Diagnosing Trunk Damage on Hollies: Three Culprits Identified

Solving the Mystery of Holly Trunk Damage

When hollies show bark damage at consistent heights across multiple plants, it's rarely a single cause. This case reveals three distinct culprits working simultaneously.

European Hornet Damage

Appearance: Irregular, shredded bark patches on lower trunks and exposed branches.
Cause: European hornets (Vespa crabro) strip bark to access sap and use fibers for nest building.
Timing: Most active late summer through fall.

Squirrel Damage

Appearance: Distinctive rectangular patches where bark has been gnawed away, often at consistent heights.
Cause: Squirrels feed on cambium layer, especially in late winter when food is scarce.
Pattern: Often appears at same level on multiple trees—squirrels work along convenient branches.

Sapsucker Damage

Appearance: Neat rows of small, evenly spaced holes in horizontal or vertical lines.
Cause: Yellow-bellied sapsuckers (Sphyrapicus varius) drill sap wells, returning to feed on sap and attracted insects.
Note: This is typically cosmetic and rarely kills established hollies.

Management Approach

• Hornets: Locate and treat nests at night; avoid broad insecticides
• Squirrels: Wrap trunks with hardware cloth or apply taste repellents
• Sapsuckers: Usually no action needed; consider visual deterrents if severe
• All: Maintain plant health with proper watering and mulching

Correct identification is crucial—each culprit requires a different response. Monitor patterns and timing to confirm which pests are active in your landscape.

European hornet damage—shredded, irregular bark removal

Close view of hornet bark stripping

Squirrel damage—rectangular gnawed patches

Sapsucker damage—neat rows of drill holes