Emerald Ash Borer
The Emerald Ash Borer (EAB) is perhaps one of the most destructive tree pests we’ve seen in decades. Larvae of this insect feed under the bark of ash trees, disrupting the tree’s ability to transport water and nutrients, which can ultimately kill the ash tree in as little as two years.
The shimmering beetle was first discovered in Southeastern Michigan in the summer of 2002, and has since spread into Ohio, Indiana, Illinois, Pennsylvania, West Virginia, Maryland, Virginia, Missouri, Wisconsin, Minnesota and Ontario, Canada. The list continues to grow.
(Click on the pictures for a larger view)
How big is the problem? Consider this:
Over 40 million ash trees have been killed in Michigan.
Millions more in the other infested states.
The majority of Iowa towns and cities have planted ash trees along streets and in parks.
Many private homes have ash trees for shade and comfort.
Removal and re-planting of dead, and dying ash trees will cost Iowa communities millions of dollars.
Research on the Emerald Ash Borer had been very limited up to 2002, when it was first found in Michigan near the port city of Detroit. There existed less than two pages of scientific literature in the entire world on this insect, and those two pages were written in Chinese.
Basically all scientific information regarding this insect had to be newly learned, as it simply did not exist.
Entomologists at the USDA and several Universities are intensely studying this small, yet highly destructive insect, in order to understand what it is. Research has included basic biology such as habitat, lifespan, flight capabilities, mating, and hosts preferences.
Additional research such as natural insect predators, preventative insecticide products; as well as, resistant varieties of ash, and trapping techniques are ongoing.
Oddly enough, EAB is not considered a destructive pest in it's native area of Asia. Natural preditors, insect disease, and ash tree resistance is enough to keep this insect in check. These natural controls were left behind when Emerald Ash Borer was accidentally introduced to North America through international trade.
Emerald Ash Borer has been found to infest only ash trees. This includes all green ash, white ash, and black ash varieties common to North America.
Trees greater than 2 inches in diameter and larger can become infested. This may occur in woodlands, as well as landscaped urban areas.
While many trees infested by insects have been stressed or diseased, Emerald Ash Borer will infest perfectly healthy trees without any problems what-so-ever.
Although EAB is a strong flying insect, human activities are the primary cause of long distance spread. This includes moving infested trees, logs, and firewood.
It is believed that Emerald Ash Borer arrived in the United States stowed away in wooden crates, pallets and shipping material containing cargo from its native area of Asia.
The biggest threats concerning Iowa’s ash resources are the transportation of firewood, ash logs, or other unprocessed ash articles from EAB infested states.
There is now a Federal Law, as well as State Laws, prohibiting the interstate and intrastate transportation of these articles from EAB infested areas.
Where Is EAB?
Link: Where is EAB currently on the map ?
In the summer of 2002, the Emerald Ash Borer (Agrilus planipennis) was discovered for the first time in southeast Michigan near the international port cities of Detroit and Windsor, Ontario.
Entomologists believe the insect was in the Detroit area anywhere from five to 15 years before its discovery. EAB is native to Asia, and is thought to have found its way to the United States through solid wood packing material, such as crates and pallets commonly used in international trade.
(Click on the pictures for a larger view)
In 2003, the insect was discovered in Maryland, Ohio, and Ontario Canada. Experts had thought the 2003 infestations were eradicated, but they have since been rediscovered in original and adjacent areas.
In 2004, the borer was discovered in Indiana.
In 2006, EAB was detected in Illinois and Maryland.
In 2007, Pennsylvania found its first infestation.
In 2008, West Virginia, Virginia, Missouri and Wisconsin have detected Emerald Ash Borer infestations.
In 2009, the closest known infestation near Iowa was found along the Mississippi River at Victory, Wisconsin near the Minnesota and Iowa borders. Another location was confirmed in St. Paul, Minnesota the same year.
EAB Basic Biology
Link: If homeowners should not plant ash trees, what species are recommended in Iowa ?
Insect Lifecycle:
Beetles emerge from infested ash trees through D-shaped exits from May through September, with peak emergence expected in mid-June
Starting two weeks after emergence, female beetles will lay 60 to 80 eggs in bark crevices.
Seven to ten days later, larvae hatch and chew their way under the bark.
S-shaped, or serpentine feeding galleries of the larvae are found under the bark, and are filled with fine sawdust-like material called "frass".
Larvae have four "instars," or growth stages, and will eventually grow to 1 - 1.25 inches long.
Larvae overwinter and finish development during the next spring, emerging as beetles starting in May. Beetles continue to emerge throughout the summer months.
In heavily infested trees or stressed trees, the EAB lifecycle is completed in one year.
In healthy trees and newly-infested trees, the lifecycle can take as long as two years.
The Emerald Ash Borer belongs to a group of insects known as metallic wood-boring beetles. Adults are dark metallic green in color, measuring approximately 1/2 inch long and 1/8 inch wide.
Larvae are a creamy white color and can be found under the bark of infested ash trees. The life cycle of this insect generally spans one calendar year, but can overlap into the following year.
Other EAB Facts:
Beetles cause very little damage to trees. They do feed on ash leaves, but not to excessive levels.
Larvae feed under the bark of ash trees disrupting the tree’s ability to transport water and nutrients, which can ultimately kill the ash tree in as little as two years.
It was originally believed that the beetles were not strong fliers, however research has shown an adult female looking for a place to lay her eggs can fly at least 12 miles.
The Emerald Ash Borer is difficult to find because the beetle does not respond strongly to pheromone-based lures; therefore, there are only marginally effective detection traps available.
Experience has taught us that infestations tend to be at least three-to-five years old before discovery, and also well established.
Ash tree symptoms can easily be confused for disease, enviromentally related, or other insect problems.
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