Bronze birch borer

Bronze birch borer adults are slender, dark, irridescent, often greenish-bronze, beetles, 7-12 mm long. A fully grown larva is slightly longer than 12 mm, very slender, and has a flattened, enlarged area behind its head.

Damage: The first indication that a tree is infested with borers is wilting and dying of the upper crown. Closer examination may reveal ridges and bumps on limbs and branches as well as “D”-shaped adult emergence holes in the bark. In some cases the trunk may have areas with a rusty brown stain. This may be an indication that this species may be present.
Removal of the bark where ridges are abundant will reveal irregular, winding, sawdust-packed tunnels called galleries that are made by larvae excavating plant material from between bark and wood. This pest usually first attacks 3/4 inch diameter branches in the crown of the tree. Girdling of the cambium by tunneling larvae interferes with movement of plant sap and nutrients that may result in partial or complete death of a branch or tree.