You don’t have to be an expert to track down these bad bugs.

Serpentine galleries left by emerald ash borer

While you may be at home binge-watching true crime television shows right now, you can become a detective in your own right by investigating the ash trees on your property. Emerald ash borer (EAB) is a non-native insect that attacks ash trees. Unfortunately, infested trees die within 3 to 5 years. Long term management of EAB in New Hampshire involves actions by homeowners, forest landowners, communities, and state and federal agencies. Check out the map of known infestations. Now is a great time of year to look for signs of EAB. With leaves off the trees, it can be easier to spot some tell-tale signs of an infestation. Become an EAB detective by following the tips below!

EAB beetle. Photo by Leah Bauer,

What to look for during your investigation

1. Learn to identify ash trees: Knowing how to distinguish ash trees from other trees is an important first step in monitoring and planning on your property and in your community. Fortunately, this pest cannot infest any trees other than ash. Check out these tips and this video to learn more about identifying ash. 

Ash tree

2. Look for blonding: Woodpeckers are often the first to detect EAB. They feed on EAB larvae by scratching away the outer bark leaving a “blonding” effect where patched of light-colored bark are exposed.

Ash tree with blonding effect from woodpeckers

3. Keep an eye out for galleries: Sometimes you can see serpentine galleries left by larvae. They leave s-shaped scars that weave back and forth across the woodgrain.

Serpentine galleries left by emerald ash borer
Small s-shaped galleries left by emerald ash borer

Understand the opposition

  • Study their tactics: Learn more about the EAB lifecycle.
  • Be careful of disguises: There are many EAB look-alikes. Don't convict the wrong bug!

After the verdict

Once you determine you ash trees are infested with EAB, it’s time to consider your options:

You can help protect New Hampshire's forests by reporting suspect trees or insects, being aware of the risks of spreading EAB, and by using best management practices to avoid transporting this pest to your favorite outdoor spot. Report suspicious insects and trees here.

Interested in NH bugs? Learn more by visiting and sign up for our e-newsletter to receive updates.

Contact your county forester today! 


Extension Field Specialist, Forest Resources
Phone: (603) 862-3883
Office: Cooperative Extension, Nesmith Hall Room 224, Durham, NH 03824