Boxelder gall midge

The boxelder gall midge (Contarinia negundinis) is a small insect belonging to the Cecidomyiidae family, commonly known as gall midges, within the order Diptera. This specific pest is known to target the boxelder maple (Acer negundo), causing the formation of abnormal, swollen buds which act as galls for its larvae.

The primary host for this pest is the boxelder tree. The insect targets the buds during the early spring development phase. By feeding on the internal tissues of the buds, the larvae induce plant reactions that result in gall formation, preventing the healthy emergence of leaves and flowers. This leads to stunted growth and disfigured shoots on the infested tree.

The life cycle of Contarinia negundinis is tied closely to the bud burst of the host tree. The insects overwinter in the soil as pupae or larvae. Once temperatures rise in spring, the adults emerge to mate and lay eggs within the developing buds. The larvae feed inside these structures throughout their developmental stages, protected from predators and external environmental factors.

The damage caused by this midge is primarily aesthetic, but it can negatively affect the physiological health of the tree if infestations are severe. Repeated annual attacks can weaken the tree's vigor, making it susceptible to other environmental stresses. In urban landscapes, the reduction of foliage density due to damaged buds is a significant concern for park maintenance.

To manage and control the boxelder gall midge, arborists recommend the following strategies:

• Applying systemic insecticides just before bud break to target the emerging adults.
• Implementing regular monitoring during the early spring to detect the first signs of gall formation.
• Pruning and destroying heavily infested branches to reduce the local population of the pest.
• Promoting general tree health through proper fertilization and irrigation.
• Encouraging the presence of natural predators like parasitic wasps that feed on gall midge larvae.