Raised ridges and volcano-shaped mounds of soil often signal the activity of a mole in a garden. These small mammals are specialized insectivores, spending almost their entire lives underground. Moles have cylindrical bodies, velvety fur, and large, paddle-like forelimbs equipped with powerful claws for digging. Their constant tunneling is driven by a relentless search for food.
The Primary Diet: Earthworms
Earthworms are the staple and preferred food source for moles, often constituting the vast majority of their diet. A mole’s tunnel network acts like a series of traps, allowing its sensitive snout and acute sense of touch to detect when a worm falls into a passage. Due to their extremely high metabolic rate, moles must consume a significant amount of food daily, often eating 70 to 100% of their own body weight.
The constant search for earthworms means moles do not hibernate and must eat year-round to survive. To manage this high-energy demand, the mole employs a remarkable strategy: they bite the worm’s head, injecting a toxin that paralyzes the worm without killing it.
The immobilized worms are then dragged to specialized underground chambers known as “larders.” This creates a cache of live, fresh food that can be consumed later, especially when foraging is difficult, such as in winter or dry spells. Researchers have discovered these storage rooms containing hundreds, and sometimes over a thousand earthworms, demonstrating the importance of this survival mechanism.
Other Invertebrate Prey
While earthworms are the primary focus, the mole’s diet also includes a variety of other soft-bodied invertebrates found in the soil. These opportunistic food sources supplement the diet when encountered during tunneling or when earthworms are scarce. The secondary menu includes insect larvae, slugs, snails, spiders, and centipedes.
Specific insect pests that moles consume include the white, C-shaped grubs of the Japanese beetle and the larvae of crane flies. Consuming these insects benefits the gardener, as moles help control populations of root-feeding pests. However, moles follow the distribution of their prey, so their presence indicates moist, healthy soil with abundant invertebrates.
Why Moles Are Not Eating Your Plants
The most common misunderstanding about moles is the belief that they eat garden roots, bulbs, and vegetable crops. Moles are insectivores, meaning their diet is based on animal matter, not plant material. They lack the necessary dentition to chew and digest fibrous plant roots.
Damage to plant roots or garden beds is usually an indirect consequence of their tunneling behavior. As a mole digs its subterranean highways, it may inadvertently sever a plant’s roots or expose them to air, causing them to dry out. The visible harm to plants is almost always caused by a different kind of animal entirely.
The true culprits for consuming vegetation underground are rodents like voles and gophers. Voles often use the mole’s tunnels for easy access and have diets that include roots, bulbs, and bark. Gophers are known to pull entire plants into their burrows to eat them, while moles are simply digging for protein-rich invertebrates.