The Emerald Ash Borer (EAB) is a small (1/2 inch long, 1/8 inch wide) metallic green beetle
that has killed millions of ash trees across the Midwest. Ash trees are
very common in landscapes and most species, namely white ash and green
ash, are native to Illinois forests. Pictures of various types of
ash trees can be viewed at the Morton Arboretum website, http://www.mortonarb.org.
of Emerald Ash Borer can be very difficult to detect until the
branches of an infected tree begin to die. The most visible sign that
the EAB is present is crown dieback, which appears after the first
year of infestation. Usually the leaves on the upper third of the tree
will begin to thin and the branches will begin to die. A number of
suckers and branches will also sprout from the base of the tree and
on the trunk. The bark may split vertically and woodpeckers may begin
to feed on the beetle larvae leaving visible damage on the bark.
Adult beetles emerging from trees will leave a very small 1/8 inch
diameter distinctly D-shaped exit hole that may appear anywhere on
the trunk or upper branches. Distinct S-shaped larval feeding tunnels
may also be apparent under the bark. Typically, the tree will die in
about three years.
this time, there is no recognized treatment for trees that have been
infested with the Emerald Ash Borer. Treatments with insecticides
are currently being studied, but residents should use caution if they
are approached by companies promising treatments to prevent Emerald
Ash Borer infestation. The best defense against this pest is to make
sure that your ash trees are healthy and maintained.