Ant holes, or ant mounds, are the visible result of ants excavating soil from their underground nests, leaving small piles of fine dirt scattered across the lawn surface. These mounds create an unsightly, uneven appearance and can harm the turf by smothering grass blades and disrupting the root system beneath. Addressing this problem involves eliminating existing colonies and modifying the lawn environment to prevent future infestations. This approach combines immediate treatment methods with long-term cultural practices to restore the turf’s uniformity and health.
Immediate Non-Chemical Elimination Methods
Boiling water kills ants on contact due to the extreme heat. Slowly pour one to three gallons of nearly boiling water directly into the center of the ant hole, aiming to scald the queen deep within the tunnel system. This method is approximately 60% effective for colony elimination but risks killing the surrounding turfgrass, so it should be used with caution and only on the mound itself.
A less turf-damaging approach uses a solution of dish soap and water poured into the mound. The soap acts as a surfactant, breaking the water’s surface tension and allowing it to penetrate the ants’ protective exoskeleton, leading to dehydration or suffocation. A mixture of two ounces of dish soap per quart of water is sufficient, applied when ants are most likely in the nest, such as early morning or late evening.
Food-grade Diatomaceous Earth (DE) is a naturally occurring powder made from the fossilized remains of diatoms. The microscopic particles are abrasive, mechanically damaging the ant’s waxy outer layer when they walk across it. This causes the ant to lose moisture rapidly and die from desiccation. DE should be lightly dusted over the mound and surrounding trails while dry, as moisture significantly reduces its effectiveness. This method primarily kills foraging ants and those near the surface, meaning it may not eliminate the entire colony.
Applying Targeted Pesticide and Bait Solutions
For complete colony elimination, specialized commercial products designed for turfgrass environments offer a systemic solution. Granular ant baits are effective because they contain a slow-acting insecticide mixed with an attractive food source, often a protein or oil base. Worker ants collect these granules, carrying them back into the nest where the toxicant is shared with the rest of the colony, including the queen.
Application requires spreading the granular bait over the mound and the foraging area, sometimes followed by light watering to activate the product and help it settle into the turf. Because the poison must be transferred throughout the colony, it is important not to disturb the ants or the bait after application. These slow-acting toxicants require several days to a few weeks to achieve complete colony collapse.
Liquid and gel baits are generally sugar-based and often come in small, spill-resistant stations placed near the ant hole entrance. These formulations encourage quick consumption and transfer back to the nest, offering a targeted kill for sugar-feeding species. Insecticide dusts provide a quick kill when puffed directly into the central opening, though this method is less reliable for deep colony elimination unless the dust transfers through contact.
All chemical treatments require strict adherence to the manufacturer’s instructions regarding application rate and safety. Homeowners must observe the Restricted Entry Interval (REI), the period after application during which access to the treated area is limited. Keep pets and children off the treated section of the lawn for the time specified on the product label, typically until the product has completely dried or for a period of 24 to 72 hours.
Lawn Management Practices to Deter Ants
Long-term ant control relies on making the lawn environment less hospitable for nesting. Ants generally prefer dry, well-drained soil with a low water-holding capacity for establishing colonies. Adjusting irrigation to water the lawn deeply but infrequently encourages deeper root growth and keeps the topsoil consistently moist, which can prompt ants to relocate.
Excessive thatch, the layer of organic debris between the grass blades and the soil surface, provides a dry, insulated nesting space for many ant species. Regular dethatching and aeration help break down this layer and improve water penetration, eliminating a preferred habitat. A healthy, dense lawn is the best defense, as ants are more likely to colonize patchy or sparse areas.
Mowing the grass at a slightly higher setting (generally between 2.5 and 4 inches) helps maintain a thicker canopy. Taller grass shades the soil surface, keeping it cooler and slightly more moist, which discourages ant nesting. Removing potential food sources is also beneficial; this includes cleaning up organic debris and controlling pests like aphids, which produce a sugary substance called honeydew that ants actively harvest.