Emerald Ash Borer

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adultemeraldashborerThe Emerald Ash Borer (EAB or Agrilus planipennis) is an invasive metallic green wood boring beetle that attacks all species of Ash trees (Fraxinus sp). After feeding on the leaves the adult beetles lay their eggs on the bark. Upon hatching, the larvae tunnel around the phloem and xylem layer creating winding tunnels and disrupting the flow of water and nutrients to the trees upper extremities.

Symptoms of infestation will generally manifest in the crown within two years, and without treatment, the tree will die within five years. Most importantly, by the time symptoms are evident, the tree has already been infested. Emerald Ash Borer kills nearly 100% of infected trees.

Though Ash species represent about 1.5% - 2% of the forest trees in our area, the more visible impact will be on residential and commercial areas where Ash have been used as a landscape staple for decades.

Sighted in NC

The Ash borer was first positively identified in four NC counties along the Virginia border in 2013. The insect is responsible for the death of tens of millions of trees since it was first detected around Detroit in 2002.

The natural spread of emerald ash borer is fairly slow, typically moving less than 20 miles per year. More often, the insect is inadvertently transported long distances by human activity such as the movement of infested firewood. North Carolina is currently under a quarantine that restricts the movement of Ash wood products from EAB affected areas within the state. On June 30, 2015, Agriculture Commissioner Steve Troxler signed an emergency quarantine order for Wake County restricting the movement of hardwood firewood, ash nursery stock and other ash materials after emerald ash borers were confirmed in the county.Read more about the quarantine.

What the Town is Doing

On October 25, 2014, certified arborists employed by the Town applied a systemic insecticide drench to 16 downtown Ash trees as a deterrent to the Emerald Ash Borer. In addition, the Cary Chamber of Commerce has coordinated with the Town in treating two prominent Ash street trees on its property.

As in the case of the discovery of Hemlock Wooly Adelgid within a Town-operated facility, an action plan is being developed with recommendations from arborists, NC State University entomologists and NC Forest Service Forest Health Program staff. This plan includes monitoring for further pest emergence and additional low impact treatments as necessary to ensure the survival of these strategic and aesthetically important trees.

What Citizens Can Do

Most of the large Ash trees in our area are part of the residential and commercial landscape. Citizens and business owners who have Ash trees on their property should watch for signs of the beetle. Even trees that have been infested and are showing signs of die-back can often be treated successfully. According to the NC Forest Service, signs that the Emerald Ash Borer is present are as follows:

  • Crown die-back becomes evident.
  • Epicormic sprouting, or sprouting from the main stem of the tree, may occur.
  • The presence of insects below the bark leads to increased woodpecker activity, which causes the tree to look like it is losing patches of bark.
  • In severe cases, the bark of the tree may split in places where the larvae are feeding beneath.
  • Residents may also notice D-shaped exit holes in the bark. Peak emergence typically occurs in early summer.

A Certified Arborist should be contacted to positively identify the presence of the insect as drought and secondary diseases can cause similar problems.

To report the location and description of potentially infested trees: call 1-800-206-9333 or email newpest@ncagr.gov.


Further recommendations and information is available at the following sites:

NC Forest Service - Emerald Ash Borer FAQ
USDA - Emerald Ash Borer
Don't Move Firewood - Emerald Ash Borer
NC Cooperative Extension - Emerald Ash Borer


Kevin L. Steed
(919) 380-5704