Ants in Apartment: How to Get Rid of Them and Who Is Responsible in Canada

TL;DR

• Use slow-acting baits rather than sprays, as UC IPM suggests. Spraying along ant trails may make the colony split into several new ones (Health Canada).
• First wipe the trail with soapy water, then wipe counters, sweep and put open food away.
• Choose bait stations with a PCP number, as Health Canada advises, and place them right on or beside the trails, out of reach of children and pets. You usually do not have to find the nest: Health Canada notes that ants bring the bait back to the nest.
• In Canada, the landlord is often responsible for ants. The tenant must keep the unit clean, report the problem and cooperate with treatment.
• Report ants to your landlord in writing, with dated photos. Don't stop paying rent: Ontario tenants do not have the right to withhold rent over pests (Housing Rights Canada).
• Need help? Get a quote from a recommended local exterminator through Pest Agent's referral form.

Grabbing the can of bug spray from under the sink feels like the obvious move against ants in an apartment, yet Health Canada warns that spraying along a trail can encourage the colony to split into several new ones. In a building where walls, pipes and wiring link neighbouring units, a colony that splits can turn one kitchen problem into a problem for the whole floor.

The ants crossing the counter are rarely the whole story. They are workers sent out to forage, and the crumbs, the slow leak or the crack that drew them inside is the part of the problem a renter can actually see and change.

Why Are There Ants in Your Apartment?

Ants in your apartment are almost always workers foraging for food and water. According to the City of Calgary, many ant species nest outdoors and come indoors mainly to forage, and scouts leave a scented trail that other workers follow back to the food. That is why one ant on the counter often turns into a line of them a day later. Many ants spend the winter in the ground and start searching for food when the weather warms up, so many renters first notice them in spring.

Food Sources

Food is the main reason ants come into an apartment. Health Canada says ants are attracted to sugary and greasy foods, and even to the sticky honeydew that aphids leave on houseplants. Crumbs on the floor, a dirty stovetop, an open cereal box, a full kitchen garbage or a pet food bowl left out all day can keep a trail going.

Water and Moisture

Water and moisture draw ants as much as food does. UC IPM notes that leaky faucets can attract ants. Odorous house ants tend to prefer moist, warm spots such as leaks and wall voids with heated pipes (Utah State University), and Health Canada says carpenter ants indoors can point to a moisture problem or decaying wood. If you see ants around a sink, a bathtub or a radiator, check for a leak and report it.

Shared Walls

Shared walls let some ants move between units. Pharaoh ants often nest in wall and cabinet voids and can use electrical wires and plumbing pipes to travel from room to room (UC IPM), and Alberta Health lists apartment buildings among the places where they can cause problems. Orkin Canada describes foraging ants entering multi-unit buildings through the tiniest of cracks. The ants in your unit may come from a nest outside your apartment, so your neighbours and landlord may need to be involved. If you suspect a nest behind your drywall, read our guide to ants in walls.

Which Ants Are in Your Apartment?

The ants in your apartment are most likely one of the species Health Canada lists as invading Canadian homes: carpenter ants, little black ants, odorous house ants, thief ants and pharaoh ants. Adults generally range from about 1 millimetre (about 1/25 inch) to about 13 mm (1/2 inch). Identification matters because each species responds differently to treatment (UC IPM).

• Carpenter ants: large, often about 6 to 25 mm, usually black. They nest in damp or decaying wood. See the signs of carpenter ants.
• Pharaoh ants: tiny, about 1.5 to 2 mm, often yellow to light brown. In Canada they generally live in heated buildings and can spread through apartment buildings. See our pharaoh ant guide.
• Odorous house ants: about 3 mm, brown to black, often with a rotten coconut smell when crushed. See odorous house ants.
• Little black ants and thief ants: among the smallest house ants, often about 1 mm. See small ants in the house.
• Pavement ants: about 3 mm, brown, often nesting under pavement and foundations and entering through cracks in concrete (Utah State University).

What Are the Signs of an Ant Infestation in an Apartment?

An ant infestation in an apartment shows up as steady trails of ants rather than a single stray ant. One ant on the windowsill is a scout. A trail that comes back every day, in the same place, means a colony has found a reliable food or water source in your unit.

Ant Trails

Ant trails are the clearest sign. Health Canada says trails are commonly found along baseboards, the carpet edge along walls, and inside cabinet edges and corners. Follow the trail in both directions: one end shows you what the ants are eating, and the other end shows you where they get in, such as a gap under a window, a crack at the baseboard or an opening around a pipe.

