High populations of some species build up during winter months on evergreens or bedding plants and populations build up rapidly on new growth in the spring. Like aphids, species are numerous and biologies differ. Generally, control includes applying dormant oil and insecticide treatments timed to correspond to the hatching of scale eggs and the appearance of the crawler stages. If practical, prevent wingless females from depositing eggs in the fall by placing a band of stick material around the base of the tree 3 to 4 feet from the soil. There are 2 to 4 generations per year.
Populations begin to build up in early spring.
If feasible, wash off nymphal populations. If present treat 3 weeks after leaves have emerged and again in 2 to 3 weeks. Maintain tree health to make trees less attractive to borer beetles. Practice proper pruning and use wound paint during the summer months. Outbreaks occur anytime during the year, particularly during dry months or following use of certain broad-spectrum insecticides.