6 Tips for Eliminating and Preventing Ant Infestations in the House

Ants in the House

jmalov / E+ / Getty Images

An ant infestation isn't the worst pest problem in the world since most species of ant commonly found in the home do no real damage. The good news is that out of more than 1,000 or so classified species of ants in North America, only a few species are likely to take shelter in homes, and even fewer are likely to sting or cause damage. The vast majority of ant species are garden dwellers that do more good than harm — such as aerating soil or controlling damaging pests such as aphids.

But ants roaming around inside the home are annoying, and they can sometimes spread unwanted bacteria. Varieties commonly known as carpenter ants (Camponotus spp.) can cause damage by burrowing through wood structural elements of the home.

1:28

How to Cheaply and Naturally Get Rid of Ants

Structure of an Ant Colony

Ants are social creatures that generally form colonies in which individuals assume different roles. One or more "queen" ants are the reproducing individuals that remain in a hidden nest; their role is to simply continue to produce more ants and maintain the colony. The other individuals—which can include several million individuals in larger colonies—are known as worker ants. The younger workers typically remain inside the nest, where they serve the needs of the queen and maintain or expand the nest, while older workers roam out from the nest to retrieve food for the colony. It is these older workers that you see when an ant infestation becomes apparent.

An ant infestation is never controlled if all you do is spray these visible ants—the older works who are following established trails to and from a hidden nest somewhere in the walls of your home. Although it sounds strange, the key to eliminating visible ants is to target those you don't see. This is because the queen—the one who lays all the eggs—never leaves the nest. She just stays there, being fed by the worker ants. So if all you do is spray the visible worker ants with pesticides, the queen simply produces more to take their place, and your infestation never ends.

The key, then, is to target the queen ant, and this can be quite tricky since the nests are often deeply hidden behind walls or beneath concrete slabs.

Tips for Dealing with Ants

Here are six tips to help you eliminate and prevent an infestation of ants in your home.

Identify Ant Trails

The key first step in eliminating an ant infestation is to identify the trails used by worker ants to move to and from the nest. Any visible ants moving inside your home are seeking food, and once an ant finds edible material, it carries it back to the nest By doing so, the ant leaves a chemical path, or trail, for its fellow worker ants to follow to collect more food.

This behavior is what makes it possible to combat ants, since you can now fool the worker ants into bringing some form of poisoned food (ant bait) back to the nest.

Use Ant Bait Indoors

Avoid the temptation to simply use pesticides to spray visible ants marching along trails in your home. Pesticide sprays can eliminate a few visible ants, but more will quickly replace them, and you'll never make real progress to eliminating the infestation. Instead, use these worker ants as the ticket into the colony by placing ant bait for them to carry back to the hidden nest.

Ant baits are edible materials, usually sweet, sugary carbohydrates, mixed with substances that are toxic to ants but which have minimal toxicity to animals or humans. Some ant baits are primarily made from boric acid, a natural substance that is entirely non-toxic to humans.

Ant baits can be "stations" containing granular materials or liquids that are sprayed onto surfaces. Whatever form of ant bait you use, try to place it close to visible ant trails but outside the reach of pets and children. The bait will work most effectively if you keep other surfaces clean so that the bait is the only sweet substance available to attract the ants.

Be Patient

The worker ants will carry the pesticide bait back to the nest, but it can take several days to eliminate the colony, or even a few weeks if the colony is very large or it has several queens, as some ant species do. You may even need to replace the bait station if the ants empty it. Gradually, though, you will see an end to the infestation.

Use Spray Pesticides Outdoors—Carefully

If you happen to follow ant trails and identify an outdoor nest for the colony, then it may make sense to apply a heavy dose of liquid pesticide that can soak down to reach the queen. Drenching the nest with an approved insecticide spray (following all label directions) can be effective. Make sure, however, to verify that this is the colony creating your indoor infestation problem. Many types of ants are helpful garden creatures that you have no reason to kill. And be aware that these pesticides are likely to be toxic to all insects, including beneficial ones, so apply them carefully according to label directions.

Keep It Clean

Sanitation is critical for the prevention and control of any pest. Like all living creatures, ants need water, food, and shelter for survival. Ants leave the shelter of their colony to find food and water. Don't make it easy for them! Keep foods sealed, floors swept, and all surfaces cleaned. Be especially careful to keep things clean while you are targeting the nest, as this will make the sweet ant bait the only thing available to the ants. But don't clean away the ant trails until you have eliminated the infestation, as these trails will allow the ants to find your bait and carry it back to the nest. Once the infestation has been eradicated, then clean up the trail surfaces and keep them clean.

Seal Entry Points

Ants are tiny creatures and can enter homes and buildings through minute cracks and crevices. To minimize this, seal around windows and doors and all cable, pipe, and wire entry points. Regularly inspect foundations for tiny cracks through which ants can gain entry to your home.

Illustration of how to keep ants out
The Spruce/Catherine Song