Updated September 2015
Where is it found
This pdf shows where Emerald Ash borer is found in the United States. It is also found in Ontario and Quebec in Canada.
How bad can the damage get
From here: If you can see damage from the beetle then
Surveys have shown that the emerald ash borer damages and kills trees
in stands within one to four years of infestation. Typically, within
six years of an infestation arriving in a woodlot, more than 99% of
the ash trees have been killed.
What can a homeowner do
This decision guide indicates that if your trees do not show damage and are less than 20" diameter you can treat them yourself with a range of pesticides or with TreeAzin. This is preventative rather than curative.
If you can observe signs of the emerald ash borer in your ash trees then it's over for them and quick removal is the best solution. The longer you delay the more likely that the ash borers will multiply and spread to other ash trees in your neighbourhood. Delaying means additional costs comes out of your neighbor's and your city's pockets.
Here are the signs to look for that will confirm whether removal is the best solution.
- D shaped holes in the trunk that are one eighth of an inch in diameter. Native borers make larger circular holes
- frass or sawdust below the exit holes confirm that a local or emerald borer is present
- two to five inch vertical splits in the bark
- heavy woodpecker activity indicates pest activity
- dieback from the top of the tree indicates pest activity
- does your local city/municipality have information on the emerald borer? Are there maps indicating if the borer is present?
See here for details.
If you don't see any of these then get one of the companies back and have them justify their opinion.
You may choose to treat the trees but this has to be done regularly and will be an ongoing cost for many years. See here for details about hiring an arborist.
Once a tree shows signs of more than 20% dieback due to EAB,
treatments may not be successful. Treatment should be considered
primarily to prevent the infestation of healthy trees.
All of the available insecticide treatments need to be repeated every
There are no guarantees that available treatment options will work.
There are many trees that are not attacked by emerald ash borer. One that is most resistant to everything is the Gingko tree.