Published by BuzzSkito Mosquito & Tick Control
Published October 7, 2026 · Drafted with AI assistance and fact-checked against the sources listed below
Does borax kill ants?
Yes. Borax and its close relative boric acid kill ants that eat them, and they are used as a bait: a little borate dissolved in something sweet that worker ants drink and carry home. The National Pesticide Information Center's boric acid fact sheet says boric acid can kill insects if they eat it, by disrupting the stomach, and that it can also affect the nervous system. Texas A&M AgriLife Extension's bulletin on household ants calls it a slow-acting stomach poison. The slowness is what makes it useful.
The ants on the counter are not the colony. Iowa State University Extension points out that a spray reaches only the small portion of the colony that is out looking for food, while the queens and the rest stay hidden in the nest. The University of California's Pest Notes on ants describes what a bait does about that: workers are drawn to it, recruit others, and carry small portions back to the nest, where it is passed mouth to mouth to other workers, larvae and queens.
Texas A&M adds that most adult ants cannot ingest solid food particles, and Iowa State calls liquid and gel baits often the most versatile and effective options for small household ants. A separate page covers how ants share liquid food and what each species eats.
Is borax the same thing as boric acid?
No, although they are closely related and both are used in ant baits. Iowa State states that borax is not the same ingredient as boric acid: boric acid, at pH 5.0, is produced by reacting borax with an acid, while borax is alkaline at pH 9.3. The National Pesticide Information Center treats them together as boric acid and its sodium borate salts, names borax as one of the most common, and says their toxicity generally depends on how much boron each contains. Products containing boric acid have been registered as pesticides in the United States since 1948, and the center's fact sheet counts over five hundred sold in the country.
On a bait label, read the active ingredient line. Borax appears as sodium tetraborate decahydrate, and boric acid may be listed as orthoboric acid, a name Texas A&M's product table uses alongside plain boric acid. The box of borax in the laundry aisle is a different kind of product. The National Pesticide Information Center lists household cleaners and laundry detergents among the non-pesticide products that contain these compounds, and a non-pesticide product carries no pest-control label, so it gives no directions or precautions for use as ant bait.
Why does a weak borax bait work better than a strong one?
Because a strong dose kills the forager before she has shared it, and may put ants off feeding in the first place. The University of California states the requirement plainly: a bait must act slowly enough for foraging ants to make their way back to the nest and feed other colony members before they die. With borates, the concentration sets how fast that happens.
The clearest numbers come from a 1998 study in the Journal of Economic Entomology by John Klotz and colleagues. They fed Argentine ants boric acid in sugar water at strengths from 0.2 to 1.0 percent. In 25 percent sugar water, half the ants were dead in about 5.0 days at the weakest dose and in about 1.7 days at the strongest. Sweetness mattered as well: ants recruited more heavily to 50 percent sugar water than to 25 percent, and more to 25 percent than to 10.
The researchers then tested a bait of 0.5 percent boric acid in 25 percent sugar water at an infested water production plant. Over 10 weeks, ant numbers at the baited structures fell continuously, by 80 percent, while structures given plain sugar water showed no significant change.
| Source | Borate strength | What the source says about it |
|---|---|---|
| University of California, Pest Notes | 5.4% (typical prepackaged station) | Can kill foragers in the home, but less effective for major infestations because foragers die before they bring the bait back |
| University of California, Pest Notes | 0.5 to 1.0% liquid in sugar water | More impact on the colony; goes in larger, refillable stations; several days to a week to see results |
| University of California, garden ant guide | Above 1% | Less effective than 0.5 to 1%, because higher concentrations become repellent to ants |
| Texas A&M AgriLife Extension | 0.5 to 3.7% in 25% sugar water | The range most attractive to Argentine ants; higher concentrations are less attractive |
| Texas A&M AgriLife Extension | 1% mixed into food | Better than higher concentrations: less repellent, and kills as efficiently |
| Klotz and colleagues, 1998 | 0.5% in 25% sugar water | 80% fewer Argentine ants over 10 weeks in a field trial |
Percentages are of boric acid or borate in the finished bait, as each source reports them.
The sources agree on the direction and differ on the details. The two University of California pages give different reasons for the same advice: one says a 5.4 percent station kills foragers before they can deliver the bait, the other that strong mixes repel ants. Texas A&M puts the top of the attractive range at 3.7 percent, well above the 1 percent ceiling in the California garden guide. Most of these figures also come from work on a single species, the Argentine ant. The California garden guide extends its 0.5 to 1 percent range to other sugar-feeding ants without naming them, and Texas A&M's 1 percent food bait is aimed at pharaoh ants. None of the sources supports the idea that more borax makes a better bait.
The same slow-poison logic applies to every bait ingredient, borate or not, and the complete guide to ants in US homes sets borax beside the alternatives.
Sugar bait or protein bait: which one will your ants take?
Borax bait is usually a sweet bait, so it suits ants that are feeding on sugar and can fail on ants that want grease or protein. Iowa State describes the standard ant bait as a food attractant, usually sugar, combined with a slow-acting insecticide, and the liquid borate baits the University of California describes are sugar water. Whether your ants will drink it depends on the species and the season.
The University of California gives the pattern for Argentine ants: sweet baits are attractive year-round, and protein baits mainly in the spring. Other species lean toward grease, protein or oil all year. Texas A&M's table of what each species goes for indoors shows how mixed the diets are:
| Ant | Foods preferred indoors | Bait notes from the sources |
|---|---|---|
| Argentine ant | Sweets, animal fat | Sweet baits attractive year-round; protein mainly in spring (University of California) |
| Odorous house ant | Sweets, meats, dairy products | One of the typical small house ants Iowa State's sugar-bait advice is written for |
| Pharaoh ant | Grease, meats, sweets | Prefers protein or greasy baits year-round (University of California) |
| Thief ant | Grease in cheeses and meats, sweets | Prefers protein or greasy baits year-round (University of California) |
| Little black ant | Grease, sweets, meats, fruits, vegetables | Mixed diet; the University of California's general advice is to offer each kind of bait and see which is taken |
| Carpenter ants | All foods, sweets | General baits are rarely effective (Iowa State) |
| Red imported fire ant | Meats, grease, sweets | Prefers baits containing oils (University of California) |
| Crazy ant | Sweets, meat | Difficult to attract to ant baits (Texas A&M) |
Food preferences are from Table 1 of Texas A&M AgriLife Extension's Managing Household Ant Pests, which covers common house-infesting ants of Texas.
You do not need a species name to find out. The University of California recommends offering a small quantity of each kind of bait and watching which one the ants prefer. Texas A&M's bulletin likewise says to note which foods the ants are attracted to, and it describes plain-food lures meant for tracing ants to their nest: sugar water, peanut butter, mint apple jelly or bacon grease on squares of aluminum foil or in bottle caps, watched as the ants find the food and carry it home. If they walk past the sweet sample, a sugar-and-borax bait is the wrong tool. For a closer identification, see the guides to telling very small household ants apart and to the species Americans call sugar ants.
Which ready-made ant baits contain borax or boric acid?
Going by the product table in Texas A&M's bulletin, borate ant baits include Terro-PCO liquid ant bait stations and Advance liquid and gel baits, listed under borax, and granular baits such as Niban and InTice, listed under orthoboric acid. The bulletin's text adds a Drax gel containing 5 percent orthoboric acid and describes the Terro product as 5.4 percent borax, which matches the University of California's figure for a typical prepackaged station. The bulletin is dated December 2005 and product lines change, so treat its list as examples of the type and check the current label.
A ready-made bait is the simplest way to use borax, because it arrives measured, enclosed and labeled, but a brand name does not tell you which active ingredient you are getting. Iowa State names Combat, Raid, Ortho and Terro as popular consumer bait brands and lists borax, at about 5 percent, first among the active ingredients; the others on its list are thiamethoxam, avermectin, indoxacarb and fipronil. Texas A&M's table, for example, files a Raid bait under avermectin and a Combat gel under fipronil.
For a weaker liquid bait there are refillable stations. The University of California names the Ant Café, Antopia, Ant-No-More and KM AntPro as examples, and calls reusable stations more useful than prepackaged baits for difficult ant problems. Its description of the KM AntPro shows the commitment involved: usually at least one dispenser on each side of the house, set in shade where ants trail, checked regularly and refilled as needed.
Bait formats are compared in the ant control product guides. Two related pages explain what a bait station does that a sticky trap cannot and sort ant killers by whether they reach the nest.
How do you make borax ant bait at home, and what are the limits?
