Trees infested with bronze birch borers usually die, eventually. Birch trees that are under attack by these insects usually show symptoms first at the top of the tree.
Symptoms are yellowing of leaves, then dieback that begins at branch tips and works down the tree.
The ridges are caused by the tunneling and feeding activities of immature beetles, which are in the larval stage. The adult beetles are present in mid- to late June, and again in July. They lay eggs in the cracks and crevices of the tree bark, the eggs hatch into the larvae, which tunnel into the tree to the region just under the bark. The larvae will become adult beetles the following summer, when they chew their way out of the tree, leaving the D-shaped holes. Unfortunately, by the time symptoms are visible, it is often impossible to save the tree.