Craw scale

The Craw scale (Aulacaspis crawii) is a significant pest belonging to the Diaspididae family within the order Hemiptera. This armored scale insect poses a serious threat to a variety of woody plants, including fruit trees and ornamental species, making it a subject of concern for horticulturists and agronomists worldwide.

The pest typically colonizes the bark of branches and trunks. Host plants commonly include various fruit-bearing shrubs and trees, as well as specific ornamental and subtropical plants. Due to its cryptic appearance, infestations often go unnoticed until significant damage to the host plant's structure has already occurred.

The biology of the Craw scale revolves around its life cycle, characterized by the sedentary nature of adult females protected by a tough, waxy scale. The lifecycle includes the egg stage, the crawler (nymph) stage, and the adult stage. The crawlers are the only mobile phase and are responsible for the dispersal of the infestation across the host plant.

The damage caused by the Craw scale is primarily due to sap extraction from the plant's vascular system. Prolonged feeding leads to bark cracking, stunted growth, yellowing, and eventually the death of branches or the entire tree. The weakened plant also becomes highly susceptible to opportunistic diseases and further environmental stress.

Effective management requires an integrated pest management (IPM) approach. Key strategies include:

• Regular monitoring for the presence of crawlers during the growing season.
• Sanitation, including the pruning and destruction of heavily infested limbs.
• Application of systemic insecticides specifically timed to the emergence of crawler stages.
• Utilizing horticultural oils during dormancy to smother overwintering female scales.