Ants are a common sight in any garden, sometimes aiding in soil aeration and decomposition, but a significant presence often signals a problem. This article provides practical, low-impact strategies to prevent ant infestations and targeted methods for control when necessary.
Eliminating Pests Ants Protect
Ants are frequently drawn to plants because they “farm” soft-bodied insects like aphids, scale insects, and mealybugs. These secondary pests secrete honeydew, a sugary waste product that ants collect as a primary food source. In return, the ants aggressively defend these pests from natural predators, allowing the pest population to flourish.
Controlling these secondary pests is the most effective way to eliminate the ants’ food source, causing them to naturally relocate or decline. For small infestations, a strong jet of water from a hose can physically dislodge aphids from plant stems and leaves. For more widespread issues, commercial insecticidal soap, made from potassium salts of fatty acids, can be applied to directly contact the pests.
Insecticidal soap works by disrupting the cell membranes of soft-bodied insects, leading to rapid dehydration and death. When applying, thoroughly coat the pests, especially on the undersides of leaves. Avoid spraying in direct sunlight or when temperatures exceed 90°F to prevent leaf burn. Introducing natural enemies, such as lady beetles or lacewings, can also help keep pest populations in check.
Cultural Practices and Physical Barriers
Proactive cultural practices focus on making the garden environment unappealing or inaccessible to ant colonies. Since ants prefer dry, undisturbed soil for nesting, maintaining consistent moisture levels through regular watering can discourage them from establishing new hills near sensitive plants. Also, clear away sources of food and shelter, such as fallen fruit, loose mulch, and wood piles, which offer ideal nesting locations.
Physical barriers can effectively block ant access to plants, particularly trees and shrubs infested with honeydew-producing insects. A common method involves applying a sticky barrier product, like Tanglefoot, around the trunk of the plant. To prevent potential damage to the bark, first wrap the trunk with a protective material, such as thick paper or vinyl tape, before applying the sticky substance.
The barrier must be checked regularly, as dead ants and debris can quickly create a “bridge” allowing other ants to cross. Natural repellents can also disrupt ant navigation by interfering with their pheromone trails. Scattering used coffee grounds or ground cinnamon along ant paths creates a sensory barrier, as the strong scent of the compound trans-cinnamaldehyde in cinnamon is known to repel them.
Targeted Colony Removal Strategies
When prevention and indirect control measures are insufficient, targeted strategies can be used to eliminate established ant colonies. Food-grade diatomaceous earth (DE) is a non-toxic powder derived from the fossilized remains of diatoms, which kills ants through a mechanical process. The microscopic, sharp edges of the silica particles scratch the ant’s protective exoskeleton, causing desiccation and death once the powder is dry.
DE must be applied as a fine, dry dust directly to ant trails or nest entrances, as it loses its effectiveness when wet. A more systematic approach involves using slow-acting baits that worker ants carry back to the colony to feed the queen and larvae. Homemade sugar baits, typically using a weak solution of borax, are highly effective because the low concentration ensures the ant lives long enough to share the bait with the colony before dying.
A common and effective liquid recipe uses a ratio of approximately three to four parts sugar to one part borax. This must be placed in a protected container, such as a sealed jar with small holes, to prevent accidental consumption by children, pets, or wildlife. For direct nest elimination, carefully pouring a gallon or more of boiling water directly into the main entrance of an ant hill can kill a significant portion of the colony. Alternatively, drenching a nest with a solution of warm water mixed with one to two teaspoons of liquid dish soap per gallon can break down the ant’s outer layer, leading to suffocation.