Cottony maple scale

Systematic position. The cottony maple scale (Neopulvinaria innumerabilis) belongs to the order Hemiptera and the family Coccidae (soft scales). It is a well-known sap-sucking pest that frequently impacts both urban landscapes and natural forested areas.

Host plants. This pest has a broad host range, primarily targeting deciduous trees. The most common host is the maple tree, but it also infests linden, elm, locust, sycamore, grapevines, hawthorn, and occasionally apple or other fruit-bearing trees.

Biology and life cycle. This species completes one generation per year. Mated females overwinter on the bark of twigs. In the spring, they produce conspicuous, white, cotton-like ovisacs containing hundreds of eggs. By early summer, these eggs hatch into tiny crawlers that migrate to the foliage and attach themselves to the leaf veins to feed.

Damage and economic impact. The injury is caused by the extraction of large quantities of plant sap. Furthermore, the excretion of honeydew promotes the growth of sooty mold, which creates an unsightly appearance and impairs the photosynthetic capacity of the leaves, potentially leading to branch dieback and overall tree decline in severe infestations.

Control measures. Management strategies include both mechanical and chemical interventions. Pruning and destroying heavily infested branches can help reduce local populations. Chemical control is most effective against the crawler stage in early summer using systemic insecticides. Dormant oils can be applied in early spring to target overwintering females. Natural predators, such as lady beetles, play an important role in suppressing populations.