Acacia scale

Systematic position: The acacia scale (Parthenolecanium glandi) is a member of the Hemiptera order and the Coccidae family. It is recognized as a significant pest of woody plants, capable of causing substantial damage to both fruit production and ornamental landscape quality.

Host plants: This pest exhibits a wide host range, primarily targeting stone fruit species like plum, apricot, peach, and cherry. It also frequently infests apple, pear, and various acacia tree species, often colonizing branches and trunks in large numbers.

Biology and life cycle: The species completes one generation per year. It overwinters as second-instar nymphs in crevices on the bark. As spring temperatures rise, these nymphs migrate to feeding sites and develop into mature females. During early summer, the females lay eggs beneath their hemispherical, hardened scales. The hatched crawlers migrate to leaves to feed before returning to the bark in autumn to prepare for winter dormancy.

Damage and severity: Acacia scale causes damage by piercing and sucking plant sap. Infestation symptoms include leaf yellowing, premature senescence, and twig dieback. The insects also excrete copious amounts of honeydew, which serves as a medium for sooty mold growth, significantly reducing the tree's photosynthetic efficiency and aesthetic value.

Control measures: Effective management requires a combination of strategies:

• Mechanical removal of loose bark and pruning of heavily infested twigs to reduce overwintering populations.
• Application of dormant oil sprays in early spring to smother overwintering nymphs.
• Targeted application of systemic insecticides during the crawler stage in early to mid-summer.
• Preservation of natural biological enemies, including parasitoid wasps and lady beetles.