What Causes Dirt Mounds in My Yard? (And How to Tell What’s Behind Them)

What Causes Dirt Mounds in My Yard? (And How to Tell What’s Behind Them)

Walk across your lawn and nothing catches your eye until you see it: a fresh pile of dirt sitting on top of your grass. Then you notice another, and another. Before long, it feels like your yard is under attack from something underground.

When you dig into the mound, you don’t always find a hole, tunnel, or anything living inside. So what’s really causing these dirt piles?

The truth is, several different pests and animals can create them, and each one leaves its own signature behind. Let’s take a closer look at the most common causes, how to tell them apart, and what to do next.

Why Dirt Mounds Appear

Dirt mounds are almost always a sign of digging or tunneling activity. But not all mounds are the same. Some come from insects like cicada killers. Others are created by larger pests such as moles or gophers. In wet areas, even crawdads (crayfish) can move in and build muddy chimneys right in the middle of your grass.

Because each culprit leaves behind a different type of mound, identifying the pattern is the fastest way to move towards a solution.

Common Culprits Behind Dirt Mounds

Here are a few of the most common culprits behind dirt mounds in the yard. At some point, you may need to call in a professional to have them properly diagnosed. 

Moles

Moles are often blamed for yard damage, and for good reason. They dig tunnels as they hunt for earthworms and grubs, pushing dirt to the surface in round, volcano-shaped piles. Unlike some other pests, mole mounds usually don’t have an open hole on top. Instead, you’ll notice raised surface trails across the lawn.

If you dig into a molehill, you’ll typically find a tunnel underneath.

• How to Tell: Volcano-shaped dirt mound with no open hole.

• Other Signs: Raised surface trails in the lawn.

• What to Do: Use traps for best results; grub control may reduce activity but isn’t a guaranteed fix.

Voles

Voles, also known as field mice, leave behind small, round holes in the turf and shallow surface runways in the grass. Their mounds are less dramatic than molehills, but the holes are the giveaway. Many homeowners will set traps right at those entry points. If you see dirt piles but no holes, voles are probably not the cause of the problem.

• How to Tell: Small round holes in turf.

• Other Signs: Shallow runways or surface trails in grass.

• What to Do: Place traps near holes or runways.

Crawdads (Crayfish)

Crawdads sometimes wander into lawns. This is mostly an issue in wet or low-lying yards. They build muddy “chimneys” with a vertical hole in the middle. These look different from a dry, crumbly mound. 

• How to Tell: Mud chimney with a vertical hole.

• Other Signs: Found in wet or low-lying yards.

• What to Do: Improve drainage; in heavy infestations, call a pro.

Cicada Killer Wasps

Large, solitary wasps called cicada killers dig burrows in the soil during late summer. They leave a small pile of loose dirt next to a round hole. The size of the Cicada Killer Wasps makes them look intimidating, but they’re generally harmless to people. Their mounds, however, can confuse homeowners because they appear suddenly and resemble rodent holes.

• How to Tell: Round entry hole with a small loose dirt pile beside it.

• Other Signs: Large wasps hovering nearby in late summer.

• What to Do: Usually harmless — leave them alone unless they become a nuisance.

Pocket Gophers

Gophers leave larger, fan-shaped mounds. Instead of an open hole, they plug the tunnel off to one side. These mounds often appear in clusters and can spread quickly across a lawn. While they’re less common in suburban yards, they are still a possibility depending on where you live.

• How to Tell: Large, fan-shaped mound with no hole on top.

• Other Signs: Tunnels are plugged off to one side; mounds often appear in clusters.

• What to Do: Trapping or baiting is most effective (check your state’s laws).

Rabbits and Other Small Animals

Occasionally, rabbits or small animals will dig shallow nests in the grass. This can leave behind a loose pile of dirt that looks like a small mound. If you are finding 20–30 mounds every week, rabbits aren’t the likely cause — but if you only spot one or two mounds, it’s worth considering.

• How to Tell: Shallow dug-out spot with loose dirt.

• Other Signs: Only a few mounds; nests may contain fur or dried grass.

• What to Do: Relocate nests carefully; if there are dozens of mounds, it’s not rabbits.

What to Do About Dirt Mounds in Your Grass

Once you know what you’re dealing with, you can take the right steps:

How to Identify the Difference

If you’re staring at mounds in your yard and still not sure what’s making them, here’s a quick checklist:

• Is there a visible hole? If yes, think voles or cicada killers.

• No hole? Likely moles or gophers — check the mound’s shape.

• Mud chimney? That’s a classic sign of crawdads.

• Are there raised trails in the grass? That points to moles or voles.

• When did they appear? Cicada killers are active in late summer; moles and gophers dig year-round.

When to Call a Pro

If you’re seeing new mounds every week and nothing you try seems to work, it’s time to bring in a professional. Lawn care providers know how to read the signs, set up the right treatments, and restore your yard before it gets out of hand.

Final Thoughts

Dirt mounds can be frustrating, but they’re also an important clue. By paying attention to the shape of the pile, whether there’s a hole, and when they appear, you can figure out whether you’re dealing with moles, voles, crawdads, cicada killers, or something else entirely.

Not sure what’s causing the mess in your lawn? GreenPal can connect you with a local lawn pro who’s seen it all and knows how to get your yard back to normal.