The Emerald Ash Borer is a new pest to the United States, located for now only in southern Michigan, and parts of southern Ontario,Ohio and Indiana. This insect kills ash trees in 2 to 4 years and there is no remedy for this problem for ash trees in the forest. There are some remedies for ash trees in the home landscape, but they must be applied every year in the spring.
This is a problem that is going to spread to other states, at least in the short term.
For a web site that is frequently updated with the latest data about this problem go to Emerald Ash Borer by MSU
How The EAB Operates
In order to have any hope of preventing the Emerald Ash Borer (EAB) from killing your ash tree(s) you need to understand the broad outlines of its life cycle.
In Mid-May - Adult EAB begin to emerge from infested trees around mid-May. Most adult beetles will live for 2 to 4 weeks, not much time to have much fun.
By Mid-June - During the brief life time the EAB will lay individual eggs on the bark of branches and the trunks of ash trees. On average each female beetle will lay roughly 75 eggs.
By Early July - The eggs hatch in about a week and the larvae will tunnel under the bark and feed in the cambium layer of the tree which lies just under the bark. The tunnels, called galleries, of these larvae spread and begin to prevent water and nutrients from getting to the top of the tree. When the upper branches are deprived of this essential water and food, they begin to die, usually from the top of the tree down. Depending on the size of the tree, it will die in two to four years.
At this stage, if the EAB is in the tree, the tree will die.