The university recipes are simple: a small, measured amount of boric acid in sugar water, or in a food the ants like, at about 1 percent. They are also narrower than many people expect. Both measure out boric acid powder, both stop at 1 percent, and both leave the safeguards to you.
- Sugar-water bait (University of California). Its guide to ants in gardens and landscapes gives 1/2 teaspoon of powdered boric acid and 9 teaspoons of granulated sugar dissolved in 1 cup of hot water, for a solution of approximately 1 percent boric acid and 19 percent sugar. It puts the effective range at 1/2 to 1 percent boric acid and 10 to 25 percent sugar, applied in refillable, reusable bait stations, and says a properly mixed bait is effective against Argentine ants and other sugar-feeding ants.
- Food bait (Texas A&M). For pharaoh ants whose nest cannot be found, its bulletin mixes 1 part boric acid powder into 100 parts of whichever food the ants find most attractive, such as peanut butter, mint apple jelly or corn syrup. That is 1 teaspoon per 2 cups. Small amounts go into bottle caps, onto pieces of foil or into 2-inch lengths of drinking straw, with 20 to 30 placements where ants have been seen and none where small children or pets can reach.
Where homemade bait falls short
- The measurements are for boric acid, not laundry borax. The University of California says the liquid bait can be made with boric acid or borax, but its worked example uses boric acid powder, and so does Texas A&M's. Iowa State is explicit that the two are different ingredients, and none of these sources gives a conversion, so swapping in borax by the spoonful means guessing at the strength.
- One percent is a small amount. California's recipe is half a teaspoon in a cup of water. A version that uses a tablespoon in the same cup is six times as strong, in the range the university says repels ants. The same guide warns that slight changes, such as too high a concentration of borate, can dramatically reduce a bait's effectiveness.
- There is no station and no label. The University of California notes that bait stations protect bait from sunlight and from disturbance by children. A bottle cap of syrup does neither, and nothing on it tells anyone else in the house what it is.
- It dries out and spoils. Texas A&M's timeline assumes the bait is kept fresh and moist, and the University of California warns that baits can dry up or turn rancid and stop attracting ants.
- It can harm plants. Texas A&M advises care with boric acid outdoors because it is toxic to plants, and the National Pesticide Information Center says boric acid and borax can kill plants by causing them to dry out.
- The powder may have a label of its own. If your boric acid is sold as an insecticide, its label governs how it may be used, and that may not include mixing it into a bait. Read it first.
A ready-made bait delivers the same kind of active ingredient with a station and a label attached. The broader question of which pest jobs are reasonable to do yourself has its own page.
How do you use borax bait so it reaches the colony?
Put it beside the trail, take away the competition, and then leave the ants alone. Every step below exists to keep foragers feeding and walking home for as long as possible.
- Check what they are eating. Offer a sweet sample and a greasy one first, as described above. A sugar-and-borax bait only makes sense if they take the sweet one.
- Clear competing food. The University of California says to remove food particles and sweet residues from cracks around sinks, pantries and other infested areas before baiting, and Texas A&M says bait is more effective once spilled food and grease are gone.
- Place bait where the ants already walk. Iowa State says to set baits next to wherever ants are seen, such as in corners and along walls, and that placements beside a trail are often the most effective. For gel or liquid from a bottle, it suggests a small drop on the non-sticky side of masking tape or on wax paper. Outdoors, the University of California puts stations near trails and nest openings, spaced every 10 to 20 feet around the foundation.
- Keep it out of reach. The University of California says to avoid places accessible to pets and small children. In a kitchen that usually means behind or under things, not on the counter; see where to put ant bait in a kitchen without getting it near food.
- Do not spray or scrub around it. The University of California says not to use any insecticide spray while baiting. Iowa State adds that cleaning agents can deter ants and that bait should not go on a surface previously treated with insecticide. Wiping trails elsewhere is fine, and a separate page looks at what vinegar does to an ant trail.
- Tolerate the crowd. Iowa State warns of an initial feeding frenzy and says to put up with the extra ants, because a bait only works if they eat it and return to the colony.
- Refill and refresh. Replenish busy placements and replace bait that has dried out. Iowa State says the best results come when ants feed over a period of time, not from one brief visit by a few ants.
- Clean up at the end. When activity stops, discard uneaten bait carefully and wash any residue off surfaces with soap and water, as Iowa State advises. Then caulk the cracks the ants were using, which the University of California recommends for keeping them out.
