Squirrels Eating Oak Galls: Natural Biocontrol

Your 25-year-old pin oak has galls; squirrels chew off galled twigs and eat the galls. Is this good?

Yes, It Helps

• Galls contain wasp larvae. Squirrels eating galls destroy the next generation.
• Twig girdler beetles also cut twigs, but they don’t chew galls—squirrels do.
• Natural predation reduces gall density over time.

Gall Impact on Tree

• Leaf galls: mostly cosmetic, minimal health effect.
• Twig/root galls: can weaken tree if severe.

Management

• No spray needed. Squirrels are doing the work.
• Rake fallen galled leaves/twigs to reduce overwintering.
• Fertilize/water to keep tree vigorous.

Bottom Line

Squirrels are free, effective gall biocontrol. Let them work; keep tree healthy.