How to Get Rid of Ants in Your House: A Step-by-Step Guide for Canadian Homes

TL;DR

• Kill the colony, not just the ants you see: use a slow-acting bait that workers carry back to the nest and share with the queens.
• Don't spray. Spraying along trails may split the colony (Health Canada).
• Wipe the trail with soapy water, store food in sealed containers and fix dripping taps, so the bait becomes the most attractive food in the room.
• Place bait right next to the trails and entry points, out of reach of children and pets. Use more than one station, and two different baits at once, which Health Canada says gives better results.
• Leave baits out for at least two weeks and don't spray near them. Seeing more ants around the bait at first is a good sign.
• Need help? Get a quote from a recommended local exterminator through Pest Agent's referral form.

Spraying the line of ants on the counter feels like progress until the same trail is back the next morning, and that is where learning how to get rid of ants really starts. The ants in view are a small share of the colony: thousands more workers and one or more egg-laying queens stay hidden in the nest.

Indoor spraying can even split that colony into several new nests. A slow-acting bait that workers carry home is the tool that reaches the queen, yet new ants keep arriving for as long as the kitchen keeps rewarding them.

Why Do You Have Ants in Your House?

Ants in your house are usually workers from a colony outside that found food or water inside and left a scent trail for others to follow. According to the City of Calgary, most ant species nest outdoors and usually come indoors only to forage. A scout finds something to eat, marks the way home with a scent trail, and the rest of the workers follow it straight to your kitchen.

Food

Food is the main reason ants come inside. Health Canada notes that ants are drawn to sugary and greasy foods, as well as the sticky honeydew that aphids leave on houseplants. UC IPM adds fats, proteins and seeds to the list. Crumbs under the toaster, a smear of jam on the counter or a full pet food bowl is enough to start a trail.

Water

Water draws ants too, especially in dry weather. UC IPM recommends fixing leaky taps because water attracts ants, and odorous house ants in particular often seek out moist, warm spots such as leaks and wall voids with heated pipes (Utah State University Extension).

Entry Points

Entry points are any small gap between the outdoors and your living space. Ants can come in through cracks in the foundation and concrete, around door thresholds and windows, and along utility pipes and wires that enter the house (Health Canada, Utah State University, University of Kentucky). Branches that touch the house act as bridges to the building.

Spring Ant Season

Spring is when most Canadians first notice ants. Many ants spend the winter in the ground and start searching for food once the weather warms up, as a University of Guelph ant collector explained to CBC. Orkin Canada also reports a spring rise in carpenter ant problems after damp, mild weather.

Which Ants Are in Your House?

Identifying the ants in your house matters because each species eats different food, nests in different places and reacts differently to treatment (UC IPM). Canada has many ant species, but Health Canada lists only a handful that commonly invade homes. Adult ants range from about 1 mm for the tiniest species to 13 mm for carpenter ants.

Carpenter Ants

Carpenter ants are the largest house ants in Canada, about 6 to 25 mm long, either dark brownish black all over or black with a reddish brown upper body (Health Canada). They do not eat wood, but they often tunnel into moist or decaying wood and push out sawdust-like shavings. Other signs include slit-like openings in woodwork, a dry rustling sound in the walls at night, and winged ants leaving the house in spring. Carpenter ants can damage the structure, so follow our guide on how to get rid of carpenter ants rather than the general step-by-step method for other ants.

Pavement Ants

Pavement ants are small brown ants, typically about 3 mm long, with fine grooves on the head and thorax (Utah State University, Maine Department of Agriculture). They nest under driveways, patio slabs, stones and foundations, and you often see small piles of soil pushed out of cracks in the concrete. The good news: the University of Kentucky notes they can easily be controlled with most baits.

Odorous House Ants

Odorous house ants are brown to black, about 3 mm long, and usually give off a rotten, coconut-like smell when you crush one (Utah State University). Their colonies have several queens, move quickly and can split, which makes them one of the hardest ants for homeowners to control. Penn State Extension advises choosing baits designated for sweet-loving ants, and repellent products may make them split into more colonies.

Pharaoh Ants

Pharaoh ants are tiny, typically about 1.5 to 2 mm, and yellow or light brown to reddish (Alberta Health). In Canada they usually live inside heated buildings, so you can see them all year. Never spray pharaoh ants: sprays make the colony bud into new nests. Our pharaoh ant guide explains the bait-only method they need.

