Orchid scale

Orchid scale (Asterolecanium epidendri) belongs to the Asterolecaniidae family. It is a highly specialized pest that primarily targets orchid species. These insects are easily overlooked due to their camouflaging appearance, as they often blend in with the leaf tissue or stems of their host plants, looking like small, shiny bumps.

The primary hosts for this scale include various orchid genera such as Epidendrum, Cattleya, and Dendrobium. While they are most problematic in greenhouses and conservatories where the climate is warm and stable, they can also become a persistent issue in home collections if introduced through new, infested plant material.

The biology of Asterolecanium epidendri involves a sedentary female stage protected by a waxy test or shell. After hatching, the first-instar nymphs, known as crawlers, are mobile and move across the plant surface to find suitable feeding sites. Once they settle, they insert their mouthparts to feed on plant sap and begin developing their protective covering.

Damage to the plant is caused by both direct sap extraction and the injection of toxins during feeding, which leads to chlorosis, leaf deformation, and stunted growth. Furthermore, the excretion of honeydew provides a substrate for sooty mold, which can further impede photosynthesis and negatively affect the plant's overall health and vigor.

Effective management requires a combination of early detection and appropriate chemical control. Because of their protective shells, contact sprays are often less effective against adult females, making systemic insecticides the preferred choice. It is crucial to repeat treatments according to the life cycle of the pest to ensure that emerging crawlers are also eliminated.

• Regular inspection of leaf undersides and pseudobulbs.
• Quarantine procedures for all new plant additions.
• Application of systemic insecticides suitable for orchids.
• Mechanical removal of scales using alcohol-soaked swabs.
• Maintaining optimal plant health to enhance natural resistance.