Macadamia scale

Systematic position. Pseudaulacaspis brimblecombei belongs to the order Hemiptera and the family Diaspididae (armored scale insects). This species is recognized as a significant pest affecting agricultural production of nut crops in various tropical and subtropical regions.

Host crops. The primary host of this pest is the macadamia tree (Macadamia integrifolia and related species). While highly specific to macadamia, it can occasionally thrive on related ornamental trees, causing stress and reducing their ornamental or agricultural value.

Biology and life cycle. The life cycle comprises egg, nymph (crawler), and adult stages. Females remain sedentary under a hard, protective wax scale. The crawler stage is the primary mobile phase, during which the larvae disperse to new feeding sites on the tree foliage, stems, or developing fruits.

Damage and severity. By feeding on the plant sap, the scale causes yellowing of leaves, leaf drop, and stunted growth of shoots. Heavy infestations can lead to limb dieback and reduced nut production, as the insect siphons vital nutrients and can cause physiological imbalances in the host tree.

Control measures. Management strategies involve a combination of biological and chemical controls. Monitoring is critical to time insecticide applications specifically against the mobile crawler stage. Cultural practices, such as pruning heavily infested branches and maintaining tree health, are also essential to mitigate the impact of the pest.

• Regular field scouting for infestation early warning.
• Pruning and destroying heavily damaged plant material.
• Application of horticultural oils during the crawler emergence phase.
• Encouraging natural predators such as ladybeetles and parasitic wasps.