Azalea Whitefly

Azalea Whitefly (Pealius azaleae)

Identification: Small white-winged insects, 1–1.5 mm, with yellow body coloration before the wax powder develops. Host-specific to azalea (Rhododendron spp.) and occasionally rhododendron. Nymphs are flat, oval, and pale yellow-green on leaf undersides, easily confused with azalea scale in early instars. Adults flush from foliage when branches are disturbed.

Life cycle: Two to three generations per season in Middle Tennessee. Overwinters as nymphs on foliage of evergreen azalea varieties, which are common landscape plants throughout the Columbia area and I-65 corridor. First adult emergence occurs in late April to May; second generation peaks in July–August. Deciduous azalea varieties escape overwintering populations but can be recolonized each season.

Damage signs: Stippled, pale or yellowed leaves on azalea, especially on shade-grown plants with dense canopy that restricts natural airflow. Honeydew accumulation leads to sooty mold on upper leaf surfaces, turning foliage black. Heavy infestations reduce vigor on established azaleas and can severely stress newly planted specimens in their first season.

Treatment window: Late April through May targeting first-generation nymphs, and again in late June through July for the second generation. Treating only adults is ineffective — target immature stages on leaf undersides.

UT-recommended approach: Insecticidal soap or horticultural oil applied to leaf undersides with thorough coverage. Imidacloprid soil drench in early spring provides season-long systemic protection on established plants. Avoid treating azaleas in bloom to protect pollinators. Improve air circulation by selective thinning of dense azalea plantings to reduce favorable whitefly habitat.