Arabis gall midge

The Arabis gall midge (Dasineura alpestris) is a small dipteran insect belonging to the family Cecidomyiidae. This pest is a specialized gall-former that primarily targets plants within the Brassicaceae family, often causing aesthetic and physiological damage to ornamental garden plants.

The primary host for this species is the genus Arabis, commonly known as rockcress. The larvae feed on the meristematic tissue of the plant, which induces the formation of characteristic galls. While often localized, infestations can be severe enough to compromise the health and vigor of the entire plant.

The life cycle begins when the adult female lays eggs in the terminal buds or leaf axils of the host plant. Upon hatching, the larvae secrete substances that stimulate abnormal plant cell growth. These structures provide both nutrition for the larvae and protection from environmental conditions and many natural predators.

Damage is characterized by stunted growth, deformed or curled leaves, and the formation of swollen tissue masses (galls) at the tips of shoots. Severely infested plants often stop growing, fail to flower properly, and may become unsightly, leading to significant economic losses in nurseries and garden centers.

Management strategies focus on a combination of cultural practices and chemical control. The most effective cultural method is the regular inspection and manual removal of infested plant parts before the larvae complete their development. If infestation levels are high, systemic insecticides are recommended to target the larvae hidden within the plant tissues.