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Many confusing Japanese beetles for more harmful emerald ash borer


Media Contact: Catherine Dehdashti, U of M Extension, (612) 625-0237, ced@umn.edu

ST. PAUL, Minn. (8/1/2011) —Minnesota has been on high alert to watch for the emerald ash borer since it was first discovered here in 2009. But experts recently inundated with reports of emerald ash borer sightings are finding it a case of mistaken identity—with the Japanese beetle, says University of Minnesota Extension entomologist Jeff Hahn.

"Not every green insect is emerald ash borer," said Hahn. "This summer Japanese beetles have been very common in the Twin Cites as well as in areas to the south and southeast, and they are often mistaken for emerald ash borer."

Unlike the destructive emerald ash borer, which threatens the health of the state's 975 million ash trees, Japanese beetles do not usually cause lasting damage.

To view a photo chart that compares emerald ash borer with the Japanese beetle and other look-a-likes, visit www.extension.umn.edu/go/1074. Emerald ash borer is a slender insect about one-third to a half inch long. Its body is widest just behind the head and then it gradually tapers back to tip of the abdomen.

"What really stands out about emerald ash borer is its bright, iridescent green color," said Hahn. "And if it lifts its wings up, you will see the body underneath is a purplish-magenta color."

By contrast, Japanese beetles are broadly oval, about three-eighths of an inch long with a bright emerald green head and upper body. Japanese beetles also have shiny bronze-colored wing covers. An easy to way to identify a Japanese beetle is by the five small white tufts of hair along each side of the abdomen and two larger white tufts on the tip of the abdomen. No similar insect will have those spots, according to Hahn.

To learn more about emerald ash borer, visit www.extension.umn.edu/issues/eab. To learn more about Japanese beetles, visit www.extension.umn.edu/go/1075.

If you see an insect that you believe could be an emerald ash borer, contact the state Agriculture Department. Call the department's "Arrest the Pest" Hotline at (888) 545-6684 or send an email to Arrest.The.Pest@state.mn.us.



Source: Jeff Hahn, entomologist, University of Minnesota Extension

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