Maple felt scale

Systematic position. The maple felt scale (Acanthococcus acericola) belongs to the order Hemiptera and the family Eriococcidae. It is a specialized sap-sucking pest that induces the formation of specific galls on the leaves of host plants, which is a key diagnostic feature.

Host plants. This pest primarily targets various species of maple, with the Norway maple being particularly susceptible. In urban environments, such as parks and botanical gardens, heavy infestations can cause significant aesthetic and physiological stress to ornamental tree plantings.

Biology and life cycle. The species completes one generation per year. Fertilized females overwinter in bark crevices or protected sites on the tree trunk. In early spring, during the bud break, they migrate to the undersides of young leaves, where they secrete a white, felt-like waxy ovisac to protect their eggs.

Type of damage and harmfulness. Damage is characterized by the presence of numerous small, pimple-like galls on the lower leaf surface, often yellow or red. Severe infestations result in leaf distortion, chlorosis, and premature leaf drop, which weakens the tree and reduces its overall vigor and decorative value.

Control measures. Effective management requires a combination of physical and chemical approaches:

• Removal and destruction of fallen leaves in autumn to reduce the overwintering population.
• Application of systemic insecticides during the crawler stage (when larvae emerge from the felt).
• Maintenance of tree health through proper fertilization and watering to improve natural resistance.
• Use of horticultural oils in early spring to coat the overwintering females.