Homemade Ant Killer: What Works, What Doesn't and Safer Options in Canada

TL;DR

• Soapy water is likely the best homemade ant killer for the ants you can see, but no kitchen mix reliably kills the whole colony.
• Spray soapy water directly on the ants, then wipe the trail to remove the scent other ants follow.
• Vinegar and peppermint oil mostly repel ants and erase their scent trails. They usually do not reach the nest.
• UC IPM notes that baits can kill the queens. Don't make borax bait at home (Health Canada). A registered borax bait station gives the same slow-acting effect in a sealed container.
• Place bait right on the trail and keep it out for at least two weeks, as Health Canada advises. Seeing more ants at first is usually a good sign, as ants recruit others to a bait (UC IPM), so don't spray or move the stations.
• Need help? Get a quote from a recommended local exterminator through Pest Agent's referral form.

The usual homemade ant killer mistake is judging a recipe by how many ants it kills on the counter. A spray of soapy water can clear a trail in seconds, yet the queens sit untouched in the nest, and UC IPM notes it removes foraging ants only temporarily, so a fresh line of workers is often back later.

Only a slow poison that workers carry home reaches the colony, and that is where kitchen recipes turn risky: Health Canada advises against making homemade pesticides with boric acid, and children can be most at risk. Each home remedy does one job, from killing on contact to repelling to baiting, and picking the right one starts with knowing which job your ant problem needs.

What Is the Best Homemade Ant Killer?

The best homemade ant killer for the ants you can see is a simple spray of soapy water, but no kitchen mix reliably kills the whole colony. Homemade remedies fall into three groups: contact killers that only kill the ants they touch, repellents that push ants somewhere else, and baits that workers carry back to the nest. Only baits reach the queens, which is why the ants often come back a few days after you spray. For a full plan, see our guide on how to get rid of ants.

Soapy Water Spray

Soapy water is the most useful homemade ant killer for a trail on your counter. Add a squirt of dish soap to a spray bottle of water, spray the ants directly, then wipe the trail. According to UGA Extension, soap most likely breaks down the insect's outer layer and lets water into the tiny holes it breathes through, but it only works on contact (UC IPM notes it leaves no residual toxicity): spraying a surface with no ants on it does nothing, and it likely has no effect if ants eat it. Wiping with soapy water also removes the scent trail other ants follow, which UC IPM recommends as a first step. Our guide to using dish soap on ants covers the method in detail.

Boiling Water for Outdoor Nests

Boiling water is the homemade option for a nest in the lawn or between patio stones. Health Canada lists pouring boiling water and detergent down the nest as a way to temporarily reduce the colony, and repeated flooding with a garden hose as a way to push ants farther from the house. Expect the ants to rebuild nearby, since the effect is temporary. Use it outdoors only, pour carefully, and keep it away from plants you want to keep.

Diatomaceous Earth

Diatomaceous earth is not homemade, but it is the natural powder most people reach for next. It is made of fossilized diatoms, and according to the US National Pesticide Information Center it kills insects by drying them out, so ants do not need to eat it. It only works while it stays dry and undisturbed, so use it in cracks, behind appliances and along baseboards, not on wet floors or outdoors before rain. Health Canada describes it as non-toxic to people and pets but advises you not to breathe in the dust. Buy a product with a PCP number on the label, which shows Health Canada has approved it, rather than pool filter powder, and see our guide to diatomaceous earth for ants for how to apply it.

Do Natural Ant Killers Like Vinegar and Peppermint Work?

Natural ant killers such as vinegar and peppermint oil mostly repel ants and erase their scent trails; they do not reach the nest. That makes them useful for cleaning up a trail and keeping ants off one spot for a while, but not for ending an infestation.

Lemon juice and other citrus sprays are often added to these lists, but we found little university or government evidence that they do more than mask the trail, something UC IPM says soapy water already does. Cinnamon and cornmeal are two other popular remedies with similarly weak evidence.

Vinegar

Vinegar works as a trail cleaner, not a colony killer. Several university extension services, including Penn State, Nebraska and Mississippi State, recommend wiping ant trails with a vinegar and water mix, often 1:1, to remove the pheromones other ants follow. The University of Minnesota notes that the effect is temporary. Use it to clean counters and entry points while a bait does the real work. For the full answer, read does vinegar kill ants.

Peppermint Oil

Peppermint oil kills some ants on contact but does not last. UC IPM notes that plant oils such as peppermint, clove, orange and thyme have excellent contact activity but limited residual activity against ants. A few drops in water can keep ants off a doorway for a short time, but you will need to reapply it often. Keep concentrated essential oils away from children and pets, as Penn State Extension advises for pesticides, and see our guide to peppermint oil for ants before using it.

Baking Soda

Baking soda mixed with powdered sugar is one of the most shared homemade ant killer recipes, but we found no university extension or government research showing that it kills ant colonies. The sugar may attract ants, but there is no good evidence that the baking soda then kills them. If you want to try it, treat it as an experiment and watch the trail. Our article on whether baking soda kills ants explains the claims and the evidence.

Is Homemade Ant Bait With Borax Safe?

