Oleander Scale

Oleander Scale

Identification: Aspidiotus nerii — an armored scale (family Diaspididae), 1.5–2 mm diameter, with a flat, circular, white to pale yellow cover. Female covers are slightly larger and more rounded than the elongated male covers. Found on bark, leaves, and fruit of a broad host range: oleander (Nerium oleander), palms, citrus, magnolia, ivy, and many others. The circular white cover distinguishes it from most other armored scales in Tennessee landscapes.

Life cycle: Two to three overlapping generations per year in Middle Tennessee. Overwinters as adults on bark. Crawlers (mobile first instars) emerge in May–June and again in August. Crawlers are yellow, oval, and the only mobile stage — they settle within hours of emergence and begin secreting their protective cover. Females remain sedentary; males are tiny winged adults.

Damage signs: Heavy bark infestations cause yellowing of foliage, reduced vigor, and branch dieback. On oleander, dense scale populations can cover entire stems with white crust. Feeding extracts plant fluids; the armor protects adults from contact insecticides. Sooty mold is less common with armored scales (no honeydew) but infested foliage develops yellow halos at feeding sites.

Treatment window: At crawler emergence in May–June — crawlers lack protective armor and are fully vulnerable to contact insecticides. A second window targets August crawlers. Treating the armored adult stage is largely ineffective with contact materials.

UT-recommended approach: Horticultural oil applied at crawler emergence smothers crawlers before they settle. Systemic imidacloprid soil drench provides uptake-based control across all mobile stages. For small infestations on accessible stems, scrubbing with a stiff brush removes adults mechanically. Monitor crawler emergence with sticky bands wrapped around stems near active infestations.