Gardening Tips: Identifying Mysterious Holes in the Ground

— Written By and last updated by Chrissy Poole

Recently, I’ve received several calls about mysterious holes in the ground. The callers want to know who made these holes, why, and what to do to stop them. There are actually many different kinds of insects and animals that leave some type of hole or holes in the ground. The key to identifying the culprit is to look at the width and depth of the hole, and examine the area around the hole.
Very small holes may be caused by birds, earthworms, or solitary ground nesting bees. Typically, these types of holes are only found during the warmer parts of the year. You likely won’t see many of these at this time of year, although worms and birds can be active if we have periods of warm weather during spring.
Larger holes tend to be caused by animals. The most common are moles and voles. Moles are easy to identify because you will see the raised tunnels they create in the lawn as they travel under ground feeding on insects and worms. The actual entrance to the tunnels is usually not visible. Voles may travel through mole tunnels if they are present or travel along the surface of the soil. The entrance to their tunnel is 1-inch to 1½ inches in diameter, with no mound of soil present. These holes will most likely be found near plants that the voles like to feed on. Moles often tunnel along the edge of flower beds or walkways, were it tends to be softer and easier to dig. Voles love traveling through these sections of tunnels because they tend to be close to plants, so you may see holes in these spots.
Squirrels will also leave holes in the lawn where they have buried and later dig up nuts in the lawn. These holes are normally about 2 inches wide and very shallow, with no mound around them. If there are oak or pecan trees in the yard, you may see these types of holes in fairly close proximity to the trees. These type of holes commonly pop up during fall and winter.
Skunks and raccoons can also dig holes in the garden while looking for grubs. These holes tend to be cone shaped, normally 2 to 4 inches wide, and clustered together in groups. You will likely see some scratching on the soil surface surrounding the holes in these cases.
In soils that are very wet, crayfish can also be a problem. Despite their name, crayfish are not fish, rather they are terrestrial aquatic crustaceans, meaning they live in wet soils. Crayfish feed on decaying plants and animals and often become noticeable when they make raised, muddy mounds in the yard. At the center of each mound is a circular silver dollar sized hole.
Control measures for these problems differ depending on who the culprit is. Many of these scenarios won’t require any control measures unless they become an overwhelming nuisance. Moles, raccoons, and skunks feed on grubs and other small insects so you can discourage them by removing their food source, and voles can be trapped using small snap mousetraps. Crayfish can be discouraged by improving soil drainage.
Matthew Stevens is the horticulture extension agent for Halifax County Cooperative Extension. If you have any questions about this article or other aspects of your home gardening, please contact Matthew at 583-5161 or matt_stevens@ncsu.edu.