Quick Facts
- White cottony egg masses on twigs and branches
- Heavy honeydew dripping from canopy
- Sooty mold coating on leaves and surfaces below
- Branch dieback in severe infestations
What Is Cottony Maple Scale?
Cottony maple scale (Pulvinaria innumerabilis) is one of the most conspicuous and common scale insects affecting maples in the Atlanta area. It attacks red maples, southern sugar maples, and Japanese maples, along with other hardwoods. The insect is most noticeable in early summer when females produce large, white, cottony egg sacs on twigs and small branches. These masses can be so abundant that heavily infested branches appear to be covered in cotton or snow — a startling sight that alarms many homeowners.
How to Identify Cottony Maple Scale
This pest announces its presence in several ways:
- Cottony egg masses: White, fluffy, elongated egg sacs (about 1/4 inch long) appear on the undersides of twigs and small branches in June and July. Each sac contains hundreds to thousands of eggs.
- Honeydew and sticky surfaces: Scale insects feed on plant sap and excrete large quantities of sugary honeydew. Surfaces beneath infested trees — sidewalks, cars, patio furniture — become coated with a sticky film.
- Sooty mold: A black, soot-like fungus grows on the honeydew, coating leaves, branches, and anything beneath the tree. While sooty mold itself is not parasitic, it blocks sunlight from reaching leaves.
- Branch dieback: In severe, multi-year infestations, twig and small branch dieback occurs as the scales drain resources from the tree.
Treatment & Management
Cottony maple scale can be managed effectively with properly timed treatments:
- Dormant oil spray: Horticultural oil applied during the dormant season (late winter before bud break) smothers overwintering scales on bark. This is the single most effective treatment and has minimal environmental impact.
- Crawler-stage treatments: Insecticidal soap or horticultural oil applied when crawlers (tiny mobile nymphs) are active in late summer targets the vulnerable juvenile stage.
- Systemic insecticides: For severe infestations, soil-applied systemic treatments can provide season-long control. These should only be applied by a professional to minimize impacts on pollinators.
- Encourage natural predators: Lady beetles, lacewings, and parasitic wasps are effective natural enemies of cottony maple scale. Avoid broad-spectrum insecticide sprays that kill beneficial insects.
When to Call an Arborist
Light cottony maple scale infestations are common and may not require treatment. However, if your maple shows heavy honeydew production, significant sooty mold, or branch dieback from scale feeding, professional plant health care is warranted. An ISA-certified arborist can design a targeted treatment program that controls the scale while preserving beneficial insects. Call EastLake Tree Services at 404-850-1174 or request a free quote.