Scale Insects on Maple: Identification and Systemic Treatment

Bumps on Maple Bark With Maggots Inside? That's Scale

The white "maggots" under bark flakes on your acer are scale insect crawlers or nymphs beneath their protective covers. Scales suck sap, causing leaf drop and dieback.

Best Treatment: Systemic Insecticide

Contact sprays struggle to penetrate the waxy cover. Use a soil-applied systemic:

• Imidacloprid (Bayer Advanced Tree & Shrub Insect Control) – applied to soil, taken up by roots, kills feeding scales for months.
• Acephate (Orthene) – has some systemic action; spray foliage 2× at 10-day intervals.

Manual Removal (Small Trees)

Rub scales off by hand—this kills the insect underneath. Practical only if canopy is reachable.

Other Labeled Sprays

Chlorpyrifos, carbaryl, malathion—require thorough coverage and repeat applications.

Follow-Up

New buds are a good sign. Treat now; monitor for crawler emergence next spring (sticky tape on branches detects them).