Maple gall midge

Systematic position. The maple gall midge (Acericecis) belongs to the order Diptera, family Cecidomyiidae. These insects are well-known for their ability to induce the formation of galls — abnormal tissue growths on plants that provide food and shelter for their larvae.

Host plants. The primary hosts are various species of the genus Acer (maple). While rarely lethal to mature trees, infestations can be severe on ornamental cultivars and young nursery saplings, impacting their aesthetic value and overall vigor.

Biology and life cycle. The life cycle of Acericecis is closely linked to the phenology of host trees. Adults emerge in spring when leaf buds begin to swell. Females lay their eggs on the surface of developing leaves. Upon hatching, the larvae secrete chemicals that trigger the plant to produce galls, which protect them while they feed throughout the growing season.

Damage and economic importance. Infestation is characterized by the appearance of numerous small, often brightly colored galls on the upper or lower leaf surfaces. Heavy infestations can lead to leaf distortion, reduced photosynthetic efficiency, and premature leaf drop. While mainly a cosmetic issue, significant damage can stress young or newly planted trees.

Control measures. Integrated pest management (IPM) is the most effective approach. Cultural controls include gathering and disposing of fallen leaves in autumn to disrupt the life cycle. In nursery settings, preventative systemic insecticide applications during the early leaf expansion stage can effectively target adult midges before they lay eggs on the foliage.