Maple eye gall midge

Acericecis ocellaris is a small insect species belonging to the order Diptera and the family Cecidomyiidae (gall midges). This specific pest is known for inducing galls on the foliage of maple trees, which serves as both food and shelter for its developing larvae.

The primary host for this gall midge is the maple tree (Acer species), with Norway maple being a frequent target. While the damage is primarily cosmetic, the presence of numerous galls can lead to heavy defoliation during mid-to-late summer, which may impact the overall vigor of young trees in nurseries.

The biological cycle of the midge is closely tied to the spring growth of the host plant. The adults emerge in early spring to deposit eggs on the leaves. Once the larvae hatch, they begin to feed, secreting biochemical agents that cause the leaf tissue to react and form a protective gall structure around them.

The damage is highly recognizable: the galls appear as distinct, circular spots with reddish or purple margins and a pale center, resembling an eye. This is why the pest is commonly referred to as the maple eye gall midge. The larvae remain protected within these structures throughout their development stage.

Management strategies focus on reducing the population and minimizing the impact on tree health. Key control measures include:

• Removing and destroying fallen leaves in autumn to disrupt the life cycle.
• Applying horticultural oils or systemic insecticides at the time of bud break if the population density was significant the previous year.
• Promoting tree vigor through proper watering and fertilization to help the plant withstand stress.