The sight of raised tunnels and displaced soil often leads to the assumption that a mole is responsible for eating tomato plants and other vegetables. Moles do not eat tomatoes or any other plant material, as they are not herbivores. While their tunneling activity causes significant disruption, the physical consumption of roots or vegetables is the work of a different creature entirely.
The Mole’s Actual Diet
Moles are classified as insectivores, meaning their diet consists almost exclusively of invertebrates found underground. These subterranean mammals have a high metabolism and must consume between 60% and 100% of their body weight in prey daily to sustain constant tunneling. Earthworms are a staple of their diet, providing necessary protein and nutrients.
Their menu also includes soil-dwelling creatures such as grubs, insect larvae, centipedes, and slugs. Moles use their acute sense of smell and touch to detect the vibrations of prey moving through the soil. The elaborate network of tunnels functions as an underground trap system designed to capture these food items.
Understanding Garden Damage and the Real Culprit
Gardeners mistakenly blame moles for eating plants because the resulting damage appears to come from below the surface. Moles cause indirect damage when their extensive tunneling disturbs and severs plant roots. This disruption leads to wilting, stunting, or death of the vegetation because the plant’s connection to the soil and water is severed.
The actual culprits for eating tomato roots, bulbs, and stems are voles, which are small, mouse-like rodents. Voles are herbivores that actively seek out and chew on plant material, including roots and bark. They often use pre-existing mole tunnels as protected runways to access food sources, making the two pests easy to confuse.
Vole damage is characterized by gnawed roots and bark, or small surface runways in the grass. Mole activity is identified by distinctive, volcano-shaped mounds of soil or raised ridges of surface tunnels. Identifying the correct pest is important because management strategies for an insectivore differ from those for a rodent.
Managing Mole Activity in Vegetable Gardens
Managing mole activity focuses on discouraging their presence by modifying the garden habitat. One method is to reduce their primary food source by controlling the population of grubs in the soil. This approach can be challenging, however, because it may also reduce beneficial earthworms.
Using repellents that moles find offensive can also encourage them to relocate their foraging elsewhere. Products containing castor oil, which can be applied to the soil, are known to deter moles due to the taste and smell. Another effective strategy is creating physical barriers around vulnerable areas.
Burying hardware cloth or wire mesh vertically around the perimeter of garden beds or under raised beds can prevent moles from tunneling into the planting space. This barrier should extend at least 12 to 18 inches deep to be effective. Placing solar-powered stakes that emit low-frequency vibrations into the soil may also make the area less appealing for tunnel building.