Willow gall midge

The willow gall midge (Rabdophaga salicis) is a species of gall midge within the order Diptera and family Cecidomyiidae. It is a well-known pest that specifically targets plants of the Salix genus, causing the development of woody galls on stems and branches.

The host plants mainly include various species of willow, which are economically important for ornamental use and basketry. By inducing gall formation, the insect redirects the plant's resources to create a protected site for its larval development, significantly impacting the structural integrity of the branches.

The biological cycle is strictly tied to the host's development. The larvae overwinter within the woody galls, protected from predators and weather. In the spring, they pupate, and the adult midges emerge to lay eggs on the actively growing shoots. The stimulus from the larvae causes the plant tissues to proliferate and swell.

The damage is characterized by distinct, swollen galls on young twigs. Inside these structures, larvae feed throughout the season. The overall impact includes deformed growth, impaired nutrient transport through the shoot, and in severe cases, the dieback of infested branches, which degrades both the quality of the wood and the aesthetics of the tree.

Management and control strategies involve:

• Pruning and destroying infested branches in late winter or early spring before the adults emerge.
• Monitoring the plants during the spring flight period to apply targeted insecticides if necessary.
• Maintaining plant vigor through proper fertilization and watering to help them withstand minor infestations.
• Removing and burning all collected gall material to prevent re-infestation of the area.