Borax Ant Killer: How It Works and How to Use It Safely in Canada

TL;DR

• Borax can kill the colony, not just the ants you see: workers eat it in a sweet bait and, as Penn State Extension notes, share it with the queen and developing ants.
• Use a registered sealed bait station or gel with a PCP number, not loose powder or a homemade borax and sugar mix (Health Canada).
• Check your ant first. Borax baits suit sugar-feeding ants (Penn State Extension), but thief and pharaoh ants often prefer protein or greasy baits (UC IPM).
• Clear away crumbs and sweet spills, then set the stations right on the ant trails, out of reach of children and pets.
• Don't spray, and don't wipe the trail with vinegar or cleaners while you bait. Spraying stops the bait from working (Health Canada).
• Need help? Get a quote from a recommended local exterminator through Pest Agent's referral form.

The borax and sugar recipe shared all over the internet is the one borax ant killer that Health Canada advises against making. Borax itself still kills sweet-eating ants, but domestic borax dusts, powders and most liquid solutions have been taken off the Canadian market, and sealed bait stations and localized gels are the formats left on the shelf.

Patience is the other hurdle. A good borax bait leaves the ants on the counter alive long enough to walk home, so the trail does not vanish the day the bait goes down. That delay is deliberate, and the reason lies in how an ant colony feeds itself.

How Does a Borax Ant Killer Work?

A borax ant killer works as a slow stomach poison that worker ants eat and share with the rest of the colony. The ants are drawn by the sugar, not the borax. Worker ants feed each other and their larvae, so a bait that one worker drinks today can reach the queen in the nest, where UC IPM says the whole colony can be killed. That is why borax can do what a spray cannot: kill the ants you never see.

What Is Borax?

Borax is a white mineral salt, sodium tetraborate, which you may know as a laundry booster. According to the National Pesticide Information Center (Oregon State University), boric acid and its sodium borate salts, borax being one of the most common, are used as pesticides. In Canada, borax is regulated as a pest control product when it is sold to kill insects, and Health Canada says to look for its PCP number on the label.

How Borax Kills Ants

Borax kills ants once they swallow it. It disrupts the stomach and digestive system of insects and can also affect their nervous system (National Pesticide Information Center). Terro, which makes a widely sold borax ant bait, says borax kills ants gradually, over 24 to 48 hours, and Penn State Extension calls boric acid baits slower acting. Ants generally will not eat borax on its own, so baits mix it with something sweet, as UC IPM describes.

Why Slow Action Matters

Slow action is what makes a borax ant killer work. Health Canada explains that a bait system must work slowly enough for the poison to be fed to all members of the nest. If the bait kills a worker on the spot, the borax never reaches the queen, and the colony simply replaces the workers it lost.

Borax vs Boric Acid

Borax and boric acid are close chemical cousins, both borates that act the same way on ants. Health Canada treats them together: its 2016 decision covered boric acid, borax and other boron compounds, and it notes that boric acid is "sometimes also called boron or borax." For a product-by-product look at the other one, read our guide to using boric acid to kill ants.

Which Ants Eat Borax Bait

Borax bait works on sweet-eating ants. Terro's label lists Argentine, odorous house, pavement, little black, acrobat and thief ants, among others. It does not recommend its borax bait for carpenter ants, says it is not effective on fire ants, and does not list pharaoh ants. UC IPM notes that thief and pharaoh ants prefer protein or greasy baits year-round. If you are dealing with tiny ants around sweets, see our guide to getting rid of sugar ants. Pale ants that spread from room to room may be pharaoh ants, which need a different bait.

Is Borax for Ants Allowed in Canada?

Borax for ants is allowed in Canada in sealed bait stations and gels, but Health Canada cancelled boron powders and liquid sprays for home use. This matters, because many recipes and old articles still tell you to sprinkle borax powder or pour a borax solution along your baseboards.

What Health Canada Cancelled

Health Canada's re-evaluation of boron pesticides (decision RVD2016-01, published July 22, 2016) covered boric acid, borax and related compounds. For home use, dust and granular products, and products in solution other than sealed bait stations or localized gels, were cancelled. Their sale was prohibited as of 2018, and Canadians were told to stop using them by 2019. In all, 25 of the 112 registered boric acid products were affected.

