Eucalyptus scale

The Eucalyptus scale (Eriococcus coriaceus) belongs to the order Hemiptera and the family Eriococcidae. It is a sap-sucking pest primarily associated with the Eucalyptus genus, causing severe infestations that can threaten the health and vigor of these trees across various geographic regions.

This pest exclusively targets Eucalyptus species. Its global spread outside of its native Australian range has made it a significant concern for arborists and forest managers, as the absence of native predators allows populations to reach levels that can lead to significant dieback in susceptible trees.

The life cycle involves egg, nymph (crawler), and adult stages. The adult female is characterized by a protective, leathery, brown ovisac. Reproduction occurs throughout the year in warmer climates, leading to overlapping generations, which complicates management strategies as multiple life stages may be present simultaneously.

Damage occurs when both nymphs and adult females feed on the phloem of leaves and stems. This feeding stress is compounded by the production of honeydew, which promotes the growth of sooty mold. This fungus blocks sunlight and restricts gas exchange, resulting in leaf chlorosis, premature senescence, and overall tree decline.

Control strategies must be integrated and timed precisely:

• Systemic insecticide applications should be targeted at the active crawler stage.
• Horticultural oils can be effective for suffocating stationary stages on the bark.
• Natural biological control agents like predatory ladybirds should be conserved where possible.
• Regular pruning of heavily infested branches can help reduce the pest population density.
• Maintaining optimal tree health through proper irrigation and nutrition helps trees tolerate scale damage.