Does lime kill moles? The short answer is no; lime is generally ineffective as a method for killing moles and is not a scientifically supported pest control solution. The claim that this common gardening additive can eliminate moles is largely anecdotal, and relying on it can prove harmful to your lawn and garden. Lime’s primary role is to change the soil’s chemistry, which fails to directly address the mole’s subterranean habits or feeding preferences.
Understanding the Mole’s Environment and Diet
Moles are small mammals built for a life spent almost entirely beneath the soil surface. Their powerful forelimbs and velvety fur allow them to tunnel efficiently through the earth, rarely venturing above ground. They are not herbivores and do not consume plant roots or turf, which is a common misconception.
The presence of moles in a yard is driven almost exclusively by the availability of food, not the condition of the surface vegetation. Their diet consists primarily of subterranean invertebrates, particularly earthworms, which often make up the majority of their food intake. They also consume insect larvae, such as white grubs, and other small soil-dwelling creatures. Since moles hunt and eat below the surface, applying lime to the top of the grass is unlikely to affect them directly.
The Chemical Properties of Lime Used in Yards
The term “lime” in gardening typically refers to two main substances: agricultural lime and hydrated lime. Agricultural lime, or aglime, is primarily composed of calcium carbonate and is used to raise the soil’s pH, making it less acidic. This process is a slow soil amendment intended to improve nutrient uptake for plants over a long period.
Hydrated lime, also known as slaked lime, is calcium hydroxide, a much more caustic and highly alkaline compound. This type of lime is dangerous to handle without protection and can cause chemical burns to skin and lungs. While some believe the caustic nature of hydrated lime will irritate a mole’s skin, it is also highly damaging to lawn grass and garden plants, posing a risk to pets and children.
Evaluating Lime’s Effectiveness Against Moles
Despite the anecdotal claims, there is little scientific evidence demonstrating that lime acts as an effective mole deterrent or killer. Moles are protected by their thick, velvety fur and their tunnels, which insulate them from surface-applied products. The small amount of lime that may fall into their tunnel network is not enough to cause significant harm or drive the mole out.
The most common theory for lime’s use against moles is the indirect approach: altering the soil pH to reduce the mole’s food supply. Lime can make the soil less favorable for earthworms, but this change is slow and rarely sufficient to eliminate the entire food source. Even if the grub population is reduced, moles will increase their foraging efforts or simply move to adjacent areas to find the remaining earthworms. Ultimately, lime functions as a soil conditioner, not a reliable pest control measure.
Proven Methods for Mole Control
For homeowners seeking effective control, methods that directly target the mole’s tunnels or diet are far more successful than soil amendments.
Trapping
Trapping is widely considered the most effective and reliable method for mole removal, using devices like harpoon or scissor traps placed in active, straight tunnels. Proper placement in the main runway is crucial for success, requiring the tunnel to be identified as active by monitoring for repair after collapsing a section.
Baits and Repellents
Another highly effective option is the use of specialized toxic baits. Moles are insectivores, so baits must mimic their natural prey, such as soft, worm-like or grub-like products containing a toxicant like bromethalin. These baits are placed directly into the mole’s active tunnel system to ensure ingestion. For a non-lethal approach, repellents containing castor oil can be applied to the lawn, encouraging the mole to relocate elsewhere in search of palatable food.