Polyaspididae scale insects

These pests predominantly affect woody plants, including various deciduous trees, shrubs, and ornamental species. Their host range is often dictated by regional climatic conditions, and they can significantly impact both managed landscapes and natural forests by colonizing trunks, branches, and leaf surfaces.

The biological cycle of Polyaspididae includes the egg stage, the crawler (nymph) stage, and the adult stage. The crawler stage is critical for population dispersal, as it is the only phase where the insect is mobile. Once a suitable site is located, the crawler anchors itself to the host plant, develops its characteristic scale, and begins feeding, remaining immobile throughout the remainder of its life.

Damage is primarily caused by the extraction of plant sap, which leads to chlorosis, stunted growth, and canopy thinning. Severe infestations can cause branch dieback and, in extreme cases, plant mortality. Furthermore, the accumulation of honeydew secreted by these insects facilitates the growth of sooty mold, which further interferes with the plant's ability to photosynthesize effectively.

Effective management requires a strategic approach throughout the growing season:

• Frequent scouting during the crawler emergence phase to time treatments correctly.
• Application of horticultural oils during the dormant season to target overwintering stages.
• Use of systemic insecticides when nymphs are most active and vulnerable.
• Mechanical removal of infested plant parts where possible.
• Enhancement of biological control through the conservation of parasitoids and predatory beetles.