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Recent Developments
Emerald Ash Borer
Biology of the Emerald Ash Borer
Ash Trees
Signs and Symptoms of EAB
Treatments
What the City of Naperville is Doing to Prevent EAB Infestation
What You Can Do
Stay Informed
City to Treat Ash Parkway Trees This Spring
The City will be treating all healthy ash parkway trees this spring for the Emerald Ash Borer. Please watch this space for further information.
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Spring EAB Notice
Inspect your ash trees for the Emerald ash borer. Signs of infestation include noticeable woodpecker damage, dieback, splits in the bark, excessive sprouts, or small D-shaped holes in the bark. Spring is the time to treat your ash trees with insecticide though certain products can be applied later in the year.
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Recent Developments
The emerald ash borer has spread to trees throughout the city. Beginning in 2012, the City will treat all healthy parkway ash trees. Most ash trees are already infested to some degree. Trees that are in poor condition will not be treated and those badly infested with emerald ash borer will be removed.
2011 - Over 400 infested ash trees were removed and over 4000 parkway trees were treated.
2010 - Trees with emerald ash borer were identifed in over a dozen subdivisions. 195 ash trees were removed and 920 trees were treated.
July 2009 - Two infestations of emerald ash borer were confirmed in Naperville at the Route 59 train station and in the Wildflower subdivision. Infested and declining trees were immediately removed. The remaining healthy trees were treated with insecticide and several additional declining ash trees were removed.
June 2008 - The city received confirmation from the United States Department of Agriculture of the presence of the emerald ash borer in a portion of southwest Naperville, making this the first confirmed case of the emerald ash borer in Naperville and Will County. The beetle was discovered during a routine inspection in the Ashwood Park Townhome development, located near 248th and 103rd streets and in Tall Grass. Trees found to be infested were removed and chipped in accordance with Department of Agriculture disposal protocol.
Emerald Ash Borer
 The emerald ash borer (EAB) is a small (1/2 inch long, 1/8 inch wide) metallic green beetle that has killed millions of ash trees across the midwest. Native to Asia, the beetle was first discovered in the summer of 2002 in southeastern Michigan. Since the infestation in Michigan, the emerald ash borer has been found in a number of states, including Ohio, Indiana, West Virginia, Pennsylvania and Maryland.
In June 2006, the emerald ash borer was discovered in Kane County. State officials found exit holes in at least 20 trees left by adult Emerald Ash Borers suggesting that the beetles have been in that area for at least three years. In July 2006, another infestation was found in the City of Wilmette in Cook County. The emerald ash borer has been confirmed in area communities such as Naperville, Aurora, Geneva, St. Charles, Evanston, Wilmette, Winnetka, Elburn, Homewood, and Hazel Crest. The emerald ash borer was also found in the City of Chicago in June of 2008.
Biology of the Emerald Ash Borer
The adult emerald ash borer emerges between May-July and feeds on the leaves of ash trees. Soon after they emerge, the adult females lay numerous eggs on the trunk and branches of the tree. The eggs hatch within 7-10 days and the larvae, which are creamy white in color, bore into the bark of the tree. The larvae begin to feed and create S-shaped galleries, which cut off the food and water supply to the tree, causing it to die.
Ash Trees
Ash trees are very common in landscapes and most species, namely white ash and green ash, are native to Illinois forests. Ash trees are the most numerous species in the city’s parkway tree inventory. More than 15,200 of the city’s parkway trees are ash trees. This is 27% of the city’s parkway tree inventory.
The planting of ash trees is not allowed on any city parkways and will not be approved on private property landscape plans reviewed by the city.
Characteristics of Ash Trees:
Ash trees feature compound leaves made up of small, glossy green leaflets Leaves, twigs and branches grow in opposite pairs Bark of mature ash trees is gray and furrowed, often appearing in a diamond pattern Some ash trees will produce small canoe paddle-shaped seeds
Signs and Symptoms of EAB
 Infestation of emerald ash borer can be very difficult to detect until the branches of an infected tree begin to die. The most visible sign that the EAB is present is crown dieback, which appears after the first year of infestation. Usually the leaves on the upper third of the tree will begin to thin and the branches will begin to die. A number of suckers and branches will also sprout from the base of the tree and on the trunk.
Adult beetles emerging from trees will leave very small 1/8 inch diameter, distinctly D-shaped exit holes. These may appear anywhere on the trunk or upper branches but are difficult to spot. Distinct S-shaped larval feeding tunnels may also be apparent under the bark.