Other Tiny Ants

Other tiny ants, such as little black ants and thief ants, are about 1 mm long (Health Canada) and easy to confuse with each other. The University of Kentucky notes that a good hand lens is often needed to see the features that separate species. If you are not sure what you have, our guide to small ants in the house walks you through the most common ones.

How to Get Rid of Ants in the House, Step by Step

Getting rid of ants in the house works best as a short sequence: clean the trail, take away food and water, bait the colony, give the bait time, then seal the gaps. Here is how to do each step.

Wipe Away the Scent Trail

Wiping the scent trail is the first thing to do when ants arrive. UC IPM recommends cleaning up invading ants with a sponge and soapy water right away to remove the trail they leave behind. A UCSF child care handout suggests one tablespoon of dish soap per quart (about 1 litre) of water in a labelled spray bottle; UC IPM uses 1 to 2 tablespoons of insecticidal soap per quart for pots. This clears the ants you see, but it does not touch the nest, so move straight to the next steps.

Remove Food and Water

Removing food and water is, according to Health Canada, the easiest way to avoid ant problems. Do this before you put out bait, so the bait becomes the most attractive food in the room:

• Store sugar, cereal, snacks and other dry food in glass jars with rubber seals or snap-tight plastic containers, not plastic bags or open boxes.
• Wipe counters and sweep or vacuum often, especially around pet dishes.
• Set your pet's food bowl in a shallow dish of water, since ants cannot swim (Health Canada).
• Rinse containers before recycling, empty the kitchen garbage often, and keep your composter well away from the house.
• Fix dripping taps and wipe up standing water under sinks.

Set Slow-Acting Baits

Slow-acting baits are what actually get rid of ants, because worker ants carry the bait back to the nest and share it with the queens and the rest of the colony (UC IPM). Place bait stations or small dots of gel right next to the trails and near the spots where ants come in. You do not need to find the nest first. Health Canada recommends setting out two different baits at once for better results, for example one sweet and one protein bait. Keep every bait out of reach of children and pets.

Give the Bait Time

Giving the bait time is the step most people skip. At first you will see more ants around the bait, not fewer. The University of Kentucky explains that this is a good sign: they are feeding and carrying it home. UC IPM says it can take 5 to 10 days to see fewer ants, and Health Canada advises keeping baits out for at least two weeks and repeating if needed. During that time, do not spray insecticides or cleaners near the baits, because that keeps ants from eating them. Replace stations as they empty, and if the ants ignore a bait, try a different product.

Seal Entry Points

Sealing entry points keeps the next colony from finding its way in. Once the ants are gone, caulk along baseboards, cracks and crevices inside, and repair visible cracks in the foundation and exterior walls (Health Canada). Pay attention to door thresholds, window frames and the spots where pipes and wires enter the house. Duct tape or petroleum jelly can seal a crack temporarily until you can caulk it. Sealing after baiting, not before, keeps the ants on their trail to the bait.

Which Ant Killers Work Best?

The ant killers that work best are slow-acting baits, because they reach the queen. Sprays, dusts and home remedies can be useful in specific spots, but on their own they mostly deal with the ants you can see. The University of Kentucky puts it simply: the foraging ants are only a small part of the colony, and many more, including one or more egg-laying queens, usually stay hidden in the nest.

Ant Baits

Ant baits combine a slow-acting insecticide with food that worker ants want. UC IPM lists boric acid or borate, fipronil, avermectin and hydramethylnon (no longer registered in Canada) among the common active ingredients, and notes that fipronil baits work faster than boric acid baits. Prepackaged or refillable bait stations are the safest and easiest to use. In Canada, consumer bait stations such as Raid Max Double Control Ant Baits are sold at Canadian Tire. For product picks, see our roundup of the best ant killers.

Ant Sprays

Ant sprays kill on contact but give only temporary control, and UC IPM notes they may not be safe to use indoors. Spraying along trails can also backfire: Health Canada warns it may split the colony, and the City of Calgary notes that some barrier sprays can make colonies bud, and UC IPM says sprays disperse pharaoh ant colonies to new locations. If you see more ants after spraying, switch to baits. If you do use a spray, check that the label allows indoor use.

