Red Maple Leaf Galls: Harmless Insect-Induced Growths

What You're Seeing

Small, round, red bumps on the upper surface of maple leaves in southeastern Michigan are galls caused by mites, aphids, or scale insects injecting hormones during early leaf expansion.

No Harm, No Foul

Galls are cosmetic. They do not affect tree health significantly. Once formed, they cannot be eliminated this season.

Optional Prevention

Next spring, apply a permethrin or Astro insecticide at bud break. Improve tree vigor with organic fertilizer (compost tea, humic acid) to tolerate minor stress.