Estimate parasite activity by checking scale covers for the round exit holes made by emerging adult parasites and flip armored scale covers and examine beneath them for immature parasites. Grow flowering plants near scale-infested trees and shrubs to help augment natural enemies. Adult parasitic wasps live longer, lay more eggs, and kill more scales when they have nectar or honeydew to feed on. Dust control is crucial to the success of biological control. Wash plant surfaces mid-season, or when the foliage is dusty, to encourage biological controls.
Natural enemies are commercially available for release against black scale and California red scale.
However, conserving resident natural enemies is a more efficient and longer lasting strategy, particularly in garden situations. If large numbers of ants are climbing up trunks to tend scales they should be controlled. If trees are young, thin-barked, or recently pruned, wrap the trunk with a strip of fabric tree wrap, duct tape, or another material first to prevent injuring the tree. Chemical Control Dormant Treatments. Dormant season applications of specially refined oils, often called narrow range, supreme, or superior type oils, are effective against most scale pests of deciduous trees and landscape plants, especially San Jose scale, walnut scale, and the lecanium scales, but not against oystershell or olive scales because susceptible stages of these pests are not present during winter.