The Emerald Ash Borer Invasion Saving Your Trees From a Six-Legged Menace

Metallic green in color and measuring just a half-inch long and an eighth-of-an-inch wide, the emerald ash borer, a beetle native to Asia and first discovered in Michigan in 2002, has been responsible for the deaths of hundreds of millions of ash trees in North America. The damage inflicted by the insect has reportedly run into the hundreds of millions of dollars. Who knew that such a tiny insect could wreak so much havoc throughout the country.

But wreak havoc it does. The EAB is now present in about 28 states, including Illinois, where according to the state's Department of Agriculture it was found in 2006—and if the invasion is not dealt with, the costs could reach into the billions of dollars, according to the Emerald Ash Borer Information Network (  

Emerald Ash Origins

The city of Chicago, which had its first confirmed case of emerald ash borer in 2008, says that ash trees make up 17 percent of the city's street tree population, or about 85,000 individual trees. And that number isn't counting the 300,000 ash trees growing on private property. Last year, Illinois announced it would drop its internal emerald ash borer quarantine, but that 10 additional counties had detected the shiny menace within their borders, bringing up the total count of affected counties to 60.

“It happened really quickly,” says Tom Tiddens, a supervisor in the plant care department of the Chicago Botanic Garden. “I've been watching this for a number of years. We found it in Illinois, then all of a sudden we found it in the next town over, and all of a sudden it was found on the next block. We thought we were going have some years to deal with this, but we saw how fast it was happening. We had to gear up really quickly.”

How It Began

It is suspected that the emerald ash borer arrived in North America via wood packing crates from Asia, says Tiddens. Interestingly, on its home turf the insect infests ash trees, but does not kill them. So why do U.S. trees fare so badly when they tangle with the EAB? “I think we have determined it has to do with the fact that the ash borer evolved in Asia along with the ash trees,” Tiddens says, “and those trees have developed some sort of defense, while ash trees in the U.S. have not. And that's what everybody's trying to figure out: How are the Asian trees different than the ones over here?”


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