Maple Leaf Galls: Natural Curiosities, Not Threats

What Are Galls?

Clusters of small green bumps on sugar maple leaves are galls—abnormal growths induced by insects (mites, wasps, aphids) or mites feeding and laying eggs. The parasite develops inside the gall.

No Control Needed

Galls are structurally diverse but rarely harm the tree. Insecticides don't work once galls form. Pruning heavily galled branches may reduce populations slightly.

Best Approach

Accept them as nature's art. The tree supports many galls and grows normally. Enjoy observing their development or simply ignore them.