Australian fern scale

Systematic position. The Australian fern scale (Pseudaulacaspis australis) belongs to the order Hemiptera and the family Diaspididae. As a specialized sap-sucking insect, it primarily resides on the bark of woody plants. Its ability to create protective shields allows it to survive in various environments, making it a significant pest in agricultural and ornamental settings.

Host plants. This species is primarily associated with various Acacia species and other legumes. However, due to international plant trade, it has been recorded on a wider range of ornamental shrubs and trees. Its broad host range makes it a quarantine concern in regions where it is not yet established but could potentially threaten local flora.

Biology and life cycle. The life cycle consists of the egg stage, several nymphal stages (crawlers), and the adult stage. The adult female is sedentary and protected by a hard, waxy cover (scale). The crawler stage is the only mobile phase, which is when the insect disperses to new parts of the plant or to neighboring plants via wind or animal contact.

Damage and severity. The pest causes damage by inserting its stylet into plant tissues to suck out sap. This feeding process results in yellowing, stunting of growth, bark cracking, and branch dieback. In cases of heavy infestation, the entire plant may become severely weakened or die due to the loss of nutrients and the development of secondary fungal infections on the damaged bark.

Control measures. Integrated pest management (IPM) is essential for effective control of Pseudaulacaspis australis:

• Regular pruning and removal of infested plant material.
• Application of systemic insecticides that target the insect through plant sap.
• Use of horticultural oils during the dormant season to suffocate overwintering scales.
• Monitoring crawler activity to time chemical applications for maximum impact.