Scales are visible as an area that resembles bumpy bark or fine ash on branches of fruit trees and shrubs. Wherever they feed, they cause a reddening of tissue, usually several times the diameter of the scale. When infested, the limbs lose vigor and die, usually in the top of the tree first. The removal of sap by thousands of scales that feed is what causes the damage.
Use horticultural oil as a "dormant oil" before bud break in spring. "Crawlers" are born over a 2-6 week period, starting about 2-3 weeks after bloom, but are controlled by horticultural oil, insecticidal soap or natural insect predators. We recommend Oil-Away™ Supreme Insecticidal Oil, Plant Guardian™ Houseplant Insecticidal Soap or Green Lacewings.