Oleander Scale

The adult female oleander scale is an armored scale that is about 0.1 inch (2.5 mm) long and oval. It has a waxy covering that is whiter than olive scale with a yellow or light brown spot near the center. The adult male scale is elongate. If the coverings are removed, the female body is yellow, while the male scale is brownish yellow. This scale is most common on leaves in the lower part of the tree. There are several generations a year.

The oleander scale infests olive fruit and delays maturity at the spot where it feeds. Thus, damage is seen as prominent green spots on purple fruit, in direct contrast to the dark spots caused by olive scale. Heavy infestations seriously deform fruit, and fruit spotting renders the olive worthless. Extremely heavy infestations reduce oil content by as much as 25%. Leaf and twig damage also result in lost production.

Oleander scale can be effectively controlled by natural enemies and does not usually cause economic damage. Preserve these natural enemies by selecting insecticides for other pests that do not kill beneficial insects. Control ants in the orchard because they disrupt biological control (for more information, see ANTS).

Several species of Aphytis, including A. melinus, are important parasites of oleander scale. Where insecticides such as carbamates (IRAC Group 1A), organophosphates (1B), and pyrethroids (3) are used, biological control will be disrupted. Be sure to monitor scale populations if disruptive insecticides are used.

Biological control and certain oil sprays are acceptable methods in an organically certified crop.

If treatments are necessary, treat the first brood in late May and June or the second brood in late July and August. Apply the first brood treatment when young scales are observed moving onto fruit. Treating scales in early July, between broods, is not recommended. Although efficacy data are not available, postharvest treatments should also be effective.