Dogwood scale

Dogwood scale (latin Chionaspis corni) belongs to the order Hemiptera and the family Diaspididae. It is a specialized sap-sucking pest that primarily targets trees and shrubs of the Cornaceae family. These insects are sedentary for most of their lives, relying on a hard protective cover to survive while feeding on plant juices.

The primary host plants include Cornus species, such as dogwood and various types of dogwood shrubs. The scale insects settle on twigs and branches, where they establish colonies. Because of their color and shape, which resemble tiny scales or bark flakes, they often go unnoticed until the plant shows visible signs of decline.

The biological lifecycle of this pest is synchronized with the seasons. They typically overwinter as fertilized adult females under their protective covers. In the spring, these females lay eggs beneath their armor. Once the eggs hatch, the tiny, mobile nymphs, known as crawlers, emerge and move across the bark to find suitable feeding sites where they settle and develop their own shells.

The damage caused by dogwood scale is characterized by nutrient depletion of the host plant. Continuous feeding leads to the yellowing and premature drop of leaves, stunted shoot growth, and severe cracking of the bark. Over time, the host plant loses its vigor, becomes unsightly, and may succumb to secondary infections or die back significantly due to systemic stress.

Effective control strategies require a combination of cultural and chemical methods. Gardeners should prune and dispose of heavily infested branches to reduce the initial population size. During the crawler stage, which is the most vulnerable period, applying contact insecticides is highly effective. Additionally, dormant season oils can be used to smother overwintering adults before the new season begins.