Treating an Oleander for Pests
Several insects attack the subtropical oleander shrub, Nerium oleander, including the oleander caterpillar and the false oleander scale. They can be subdued by manual removal and by application of specific pesticides.
The oleander caterpillar is the bright orange, fuzzy offspring of the polka-dot moth. The adult female lays eggs in clusters on the undersurface of leaves. The caterpillar larvae devour the leaf between the veins and the midstem, known as "skeletonizing". Just before cocooning, the caterpillars will eat the rest of the leaf to the midrib.
Controlling Oleander Caterpillars
Diligently hunting and destroying the egg clusters in December, March and early summer will help suppress the oleander caterpillars. Once the caterpillar larvae hatch, insecticides with Bacillus thuringiensis bacterium are most useful against them.
False Oleander Scale
This insect appears on the leaf tops, forming 3 mm white spots. They pierce the leaves to siphon out the sap, defoliating the oleander plant. Adult females lay eggs inside their body shell. When the nymphs hatch, they attach their mouth parts to the leaves and begin to drain the sap.
Controlling False Oleander Scale
Apply horticultural oil insecticide every 5 to 6 weeks to suppress scale. Afterwards, scrape the white spots on the leaves. If dry flakes fall off, the scale has been eliminated.