Those of us who live in Maryland have heard the Department of Natural Resource’s warnings about the Emerald Ash Borer beetles. They have spread all throughout Maryland and wreak havoc on our ash trees. Not only have they devastated Maryland’s ash tree population, they’ve also spread to neighboring states and are manifesting themselves nationally.

If you have ash trees on your property, now would be a great time to take a look at them and evaluate them for the Emerald Ash Borer (EAB). Why? These bugs will infest and kill your ash trees leaving you with the mess to clean up while putting other ash trees at risk.

EABs are hard to see on ash trees because they live underneath the bark. The better way to look for these beetles is to identify signs of their destructive work. Once you’ve identified the ash trees on your property, here are a few items to keep an eye on:

Woodpecker Damage. Look for an extensive amount of woodpecker damage, as woodpeckers will be drawn to these trees to feed on the beetles beneath the bark. They’ll even strip the bark off in chunks to catch their prey beneath the surface. Aggressive woodpecker behavior may be a sign of heavy beetle presence.

Crown Dieback and Thinning. This will not be an immediate symptom of EAB, but over time the top of the tree will begin to look sparse and leggy. Branches in the upper crown of the tree will begin to die, fracture and reduce leaf production. This is because the larva disrupts upward flow of water and nutrients, so the tree cannot successfully reach the upper canopy.

Bark Splits. Where the larval galleries lie beneath the bark, you might see vertical splits in the trunk of the tree. The beetle larva are feeding in mass in these areas.

S-Shaped Tunneling. Beneath a stripped piece of trunk bark, you will see S-shaped tunneling lines from the beetle larva winding back and forth beneath the bark.

D-Shaped Exit Holes. When larva reach adulthood, generally between the months of May and June, they emerge through the bark of the ash tree leaving D-shaped exit holes. Other wood-boring beetles do this too – but the EAB bore leaves a distinctive small D-shape.

Epicormic Shoots. When a tree (and this applies to many types of trees, not just ash) is stressed, it tends to produce epicormic shoots from the base or trunk of the tree. This is like a “last resort” method the tree uses to try to save itself from death by re-initiating new growth. When the ash tree is stressed by the EAB, it produces shoots from the trunk which can grow very quickly and densely and put out a lot of huge leaves.

What to do. You have two options. You can treat the tree with an injection of a pesticide that may or may not be successful. Insecticide treatment is most successful when the Emerald Ash Borers are determined early on, which is very difficult to do. Additionally, insecticide treatment would have to continue on an annual basis to prevent re-infestation.  The second option is to have the tree entirely removed from your property. Tree removal will ascertain that the problem is solved and will help reduce the spreading population to nearby ash trees.

At Manor Tree Service, we are Maryland Licensed Tree Experts and would be happy to assess your ash trees for signs of Emerald Ash Borer infestation. Call us today to schedule your free evaluation or submit a request form online!


Note: For additional DNR Information and photographs of ash bore beetles and their damage, please visit: