Due to the fact that emerald ash borers do most of their damage inside the tree, visible signs of damage are not easily detected in the early stages of infestation. Trees typically are killed in two to four years. When trees are first attacked by EABs, the symptoms are inconspicuous and hard to notice. By the end of the second year, thinning foliage and dieback in the crown begins to be apparent. By the third year, there is severe dieback and significant canopy loss. Other symptoms may include vertical splits in the trunk and woodpecker holes.