In North America the emerald ash borer is an invasive species, highly destructive to ash trees. The green ash and the black ash trees are preferred, however white ash are also consumed rapidly, after green and black ash trees are eliminated. The Blue ash species has shown some signs of resistance to the emerald ash borer, however eventually they are killed-off as well.
This dark metallic green, bullet-shaped beetle was accidentally introduced into the United States and Canada in the 1990s. Since that time, the emerald ash borer has become a serious pest control problem in 14 U.S. states and adjacent parts of Canada. In their path, these pests have destroyed an estimated 100 million ash trees, and contributed to $3.5 billion in wood-boring pest damage annually; in the United States.
When the adult emerald ash borer emerges in May to July, the female members of this beetle species lay their eggs in bark crevaces, and between layers of bark. When the eggs hatch in approximately 7 to 10 days, the emerald ash borer larvae will bore into the tree, where they chew the inner bark and phloem; creating winding galleries as they feed. This activity eventually cuts off the flow of the water and nutrients to the tree, causing dieback and eventual death.
Evidence of an emerald ash borer invasion, can sometimes take up to a year to recognize. Signs of the emerald ash borer’s presence in a tree, are D-shaped holes in the bark of the trunk or branches, and shoots growing from the base of the tree.