside of the cable or pipe only; do not open electrical boxes.
• Check door sweeps and the gap under exterior doors, and the seal along the bottom of the garage door.

Keep the yard from touching the house

Trim trees and bushes away from the house. Branches that touch the building give ants a bridge to it, which matters most for carpenter ants.^[1] The ground next to the foundation matters too. Mulch and ground cover hold moisture better than bare soil or concrete, which is why ants like to nest in them next to the foundation.^[1] As a rule of thumb, keep vegetation, shrubs and wood mulch at least 18 inches away from your house.^[8]

• Store firewood several feet away from buildings and off the ground.^[6]
• Old stumps and dead trees may harbor a nest.^[6] Leave felling a tree to a tree service.
• Watch shrubs near doors for aphids. Ants often tend aphids and scale insects to collect the sweet honeydew they produce,^[1] and a busy aphid colony beside the porch keeps a trail of ants close to the house.

Know the seasonal visitors

The soil of a potted plant gives ants a moist, protected place to nest, so check plants that have been outdoors before you bring them in.^[1] Pavement ants nest under stones and the edges of pavement, and in winter they may nest in crevices next to a heat source indoors.^[1]

Swarms of small yellowish winged ants around the foundation or in the basement may be yellow ants. Yellow ants are largely underground and rarely come into houses for food, but colonies next to the foundation can send out swarms of winged ants, sometimes into basements.^[4] Vacuum up any that get in.^[4] If they came in through a crack in the foundation or a hole in a wall, caulk the opening thoroughly.^[4] Yellow ants are not structural pests and do not damage wood.^[4]

Check monthly and act early

A regular monthly visual inspection is the best way to monitor for ants.^[1] In spring and summer, look along kitchen baseboards, under sinks, around windows and along the outside of the foundation. A short trail you find in April is far easier to deal with than a colony that has settled in by July. If you find a nest, do not stir it up; some species move or split the nest when disturbed.^[1]

Use baits only for an ant problem you actually have. Baits set out when there is no problem can attract ants to the house, and leftover bait should be removed once the ants are under control.^[1] When ants do show up, how to get rid of ants in the kitchen walks through baiting them properly.

Some homes get ants every year despite good housekeeping. For those, perimeter sprays and granular baits applied by a professional pest control operator will significantly reduce pest entry.^[2] The perimeter spray should be applied in early spring when ant populations are low, and one application should last all season.^[2]

Stop and call a pro if

• You see large black ants indoors in winter. When carpenter ants are active indoors in late winter or early spring (February and March), the nest is probably inside the house.^[3] See whether you need a professional for carpenter ants.
• You find ants that sting nesting in the yard where children or pets play, or nesting indoors.
• Ants come back every spring however well you clean and seal, and you want a seasonal treatment. Any company you hire must be licensed: in Virginia no one may apply or recommend a pesticide commercially without a pesticide business license and a certified commercial applicator.^[9] What ant control costs in Virginia explains the options.

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