Pharaoh Ants: How to Identify Them and Get Rid of an Infestation

TL;DR

• Pharaoh ants are tiny yellow to light brown ants, usually about 1.5 to 2 mm long, that nest inside heated buildings. An infestation can stay active all year.
• To tell them from thief ants, check the antennae with a magnifying glass: pharaoh ants have 12 segments ending in a club of 3, thief ants 10 segments ending in a club of 2 (UC IPM).
• Don't spray: it can make the colony bud into new nests (Alberta Health). Vinegar and essential oils may have the same effect.
• Use a slow-acting bait labelled for pharaoh ants. Place it on active trails and in every area where you see ants, not only in the kitchen, as UC IPM advises.
• It can take several weeks to several months. Don't wipe the trails or move the baits, and keep going until no ants have been seen for a few weeks.

Pharaoh ants punish the most natural reaction to a trail on the counter: reaching for a spray. The ants that survive carry eggs and larvae to a new spot in the walls, and one colony becomes several, often in an apartment building where the nests were already hard to reach.

Getting rid of pharaoh ants works the other way around. A slow-acting bait, placed where the ants travel, lets workers carry it back to every queen, and results can take several weeks to show. That approach only pays off on the right ant, so the first task is confirming that the tiny pale ants in your kitchen really are pharaoh ants.

What Are Pharaoh Ants?

Pharaoh ants (Monomorium pharaonis) are tiny yellow to light brown ants that nest inside heated buildings and often live in colonies with many queens. They are one of the most persistent indoor ants in North America, found in homes, apartment buildings, grocery stores and hospitals. Because they live indoors, a pharaoh ant infestation can stay active all year, even in the middle of a Canadian winter.

What Do Pharaoh Ants Look Like?

Pharaoh ant workers are about 1.5 to 2 mm long, yellow or light brown to reddish, often with a darker tip on the abdomen (UF/IFAS, Alberta Health). All workers in a colony are the same size. Queens are larger and slightly darker, and males are black. Like other ants in their group, they typically have a two-segment waist (two small bumps between the thorax and the abdomen).

Because they are so small and pale, pharaoh ants are easy to overlook until you notice a steady trail of them on a counter or along a baseboard.

How Are Pharaoh Ants Different From Thief Ants?

Pharaoh ants differ from thief ants mainly in their antennae. According to UC IPM, pharaoh ant antennae have 12 segments ending in a club of 3 segments, while thief ants have 10 segments ending in a club of 2 segments. Thief ants are also usually even smaller and tend to have tiny eyes. You need a magnifying glass to see the difference, or you can ask a pest control professional to confirm the species.

Getting the species right matters, because the method that works on pharaoh ants is different from the one for many other ants. If your ants turn out to be another species, our guides to getting rid of small ants in the house and getting rid of sugar ants can help.

Where Do Pharaoh Ants Live in Canada?

Pharaoh ants generally live inside heated buildings in Canada. They are probably native to Africa and have spread around the world through trade (UF/IFAS). They cannot survive Canadian winters outdoors, so they nest in warm, protected spaces indoors: wall voids, cabinet voids, under floors, behind baseboards, inside furniture and near hot water pipes and heating ducts. Alberta Health Services names apartment buildings, hospitals, grocery stores and food businesses as places where they can cause problems.

How Does a Pharaoh Ant Colony Spread?

A pharaoh ant colony spreads by budding. A colony can hold many queens and, according to UC IPM, up to 300,000 workers. When the colony grows large or is disturbed, a group of workers may carry brood (eggs, larvae and pupae) and often a queen to a new nest site nearby. Workers can even raise a new queen from the brood they carry. This is why one building often has several nests at once, and why killing the ants you see does little to the colony.

Are Pharaoh Ants Dangerous?

Pharaoh ants are not aggressive and do not bite people (Alberta Health). The real concern is hygiene. In hospitals, they have been found carrying more than a dozen kinds of disease-causing bacteria, including Salmonella and Staphylococcus (UF/IFAS, Texas A&M AgriLife). At home, they can get into food packaging and contaminate food with germs picked up as they travel through the building, so throw out any food they have reached.

What Are the Signs of a Pharaoh Ant Infestation?

A pharaoh ant infestation shows up as steady trails of tiny pale ants indoors, often near water, at any time of year, including winter. Look for these signs.

Ant Trails

Ant trails are the most visible sign. Pharaoh ants follow set paths along baseboards, counters, cabinet edges and carpet edges, and they often use electrical wires and plumbing pipes to move between rooms and floors (UC IPM). A trail that disappears into an outlet, a gap behind a backsplash or a crack in the wall usually leads toward a nest.

Ants Near Water

Ants near water can be typical of pharaoh ants, which tend to prefer warm, humid spots. You often find them around sinks, bathtubs, leaky taps and the cabinets under sinks, as well as near hot water pipes and heating ducts.

