Prickly Balls on Live Oak: Harmless Insect Galls

What They Are

The "sea urchin" balls are woody twig galls caused by tiny cynipid wasps (Callirhytis spp.). Females lay eggs in twigs, secreting chemicals that force the tree to form a protective gall around the larvae.

Common Species

• Horned oak gall (C. cornigera) – small horns around gall.
• Gouty oak gall (C. quercuspunctata) – smooth, rounded.

Impact

• Leaf galls: cosmetic only.
• Twig galls: heavy infestations can girdle branches, cause dieback.

Management

• No spray needed for light infestations—natural enemies control populations.
• Prune and destroy galled twigs when small and fresh (winter).
• Rake/destroy fallen leaves (some gall makers overwinter there).
• Insecticides rarely justified; timing is nearly impossible.

Bottom Line

Galls won’t kill the tree. Most years they’re barely noticeable. Remove only if twig dieback becomes significant.