What Is Still Allowed

Sealed bait stations and localized gel treatments are still allowed, since they generally expose people to much less borax than loose powder; Health Canada says to keep them out of the reach of children and pets. Under Health Canada's decision, their labels must say "Apply/use only in areas inaccessible to children and pets." The other registered products stayed on the market with stronger label directions.

Homemade Borax Pesticides

Health Canada advises against making homemade pesticides with boric acid, and it notes that borax can produce boric acid. The concern is not one bait on its own. Overexposure to boron can cause developmental and reproductive health effects, and people are exposed from many sources at once: pesticides, cleaning products, homemade craft materials such as slime, and cosmetics. A jar of homemade borax syrup on the floor adds to that total, with no label, no child-resistant container and no tested strength.

The PCP Number

The PCP number is your proof that a borax ant killer is registered in Canada. Health Canada advises you to always look for a Pest Control Products (PCP) number on the label, and to follow every direction and warning on it. A box of laundry borax has no PCP number and no pest control directions, so it is not sold as an ant killer.

How to Kill Ants With Borax, Step by Step

Killing ants with borax means letting them feed on a borax bait, undisturbed, until the colony dies. Follow these steps with a registered borax bait station.

1. Identify the ant.
2. Remove competing food.
3. Place baits on the ant trails.
4. Stop spraying.
5. Check and replace the baits.
6. Wait for the colony to die out.

Identify the Ant

Identifying the ant tells you whether borax will work at all. Borax baits are sweet baits, so they suit sugar-feeding ants such as odorous house ants and pavement ants. Health Canada lists the carpenter ant, little black ant, odorous house ant, thief ant and pharaoh ant among the species known to invade homes in Canada, and the City of Calgary notes there are many species of ants in the country. If you are not sure what you have, our guide on how to get rid of ants walks you through the common ones.

Remove Competing Food

Removing competing food makes the bait the best meal in the house. Wipe up crumbs and sweet spills, store sugar, cereal and pet food in sealed containers, and empty the garbage often. Terro's directions say to remove other food sources before placing its stations.

Place Baits on Ant Trails

Ant trails are where the bait belongs. Health Canada advises placing bait stations directly in the path of foraging ants, but out of the reach of children and pets. Indoors, trails often run along baseboards, carpet edges and cabinet corners, and Terro also suggests countertops, windowsills and spots under or behind appliances. Use all the stations in the pack, and put some where the ants come inside.

Stop Spraying

Stopping all sprays is what lets the bait do its job. Health Canada warns that if you spray chemicals to kill ants while using a bait system, the bait system will not work, and that spraying trails indoors may split the colony into several new ones. UC IPM gives the same advice. The Green Way bait label also warns against using cleaners near the bait, so do not wipe the trail with vinegar or cleaners while you bait.

Check and Replace Baits

Checking the baits regularly keeps the ants feeding. Liquid baits get used up and can dry out or spoil (UC IPM), so replace a station once it is empty. If the ants ignore a bait for a few days, move it closer to the trail or try a different product. Once the ants are gone, Terro suggests replacing the stations every 3 months, and UC IPM advises checking and refreshing bait stations regularly.

How Long Borax Takes

A borax ant killer takes days to weeks, not hours. Expect a crowd of ants on the bait at first: Terro says ants appear in large numbers, then disappear as the bait takes effect. UC IPM says it can take 5 to 10 days to see fewer ants, while complete control may take several weeks or more. Terro says complete control may take up to two weeks, or 2 to 3 weeks for a larger colony, and Penn State Extension says two weeks or longer. Do not crush the ants on the bait, since they are the ones carrying it home.

Borax and Sugar Ant Killer: Store-Bought or Homemade?

A borax and sugar ant killer pairs a sweet syrup the ants want with a small amount of borax they will not notice. In Canada, a registered store-bought bait is the better choice, for both safety and results.

