Video of a gray ant eating a Comperiella waspGray ant eating a Comperiella wasp
Below is a summary of control methods. For more detailed explanations, consult the UC IPM Guidelines for Citrus: California red scale.
Biological Control: Aphytis melinus wasps are reared in insectaries and can be released in orchards to augment control. To ensure their success, you must avoid broad spectrum insecticides, internally prune the trees and reduce dust and other materials that coat the leaves. Nuts Bolts of Aphytis Releases
Cultural Control: Reduce dust and ants that may hinder natural enemies and conduct activities that produce a vigorously growing tree.
There are four groups of insecticides that are effective in reducing scales, but each has characteristics tht may make it more more appropriate for a a particular orchard.
Organophosphate and carbamate insecticides
These pesticides act as broad spectrum nerve poisons. They are toxic to the scales and their natural enemies. They were very effective for many years until resistance developed in some scale populations. They are best applied in the first or second generation of crawler activity, as the crawlers become white caps.
Insect Growth Regulators:
These pesticides prevent scales from molting to the next stage. They are slow acting, but allow most natural enemies to survive. The predatory vedalia beetle is harmed by them. The are best applied after vedalia activity ends in early June. Apply to the white cap stage to prevent molting to the second stage.
Narrow Range Petroleum Oils:
Oils kill by smothering the insect on contact. They are only temporarily toxic to natural enemies. The are best applied to the first or second generation of scale crawlers.
415, 440, and 450 distillation point oils
Tetramic Acid Insecticides:
This insecticide is foliarly systemic, that means that it is sprayed on the foliage and moves up and down distributing itself throughout the tree. It is very selective allowing both parasites and predators to survive. It is best applied several weeks before the 2nd generation, to allow uptake into the tree.