Ant activity in the yard is normal, but when trails lead directly toward a home’s foundation, management is necessary to prevent indoor invasions. Keeping ants away from the house involves a multi-step strategy: eliminating food and water sources, creating physical boundaries, and using targeted treatments to eliminate the colony. Focusing efforts outside the structure is the most successful way to maintain a pest-free interior environment.
Eliminating Outdoor Attractants
Preventative measures start with sanitation and removing resources that draw ants close to the home. Since ants are constantly foraging for food, managing waste is an important first step. Properly storing and regularly disposing of food waste, especially in outdoor trash and recycling bins, minimizes the availability of easy meals.
Pet food left outside is a common attractant and should be removed immediately after a pet finishes eating. Even small water sources, like leaky outdoor faucets or standing water in planters, can draw thirsty ants toward the foundation. Repairing these leaks eliminates a water source that ants seek out, particularly in dry weather.
Landscaping practices around the house also play a large role in ant management. Ants are attracted to plant pests like aphids, mealybugs, and scale insects because they feed on the sugary “honeydew” these insects excrete. Controlling these pests on shrubs and plants near the house removes a major food reward for ants. Trimming back vegetation so it does not touch the structure’s walls or roof eliminates the natural bridges ants use to access the house.
Creating Deterrent Barriers
Once attractants are minimized, the next strategy is applying a physical or chemical barrier to the home’s perimeter. These barriers disrupt the foraging ants’ scent trails or create an impassable boundary. Diatomaceous Earth (DE) is a popular, non-chemical option consisting of the fossilized remains of microscopic aquatic organisms.
When ants walk through food-grade DE, the fine, abrasive powder damages their protective exoskeleton, leading to dehydration and death. For DE to be effective, it must remain completely dry. It should be applied in a thin, visible band around the foundation, doorways, and window sills during dry periods. Any moisture will require reapplication to maintain the barrier’s integrity.
Other deterrents rely on strong scents to interfere with the ants’ pheromone trails. A simple mixture of equal parts white vinegar and water can be sprayed along trails and entry points, repelling ants without harming them. Peppermint oil or a chalk line applied to the perimeter can also create a temporary, non-toxic boundary. While these methods may cause ants to seek a new route, they do not kill the colony and must be reapplied frequently.
Targeting the Colony with Baits and Treatments
The most effective long-term solution involves targeting the entire colony, including the queen and developing larvae. This is best achieved using slow-acting insecticide baits, which are superior to quick-kill sprays that only eliminate visible foraging ants. Worker ants consume the bait, often a mixture of an attractant and a delayed-action poison like borate, and carry it back to the nest to share with the colony.
Ants’ nutritional needs change depending on the species and the colony’s current stage of development, meaning they may prefer different types of food at various times. Foraging ants are classified as either sugar-feeders, attracted to liquid baits, or protein/grease-feeders, which prefer solid or granular baits. To determine the ants’ current preference, place a dot of honey and a small amount of peanut butter near an active trail and observe which one they flock to.
Once the preferred food source is identified, the appropriate bait should be placed along active ant trails or near the nest entrance within a protected bait station. Patience is necessary, as the slow-acting poison must be distributed throughout the colony. Full colony elimination can take anywhere from a few days to over a week. Replenishing the bait is important as long as the ants continue to feed on it.
For visible ant mounds, direct nest treatment offers an immediate reduction in the ant population. If a nest entrance is located in a lawn or garden, pouring boiling water directly into the opening can kill many ants on contact and potentially eliminate a significant portion of the colony. Alternatively, a non-repellent liquid insecticide can be mixed and poured directly into the nest entrance for deep penetration and lasting effect. Treat the nest late in the evening or early morning when most of the ants are likely to be inside.