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Lesson Four:  Looking for Clues

Signs and Symptoms of Emerald Ash Borer Infestation

Purpose of Lesson

In order to cultivate environmental stewardship in youth, it is important to educate them about the threat of invasive species like the Emerald Ash Borer and the environmental and economic damage they can do to the natural and urban landscape. In this lesson, youth will learn how to identify the signs and symptoms of EAB in nature, so that they will be better able to communicate the danger of invasive species (like the emerald ash borer) to others.

Learning Objectives

Youth will be able to:

Educator Preparation

Materials and Resources

Teaching Tips

As youth break into groups to share information from their EAB Research Logs, it is more important that they focus on discussing the questions in depth, rather than how they write. To encourage discussion and save time, have one member act as scribe for the team to record answers.



Lesson Four reviews what youth have already learned about EAB and incorporates new information about infestation and the signs and symptoms of EAB. Youth will work cooperatively to identify the main idea and the three most important details of their assigned reading section and record them in the Research Log. After they have completed this task, the large group will reconvene to share what they have learned.


Why are trees so important?


SECTION ONE: How does Emerald Ash Borer infest and kill an ash tree?

In North America, the Emerald Ash Borer (EAB) has only been found in ash trees. These trees are called a host species. Emerald Ash Borer will attack any size or species of ash in any location – large or small, urban or forest, healthy or stressed; among ash, the borer does not discriminate (Note: EAB does not attack Mountain Ash because it is not a true ash tree.)

The female beetles lay their eggs in the crevices found in the bark of the tree. Once these eggs hatch, the larvae chew “S” shaped tunnels called galleries underneath the the wood. There they feed on the living tissue of the tree, preventing the flow of nutrients and water from the roots to the branches and leaves of the tree. The tree literally starves to death in as little as 1 to 3 years.

Ash trees in North America have little or no resistance to EAB. Scientists have found that EAB adults are more attracted to stressed trees and that the larvae develop more rapidly in these trees, but even the healthiest trees have been killed when EAB population densities are high. Up until now, natural enemies have had little impact on EAB.

SECTION TWO: What are the signs and symptoms of an ash tree infested with EAB?

The canopy of heavily infested trees will begin to die, usually near the top of the tree and progressing down the trunk. Infested trees may produce epicormic sprouts or what are sometimes called “water sprouts” or “witches brooms” on the trunk or large branches where EAB damage is heavy.

Bark may crack over larval galleries and result in vertical splits through which distinctive “S” shaped galleries can be viewed. As the borer chews out these tunnels, it leaves behind insect excrement, or what scientists call frass. Adult beetles leave a characteristic “D” shaped exit hole in the bark, roughly 1/8” in diameter when they emerge in June.

Woodpeckers often attack larvae, especially during the winter. Woodpecker holes are larger and easier to see than the D-shaped holes left by EAB. Several infestations have been discovered because people noticed woodpecker damage in trees.


Once youth have finished, reassemble as a large group. Cover the main ideas and other details learned from the Powerpoint presentation and reading their assigned section. Add information to a flip chart list or bulletin board. Discuss the following:

Assessment: Online quizzes coming soon!

Concept Extension

Have youth work together in teams to develop outreach campaigns to get the community involved in looking for the signs and symptoms of EAB and how to prevent or reduce the spread. Students can draw or download images of the EAB, evidence of EAB, and information about ash trees at www.eabindiana.info.

Reconvene the large group for presentations of community outreach campaign ideas. Campaigns should be judged with the following criteria in mind: