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Maple Leaf Galls: Insect Galls, Systemic Control Optional

Crimson King maples covered in tiny red/brown nodules with yellow margins, clustered and single. Empty bumps. Woodpeckers feeding. Spread to conifers?

ID: Insect Galls

Empty bumps = galls from gall-making insects (mites, midges). Cosmetic. Woodpeckers eat larvae.

Spread

To dicots (oak, birch) — yes
To conifers (cedar, fir, spruce) — unlikely

Options

Systemic imidacloprid soil drench (1 year)
Or monitor — won't kill trees
Woodpeckers protected

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