Purple scale

Purple scale (Lepidosaphes beckii) is a destructive insect species belonging to the family Diaspididae, order Hemiptera. It is a cosmopolitan pest recognized for its significant impact on citrus orchards worldwide. Its common name, purple scale, is derived from the distinct dark purple or brown color of the female's protective shell.

This pest primarily attacks citrus trees, including oranges, lemons, mandarins, and grapefruits. However, it can also infest various ornamental evergreens in greenhouse environments. Because the pest feeds on sap, it is capable of causing severe debilitation of the host plant if left unchecked over multiple growing seasons.

The biology of Lepidosaphes beckii is characterized by a sedentary lifestyle for females. They remain fixed to the bark, leaves, or fruit throughout their adult life, covered by a rigid, oyster-shaped scale. Reproduction is sexual, and the lifecycle involves a mobile crawler stage that is critical for the dispersion of the infestation within the orchard.

Damage is caused by the insertion of the insect's stylets into the plant tissue, where it extracts nutrients and sap. This leads to yellow spotting on leaves, twig dieback, and significant loss of leaf area. Furthermore, the presence of the scales on fruit renders them unmarketable, causing substantial financial losses for commercial citrus growers.

• Regular orchard scouting to detect initial crawler activity.
• Chemical control using systemic insecticides applied at the crawler stage.
• Application of horticultural mineral oils to smother the scale insects.
• Promotion of natural biological enemies, such as parasitoid wasps.
• Pruning of heavily infested branches to reduce population density.