Maple Tree Galls and Aphids: Identification and Systemic Treatment

Five maples on corner lot. Two 3-story trees have "pimple" galls on leaves. Another loses sticky leaves in July (aphids). Dry, cool summer with recent rain.

Galls: Cosmetic Only

Small wasp lays eggs, secretes chemical causing leaf cells to grow over them. Not a health hazard. Populations vary yearly.

Aphids/Scale: Sticky Honeydew Problem

Sucking insects secrete honeydew (sticky, high sugar). Leads to sooty mold. Weakens tree over time if population builds.

Treatment for Large Trees

Use Bayer Advanced Tree & Shrub Insect Control (imidacloprid) — soil-applied, systemic. Roots absorb, transport to leaves, kills feeding insects. Long-lasting. Avoids difficult canopy spraying.

Link: Product info

Monitoring

If sticky sap doesn't bother you and foliage looks healthy, can wait. Watch for: curling leaves, smaller leaves, heavy sap, black sooty mold.