Will Borax Kill Ants Under a Concrete Patio?

By Home & Garden Last updated Monday, May/20/2024

Borax versus Boric Acid

The terms "borax" and "boric acid" are often used interchangeably, even though they are not the same thing. They are incredibly similar in appearance, toxicity and physical properties. They also contain the same active ingredient, borate. More importantly, they will have the same effect against ants. Borax is also known as sodium borate; sodium octaborate; sodium tetraborate and disodium octaborate tetrahydrate.

Using borax to control ants can be difficult because you must first find bait that will attract the ants that you're dealing with. Ants are usually considered either grease-, protein- or sweet-eating. The most obvious culprit for nesting under patios is the pavement ant, which prefers proteins. But a number of other ants will also build nests there including odorous house ants and small honey ants, which prefer sweets. To decide what to use, Place dabs of honey, peanut butter, apple jelly, bacon grease, corn syrup and similar materials on pieces of aluminum foil near the ant nests and see what attracts them. Wait an hour and check back to see which bait was consumed most.

Figure out the precise ration of bait-to-borax that will effectively control the colony. If you use too much borax, the bait will kill the ants before they can create a trail from the nest to the food, or pass it on to other members of the colony. If you don't use enough borax, the poison won't be strong enough to kill the ants. According to research done by University of California entomologists, the bait should contain 5 percent borax to be most effective.

For grease-eating ants, University of Nebraska Extension Educator Barb Ogg recommends using a mixture of 4 tbsp. peanut butter, 6 tbsp. honey and 3/4 tsp. borax. For sweet-loving ants, mix 1 cup water, 1/4 cup sugar and 1 1/2 tsp. of borax together. Use the liquid to saturate several cotton balls. Once the bait is ready, put it inside small jars with several holes punched in the lid. Place the jars near the ant nest. Replace the bait when it gets old or the ants appear to stop feeding on it. Keep baiting for at least three weeks until the ants are gone.