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Emerald Ash Borer (Invasive)

Scientific name: Agrilus planipennis

Tens of millions of ash trees in this country have been killed SO FAR and it is possible that most of the 8.7 billion ash trees in North American will succumb eventually the ash borer.

This wood-boring beetle was accidentally introduced to the U.S. from Central China and was first identified here in 2002. It is suspected that they hitched a ride in packing crates.

Here is good example of how flora and fauna, once outside their native range, can wreak havoc on another ecosystem.

The beetle larvae tunnels through the tissue of the tree in “S” shaped galleries girdling the tree which prevents the flow of nutrients.

Our trees have no immunity to this insect.

Trees are often killed in about four years, although it can take as little as two years. When trees are first attacked by EAB, the symptoms are hard to notice.

  • During the second year, woodpecker pecks and thinning foliage begin to be apparent.
  • By the third year, woodpecker activity is more common and canopy thinning is more pronounced.
  • You may see vertical bark cracks due to the tree trying to heal over old galleries (the S shaped tunnels).
  • Although woodpecker activity and vertical bark splits are not always caused by EAB, they are common symptoms in EAB-infested ash trees.
  • By the fourth year, the canopy has seriously declined and may even be dead.

Symptoms of emerald ash borer infestation

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Life Cycle

Emerald ash borers generally have a one-year life cycle that can extend to two years in a vigorously growing tree.

  • Adults emerge from ash trees any time from late May to August.
  • After feeding on leaves, adults mate and females lay eggs on the bark or in small cracks.
  • Eggs hatch in seven to ten days.
  • The larvae tunnel under the bark of ash trees and feed until fall.
  • The fully grown larvae live through the winter in chambers constructed under the bark.
  • They transform into pupae in early spring.

Human Connections

Ironically, the ash was widely planted once our native elm trees were decimated by Dutch Elm disease!

The lesson learned is that it is always best to plant a diversity of native plants. This cuts down on the transmission of pests and disease. It is one reason why the elm tree still exists in Central Park in NYC. They were isolated from greater populations!

There are many resources where you can learn more. In New York, the DEC has issued this article. 


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