Ash Trees and the Emerald Ash Borer

Emerald Ash Borer (EAB) in Lake Zurich
The first positive find of Emerald Ash Borer (EAB) was on March 2, 2011 in the Manor subdivision. This was confirmed by an inspector for the Illinois Department Agriculture.
Subsequently, additional infestations of EAB have been found throughout the Village.

The Village of Lake Zurich's EAB action plan is available here.

Ash Trees in Illinois
green ash leafAsh trees are very common in landscapes and most species, mainly white ash (Fraxinus Americana) and green ash (Fraxinus Pennsylvanica), are native to Illinois forests. It is estimated that as much as 20% of street or parkway trees in the Chicagoland Area are ash trees.

In Lake Zurich, the population of parkway or street trees and trees in our parks is 7,900. The total number of ash trees is estimated at 38 percent of the tree population in Lake Zurich.

Characteristics of Ash Trees
  • Compound leaves made up of seven small, glossy, green leaflets
  • Leaves, twigs, and branches grow symmetrically in opposite pairs
  • Bark of mature trees is gray and furrowed, often appearing in a diamond pattern
  • Some ash trees will produce small canoe paddle shaped seeds
  • Seedless ash trees are common
  • Some ash trees produce conspicuous, hard, brown “flowergalls” on their twigs
Emerald Ash Borer
eab adultThe Emerald Ash Borer (EAB) is a small (1/2” long, 1/8” wide) metallic green beetle native to Asia. While it was first found in Michigan in 2002, it is likely that EAB had become established quite a few years before discovery.

EAB’s natural spread is moderate; but its artificial spread can be rapid by people unwittingly transporting this pest through infested firewood and landscape waste. To protect our ash trees, it is our responsibility to minimize the spread of EAB by following a few simple rules:
  • Purchase firewood locally (within county) from a known reputable source
  • Campers should buy firewood at your destination and burn all wood before leaving the campsite.
EAB Life Cycle
eab larvaeThe adult EAB emerges May-July and the female lays numerous eggs in bark crevices and between layers of bark. The eggs hatch into larvae in 7-10 days, which bore into the tree, where they chew the inner bark and phloem, creating winding galleries in the vascular tissue of the tree as they feed. This action cuts off the flow of water and nutrients in the tree, causing dieback and death of the tree.

Signs and Symptoms of the EAB
Monitor the health of ash trees in at and around your home!
  • Look for dead and dying branches at the top of tree’s crown, commonly referred to as “crown dieback”
  • As the tree declines, “suckers” or new young branches will sprout from the base of the tree and on the trunk
  • Vertical splits in the bark from the tree attempting to heal itself from larvae feeding in the vascular area of the tree
  • Visual evidence of woodpecker damage on the outer bark from the birds feeding on the larvae in the vascular area of the tree
  • Adult beetles emerging from trees (May-July) will leave a unique “D” shaped exit hole, approximately 1/8” diameter. The holes may appear anywhere on the trunk or upper branches
Other Stressors of Ash Trees
Ash trees may suffer from a number of insect, disease, or other problems that can cause similar symptoms. Native insect borers also attack ash trees and leave different exit holes. Native insect borers do not cause the devastating damage to the vascular system that EAB does.

The round or oval exit holes of native insect borers are not “D” shaped and usually smaller or larger than those of the EAB.

For Further Information or Assistance
  • Visit Illinois Department of Agriculture Emerald Ash Borer website
  • Contact a private certified arborist. To find one in your area visit the Illinois Arborist Association website
  • Additional EAB information visit the EAB informational website