Bait is one part of the job. Finding the entry point, fixing moisture and dealing with a nest inside a wall are covered in the room-by-room plan for ants in the house.
How long does borax take to kill ants?
Individual workers die within days, the trail usually thins in 5 to 10 days, and the colony takes several weeks or longer. The published figures line up like this:
| What you are waiting for | How long | Source |
|---|---|---|
| Half the workers that drank the bait to die (laboratory) | About 5.0 days at 0.2%; about 1.7 days at 1.0% | Klotz and colleagues, 1998 |
| First visible results from a 0.5 to 1.0% liquid bait | Several days to a week | University of California, Pest Notes |
| Fewer ants on the trail | 5 to 10 days | University of California, Pest Notes |
| Ants controlled by a careful, thorough baiting program | 3 to 4 weeks, sometimes more | Texas A&M AgriLife Extension |
| Complete control | Several weeks or more | University of California, Pest Notes |
| 80% fewer Argentine ants at an infested site | 10 weeks of baiting | Klotz and colleagues, 1998 |
Two cautions keep expectations realistic. Texas A&M notes that baits usually kill many, but not all, of the ants in a colony, particularly when the colony is large and cannot also be treated directly. And the 80 percent in the field trial was a steady decline across 10 weeks, not an overnight collapse. Ants still feeding at the bait are doing what the bait needs them to do, so keep it supplied.
Is borax ant bait safe around children and pets?
It is low in toxicity but not harmless, so the rule is to keep both the bait and the powder out of reach. The National Pesticide Information Center rates boric acid as low in toxicity if eaten or if it contacts skin. It adds that borax can be corrosive to the eye and irritating to the skin, and that people who breathed in borax had a dry mouth, nose and throat, with coughing, sore throat, shortness of breath and nosebleeds also reported. Those warnings matter most to anyone spooning out powder for a homemade mix.
Swallowing it is the main concern. People who have eaten boric acid have had nausea, vomiting, stomach aches and diarrhea, and the center notes that the vomit and diarrhea may be blue-green. Eating extreme amounts has resulted in a red skin rash followed by skin loss, and some infants who ate large amounts had convulsions, confusion and coma. Whether children are more sensitive to boric acid in particular is not settled. The center says seizures and deaths have been reported more often in infants exposed long-term than in adults, but that data allowing a direct comparison are not available.
Its practical point is about behavior. Children crawl, play on the floor and put their hands and other things in their mouths, so the center suggests getting down to a child's level after placing a product to see what can be reached. It also records why an unlabeled container is dangerous: in the 1960s, several infant deaths were reported after improperly labeled boric acid disinfectants were accidentally used in infant formula.
Pets are affected in a similar way, and the center says signs of poisoning in animals can start within 2 hours of eating boric acid. The amount is what separates a bait station from a box of powder. Iowa State says the active ingredients in ready-to-use ant baits, borax at about 5 percent among them, have little to no toxicity to people, pets or wildlife at the concentrations those products contain, and in the same paragraph tells readers to keep baits away from children and pets. The larger hazard in most homes is the supply: an open container of borax or boric acid, or a jar of homemade syrup.
When does borax fail, and what should you do then?
Borax bait fails when the ants will not eat it, when it kills them too fast, or when the colony is one a sugary bait cannot reach. Check these in order:
- They want protein or grease. The University of California says thief ants and pharaoh ants prefer protein or greasy baits year-round, and Iowa State says general ant baits are rarely effective against tiny grease ants. Switch to a bait made for those ants.
- They are fire ants. The University of California says fire ants prefer baits containing oils. A separate guide covers how fire ants and other red ants are identified and controlled.
- Their tastes changed. Iowa State notes that ants can be finicky at different times of the year and advises trying several brands of bait until one is accepted.
- The bait is too strong. If a prepackaged station is only thinning the foragers, the University of California's answer for severe Argentine ant problems is a 0.5 to 1 percent liquid in a refillable station.
- Something is driving them off. Insecticide spray, cleaner residue around the placement, competing food and dried-out bait all reduce feeding.
- They are carpenter ants. Iowa State says general ant baits are rarely effective against large, black carpenter ants, and Texas A&M notes that carpenter ants can keep satellite colonies apart from the main nest. The job is finding the nest; see how carpenter ant nests are located and treated.
- They are a hard-to-bait species. Iowa State puts soil-nesting field ants on the same rarely-effective list, and Texas A&M describes crazy ants as difficult to attract to ant baits.
