Convex soft scale

The convex soft scale (Stictolecanium convexum) is a specialized insect pest belonging to the order Hemiptera and the family Coccidae. This scale insect is frequently found infesting the bark of woody plants, where it thrives by extracting sap from the phloem, causing cumulative stress to its host trees.

Primary hosts for this pest include various deciduous tree species, with a particular affinity for oaks. The pest is typically observed on the trunks and main branches of trees, where the females form protective, convex-shaped structures that allow them to blend into the texture of the bark, making them difficult to detect during early infestation stages.

The biological cycle of Stictolecanium convexum typically spans one year. The overwintering stage consists of second-instar nymphs sheltered within the crevices of the host plant's bark. As temperatures rise in spring, the nymphs emerge to resume feeding, eventually molting into adults to begin the reproductive cycle.

The damage caused by this insect is characterized by the weakening of the host tree's physiological state. Heavy infestations lead to chlorosis, stunted growth, and the eventual dieback of branches. Additionally, the secretion of honeydew promotes the growth of sooty mold, which coats leaves and inhibits the efficiency of photosynthesis.

• Conduct systematic visual inspections of tree bark during late winter and early spring.
• Apply horticultural oils to smother overwintering nymphs before bud break.
• Use systemic insecticides specifically during the crawler stage for maximum efficacy.
• Maintain tree vigor through proper irrigation and fertilization practices.
• Encourage biological control agents such as parasitic wasps and ladybird beetles.