Water is a common household tool for both cleaning and yard work, leading many to wonder if it can be an effective means of ant control. While the idea of drowning an ant colony is appealing for its simplicity and lack of chemicals, the effectiveness of water varies greatly. A single ant can indeed be killed by water, but eradicating an entire subterranean colony presents different biological and architectural challenges. The success of water as a pest control solution depends on understanding the specific biological mechanism by which water kills an ant and how the colony structure offers protection.
The Biology of Ant Suffocation
Ants, like all insects, do not possess lungs but instead rely on a passive respiratory system. They breathe through tiny valve-like openings called spiracles, positioned along the sides of their abdomen and thorax segments. These spiracles connect to an internal network of tubes known as tracheae, which transport oxygen directly to the ant’s tissues.
When an ant is submerged in plain water, this respiratory system is disrupted, leading to suffocation. The water acts as a barrier, preventing oxygen from entering the spiracles and blocking gas exchange. Ants possess a waxy, hydrophobic exoskeleton that naturally repels water. Combined with their ability to close their spiracles, this provides temporary protection, allowing some species to survive underwater for up to 24 hours before the lack of oxygen becomes lethal.
Limitations of Using Plain Water on Colonies
The natural resilience of the individual ant is compounded by the complex architecture of the colony, making plain water ineffective for eradication. Ant nests are elaborate, multi-chambered structures that can extend deep underground, often several meters in depth. The queen and the bulk of the brood are protected in the deepest chambers.
Pouring water onto the surface of an ant mound typically only affects the top layer of workers. The surrounding soil quickly absorbs and cools the water, preventing it from reaching the colony’s core. Many ant species have evolved sophisticated defenses against flooding, such as constructing nests in well-drained soil or building earthen levees to divert water. Some species can even evacuate the nest and link their bodies together to form buoyant, living rafts that protect the queen and larvae until the floodwaters recede.
Enhanced Water Solutions for Eradication
To overcome the ant’s natural defenses, water can be combined with other factors to become a much more effective tool.
Boiling Water
One method involves using extreme heat, as boiling water kills ants not by drowning, but by instantaneous thermal shock. The intense heat, approximately 212°F (100°C) at sea level, causes the immediate denaturing of proteins and the catastrophic failure of cellular structures in the ant’s body.
Pouring two to three gallons of boiling water directly into the main nest entrance offers a greater chance of success. However, the soil rapidly draws heat away from the water as it percolates down. Even with a large volume, this method is still unlikely to kill the entire colony, as the queen may be too deep to be affected by the lethal temperature. This technique also carries risks, including severe burn hazards to the user and the potential to kill surrounding desirable plants.
Soapy Water
A safer and more effective household solution is the addition of ordinary liquid dish soap or detergent to the water. The soap acts as a surfactant, which dramatically reduces the water’s surface tension. By lowering the surface tension, the water can more easily penetrate the ant’s naturally water-repellent, waxy exoskeleton.
This soapy mixture allows the liquid to flow into and clog the spiracles, leading to rapid suffocation. The soap also helps break down the protective oily layer on the ant’s body, which can lead to dehydration. Spraying a visible ant with a simple mixture of water and a few drops of dish soap is the most reliable way to kill individual ants on contact.