Yet another pest that doesn’t belong here. The emerald ash borer, known to those who deal with it daily as EAB, is threatening Minnesota’s ash trees. It’s not a matter of if Minnesota could lose many of its millions of ash trees, but when.
We’ve been hearing the warnings for years, but the stakes just got higher. Emerald ash borer was found and confirmed on the southern border of Chisago County in 2015. Once adults are found, it’s likely that they have already spread and infested a much larger surrounding area.
EAB is from Asia and is a fairly recent immigrant. The first beetle was discovered in North America in 2002 and in St. Paul by 2009. Now there are 14 counties in an EAB Quarantine Area, including Chisago County. Firewood of any kind cannot be transported out of quarantined areas because it could help the beetle in spreading more quickly.
Emerald ash borers are small – they can fit on a penny. It’s not likely that you’ll see an adult EAB because they are normally up in the tree canopies. You are more likely to notice symptoms of stress in your tree, including heavy woodpecker activity, canopy thinning and dieback, and watersprouts at the base of the tree. By the time you notice the symptoms, the tree is likely past saving and will die within a year.
Under the bark of an infested tree, there will be weaving galleries, or “trails” where the larvae tunneled and ate. You may also notice “D” shaped exit holes, although it can be hard to tell sometimes.
If you think you may have EAB, the first thing to confirm is that you have an ash tree. Believe it or not, we get many reports of EAB that are not even on ash trees. EAB, so far, can only complete its life cycle on ash and white fringetree, which doesn’t grow in Minnesota.
Next, if you have the insect, make sure it would fit on a penny. If it’s larger than that, it’s something else. If you have the weaving, s-shaped galleries under the bark, then it may be time to call Arrest the Pest (888-545-6684).
For more information on EAB, including infestation locations and quarantine maps, visit www.dnr.state.mn.us/invasives/terrestrialanimals/eab.
Mary Jo Youngbauer is a Conservation Technician with the Chisago Soil & Water Conservation District.