Ants climbing on trees and garden plants often signal a hidden problem, causing frustration for gardeners seeking healthy growth. While ants rarely harm plants directly, their presence indicates other pest issues that require attention. Successfully removing ants and preventing their return involves a multi-step approach that targets the underlying cause, establishes physical barriers, and addresses the source colony. These steps provide safe, effective methods for regaining control of your garden and protecting your greenery.
Understanding the Ant-Pest Connection
Ants are frequently found on plants because they protect and manage populations of sap-sucking insects like aphids, mealybugs, and scale. These pests feed on the plant’s phloem sap and excrete excess sugar as a sticky, sweet waste product called honeydew. Honeydew is a favored food source for many ant species, creating a mutually beneficial relationship known as mutualism. The ants “farm” these pests, defending them from natural predators and sometimes moving them to new parts of the plant to ensure a continuous food supply. High ant activity almost certainly indicates an established infestation of honeydew-producing pests being protected. Long-term ant control depends entirely on eliminating these pests, breaking this symbiotic cycle.
Immediate Physical and Barrier Controls
The first step in protecting your plants is to interrupt the ant traffic flow using physical methods. A strong, direct jet of water can knock ants and accessible soft-bodied pests off the plant’s leaves and stems. This action offers quick, non-chemical relief and physically removes the insects from the foliage.
For trees and woody plants, create a physical barrier around the trunk to prevent ants from climbing up. Apply a commercial sticky barrier product, such as Tanglefoot, to a protective wrap of duct tape or vinyl tape placed tightly around the trunk. Applying the substance to a wrap, rather than directly to the bark, prevents potential damage to the tree’s living tissue. The tape must be wrapped securely to ensure ants cannot crawl underneath. Prune any branches touching the ground or nearby structures to prevent alternative routes.
Another physical control option involves using food-grade diatomaceous earth (DE), a fine powder made of fossilized aquatic organisms. When sprinkled in a band around the base of the plant, the microscopic, sharp edges of the powder abrade the ant’s exoskeleton, causing dehydration. Because DE is ineffective when wet, it must be reapplied after rain or watering to maintain its effectiveness as a barrier.
Eliminating Honeydew Producing Pests
Since ants are on plants to harvest honeydew, eliminating the pests that produce it is the most effective long-term strategy. Common pests like aphids, mealybugs, and scale are soft-bodied and vulnerable to low-impact treatments. Horticultural oils, such as mineral or neem oil, work by coating the insects and their eggs, effectively suffocating them.
Insecticidal soaps, which are potassium salts of fatty acids, disrupt the insect’s cell membranes, leading to their demise. Both oils and soaps are contact-based treatments, meaning the spray must directly hit the pest to be effective. Thorough coverage of the entire plant, including the undersides of leaves, is required. Apply these treatments when temperatures are moderate, avoiding high heat or direct sun, which can cause leaf burn.
Proper application involves following the manufacturer’s directions, as overly concentrated solutions can damage foliage. Test a small area first, especially on sensitive plants like certain Japanese maples or ferns. Applying at dawn or dusk helps protect pollinators on flowering plants, as the materials are safe once dried.
Targeted Colony Elimination Strategies
While physical barriers and pest control address the immediate presence on plants, eliminating the entire ant colony provides the final solution. Targeted baiting is the most effective method for eradicating the nest, using the ants’ natural foraging behavior against them. Ant baits consist of an attractive food source mixed with a slow-acting insecticide.
Worker ants collect the bait (liquid, gel, or granular) and carry it back to the nest to share with the queen and other colony members. The slow-acting insecticide is widely distributed throughout the colony before the ants die, ensuring the queen is eliminated and the colony collapses. Place baits strategically near ant trails or the colony entrance, but always away from plants and soil to minimize environmental impact.
Ants’ food preferences can change seasonally, requiring rotation between sugar-based liquid baits and protein-based formulations to ensure acceptance. This targeted approach is preferable to broad-spectrum insecticide sprays on plants, which kill beneficial insects that naturally control honeydew pests. Focusing on eliminating the source colony prevents future generations of ants from re-infesting.