Experts explain signs of Emerald Ash Borer

3:59 PM, May 8, 2013   |    comments
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Emerald Ash Borer

ROSEVILLE, Minn. - First discovered in Twin Cities in 2009, Emerald Ash Borers have been identified in Ramsey, Hennepin, Winona and Houston counties.

Roseville residents are getting a lesson in how to notice the little green insects.

Heavy woodpecker activity is one of the signs you might first notice on a tree that's been infested with emerald ash borer. Residents should look for dime sized holes from the trunk all the way to the upper canopy, something that is easier to spot without leaves on the trees.

"Adult beetles lay their eggs on the bark. They prefer the upper canopy," says Erika Commers, a plant specialist from the Minnesota Department of Agriculture."The bark is thinner and it's warmer. As the tree is more heavily infested over time, they'll move further down into the trunk and then we'll see it at eye level.

The EAB only affects native ash trees in the Fraxinus family, including the white, green and black ashes. It does not target American Mountain or European Ash, which are in the Sorbus family.

"Essentially the tree dies because it's not able to conduct any water or nutrients from the roots to the canopy, or the canopy to the roots. The larvae eat the vascular tissue," Commers explains.

Woodpeckers eat the larvae are a native and natural predator for the EAB, but wasps from Asia have been released in Minnesota to help control the population.

"It's called a parasitoid. It's a tiny, tiny wasp that's totally stingless, and it has no interest in anything else than this insect for its own life cycle," she says.

Other states have seen success, but ongoing research will tell if those wasps are doing their jobs.

"The whole point of that is just to control the numbers, it's not an eradication system either," Commers added.

If you suspect EAB on your property. Take pictures and contact the Minnesota Department of Agriculture via phone at 888-545-6684 or via email at

For an interactive map outlining where emerald ash borer has been found in Minnesota visit the Minnesota Department of Agriculture site.

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