What Is in a Store-Bought Borax Bait

A store-bought borax bait is a measured sugar syrup inside a closed plastic station. Terro Liquid Ant Baits contain 5.40% borax (sodium tetraborate decahydrate) and are sold at Canadian Tire, Home Depot Canada, RONA and Home Hardware. Ortho Ant B-Gon traps sold at Canadian Tire list 5.0% borax, and Green Way Liquid Ant Killing Bait lists a related boron compound at 1%. To compare ready-made baits, see the best ant killer roundup.

Why Strength Matters

Strength decides whether the bait reaches the queen. UC IPM explains that prepackaged stations, which usually contain 5.4% borate, kill foraging ants well but are weaker against large infestations, because some foragers die before they get back to the nest. Weaker liquids of 0.5 to 1% borate in sugar water have more effect on the whole colony. Researchers at UC Riverside note the same problem with baits of 5% or more. The lesson for you: more borax is not better, and a bait that piles up dead ants next to it is too strong to wipe out the nest.

Problems With Homemade Borax Bait

Homemade borax bait has three problems. First, Health Canada advises against making homemade pesticides with boric acid, and borax can produce boric acid. Second, you cannot control the strength, so a homemade syrup is easily too strong or too weak. Third, it sits in an open lid or jar that children and pets can reach, and it dries out quickly, a Canadian review site found, so it needs constant refilling. If you want a do-it-yourself option, our guide to homemade ant killers covers methods that do not involve borax.

Is Borax Ant Killer Safe for Children and Pets?

A borax ant killer is low risk when it stays inside a sealed station out of reach, but borax itself can harm people and pets who swallow or breathe it. Health Canada says baits containing boric acid are generally of low toxicity to other animals, as long as they are used as the label directs.

Health Effects of Borax

Borax can irritate skin and can be corrosive to the eyes, according to the National Pesticide Information Center. Swallowing it can cause nausea, vomiting, stomach pain and diarrhea, breathing in borax dust can cause coughing, a sore throat and nosebleeds, and the National Pesticide Information Center notes that some infants who ate large amounts had convulsions. This is why Health Canada removed loose powders from home use.

Borax and Pets

Pets can react to borax much like people do, and the National Pesticide Information Center says signs of poisoning can start within 2 hours of eating it. Place stations behind appliances, under cabinets or inside cupboards they cannot open. For other options, read our guide to pet-safe ant killers.

Safe Handling

Safe handling starts with not opening or refilling the bait stations. Wear gloves if a label tells you to, avoid any dust, keep bait away from food, dishes and counters where you prepare food, and wash your hands after placing or removing stations.

Safe Storage

Safe storage means keeping unused baits in their original package, with the label, away from food and out of reach of children and pets. Never move borax into a food or drink container.

If Someone Swallows Bait

If a child or pet gets into a borax bait, call your doctor, a poison control centre or your veterinarian right away, and have the product label or safety data sheet in hand, as Terro and the National Pesticide Information Center advise. Do not try to treat it yourself at home.

When Borax Is Not the Right Ant Killer

Borax is not the right ant killer when the ants ignore sweet bait, nest in wood, or keep coming back after a few weeks of baiting. In those cases, a different product or a professional is the faster way out.

Carpenter Ants

Carpenter ants are a common case where borax falls short. Terro does not recommend its borax bait for them, and carpenter ants often build satellite nests that bait may never reach the main colony from. Health Canada also notes that carpenter ants can damage wood in your home, so treat them as a structural problem. See our guide on how to get rid of carpenter ants.

Other Ant Killers to Consider

Other ant killers can replace or back up borax. Diatomaceous earth is a non-toxic dust for humans and pets according to Health Canada, though you should not breathe it in, and it only works while dry: compare the two in our diatomaceous earth vs borax guide. For ants nesting in the yard, see how to get rid of ant hills.

Calling a Pest Control Professional

Calling a licensed pest control professional makes sense when ants keep coming back after several weeks of baiting, when you suspect carpenter ants, or when ants appear in many rooms at once. A professional can identify the species, find the nest and choose a treatment suited to it. To see what is involved, read about the cost of ant extermination in Canada, or get a quote from a recommended local exterminator through Pest Agent's referral form.