Emerald Ash Borer
Since its initial discovery in Michigan and Ontario (2002), Emerald Ash Borer (Agrilus planipennis Fairmaire) has expanded its range further into Canada and from the mid-west to the eastern part of the United States. It has been detected in at least 24 states, including Kansas in 2012. A Federal quarantine is in place in entire or portions of states that have confirmed the presence of this harmful insect. Wyandotte (2012), Johnson (2013), Leavenworth (2014), Douglas (2015), Jefferson (2015), Atchison (2016), and Doniphan (2017) are currently the only counties where EAB has been found in Kansas.
Emerald Ash Borer (EAB) is an exotic invasive beetle from eastern Russia and northeastern Asia that likely was brought to the U.S. in infested packing material. This beetle threatens our urban and riparian forests by killing North American ash species (Fraxinus sp.) and their cultivars. At least 70 million ash trees have been already been destroyed due to EAB, and it appears likely that the nearly 9 billion North American ash trees will be eventually be functionally extirpated from the continent.
Adults are usually present during the summer months (May-August) depending on the weather patterns. A few weeks after eggs are deposited in crevices in the bark they hatch and the larvae begin to chew through the outer bark to the phloem. When feeding they begin forming S-shaped galleries (July-October) that expand as they grow. This feeding disrupts the transport of water and nutrients within the tree. The larvae overwinter as prepupae in the sapwood and in the spring after a few weeks pupate and emerge as adults (May-June) creating a D-shaped exit hole. As adult beetles, they feed on the foliage during their 3-6 week lifespan, mate, and then the process begins again each year. Weather is a key player on timing for the beetle. For example: if it is a warmer than usual year then emergence and flight will occur earlier.
What does EAB look like?
- Adult beetles are a rich metallic green in color, with a purple to reddish copper colored abdominal segments under the wings. The insect is approximately half an inch long and an eighth of an inch wide.
- Larvae are legless, with bell-shaped body segments that have a flattened appearance. They are creamy white in color and are found under the bark.
- When adult beetles emerge from the tree, they leave distinctive D-shaped (half-moon shaped) exit holes in the outer bark of branches and the trunk. Their presence typically goes undetected until trees show symptoms of being infested.
What are the signs or symptoms of EAB?
- Canopy Dieback: starts from the top down. Thinning of the crown will occur until the tree is bare and heavily infested.
- Epicormic Shoots: sprouts grow from the roots and trunk. The leaves are often larger than normal.
- Increased Woodpecker Activity: Bird peck while foraging creates larger holes when extracting insects.
- Bark Splitting: Vertical fissures on the bark due to callous tissue formation. Galleries should be visible under the exposed bark split.
- Serpentine (S-Shaped) Galleries: Larval feeding creates galleries shape weaving across the woodgrain. Packed with frass (mix of sawdust and excrement).
- D-Shaped Exit Holes: Happens upon emergence of adult beetles.
Why should Kansans care about EAB?
Green ash was planted in many of our urban and rural settings. A loss of this tree in our landscape will have a significant impact on the ecology and economy of infested areas. The loss of ash in floodplain shelterbelts will reduce crop protection. Riparian corridors will be impacted as large gaps, due to the loss of green ash (a significant component of the overstory in our riparian forests) allow increased light to alter the quality of these areas. In addition, the financial cost to municipalities, rural and urban property owners, nursery operators, and industries related to forest products will be significant. Depending on the vigor of the tree, an infested tree can die from the top down within 4 years.
Ash is a common component in our urban and rural forested areas. There are an estimated 56.1 million green and white ash trees in our rural and urban landscape. Most occur along rural riparian areas, but the 1.5 million ash trees that occur in our towns and cities will cost much more in removal, stump grinding, and replacement. The economic impact of removing thousands of street and yard trees will need to occur not just for mitigation, but also because the dead trees pose a hazard and liability.
A community tree assessment protocol has been running since 2011 to inventory pine, walnut and ash in Kansas communities. This will be used to help community officials estimate removal and replacement costs if these insects become established.
What can Kansans do to prevent EAB?
When EAB is discovered in a state, federal and state quarantines (county level or larger) are enacted over a geographical area that may contain small aggregates of infested trees and not be evenly distributed throughout the quarantined area. Ash tree parts (saw logs, branches) and nursery stock, have a greater chance of being infested, and therefore should not be moved from the area to lower the risk of spreading the insects to new hosts. EAB is active when the weather starts to get warm. Their active period could start as early as April and go into September if high temperatures persist.
EAB is dormant inside the tree during the late fall and winter months. During this timeframe, pruning and removal of trees is desired. If an entire ash tree cannot be removed, the outer inch of bark and wood can be chipped (less than 1 inch in two dimensions), and take to a facility that will process the material or where it can be burned or buried. This ensures that any EAB that is present in the material will be destroyed. If the tree poses a hazard during the time the beetles are active, then chip at minimum the outer inch of bark and wood to less than an inch. Then it can be processed.
Familiarize yourself with the federal quarantine areas and regulations. Learn the basic signs and symptoms of EAB. Attend workshops in your local area provided by Kansas Forest Service or your local KSU extension. Do not bring firewood from another state. Use local sources for firewood where you are traveling in the state.
Links & Resources
Kansas Department of Agriculture
- Emerald Ash Borer Information
- EAB Frequently Asked Questions
- Insects in Kansas That May Be Confused With Emerald Ash Borer
- Do I Have EAB?
Insecticide Treatment Options
- Instructional Videos on Treatment Methods - Purdue University Extension
- EAB Homeowner Guide to Insecticide Selection, Use, & Environmental Protection
- Effectiveness & Damage Rates of EAB Treatments
- Insecticide Options for Protecting Ash Trees from Emerald Ash Borer
Information on Common & Native Borers of Kansas
- Common Kansas Borers
- Common Problems of Ash Trees
- Management & Prevention of Common Borers
- Ash/lilac Borer Information for Kansas
- National Multi-State EAB Information
- EAB Resources
- Info on EAB for Homeowners