Finding unexpected holes scattered across a lawn or garden is a common observation for many property owners. These small excavations are almost always a sign of biological activity, indicating the presence of insects, crustaceans, or small vertebrates beneath the surface. The appearance of the hole—its size, shape, and surrounding debris—provides immediate clues about the organism responsible for the digging. Identifying the source of these disturbances is the necessary first step before deciding on any management or control strategy, as different organisms require varying approaches.
Identifying Holes from Burrowing Insects
Holes created by insects and other arthropods are typically the smallest disturbances found in the yard, often measuring no more than the diameter of a pencil or a dime. These burrows usually feature a clean, neat opening without significant soil mounding around the entrance. Their presence is often temporary, as they relate to specific stages of an insect’s life cycle, such as emergence or nesting.
One of the most frequently observed insect holes is the exit tunnel left by emerging periodical cicadas after their subterranean nymph stage. These holes are circular, about a half-inch wide, and can appear in overwhelming numbers across a localized area when a brood emerges. Solitary ground-nesting bees also create small, individual burrows that are sometimes mistaken for wasps. These pollinators prefer well-drained, sparsely vegetated soil and rarely pose a threat.
Ant colonies, depending on the species, can create a wide range of surface disturbances, from small, simple entry points to larger, complex mounds made of fine soil particles. Certain species of spiders, such as wolf spiders, excavate small, vertical shafts in the ground that they use for shelter and hunting. These burrows are generally tidy and are often lined with silk near the opening to help stabilize the structure. Unlike the damage caused by larger animals, these insect-related holes rarely compromise the structural integrity of the lawn and often disappear naturally once the arthropod has moved on.
Tunnels and Excavations by Small Mammals
When holes are accompanied by more extensive surface damage, the culprit is often a small burrowing mammal, which can cause significant and lasting disruption to the landscape. Distinguishing between the two most common offenders, moles and voles, relies entirely on observing the specific structure of their excavations. Moles are insectivores, meaning their digging is primarily motivated by a search for earthworms, grubs, and other subterranean invertebrates, not plant matter.
The signature sign of a mole is the volcano-shaped hill of soil, correctly termed a molehill, which results from the animal pushing excavated soil to the surface during deep tunneling. Moles also create shallow, raised ridges of turf known as feeding runs, which are the visible signs of their tunnels just beneath the grass roots. These tunnels often meander across the lawn as the mole follows the paths of its prey, causing the turf to feel spongy or loose underfoot. These animals rarely leave an open hole, instead preferring to keep their tunnel system sealed.
Voles, sometimes called meadow mice, are herbivores that cause damage by consuming plant roots, stems, and bulbs. Their activity is characterized by small, clean entry holes that are typically about the size of a golf ball and often lack any significant soil mounding. These holes are usually located close to protective cover, such as near shrubs, flower beds, or thick ground cover.
The most telling sign of a vole infestation is the presence of well-defined surface runways, which are narrow, clipped paths of grass leading between their holes. Voles use these pathways for safe travel, and they keep the vegetation along the run consistently cropped short. Identifying these specific structural features is paramount to choosing an effective management strategy.
Holes in Wet Areas
Certain holes are unique to environments with consistently high moisture levels, particularly in low-lying, poorly drained sections of the yard or near permanent water sources like ponds and streams. The presence of water is the primary identifier for these types of burrows, which are often created by crustaceans. Crayfish, also known as crawdads, are the most common burrowers in saturated soil and leave a highly distinct signature.
A crayfish burrow is characterized by a turret or “chimney” of mud pellets surrounding the entrance. These structures are built from the soil the crayfish excavates from its tunnel, which can extend several feet down to reach the water table. The size of the hole itself is usually about an inch or two in diameter, but the mud chimney makes the identification certain.
Determining the Cause and Control Methods
Successfully managing yard holes begins with a precise identification strategy that relies on the visual evidence left behind by the animal. A simple assessment of the physical characteristics of the excavation can quickly narrow down the possibilities. Once the organism is identified, the appropriate control method can be implemented, recognizing that approaches vary drastically based on the biology of the pest.
Insect and Arthropod Control
In the case of ground-nesting insects like solitary bees or cicadas, intervention is often unnecessary, as the activity is either benign or temporary.
Mammal Control
For moles and voles, management usually requires more assertive measures, such as the strategic placement of traps or the use of targeted baits and repellents. Since moles tunnel to feed on the soil ecosystem, controlling their food source with grub treatments can sometimes reduce their activity, though trapping remains the most reliable method.
Crayfish Control
Crayfish activity is best mitigated by improving yard drainage to eliminate the saturated soil conditions they require for survival, or through physical removal if the water source cannot be controlled.