The emerald ash borer is a small beetle that was accidentally introduced from East Asia into the Detroit Michigan metro region sometime during the 1990s. Since that time, it has spread out into 33 states and three Canadian provinces including Minnesota, Iowa, Nebraska and now South Dakota. The emerald ash borer has killed nearly 100 million ash trees since the beetle was discovered in this country.
The adults are slender, green metallic beetles about ½ inch long. They begin emerging from infested trees and wood in early summer. The adults fly to nearby ash and deposit eggs on the bark. The larvae hatch in about a week or two, burrow into the inner bark of the tree, and begin to feed. The larvae are flat, white (worms) with bell shaped segmented bodies and will reach a length of 1 inch long by fall. The larvae create S-shaped galleries or tunnels just beneath the bark which become packed with a sawdust like material called frass. The galleries cut off the movement of food from the leaves to the roots which results in the trees decline and eventual death. The larvae form a whitish pupa just beneath the bark in the spring and the new formed adult emerges in a few weeks.
Infested trees can survive 1-7 years but typically die after five years of continued attacks.