Leaf Galls on Walnut and Oak: Harmless Insect Architecture

Small Green Bumps = Insect Galls

The ¼-inch round green growths on your walnut and oak leaves are insect galls—likely caused by phylloxera or similar tiny insects. The insect manipulates the leaf to form a protective nursery.

No Action Needed

• Galls don’t affect tree health.
• Rake and destroy fallen leaves in winter to reduce next year’s population.

Enjoy the tiny ecosystems on your leaves.