Homemade ant bait made with borax and sugar is the one kitchen recipe that can reach the colony, but Health Canada advises against making it at home. A registered borax bait station gives you the same slow-acting effect in a sealed, tested container.

How Borax Bait Works

Borax bait works because it is slow. Ants eat the sweet mix, carry it back and share it with the other workers, the larvae and the queens. According to UC IPM, the poison must act slowly so workers are not killed before they get back to the nest, and liquid borate baits work best at only 0.5 to 1% borate in sugar water. Many online recipes, including the 1 cup of borax to 1 cup of sugar mix that used to appear on this page, are far stronger than that, so they tend to kill the ants at the bait instead of in the nest. Our guide to using borax on ants explains how borax and boric acid differ.

What Health Canada Says

Health Canada's advice is clear: do not make homemade pesticides using boric acid, and borax can produce boric acid. Overexposure to boric acid may harm human development and reproduction, and children are at the highest risk. In 2016, after re-evaluating boric acid, Health Canada cancelled 25 of the 112 registered boric acid pest products, mainly home products in powder and other formats with a risk of overexposure. Homemade mixes also have no tested strength and no safety label. The University of Saskatchewan adds that borax mixed with sugar can harm or even kill children or pets that eat it.

Registered Borax Bait Stations

Registered borax bait stations are the safer way to use the same idea. They are pre-filled, closed containers that ants can enter but children and pets cannot easily reach, and UC IPM notes that prepackaged stations usually contain 5.4% borate. Before you buy any ant bait in Canada, check that the label shows a PCP number, which means Health Canada has registered it, and that your ant is listed on the label. Our roundup of the best ant killers and our guide to pet-safe ant killers can help you choose.

How Do You Use Ant Bait for DIY Ant Control?

DIY ant control with bait works when you give the ants a food they want, put it right on their trail and then leave it alone. Most failures come from the wrong food, the wrong spot or spraying the ants that come to the bait.

Sweet Versus Protein Test

A sweet versus protein test is the one homemade ant bait you can safely make, because it contains no poison. Put a drop of something sweet (honey or jam) and a dab of something greasy or protein-rich (peanut butter) side by side on a piece of tape near the trail. After a few hours, see which one the ants crowd around. UC IPM recommends this kind of test because ants prefer different foods depending on the species and the season. Then pick a registered bait of that type.

Bait Placement

Bait placement matters as much as the product. Mississippi State Extension advises placing bait as close to the trailing ants as possible, and Health Canada recommends placing stations in the path of foraging ants, with two different baits at once for better results. Outdoors, UC IPM suggests stations every 10 to 20 feet (about 3 to 6 metres) along the foundation and at nest openings. Do not spray ants or move the stations while you are baiting, or the baits will not work.

How Long Baits Take

Baits take days to weeks, and seeing more ants at first is a good sign. Mississippi State Extension notes you may see more ants coming to the bait at first, and that numbers go down as they carry it back to the colony. UC IPM says it can take 5 to 10 days to see fewer ants, and Health Canada recommends keeping baits available for at least two weeks. Replace stations when they are empty, and if the ants ignore them, move them or try the other food type.

Child and Pet Safety

Child and pet safety comes first with any ant bait, homemade or bought. Health Canada advises using home pesticides only where children and pets cannot reach them, such as behind appliances, in cracks and crevices, or in enclosed bait stations. Store unused products out of sight and reach of children, and follow every direction on the label. If you have a dog or cat that noses around baseboards, choose enclosed stations over gels or loose powders.

Prevention After Baiting

Prevention after baiting keeps a new colony from finding your kitchen. Health Canada recommends storing sugary and greasy foods in jars with rubber seals or tight-lidded containers, sweeping often around pet dishes, rinsing recyclables and emptying the kitchen garbage often. A pet food dish set inside a shallow dish of water stops ants, because they cannot swim across it. Once the ants are gone, caulk the cracks they used to get in.

When Is a DIY Ant Killer Not Enough?

A DIY ant killer is not enough when the ants damage wood, split into new nests when disturbed, or keep coming back after weeks of careful baiting. In these cases, a licensed pest control professional can usually identify the species and treat the nest directly.

Carpenter Ants

Carpenter ants are the ants in Canada that can damage your home, according to Health Canada, and piles of sawdust near wood can be a sign. Homemade remedies usually will not reach a nest inside a wall or beam. Our guide on how to get rid of carpenter ants explains what to look for and what works.

Pharaoh Ants

Pharaoh ants are tiny yellowish ants that can react badly to most homemade remedies. Alberta Health and UF/IFAS warn that sprays and repellents, including the natural ones, can make the colony split into new nests, and UC IPM says sprays only make infestations worse. If you see tiny pale ants trailing indoors, read our guide to pharaoh ants before you try anything.

Repeat Infestations

Repeat infestations after several rounds of baiting can mean the nest is somewhere you cannot reach or the species needs a different approach. A licensed professional can find the nest and use some products and methods that are not sold to homeowners. When you are ready, you can get a quote from a recommended local exterminator through Pest Agent's referral form.