Controlling Sugar Maple Borers in Red Maple

Identifying the Pest

Small white larvae with brown heads (¼–⅜ inch long) boring into the lower trunk of a red maple, accompanied by sap-oozing wounds, indicate sugar maple borer (Glycobius speciosus) infestation.

Control Measures

1. Bark spray: Apply a labeled borer insecticide (e.g., Onyx / bifenthrin, or a permethrin-based product) to the trunk and lower branches in late spring and again in mid-summer to intercept egg-laying adults and newly hatched larvae.
2. Trunk injection: For valuable trees, a certified arborist can inject systemic insecticides (e.g., emamectin benzoate) for longer protection.
3. Cultural practices: Maintain tree vigor with watering and mulching; avoid wounding the trunk with mowers or trimmers.

Monitoring

Inspect the trunk monthly for fresh frass or new entry holes. Prompt treatment of new activity prevents extensive internal damage.

Reference

U.S. Forest Service guide: Sugar Maple Borer.