The most visible sign of infestation is crown dieback, which appears after the first year. Branches at the top of the crown will die back to the trunk and more branches will die in subsequent years. This is the progression of the insect and will lead to the decline of the infested tree.
Typically, the tree will be completely dead in about three years, though suckers will sprout from the base of the tree and on the trunk.
Woodpecker damage is a close second in terms of identifying Emerald Ash Borer (EAB) presence in a tree. Woodpeckers feed heavily on the larva present underneath the bark layer of the tree. If a tree is heavily infested, the branches will be riddled with woodpecker holes.
S-Shaped Serpentine Galleries
the bark is peeled from the area with woodpecker activity, then the
presence of the insect can be confirmed by S-shaped serpentine galleries
underneath the bark. On infested younger trees with a smaller
diameter, the bark may also split vertically.
Other Signs & Symptoms
D-shaped exit holes may also be present in the tree form EAB adults but
they are extremely difficult to identify and less reliable for