Diatomaceous Earth

Diatomaceous earth is a fine powder that dries out ants when they walk through it. Health Canada describes it as non-toxic to humans and pets and effective in cracks and crevices while it stays dry. UC IPM adds that it loses its effect when wet and can irritate the lungs, so apply a light layer in dry spots such as wall gaps and behind appliances, and avoid breathing the dust.

Home Remedies

Home remedies such as vinegar, peppermint oil and cinnamon act as repellents, not colony killers. Wiping a trail with vinegar and water can erase the scent the ants follow, just like soapy water does, but a pest control company citing University of Minnesota Extension describes it as a temporary fix that will not reach the queen. Repellents can also push colonies of some species, like pharaoh ants and odorous house ants, to split. Our guide to homemade ant killers explains what each remedy can and cannot do.

Boric Acid

Boric acid is one of the most common active ingredients in ant bait stations, and Health Canada regulates it closely. Boric acid products for home use are now generally limited to sealed bait stations or gel treatments, and Health Canada advises placing bait stations out of the reach of children and pets. Health Canada also advises: do not make homemade pesticides using boric acid. Borax, the laundry booster in many online ant recipes, is a mineral that may produce boric acid, so the safer choice is a registered bait station. You can read more about how borax works on ants in our borax guide.

The PCP Number

The PCP number is the Pest Control Products registration number printed on the label, and it shows that Health Canada has approved the product for use in Canada. Before you buy any ant killer, check that it has a PCP number, that the label lists the type of ant you have, and whether it is meant for indoor or outdoor use. Then follow every direction and warning on the label.

How Do You Stop Ants Outside Before They Come In?

Stopping ants outside means finding the colony they come from and making the edge of your house less inviting. You will never remove every ant from your yard, and you do not need to: ants outdoors are beneficial, eating insects such as young silverfish and moths (Health Canada). The goal is to keep them out of the house.

Finding the Nest

Finding the nest starts with the trail. Follow the ants back as far as you can, outside if possible, and look for small piles of soil with ants going in and out, often at the edge of a driveway, patio or foundation (Health Canada, UC IPM).

Treating Outdoor Nests

Treating outdoor nests with bait is the approach UC IPM recommends, by placing bait stations near trails and nest openings. Health Canada notes that flooding a nest repeatedly with a garden hose can push ants farther from the house, and that boiling water with detergent only reduces the colony temporarily. UC IPM also advises against spraying pyrethroid insecticides on driveways, sidewalks or around the foundation, because they wash into waterways. Some provinces and municipalities restrict certain lawn and garden pesticides, so check local rules first. Our full guide on dealing with ants outside covers lawns, patios and gardens.

Yard Habits

Yard habits make your foundation less attractive to ants. UC IPM recommends keeping plants, grass and mulch at least a foot (about 30 cm) away from the foundation. Trim shrubs and branches that touch the house, and keep firewood and decaying wood away from exterior walls, which also discourages carpenter ants (Health Canada, University of Kentucky).

When Should You Call a Pest Control Professional?

Calling a pest control professional makes sense when ants are damaging wood, keep coming back after weeks of careful baiting, or are coming from somewhere you cannot reach. Most ant problems can be handled at home, but these situations are the exceptions.

Carpenter Ants

Carpenter ants are the clearest case for professional help. They can damage wooden structures, the University of Kentucky notes that retail baits usually will not control them, and Penn State Extension says the ants frequently ignore baits. Health Canada recommends a professional exterminator in difficult situations, since the main nest often has to be found and treated directly.

Ants That Keep Coming Back

Ants that keep coming back after two or more rounds of baiting may be a species with many queens and mobile colonies, such as odorous house ants or pharaoh ants. These are hard for homeowners to control, and a professional can identify the species and choose the right bait and treat wall voids and other spots you cannot reach.

Apartment Buildings

Apartment buildings are tricky because ants travel between units along pipes and wires. If you rent, tell your landlord or property manager as soon as you see ants, and ask whether neighbouring units will be treated too.

Questions to Ask a Pro

Questions to ask a pest control company start with the method. UC IPM suggests asking for baits and spot treatments rather than perimeter treatments or monthly sprays. Also ask which species they identified, which products they will use (with PCP numbers), how many visits are included and whether re-treatment is guaranteed, as many Canadian companies offer it. Our guide to ant exterminator costs in Canada explains what affects the price, and you can get a quote from a recommended local exterminator through Pest Agent's referral form. For more ant guides, visit our ant hub.