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A close up dorsal view of an Emerald Ash Borer with it's wings open showing its luminescent, purple abdomen.
Extreme overhead view of a long, white worm shaped Emerald Ash Borer larva tunneling through a woody surface.
The trunk of an ash tree with bark removed showing many underlying "S" shaped eating trails of EAB Larvae
Front view of two Emerald Ash Borers exiting "D" shaped holes through the bark of an ash tree.
An overhead view of an Emerald Ash Borer sitting on top of, and within the boundaries of an ordinary penny.

Emerald Ash Borer

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What is it?

The Emerald Ash Borer, otherwise referred to as EAB, is a small, green beetle from northeastern Asia; it was introduced to North America in 2002. During the larval stage, the EAB can be found under the bark of ash trees, feeding within the sapwood; adult beetles can be found feeding on the leaves. Upon arrival in Michigan, in Michigan in 2002, EAB infested our native ash trees at an alarming rate. Much the same as other invasive species, the EAB, spread throughout eastern North America with ease due to a lack of natural predators, parasites, and pathogens. This contributed to the EAB earning a pest status in North America whereas the EAB is not considered a pest in Asia. Limited funding and growing EAB populations lead to the abandonment of eradication efforts early on. The speed at which EAB populations have grown and spread are problematic to the U.S. and Canada, both of which have extensive populations of ash trees.

As an adult, the insect is recognizable by its bright green, metallic sheen; hence its common name, “Emerald” Ash Borer. The adult EAB is quite small, shorter in length than a penny is in diameter (width). While adult EAB’s feed on the leaves of ash Trees, this does little in the way of harming the tree. It is instead the larvae that kill the trees.

How does it cause harm?

When a female EAB is ready to lay her eggs, she locates a healthy ash tree, and then deposits nearly 100 eggs in the cracks and crevices of the bark. In its native range, EAB females oviposit in injured or stressed trees, making them less of a concern to ash tree growers. The eggs remain on the tree until they hatch, approximately two weeks later. Upon hatching, the larvae will bore a hole through the bark and eat through the phloem of the tree; this is the outermost layer of tissue directly beneath the bark. The phloem acts as a transport system for important nutrients and sugars made in the leaves and sent to the flowers and roots. The larvae eat this phloem and the tree loses the ability to transport its food from the leaves to other parts of the tree. The tree will gradually starve, showing visible signs of stress such as losing the leaves on the uppermost branches; this is called “crown dieback”. The tree will eventually die and in this way, the EAB larvae kill the ash tree from inside out.

How do we stop it?

Entomologists, scientists who specialize in the study of insects, have already begun taking actions to try to control the EAB population in states and counties that the species has been found. Methods to do so include introducing the insect’s natural enemies, predators, and parasites. These good bugs are screened by entomologists and environmental scientists to make sure that they bring down the EAB population without harming any other trees or animals in the environment.

Such methods will take time, but there are things you can do to help control the EAB population. The EAB and other invasive species move across counties and state lines with the help of humans by hiding in plant products like fire wood, lumber, and saplings. One way to prevent this spread is to buy your wood locally and burn it there instead of taking it back home with you. For a full list of tips on how to prevent the spread of such species to your home, check out hungrypests.com.