Chicago emerald ash borer

Of the nearly 7 million ash trees left in the region, about half are in poor or declining condition. The emerald ash borer is an insect from Asia that was accidentally imported to the United States. It feeds easily on American ash trees that have no natural resistance. As an adult, the insect is a striking metallic green beetle, but it is at the larval stage that it destroys ash trees.

The wormlike larvae chew tunnels through the wood just beneath the bark, severing the vessels that carry water between the roots and the leaves. The larval-stage borer turns into an adult beetle that can fly to another tree to lay eggs. In the years since the emerald ash borer was discovered in southeast Michigan and Ontario in , it has spread to 35 states as far west as Colorado, and five Canadian provinces.

It was found in Illinois in Many of these saplings have likely sprouted from the stumps of ash trees that died and fell or were cut down. The borers only attack trees old enough to have trunks about 3 inches in diameter. Beetle larvae feed under the bark and outer sapwood of the ash tree, producing galleries that eventually kill branches and entire trees. When adding an estimated , ash trees from private property to the total, ash trees become one of the most numerous trees in the City.

Dedicated Forestry crews are working city-wide to inject trees to slow the progression of the insect and manage tree mortality. Crews will treat 35, ash trees this year and another 35, next year. Every three years, our crews will go back to assess the health of tree to determine whether we will retreat the tree or remove the tree.

Residents should consult with an International Society of Arboriculture ISA certified arborist to determine the best management solution for ash trees on privately owned property.

If you suspect you have emerald ash borer please call or the beetle hotline, The battle against the Emerald Ash Borer has also generated a vast supply of online information about this invasive species. Here are just a few of the available links that we believe will prove useful to you. An official website of the City of Chicago Here's how you know.

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