What Causes Rows of Holes in Trees

What Causes Rows of Holes in Trees

What Causes Rows of Holes in Trees? If you’ve noticed neat rows of small holes running up and down your tree trunk, you’re not alone. This pattern is most commonly caused by the Yellow-bellied sapsucker, a type of woodpecker found throughout Wisconsin and the Coulee Region.

Sapsuckers drill evenly spaced holes in horizontal or vertical lines to access the tree’s sap. They return to these same rows repeatedly, feeding on both the sap and the insects it attracts. While the pattern can look alarming, it’s actually a natural behavior and, in many cases, doesn’t cause serious long-term harm to healthy, established trees.

However, repeated feeding can stress a tree over time—especially younger or already weakened trees. You may notice bark damage, oozing sap, or even minor dieback in heavily targeted areas. Trees like maple, birch, and fruit trees tend to be favorites.

Not all holes are caused by birds. Insects such as the Emerald ash borer create exit holes as they emerge from under the bark, but these are typically scattered and irregular rather than neatly lined up. Recognizing the pattern is key to identifying the cause.

If your tree is otherwise healthy, there’s often no need to intervene. For high-value or ornamental trees, protective wraps or deterrents can help limit repeated damage. Maintaining proper watering, mulching, and overall tree health will also reduce stress and improve resilience.

At Johnson Ops Tree Care, our Certified Arborists can evaluate your trees and determine whether the damage is cosmetic or something that needs attention. We’re here to help you protect the long-term health, safety, and beauty of your landscape. Call us today, we can help address any concerns you may have with your trees.

Products Available: Mulch • Dirt • Compost • Landscaping Rock • Live Edge Slabs • Lumber • Trees • Firewood