Fan-shaped scale

Systematic position: The fan-shaped scale (Hemiberlesia flabellata) belongs to the order Hemiptera and the family Diaspididae. These insects are classified as specialized sap-sucking pests that reside under a protective waxy cover, commonly known as a scale, which makes them highly resistant to many environmental factors.

Host plants: This pest primarily targets woody plants and shrubs. It is frequently observed on various tropical and subtropical crops, including citrus trees and numerous ornamental plants. Its ability to infest greenhouse crops often makes it a significant concern for controlled-environment agriculture.

Biology and life cycle: The life cycle includes an egg stage, a mobile crawler stage, and a sedentary adult stage. The crawlers are the most active and dispersive phase, moving across the host plant before settling. Once a site is chosen, the insect forms a shield and remains fixed, feeding on plant sap for the remainder of its lifespan.

Nature of damage: Damage is caused by the extraction of plant fluids, which leads to general chlorosis, reduced plant vigor, and stunted growth. In severe infestations, the presence of these scales can cause bark cracking, dieback of twigs, and eventually the death of the infested plant part or the entire plant.

Protection measures: Effective management strategies include:

• Monitoring and early detection of crawler emergence.
• Application of systemic and contact insecticides during the crawler phase.
• Use of horticultural oils to suffocate the insects under their shields.
• Strict quarantine and inspection of new planting material to prevent outbreaks.