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How to Make Borax Ant Bait for Indoor and Outdoor Use

ants farming scale pest insects collecting honeydew

Ants can be a major pest in the garden because they ‘farm’ aphids and scale – they safeguard them in their nests over winter, then bring them out in spring and carry them onto the new plant growth, then collect the honeydew that aphids and scale excrete as they feed off the plant’s sap.

To make matters worse, ants defend these pests from their natural predators, but ants are easily excluded from fruit trees by using horticultural glue bands around the trunks. Once ants are prevented from climbing trees, the unprotected aphids and scale are quickly eliminated by predators.

The activities of ants aren’t restricted to the garden though, they do have a habit of annoyingly invading kitchens in search of food, and bringing pest insects onto indoor plants too.

When ant populations become excessively large and invasive, they can be sensibly reduced with the use of ant baits which have a low environmental impact.

How to Make Borax Ant Bait

The best way to reduce ant numbers is to use a bait which is toxic to them but doesn’t kill them instantly, so they can take it back to their nest and feed the rest of the ants there, slowly destroying the whole colony.

What is Borax?

Borax is a natural occurring mineral salt, sodium tetraborate decahydrate, and is commonly used as a laundry detergent booster and a multi-purpose cleaner. Like other laundry products, it’s poisonous when swallowed, so be sure to keep out of reach of children and pets.

When insects ingest borax, it acts as a stomach poison. The exact mode of action is not yet understood, but when borate salts dissolve inside an insect body they form boric acid. After ingestion, insects reduce their feeding, dry out and are eventually killed.

Borax Ant Bait Recipe

The following materials are required to make borax-based ant bait insecticide:

To make the ant bait, follow the steps below:

  1. Pour 1/2 cup of sugar, 2 level teaspoons of borax and 350ml (12 ounces) of water into a glass jar or plastic bottle. Use a funnel if the bottle has a narrow mouth.
  2. Put the lid on the jar or bottle and tighten it firmly.
  3. Shake thoroughly until all the crystals are dissolved, this is the finished bait solution.
Step 1. Add 2 level teaspoons of borax into 350ml (12 ounces) of water
Step2. Add 1/2 cup of sugar
Step 3. Shake well to dissolve all the sugar and borax in the water

To mix up bigger batches of the borax ant bait, just double the quantities of ingredients, combine 1 cup of sugar, 4 level teaspoons of borax and 700ml (24 ounces) of water. That much ant bait should last quite a while, and stores well in a cool, dark place such as a laundry or kitchen cupboard.

How to Make an Ant Trap to Use With the Borax Ant Bait

Construction details for DIY borax ant bait trap for indoor use

The following materials are required to make an ant trap to use with the borax-based ant bait insecticide:

To construct the ant bait trap for indoor use, follow the instructions below:

  1. Place the cotton wool balls into the smaller jar and fill to half the height of the cotton wool with the bait solution. The cotton wool balls need to extend above the surface of the liquid so the ants can walk across the top of them to reach the bait solution.
  2. Make a few small holes in the centre of the lid of the small jar using an awl punch, drill or other suitable tool.
  3. Firmly screw the lid back onto the small jar, , this is the finished baited trap.
  4. Put trap near the entrance of the nest, or wherever ants have made a path into the house.

With this indoor ant trap, the holes for the ants to enter through are located at the top of the container. This isn’t suitable for outdoor use as the container will fill with water if left out in the rain.

It’s also possible to use the indoor trap outside by making a simple rain cover for it from a plastic bottle, as shown below.

How to Use the Indoor Ant Bait Trap in the Garden

When baiting ants outdoors, the trap needs to be protected from rain, otherwise it will flood and overflow, diluting the mixture and ruining it.

A simple rain cover that fits over the ant bait trap can be made from an empty soft drink bottle.

To make this ant bait trap rain cover:

  1. Get a soft drink bottle that is wide than the jar used for the trap.
  2. Cut off the top section of a soft drink bottle, allowing enough height so that the lid of the jar will not rest against the inside of the bottle.
  3. Cut out small doors along the bottom edge of the top section of soft drink bottle to allow the ants to enter through to reach the trap, make them large enough for unobstructed easy entry on uneven ground.
  4. Leave the cap on the top section of soft drink bottle to prevent any rain getting in.

Once the rain cover is placed over the ant bait trap jar, it should stay in place on its own, but if strong winds are blowing the cover off, a rock or other heavy object can be placed on either side to secure it better.

In very hot weather, the water may evaporate from the bait solution in the trap. To get around this problem, mark the water level on the side of the jar, and when it evaporates, top up with some plain water. Be aware that as the ants consume the liquid, its level will reduce, so don’t top up the water level if ants are coming, top up with more bait solution instead!

Protecting the ant trap when used outdoors with a simple rain cover

For a more permanent outdoor solution to ant problems, I’ve designed an ant trap specifically for outdoor use, made out of a plastic take-away food container that isn’t affected by rain for outdoor use in the garden, and to protect fruit trees, as pictured below. It also works indoors perfectly well too!

DIY outdoor ant trap for use in the backyard and garden, and for protecting fruit trees from pest aphids and scale insects

Further instructions for making the outdoor ant bait trap can be found in the article – How to Build a DIY Outdoor Ant Trap to Protect the Garden and Fruit Trees

Adjusting the Ant Bait Trap Mixture

The key is that the ants will get into the jar to eat the sugar and return to the nest and pass it on to the rest of the colony.

If many dead ants are found beside the jar, then the mixture is too strong, so dilute the solution by adding more sugar and water, or make a new batch with less borax and try again.

Some recipes specify using 2 tablespoons of borax rather than 2 teaspoons, which is three times as much (1 tablespoon = 3 teaspoons). Even using the amount in this recipe, I found some dead ants around the jar on the second day, so I suspect it’s strong enough. If the mix contains far too much borax, the ants will reject it and refuse to eat the bait.

With a proper mixture the colony may be destroyed in a few weeks, though it does take the destruction of the queen to completely eradicate a colony.

Ants Can Be Pests, But They’re Also Ecologically Beneficial

Though it may be sometimes necessary to control ant populations in the garden, or remove ants from the home, the goal is never to completely eradicate them from the garden, because they’re beneficial insects.

Here is a range of ecologically beneficial functions carried out by ants:

It’s important to keep in mind that natural ecosystems are in a state of balance, and when dealing with garden pests, we should only do just enough to address the problem, and no more than that. A heavy-handed approach, such as spraying with toxic synthetic pesticides, always throws nature out of balance, needlessly killing off the more vulnerable beneficial predator insects and causing population explosions of pest insects.

For more information on ant control, see article – How to Make an Outdoor Ant Trap to Protect Fruit Trees from Aphid and Scale Pests

More articles on Garden Pests, Diseases and Problems


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