Ants in Several Rooms

Ants in several rooms at once suggest a bigger problem than a crumb on the counter. Seeing tiny pale ants in the kitchen, the bathroom and a bedroom is typical of pharaoh ants, which often nest in several places inside a building. In an apartment, this is a sign to tell your landlord early, because the colony may extend into neighbouring units.

Sawdust-Like Shavings

Sawdust-like shavings near baseboards, window frames or door frames point to carpenter ants. Health Canada explains that carpenter ants tunnel into wood and push the wood out as shavings rather than eating it, and that a dry rustling sound in the walls at night can mean a colony. Report it to your landlord right away.

Winged Ants Indoors

Winged ants indoors, especially in spring, can mean a colony is close by. Health Canada notes that winged carpenter ants leaving a building, usually in spring, suggest a nearby colony. If you find winged ants on your windowsills, collect a few in a sealed bag or take a clear photo so a professional can identify them.

How Do You Get Rid of Ants in an Apartment?

Getting rid of ants in an apartment works best with slow-acting baits, not sprays. The ants you see are only a small part of the colony, so the goal is to get poison back to the nest and the queens. Follow these steps in order.

Wipe the Trail With Soapy Water

Wiping the trail with soapy water is the first step. UC IPM recommends cleaning up invading ants with a sponge and soapy water as soon as they come in, because it removes the scent trail other workers follow. Then clean up the food that drew them: wipe counters, sweep, and put open food away. Leave a short section of trail near the entry point untouched if you plan to bait there.

Why You Should Not Spray Ants

Spraying ants in an apartment usually makes things worse. Health Canada warns that spraying indoors along ant trails may encourage the colony to split into multiple new colonies, and Alberta Health puts it simply: "A spray will kill some ants, but not a colony." In a multi-unit building, a split colony may move further into the walls or into the unit next door. UC IPM adds that sprays only provide temporary control and that spraying ants indoors will not prevent more ants from entering.

Ant Bait Stations

Ant bait stations are often the best tool for renters; NC State Extension calls baits the best approach to dealing with ants. A bait mixes a slow-acting insecticide with food, so workers carry it back to the nest and share it with the colony, including the queens (UC IPM). Prepackaged bait stations are the safest and easiest option. Before you buy, check the label for a Pest Control Products (PCP) number, which shows the product is approved by Health Canada, and follow the directions exactly.

Boric acid ant products for home use in Canada are now generally sold only as sealed bait stations or gels, and Health Canada advises against making homemade pesticides with boric acid, because children are most at risk. Store-bought stations are a better choice than a homemade mix. For tested options, see our picks for the best ant killer, and if you have pets, choose a product whose label allows use around them.

Bait Placement

Bait placement decides whether the bait works. Health Canada recommends using plenty of bait stations and two different baits at the same time for better results. Place them right on or beside the trails and near where the ants come in. You usually do not have to find the nest (UC IPM). Keep stations out of the reach of children and pets, and do not spray insecticides or use cleaners around them: NC State Extension warns that ants will avoid bait in sprayed areas.

How Long Baits Take

Baits take days, not minutes. UC IPM says it can take 5 to 10 days to see fewer ants, and Health Canada advises keeping baits available for at least two weeks. Expect more ants around the bait at first: the University of Kentucky Cooperative Extension explains this shows they are feeding and carrying it back. Replace stations when they are empty, and if the ants ignore the bait, move it or try a different product, since some ants prefer sweets and others protein.

Diatomaceous Earth

Diatomaceous earth is a non-chemical option for cracks and crevices. Health Canada says it can be placed in cracks and crevices, and that it is non-toxic to people and pets, but you should not inhale the dust. It stops working once it gets wet (UC IPM), so it is not useful under a leaky sink.

Vinegar

Vinegar wipes away the scent trail but does not kill the colony. It may reduce the ants you see for a short time, but it does not reach the queen. For pharaoh ants and odorous house ants, repellents may even cause the colony to split.

When to Call a Professional

A licensed pest control professional is the right call when you see sawdust-like shavings or large black ants (carpenter ants), tiny pale ants in several rooms (often pharaoh ants), or ants in several units, or when at least two weeks of careful baiting have not reduced the trails. Health Canada says carpenter ants in difficult situations call for a professional, and the University of Kentucky notes that retail baits often will not control them; Penn State Extension adds that carpenter ants frequently ignore baits.

