Anderson scale

The Anderson scale (Cribrolecanium andersoni) is a member of the Coccidae family within the order Hemiptera. As a specialized pest, it targets woody plants, utilizing specialized mouthparts to pierce plant tissues and extract sap, which can significantly debilitate host plants if left unmanaged.

These pests primarily affect various deciduous trees and ornamental shrubs. By clustering on stems, twigs, and bark, they create colonies that are often camouflaged by their physical resemblance to the host's bark, making early detection a primary challenge for arborists and gardeners alike.

The biological cycle of Cribrolecanium andersoni consists of eggs, mobile nymphs (crawlers), and sessile adults. Adult females develop a protective test or "scale" that serves as a shield against environmental factors and many chemical treatments. Overwintering typically occurs in the nymph stage or as fertilized females tucked away in bark crevices.

Damage caused by this insect is twofold: direct loss of sap leads to chlorosis and stunted growth, while indirect damage stems from the excretion of honeydew. This sugary substance facilitates the growth of sooty mold, which coats leaves and inhibits photosynthesis, ultimately compromising the overall health and vigor of the plant.

Integrated pest management (IPM) strategies for controlling Anderson scale include the following:

• Applying dormant oil sprays to smother overwintering stages before bud break.
• Targeting crawler stages with contact insecticides when they are most susceptible and mobile.
• Pruning and destroying heavily infested branches to reduce local pest pressure.
• Encouraging natural predators, such as ladybird beetles and parasitic wasps, to balance the population.