Boxelder Twig Borer

Problem type: Insect

Name of problem: Boxelder Twig Borer

Plant name(s): Manitoba maple

Symptoms / Characteristics:
The boxelder twig borer, Proteoteras willingana, destroys dormant buds of Manitoba maple in the fall and spring. After bud break, it tunnels into new shoots causing the formation of swollen, gall-like tissue. Normal growth is inhibited and repeated attacks can stunt the growth of the tree. Leaves may appear skeletonized in mid-summer and silk webbed feeding nests, combined with frass (droppings) may also be visible.

Twig burrowing and leaf skeletonizing both occur during the larval stage of development. Immature larvae are light green with black heads. Mature larvae are about 1cm long with a yellowish body and a dark brown head. The adult moth is speckled-gray with a 1- 2 cm wingspan.

Control / Preventions:
Remove and destroy basal suckers in both fall and spring as this succulent tissue tends to harbor the twig borer larvae. In late spring, remove and destroy swollen twigs. This will disrupt the life cycle and prevent further infestation. Chemical insecticide is best applied between mid-July and early August when the newly-hatched larvae are most vulnerable.