Emerald Ash Borer General Information

By now we've all heard of the emerald ash borer and know that it's bad. But why? Most of us know that these beautiful but extremely devastating insects kill off ash trees in large numbers.

The EAB came to North America during the 1990s, although a specific year is unknown. In 2002, the Detroit and Windsor areas first began reporting ash trees dying off due to the insect. As of now, the EAB is destroying ash trees in the Great Lakes region of lower Michigan, northern Indiana, Ohio, the Chicago area, Maryland and Pennsylvania. (US Forest Service). Other states, including New York, Missouri, Tennessee, Kentucky, Virginia, West Virginia, Wisconsin,  and Iowa also have either localized or state-quarantined areas of infestation.

Description:

• Metallic green wings, although sometimes seen as metallic reds and purples
• Cylindrical and linear body shape
• Approximately 1/3- to 3/4-inch long
• Top of abdomen metallic purple or red
• Blunt head
• Larvae are transparent white to creamy white and up to 1-inch long

Life Cycle:


Adults emerge from underneath the bark of host trees in late May and through mid-summer. Egg-laying season lasts through mid- to late-summer in many cases. After 7 to 10 days, the eggs hatch and the larvae bore beneath the bark and feed upon the vascular tissue of the tree. They leave an S-like pattern of zig-zags underneath the bark as they feed. The larvae continue to mature underneath the bark, growing as they feed voraciously on the vital system of the ash tree. The larvae overwinter under the bark, protected from the cold. Once it begins to warm up in early spring, the larvae begin their pupal stage. They emerge as adults in late May and the process continues over and over.

Ash Tree Identification:

• Opposite branching
• Compound leaves
• 5 to 9 leaflets (white and green ash)
• 7 to 11 leaflets (black and blue ash)
• Terminal bud

Symptoms:

• Dieback of the top leaves/crown of ash trees
• Vertical splits in the bark
• D-shaped exit holes (where adults emerge from)
• S-shaped zig-zags under the bark

Note that there are many, many native relatives of the EAB throughout North America that also feed on Ash trees or other trees. The difference is that native insects are part of the regular food chain and ecosystem; their numbers are easily controlled without any influence from man. As an invasive species, the EAB still doesn't have the right number of predators to help control the population naturally.


For more information:
Purdue University: Emerald Ash Borer
Emerald Ash Borer; Gary L. Parsons; Michigan State University Department of Entomology