Q: Can emerald ash borers be attacking an elm tree?
Wednesday, March 30, 2016
Q: I live in the Chicago area. I have an elm tree that I recently discovered is covered in small holes, similar to what you might see caused by an emerald ash borer in an ash tree. Is it possible the insect is adapting and finding new tree species to attack, or is there another explanation?
A: The answer to your EAB question is "absolutely not." Since EAB was identified/named in Michigan sometime after its initial discovery in 2002, scientists actually introduced Agrilus planipennis to as many tree species as they could. This was done to fully understand the potential scope and magnitude of the problem. Thankfully, EAB is almost exclusively active on Fraxinus (ash) species, with a lesser degree of activity on Fringetree (Chionanthus). So EAB is definitely not attacking your elm.
Most often, boring insects seem to find their way to trees that are in decline or suffering from some malady. You may have an unhealthy elm that attracted the borer. In some cases, their activity is not a problem, while in others, it can lead to tree mortality. You might do some internet research on elm boring insects to see if you can match their exit hole on the bark to an online photo. With a positive ID, you'll know better if action is required. Good luck.
Responder: David Jahn, RCA #425, Des Moines, IA