Emerald Ash Borer

The emerald ash borer, Agrilus planipennis, is a green beetle native to Asia.

In North America the emerald ash borer is an invasive species, highly destructive to ash trees in its introduced range. The potential damage of this insect rivals that of Chestnut blight and Dutch Elm Disease. Since its accidental introduction into the United States and Canada in the 1990s, and its subsequent detection in 2002, it has spread to 14 states and adjacent parts of Canada. It has killed at least 50 to 100 million ash trees so far and threatens to kill most of the 7.5 billion ash trees throughout North America. The emerald ash borer is now one of the most destructive non-native insects in the United States; it and other wood-boring pests cause an estimated $3.5 billion in annual damages in the U.S.

The insect threatens the entire North American Fraxinus genus, unlike past invasive tree pests, which have only threatened a single species within a genus. The green ash and the black ash trees are preferred. White ash is also killed rapidly, but usually only after green and black ash trees are eliminated. Blue ash displays some resistance to the emerald ash borer by forming callous tissue around EAB galleries; however, usually they are eventually killed also.