Oak Galls in Arizona: Tiny Wasps, Harmless Growths

What Those Round Balls Are

The galls on your Sedona oak are Cynipid wasp galls (also called oak marble galls). A minute wasp lays an egg; the tree forms a protective chamber around it. The larva develops inside and emerges—end of story.

No Harm, No Foul

• Galls don’t affect tree health.
• No control needed or practical.
• They’re a fascinating bit of insect-plant interaction.

Enjoy the natural history; your oaks are fine.