EAB – it ain’t leavin’

Fri. May. 1, 2020

Click below to listen to my 2 min. Garden Bite radio show: EAB – it ain’t leavin’

Emerald Ash Borer ain’t goin’ nowhere… except closer. More counties in Minnesota and Wisconsin have recently reported the Ash tree killing insect.


There’s an irony in reporting on EAB amid Covid-19.

They are both suspected everywhere but have not yet reared their ugly heads everywhere. And they’re both requiring quarantines to try to stop the spread. Those tactics are certainly slowing things down.

In the case of EAB, scientists continue to work on ways to combat the beast and save those trees.  University of MN Ext. Entomologist, Jeffrey Hahn, says now is a great time to examine your ash trees for evidence of EAB).  It may seem early, that maybe you need the leaves on the trees to check the canopy, but Hahn says that’s not a good indicator of whether your ash is infested, in fact, having a leafless tree makes it easier to search for EAB clues. 

So what do you look for? Symptoms include woodpecker pecking!  EAB larvae is a favorite snack.  Hahn says, although woodpeckers eat other insects, their presence on an ash tree is definitely a red flag. 

Pileated woodpecker in Lakeville

Another sure symptom is small, 1/8th inch sized D-shaped exit holes. Unfortunately, they’re easy to overlook because of their size. 

EAB d-shape exit hole by Jeffrey Hahn

Also, EAB starts infesting trees at the top of the canopy and then work their way down, so by the time you see those holes, your tree’s been infected for a while.  Another definitive symptom is S-shaped squiggles, (my unofficial term) under the bark.  Obviously you can’t see these unless you take the bark off.

EAB larvae by Jeff Hahn