Emerald Ash Borer

The Emerald Ash Borer is a BIG problem in the Northeast region of the United States, and the problem is getting bigger daily. These pests attack all species of Ash trees here in the US. Fortunately, they only attack Ash trees, and nothing else. They are believed to have come from China, Russia, Japan or Korea. They have only been around in the US since 2002. Since then they have spread to Iowa, Illinois, Indiana, Kentucky, Minnesota, Maryland, Missouri, Ohio, New York, Virginia, West Virginia, Pennsylvania, Tennessee, Wisconsin, Quebec and Ontario. Efforts to keep them contained thus far have failed. However, there are ways to combat the EAB.

Here's a quick video about what's being done to help slow down the spread of EAB:

Is your Ash tree dying? Here's how to tell if it's the EAB. As you can see in the picture above, the bug is very easily identified. It is almost fluorescent in color, and glints in the sunlight, making it somewhat easy to spot when on leaves. The problem, however, is that it bores into the trunk of the tree, eating away at the inside. The bug destroys the layers under the bark that transport water and nutrients, which makes the tree start thinning from that point up. In most cases, the top of the tree starts to thin out first, working its way down. This can happen as fast as half a tree in one year, and within two years it can completely kill the tree. When the tree can no longer handle the stress of trying to keep the top alive, it often starts pushing out new branches on the trunk. This is a good indication that there is an infection. Another sign that you've got an EAB problem is seeing "D" shaped exit holes in the bark of the tree.

What to do if you have an EAB infection:

Unfortunately, treatment for this issue is very limited due to it's somewhat sudden impact. All agencies involved in treatment recommend certain insecticides, however they are mostly only available to tree care professionals. You're best, and seemingly only, option for treatment is to call your local tree care company for an assessment and estimate. It can be pricey to save these trees, but without treatment the tree will die. Once the EAB starts a colony in the tree it's only a matter of time before it's chewed inside out.  

Source: http://minnesota.publicradio.org/display/web/2009/05/14/ash_borer_found/