Bronze Birch Borer
The adult is a small beetle native to North America. It resembles a tiny house fly. The damage is done by the larval stage feeding on the cambium layer just underneath the bark. Injury occurs by the creation of feeding galleries that, in effect, girdle the trunk or branch. Left unchecked, the birch borer will always kill its host. Since it feeds underneath the bark, spraying is not effective. However, systemic materials injected into the vascular system of the tree will control birch borer.