Ants in Food Packages

Ants in food packages are a common sign because pharaoh ants feed on almost everything: sweets such as syrup and jelly, greasy foods such as butter and bacon, bread, pet food and dead insects (Texas A&M AgriLife, Utah State University). Pet food bowls are a frequent target.

Ants in Several Rooms

Ants in several rooms usually mean several nests. Because colonies can bud, a pharaoh ant infestation in a house or apartment rarely stays in one spot. Seeing them in the kitchen, the bathroom and a bedroom at the same time is a strong sign of pharaoh ants rather than a single outdoor colony coming in.

How Do You Get Rid of Pharaoh Ants?

Getting rid of pharaoh ants takes slow-acting bait that worker ants carry back to the nest, not sprays, which UC IPM says are not effective for them. Start by understanding why sprays fail, then follow the steps below.

Why Sprays Make Pharaoh Ants Worse

Sprays make pharaoh ants worse because they trigger budding. Alberta Health advises against insecticidal sprays because they can cause the colony to bud, and Utah State University warns that liquid and dust insecticides can spread the ants and worsen the problem, as UC IPM also notes for sprays. Repellent products, including vinegar and essential oils, can have the same effect: the colony may sense danger, split, and move to new spots in your walls. Instead of one colony, you end up with several.

Slow-Acting Baits

Slow-acting baits are often the most reliable way to get rid of pharaoh ants: UC IPM says baits are more effective and safer than sprays. Worker ants eat the bait, carry it back to the nest and share it with the queens and larvae. The bait must act slowly so workers survive long enough to spread it through the whole colony (UC IPM). Bait stations and gel baits labelled for pharaoh ants are the usual choices. For tested products, see our picks for the best ant killer.

Sweet Versus Protein Baits

Pharaoh ants switch between sweet and protein or fatty foods, so the best bait is the one they are eating right now. UC IPM recommends testing small amounts of each bait type first and using the one the ants prefer, and notes that combining fat-based and sweet baits keeps them feeding longer than sweet baits alone. Watch the bait for a day: if the ants ignore it, switch type.

Bait Placement

Bait placement decides whether the bait reaches the colony. Place bait stations or small dots of gel directly on active trails and in every area where you see ants, not only in the kitchen. Keep baits out of reach of children and pets. While baiting, do not spray, do not wipe the trails with cleaners, and do not move the baits around, so the ants keep feeding: UC IPM says baiting is the best way to manage pharaoh ants.

How Long Baiting Takes

Baiting pharaoh ants can take several weeks to several months, depending on how many colonies are in the building (UF/IFAS, Utah State University). Replace baits as they empty, and keep going until no ants have been seen for a few weeks.

Bait Active Ingredients

Bait active ingredients that work on pharaoh ants include boric acid and fipronil, according to UC IPM, as well as insect growth regulators that stop the queens from producing workers (UF/IFAS). Before you buy, check that the label lists pharaoh ants and shows a PCP registration number, which means the product is registered for use in Canada by Health Canada. If you have pets, read our guide to pet-safe ant killers.

Homemade Borax Bait

Homemade borax bait is often suggested for pharaoh ants, but Health Canada advises Canadians not to make homemade pesticides using boric acid, and UC IPM lists both borax and boric acid as borate ingredients. A strong mix kills workers before they get back to the nest. UC IPM recommends low concentrations of boric acid, under 1% active ingredient. Choose a registered bait station or gel that matches the food the ants prefer, sweet or greasy. Our guides on using borax to kill ants and homemade ant killers explain why registered baits are the safer choice, away from children and pets.

When to Call a Pest Control Professional

Calling a pest control professional makes sense when ants are in several rooms, when you live in an apartment or condo building, or when weeks of careful baiting have not reduced the trails. Alberta Health notes that serious infestations may need a certified professional and several visits over days or weeks. In multi-unit buildings, treating only one unit often fails because the colony can simply move next door. To know what to expect, read about what professionals use to kill ants and the cost of ant extermination in Canada.

How Do You Prevent Pharaoh Ants From Coming Back?

Preventing pharaoh ants comes down to removing the food and water that feed the colony and closing the gaps they travel through. These habits also make baits work better, because the bait becomes the easiest food available.

Food Storage

Food storage is the first line of defence. Keep sugar, cereal, snacks and pet food in sealed containers, wipe up crumbs and spills right away, and pick up pet food bowls when your pet is not eating. Alberta Health also advises not leaving food out.

Moisture Control

Moisture control removes the water pharaoh ants need. Fix leaky taps and pipes, wipe sinks and tubs dry at night, and avoid leaving damp sponges or cloths on the counter.

Sealing Cracks

Sealing cracks and gaps around baseboards, pipes, outlets and backsplashes cuts off the paths pharaoh ants use. Do it after the colony is gone, not during baiting, so you do not disturb the ants and possibly trigger budding.

Apartment Buildings

Apartment buildings usually need a building-wide approach, because pharaoh ants can travel between units along pipes and wires. If you rent, tell your landlord or property manager as soon as you see them, and ask whether neighbouring units are being treated too. Our guide to ants in an apartment covers your next steps.