Willow terminal gall midge

Systematic position: The willow terminal gall midge (Rabdophaga terminalis) belongs to the order Diptera, family Cecidomyiidae. It is a highly specialized insect that targets specific willow species, primarily affecting the growth of terminal shoots.

Host plants and damage: The primary hosts are various species of willow (Salix). The damage is characterized by the formation of rosettes or galls at the terminal buds. As larvae feed inside the tissue, they induce physiological changes, causing the leaves to curl, the shoot growth to stop, and the stem to branch abnormally, which ruins the quality of the wicker.

Biology and life cycle: The adult midge is a small fly that lays eggs in the unfolding buds at the tips of willow shoots. Upon hatching, the larvae penetrate the tissues, triggering the plant to form a gall. This growth provides the larvae with protection and nutrition. Depending on environmental conditions, the insect can complete several generations throughout the growing season.

Economic importance: The damage is particularly severe in commercial willow plantations used for basketry or biomass production. By destroying the apical bud, the midge prevents the formation of long, straight rods. The resulting stunted and branched shoots have little to no commercial value, leading to significant financial losses for growers.

Control measures: Managing the willow terminal gall midge requires a combination of sanitation and chemical strategies:

• Regular pruning and destruction of infested shoot tips before the adult midges emerge to lay the next batch of eggs.
• Selection of willow cultivars known to be resistant or less susceptible to terminal gall midge infestations.
• Application of targeted insecticides during the peak flight of adults to prevent egg-laying.
• Maintenance of plant health to ensure vigorous growth that can withstand minor infestations.