When you can find the nest, Texas A&M calls treating it the most effective way to eliminate the ants, using a product labeled for that pest and that location. When you cannot, and a fresh, correctly placed sweet bait has been taken for several weeks without ending the problem, its advice is plain: ant control can be difficult, and if you are not successful, call a commercial pest control operator. A related page sets out why baiting beats spraying, which is the approach to ask a company about.
Use any pesticide exactly as its label directs. The label is the law, and what is registered and sold varies by state.
Frequently Asked Questions
Can you just sprinkle dry borax where ants walk?+
That is not what these sources recommend. The National Pesticide Information Center says boric acid kills insects that eat it, and the university guidance describes borates for ants mainly as a bait that workers carry back to the nest. Texas A&M's product table does include a boric acid dust for indoor use, but its advice on dusts is to apply them sparingly, in thin, even layers, in the nest area. Powder scattered along a trail may harm ants that walk through it, since the center says boric acid can also scratch and damage the exterior of insects, but it reaches foragers, not queens, and it leaves borate where children and pets can touch it.
Why are there more ants after putting out borax bait?+
Because the bait is doing its job. Foragers that find food recruit nestmates to it, and Iowa State University Extension describes an initial feeding frenzy around a new bait placement. It advises tolerating the extra ants, since a bait only works if they eat it and carry it back to the colony, and says activity may decrease after that first rush. Do not spray them or wipe them up at the bait. The University of California says it can take 5 to 10 days to see fewer ants, so judge the bait after a week or two, not on the first evening.
Does borax bait kill the queen?+
It can, if the bait is weak enough to be shared. The University of California explains that workers carry bait back to the nest, where it is passed mouth to mouth to other workers, larvae and queens, and that this is how a bait can kill an entire colony. That only happens when foragers survive long enough to deliver it, which is the reason for low concentrations. Results are not total every time. Texas A&M says baits usually kill many, but not all, of the ants in a colony, especially a large one, and a field trial of 0.5 percent boric acid bait recorded an 80 percent reduction over 10 weeks.
Can you use borax ant bait outdoors?+
Yes, in stations and where the product label allows. The University of California places baits near ant trails and nest openings outdoors, spaced every 10 to 20 feet around the foundation, and says refillable dispensers are usually installed on each side of a house, in shady areas where ants trail. Its garden guide suggests starting in late winter or early spring, when ant populations are lowest. Two cautions apply. Texas A&M warns that boric acid is toxic to plants, so keep the bait inside its station, and outdoor bait still has to be out of reach of children and pets.
What should you do if a dog or cat eats borax ant bait?+
Call your veterinarian and have the product label in hand. The National Pesticide Information Center says boric acid affects animals in a similar way to people, who have had nausea, vomiting, stomach aches and diarrhea after eating it, and that signs of poisoning in animals can start within 2 hours. The amount matters: Iowa State University Extension says ready-to-use ant baits hold their active ingredients at concentrations with little to no toxicity to pets, and a ready-made station holds far less borate than a box of powder. The center also answers pesticide questions at 800-858-7378.
Does borax kill carpenter ants?+
Not reliably. Iowa State University Extension says general ant baits are rarely effective against large, black carpenter ants, even though Texas A&M's food table shows carpenter ants eating sweets along with almost everything else. The bigger issue is the nest. Texas A&M notes that carpenter ants can keep satellite colonies apart from the main nest, calls treating the nest the most effective way to eliminate ants, and recommends a professional when reaching a colony means drilling into wood or wall voids. It also suggests setting out plain food and following the ants that take it to see where they are nesting.
Sources
- Boric Acid Fact Sheet — National Pesticide Information Center
- Ants (Pest Notes, UC ANR Publication 7411) — University of California Statewide Integrated Pest Management Program
- Ant Management in Gardens and Landscapes — University of California Statewide Integrated Pest Management Program
- Liquid Boric Acid Bait for Control of the Argentine Ant (Hymenoptera: Formicidae) — Journal of Economic Entomology (Oxford University Press)
- Managing Household Ant Pests (B-6183) — Texas A&M AgriLife Extension Service
- Ant Baits for Small Household Ants — Iowa State University Extension and Outreach
How this guide was made: it was researched and drafted with AI assistance from the sources listed above. A second, independent AI pass then checked each factual claim against those sources. Found an error? Email support@buzzskito.ca.