Woodpecker damage to tree.
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An early indication of infestation is woodpecker damage as they feed on the EAB larvae beneath the bark. This is especially evident during the winter when the trees are bare, The woodpeckers leave noticible damage to the bark which is easier to see than the D-shaped exit holes. An infested tree left untreated will typically die in about three years.
Other Stressors
Ash trees may suffer from a large number of pest and disease problems that cause similar symptoms as the emerald ash borer. Native borers also attack ash trees, although they leave larger exit holes, up to a 1/4 inch in diameter, that are usually circular or oval in shape. If you are concerned about the health of your ash tree and suspect that your tree has been infested by a pest, contact the city's Forestry Section at (630) 420-6095.
Treatments
There are several treatments against EAB available (see Insecticide Options for Protecting Ash Trees from Emerald Ash Borer.) If a tree care company provide a service or removes a tree, residents should ask if the company has current certificates of insurance, employs certified arborists, is licensed to apply the chemicals and has current references. It is recommended residents get more than one estimate to help make an informed decision. Tree owners are encouraged to thoroughly research the various treatment options currently available and carefully weigh the costs associated with the required repeated treatments. Research has been ongoing since the borer first arrived in this country and many trees are being saved. The healthier the tree is when treatment begins seems to be a large factor in the survival of the tree. Treatment of an ash tree will not guarantee that a specific tree might not eventually be required to be removed should it decline due to the borer. To search for a certified arborist visit the Illinois Arborist Association at www.illinoisarborist.org/CertifiedArboristsNew.htm for more information.
Ash trees that are not treated will sucumb to the the EAB. To ensure the insecticide is in the leaves by the time adults emerge to feed in early June, products are most effective when applied mid-April until the end of June. The larger the diameter of the tree, the earlier the product should be appled. Trees over 15 inch diameter should be treated professionally. The imidacloprid strength in the home use product is much less than the product available by professional arborists.
See the document Insecticide Options for Protecting Ash Trees from Emerald Ash Borer for the most up to date research on Emerald Ash borer control options and effectiveness.
The applications of emamectin benzoate (TREE-äge®,) imidacloprid or dinotefuran, which move systemically through the tree, are more likely to provide useful control. These options require a licensed professional to apply the insecticidal control to the tree.
Beginning in 2012, the City will treat all healthy parkway ash trees. Treatment of private ash trees can be documented as to what chemical was used, when it was treated, and by whom. These records will be collected and stored in a city database. If you decide to treat your ash trees, please complete the Emerald Ash Borer Treatment Form and return it to the Department of Public Works each time the tree is treated. If an arborist identifies an emerald ash borer infested tree anywhere on your property, please notify the Department of Public Works at (630) 420-6095.
Visit the State of Illinois web site at www.agr.state.il.us/eab or www.emeraldashborer.info for more emerald ash borer information.
What the City of Naperville is Doing to Prevent EAB Infestation
The City's Forestry Division is dedicated to protecting Naperville's ash tree population. For the past several years, the city has worked in cooperation with the Morton Arboretum and the Illinois Department of Agriculture on their survey projects to test for Emerald Ash Borer. These projects use 'test' trees to determine whether there are undetected pest populations in our region.
In order to prevent the spread of the Emerald Ash Borer, the Department of Public Works has developed a containment strategy which consists of removing all infested ash trees, inspecting ash trees, and coordinating efforts with the State of Illinois, the townships, and the Naperville Park District. As part of the City’s containment strategy, the city will be treating all parkway ash trees.
The City’s Forestry Division has ten certified aborists that are trained to look for signs of the presence of the Emerald Ash Borer and actively check ash trees everyday during their regularly scheduled work. The City's Forestry section will continue to evaluate all parkway ash trees and remove any diseased or weakened trees in an effort to reduce the overall percentage of ash trees in the City’s urban forest. Residents are encouraged to report sick or dead trees by calling (630) 420-6095.
What You Can Do
Do Not Transport Firewood: Emerald Ash Borer can easily be transported in ash logs. Make sure to purchase firewood locally from a known source and be sure to use all of the firewood in the cold months so that no hidden Emerald Ash Borer larvae or adults can survive on logs left through the spring.
Monitor the Health of Your Ash Trees: Look for dead and dying branches at the top of the tree's crown. If you suspect an ash tree located in the parkway seems sick or needs maintenance, call the city's Department of Public Works Forestry Section at (630) 420-6095.
Stay Informed
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