In a rental, ask your landlord or property manager to arrange the treatment. Landlords are generally advised to hire a licensed applicator, explain how to prepare the unit and tell tenants when they can safely return, and Health Canada says to use only products registered for use inside the home. UC IPM suggests asking for baits and spot treatments rather than routine sprays. To understand what a visit involves, read our guide to ant pest control. If you own your condo or your landlord asks you to find someone, you can get a quote from a recommended local exterminator through Pest Agent's referral form.

Who Is Responsible for Ants in an Apartment in Canada?

Responsibility for ants in an apartment often falls on the landlord in Canada, while the tenant is generally expected to keep the unit clean, report the problem and cooperate with treatment. The rules come from provincial tenancy laws and local bylaws, so they vary. This section summarizes what official and tenant-rights sources say; it is not legal advice.

Landlord Responsibilities

Landlord responsibilities for pests are set out in several provinces:

• Ontario: the City of Hamilton states that "a landlord is responsible to pay for pest control if there are pests in their building", citing the Residential Tenancies Act.
• Alberta: Alberta Health says that if you rent, your landlord is generally required by law to keep the home pest-free and hire a professional as needed.
• British Columbia: the Tenant Resource and Advisory Centre explains that, under Residential Tenancy Branch Policy Guideline 1, the landlord is generally responsible for insect control.
• Quebec: Educaloi tells landlords that pest control is generally their responsibility, although a tenant whose fault caused an infestation can be ordered to pay.

Tenant Responsibilities

Tenant responsibilities are mostly about cleanliness and cooperation. Housing Rights Canada explains that Ontario tenants are generally responsible for the ordinary cleanliness of their unit, must prepare it for inspection and treatment, and must allow entry after proper notice. In Hamilton, landlords may inspect after giving written notice, usually 24 hours. In BC, TRAC notes that tenants are more likely to be held responsible for making an infestation worse by not reporting it promptly or not cooperating with treatment than for causing it.

How to Report Ants to Your Landlord

Reporting ants to your landlord works best in writing. Send an email or letter that says when you first saw the ants, which rooms they are in, how many you see, and whether you have noticed shavings or winged ants. Add dated photos or a short video of the trail. Ask whether other units have reported ants, because a building-wide problem needs a building-wide treatment, and keep a copy of everything you send.

If Your Landlord Does Not Act

If your landlord does not act, you still have options, but do not stop paying rent. Housing Rights Canada warns that Ontario tenants do not have the right to withhold rent over pests. Instead, in Ontario you can usually call your local property standards office (311 in many cities) or file a T6 application with the Landlord and Tenant Board. In Toronto, contact the owner first, then 311 if nothing happens. In Alberta, you can call the Safe Healthy Environments contact centre at 1-833-476-4743. The same steps apply to other pests: see our guide to mice in an apartment.

How Do You Keep Ants Out of Your Apartment?

Keeping ants out of your apartment comes down to removing their food and water and closing the gaps they use. These habits also make baits work better, because the bait becomes the easiest meal in the unit. For general methods that also apply to houses, see how to get rid of ants.

Food Storage

Food storage is your first line of defence. Health Canada recommends glass jars with rubber gaskets or plastic containers with snap-tight lids for ant-attractive foods such as sugar, honey, cereal and snacks. Keep counters clean, sweep or vacuum often, rinse jars and cans before they go in the recycling, and take the kitchen garbage out often.

Pet Food

Pet food is an easy target for ants. Pick up bowls when your pet has finished eating, store kibble in a sealed container, and try a trick from Health Canada: set the pet food dish in a shallow dish of water. Ants can't swim, so they cannot reach the food.

Leaks

Leaks give ants the water they need. Fix or report dripping taps, wipe sinks and tubs dry at night, and do not leave wet sponges on the counter. Tell your landlord about any leak under a sink or around a window, since moisture also attracts carpenter ants.

Sealing Gaps

Sealing gaps cuts off the routes ants use. Health Canada suggests caulking along baseboards, cracks and crevices, and notes that duct tape or petroleum jelly can seal a crack temporarily. Seal after the baits have done their work, not during baiting, so you do not push the colony somewhere else. Ask your landlord to repair larger cracks, gaps around pipes and damaged window seals, since these are part of the building.