Emerald Ash Borer (EAB) is a serious threat to Maryland ash trees. It has killed many millions of ash trees across the Mid-West and Eastern U.S and is well-established in Maryland and in the summer of 2015 it was also found on the eastern shore. Adult beetles begin flying about the time that black locust is in bloom.
The EAB is an invasive pest from Asia that feeds on and kills ash trees. EAB will kill even large ash trees within three years after infestation. Ash trees are one of the most common and important landscaping trees used in Maryland and are common in western Maryland forests. Ash wood is used for all traditional applications of hardwood from flooring and cabinets to baseball bats.
Presence of the emerald ash borer typically goes undetected until trees show symptoms of being infested – usually the upper third of a tree will thin and then die back. This is usually followed by a large number of shoots or branches arising below the dead portions of the trunk. Other symptoms of infestation include: small D-shaped exit holes in the bark where adults have emerged, vertical splits in the bark, and distinct serpentine-shaped tunnels beneath the bark in the cambium, where larvae effectively stop food and water movement in the tree, starving it to death.
From the University of Maryland Extension.