Cottony Maple Scale: A Nuisance in West Bloomfield, MI

West Bloomfield, Michigan residents may have noticed peculiar white, cotton-like masses on their maple trees this summer. These are likely the egg sacs of the cottony maple scale, a common insect pest in the area.

What is Cottony Maple Scale?

Cottony maple scale (Pulvinaria innumerabilis) is a soft scale insect that primarily targets silver and red maples, but can infest over a dozen tree species.
The most noticeable sign of infestation is the appearance of white, cottony egg sacs on branches, resembling popcorn kernels.

Life Cycle and Damage

These pests have one generation per year in West Bloomfield. In early summer, mature cottony maple scale females produce egg sacs containing up to 1,500 eggs. The eggs hatch into crawlers that feed on leaf sap, potentially causing leaf stunting and branch dieback in severe cases.

Natural Control

Fortunately, cottony maple scale populations are often kept in check by natural predators, particularly lady beetles. In most years, this pest is considered minor, with outbreaks occurring every few years.

Management Tips for Cottony Maple Scale

1. Observe: Watch for cottony maple scale adults on the bottom side of branches.
2. Timing is crucial: If treatment is necessary, target the crawler stage from late June through July.
3. Soil Injections: Soil injected insecticides can be applied in cases where tree spraying would not be possible or practical.
4. Promote tree health: Proper fertilization, mulching, and watering can help trees resist or recover from scale damage.

Remember, a healthy tree can typically withstand scale infestations. By promoting tree vigor and preserving natural predators, West Bloomfield residents can often manage cottony maple scale without resorting to chemical interventions.