Emerald Ash Borer

Emerald Ash Borer

Emerald Ash Borer

The Emerald Ash borer is a green metallic beetle about ½ inches in length and 1/8 inches in width. It has a flat back and a rounded belly.

The Emerald Ash Borer is a beetle that destroys the ash tree by cutting the plumbing of the tree.  First, the female lays eggs in crevices of the bark. The eggs hatch and larvae chew through the bark and start burrowing in the cambium layer of the tree. They progress through four larval stages. In the process, EAB eat through the active phloem and xylem of the ash tree, effectively strangling the tree by depriving it of water and nutrients. Each female adult lays about 60-90 eggs (one at a time), so the infestation can progress rapidly once the beetle is established. Mated females have been shown to fly farther in flight mill studies than unmated females.

The larvae spend the winter beneath the bark and feed for a short time early spring.  Then EAB pupates (similar to caterpillar becoming a butterfly) and emerges as a beetle (usually late May through August). Adults fly to the top of the ash tree and feed on the leaves; approximately two weeks later the beetles mate and begin the egg laying process. If an Ash tree is infested with EAB it will die within 2-4 years.

One of the reasons EAB has proliferated is because it is not native to North America, and its natural enemies (predators and parasitoids) were not brought from EAB’s homeland at the time of initial introduction. All ash (Fraxinus) trees are susceptible to EAB, and EAB will infest any ash tree, but prefers damaged or stressed trees.

The Emerald Ash Borer was accidentally introduced into the United States. The theory is that it came from Asia on wooden crates carrying cargo. The first location of infestation was Detroit, Michigan, and although the beetle was discovered there in 2002 it is thought to have resided there for 10 or more years before it was finally discovered. DNA testing has revealed that 3 distinct populations of EAB occur in the USA. Since that time the borer has made its way (or has been moved by man) throughout Michigan, and to Ohio, Virginia, Maryland, Indiana, Pennsylvania, West Virginia, Illinois, Wisconsin, Minnesota, Iowa and Missouri. Although the borer is able to fly (estimates of 2 – 5 miles), it is moved long distances in infested logs, firewood and nursery stock.

Some telltale signs that EAB has infested an ash tree are: waterspouts; crown dieback; D-shaped exit holes in the bark (1/8 inches in width); S-shaped, grass-filled feeding paths under the bark; woodpecker holes; vertical splits in the bark over larval feeding areas; and notching on the edges (only) of leaves. Although these signs can be helpful diagnostic tools, they are by no means fool proof. Some of these same signs can be made by native pests of ash trees.

The impact of EAB is devastating. Not only is the replacement and removal of destroyed trees financially taxing, but the loss of such a large amount of trees has a severe environmental impact as well. There are millions of ash trees in South Dakota, many of them in cities and neighborhoods. Loss of these ash trees may very well increase heating, cooling, and watering costs for residential areas.

If you think you have an ash tree infested with EAB Click on the link below for a brochure to help with the determination, and call the district at 345-4661 ext. 3.

Is My Ash Tree Infested with Emerald Ash Borer?
pdfEmerald Ash Borer Brochure
pptEmerald Ash Borer Powerpoint Show (download)
 EAB Brochure
Contact Information
Day County Conservation District
600 E Hwy 12 Suite 1
Webster, SD  57274
Tree shed address:
43423 143rd Street
Webster, SD  57274