Emerald Ash Borer Tree DamageThe emerald ash borer (Agrilus planipennis) is the invasive beetle that has destroyed tens of millions of ash trees over the past ten years.

This borer insect is native to certain parts of Asia, including Russia, Korea, Japan and China. It is believed to have been introduced to the United States in the 1990’s through wood aboard cargo ships or that used in shipping materials.

In the United States, this ash borer lacks natural predators to keep its population in check. Without natural defenses, our native ash trees are at the mercy of this pest, which is predicted to infest all unprotected ash trees in the United States and Canada over the next 20 years. If nothing is done, we’ll lose our ash trees as the presence of the emerald ash borer continues to spread across the country. That’s why it’s so important to understand all you can about this pest and to take action when you see it.

What the Emerald Ash Borer Looks Like

Picture of Emerald Ash BorerThe emerald ash borer is dark green and is 1/4 to 1/2 of an inch long.  Although this ash borer is most visible in last spring and early summer – when females are laying their eggs – most people will never notice its presence because it stays in the tops of ash trees.

When female borers’ eggs hatch as larvae in early to mid-summer, the larvae bore through the bark and into the ash tree’s cambium. The cambium is the area under the bark of the tree that is high in nutrients.

Larvae grow and feed until late summer or fall, until they are 1 to 1.25 inches long. They spend the winter in the tree, emerging as new adults the following May or June and begin the cycle again.

The life span of an emerald ash borer is one or two years.

How Emerald Ash Borer Spreads

There are two ways that emerald ash borer infestations can spread into new territory. First, adult ash borers can fly into new areas, although they only move ½ mile or less in most cases.

Secondly, humans can unknowingly transport these pests from infested areas to un-infested areas. This can happen from the movement of:

  • Infested firewood
  • Infested nursery stock
  • Infested ash waste