“Mom, there’s a hole in the garden!” are not words any gardener wants to hear, especially when the hole happens to be perilously close to a prized plant. When my son alerted me to the one pictured above, I had to do a little research to determine whether the resident of the hole needed to be evicted. It can be tricky to identify the critter by the hole, so I started by researching the “usual suspects”. Two of the most common tunneling pests in our area are moles and voles. Although their rhyming names can cause confusion, only one of these makes a meal of your plants.
Moles: If you have raised tunnels in your yard, moles are probably to blame. Moles are 4 – 6 inches in length, have small eyes and concealed ears, and paddle-like front feet designed for digging. They tend to be solitary creatures, and 3-5 moles per acre is considered to be a high population. While hunting areas are close to the surface, a mole’s den is located deeper underground. Entrances to dens may have mounds of soil – molehills – around them. Moles don’t eat plants, but their tunnels can cause damage by disturbing the root systems of plants growing above them. These tunnels are where moles hunt for the grubs, earthworms, and other invertebrates that make up their diet. Some of the grubs and insects in moles’ diets are lawn and garden pests. Mole tunneling also helps to aerate the soil, which can improve drainage and move mineral nutrients and organic matter around. Still, the tunnels’ damage to the landscape causes many homeowners frustration.
North Carolina is home to more than one species of mole. The Eastern mole (Scalopus aquaticus) is the most common. The star-nosed mole (Condylura cristata parva) is less common in our area, but is a protected species. This limits control options for all moles. Moles can be trapped, but a permit is required. There are no pesticides approved to kill moles in NC. Commercial repellents are available but need to be reapplied frequently. “Home remedies” such as gum or glass shards have not been shown to be effective. If tunnels are not extensive, simply pressing soil back down will lessen the nuisance factor.
Voles: Voles are small rodents that resemble mice. Pine voles (Microtus pinetorum) and meadow voles (Microtus pennsylvanicus) are two of the vole species found in our area. Meadow voles live mostly above ground, make runways through grassy areas, and gnaw on plants at ground level. Pine voles dig a series of underground tunnels less than a foot deep, and sometimes also use mole tunnels. One to two inch diameter entrance holes may be found in garden beds. Pine voles eat bulbs, tubers, and roots of plants, and can cause a lot of damage to ornamental plants. They may also feed above ground at night. Several adults and young can live within a tunnel system, and adults can have as many as 5 litters in a year.
Voles prefer to have some protection from predators. To make your yard less attractive to voles, keep grassy and weedy areas mowed, and do not mulch deeply. Trapping is most effective in fall and winter, when their food supply is less abundant. A trap baited with apples and peanut butter, placed under a bucket next to a vole hole, is recommended. Baits can be used to poison voles, but must be used carefully. Valued plants can be protected by using a barrier (such as hardware cloth) or planting in pots, but this may not be feasible for large shrubs and trees.
After spending some time watching the hole in our garden my family determined that neither moles nor voles were responsible.
Chipmunks: I had expected to find a vole using the hole in the garden, but it was home to a chipmunk. Chipmunks (Tamias striatus) are a type of ground squirrel that live in wooded areas and around homes where food is plentiful. Like moles and voles, chipmunks live in underground tunnels. Chipmunks are omnivores, eating a variety of foods including seeds, nuts, berries, and insects. Some food is stored for winter in their burrows. Although they are not usually a major nuisance in the landscape, chipmunks can feed on flower bulbs and seeds for vegetable gardens. They also can burrow under foundations, patios and sidewalks, which may cause structural damage. Hardware cloth or other barriers can be used to keep chipmunks from tunneling under sidewalks or entering buildings. Reducing cover for chipmunks and keeping bird feeders away from structures will make your house less attractive to them. Repellents can be used but must be reapplied frequently. Chipmunks can also be trapped if they are causing damage to property.
These are not the only animals that could be digging in your yard. An environmentally friendly approach to a “mystery hole” would be to observe the area to find the hole’s owner, then assess whether the animal is likely to cause enough damage to require treatment. In our case, the family enjoys watching the chipmunk and have decided to leave it alone.