The Emerald Ash Borer (EAB), discovered in Michigan in 2002, is thought to have been introduced into Detroit in the 1990s from wood packing material on cargo ships from Asia. The insect is now found in 13 states, and has been confirmed in our local area. The EAB attacks any age and variety Ash tree.
Tree owners fearing infestation should be alert for the May and early June emergence of adult insects through D-shaped exit holes in the bark. Others signs include dieback, woodpecker damage, and frequent, irregular branching from the main trunk.
PA Dept of Conservation and Natural Resources (DCNR)
http://www.dcnr.state.pa.us/forestry/insectsdisease/eab/index.htm
Penn State College of Agricultural Sciences / Entomology
http://ento.psu.edu/extension/trees-shrubs/emerald-ash-borer
National EAB information website - Collaboration of USDA Forest Service, Michigan State University, Purdue University, and Ohio State University.