Purple tea scale

The purple tea scale (Parlatoria theae) is a significant scale insect pest belonging to the Diaspididae family. It is widely recognized as a serious quarantine pest in many parts of the world, capable of infesting a variety of economically important ornamental and agricultural crops, particularly in subtropical and temperate climates.

This pest is highly polyphagous, meaning it feeds on a broad spectrum of host plants. While the tea plant (Camellia sinensis) is its primary target, the scale is also frequently found on Camellia japonica, citrus trees, Japanese maples, roses, quince, and various other woody perennials. Its presence often goes unnoticed until the plant shows significant signs of decline.

The life cycle of Parlatoria theae involves the egg, the mobile crawler (nymph) stage, and the sedentary adult stage. Females are covered by a distinct, dark, shield-like scale. The crawlers are the primary dispersal stage, moving to new sites on the host or being carried by wind to nearby plants. Once they settle and begin feeding, they develop their protective covering, making them difficult to eradicate.

Damage is primarily caused by the extraction of plant sap, which drains the host's vitality. Symptoms include chlorotic spotting, leaf drop, stunted growth, and the distortion of young shoots. In cases of high infestation, the dense covering of scale insects on branches can lead to dieback and, if left untreated, the eventual death of the entire plant.

Integrated Pest Management (IPM) is essential for controlling the purple tea scale. Effective strategies include:

• Rigorous quarantine inspections of imported plant material to prevent entry.
• Systemic insecticide treatments applied during the crawler emergence phase.
• Dormant or summer horticultural oil applications to suffocate the insects.
• Pruning and destroying heavily infested branches to reduce the pest population density.
• Monitoring for and protecting natural predatory insects and parasitoid wasps.