Invasive Species: Stingless Wasps Deployed to Stop Emerald Ash Borers in Minnesota

Jun 29, 2010· 1 MIN READ
Salvatore Cardoni holds a political science degree from the George Washington University. He's written about all things environment since 2007.
This borer won't be worth a nickle once the wasps are set free. (Photo: Eric R. Day/Virginia Polytechnic Institute and State University)

It’s a visitor from a foreign land. It has no natural adversary. And it threatens Minnesota’s 900 million ash trees. It is the emerald ash borer, an exotic beetle first discovered near Detroit, Michigan, in 2002. Now, researchers from the North Star State are drawing up battle plans to combat the invasive species—deploying hundreds of stingless, gnat-sized wasps to eat the beetle’s larvae.

"I would not use the words 'silver bullet' at all," Paul Chaloux, coordinator of the U.S. Department of Agriculture's wasp program, told the Star Tribune. "But it's the most promising tool we have right now."

Chaloux hopes that the wasp approach will yield better results than previous attempts to curb the beetle, including tree removal, insecticides, and quarantines.

According to the Star Tribune:

Officials with the Minnesota Department of Agriculture, the lead agency in Minnesota's ash borer war, received a federal permit to release the wasps but are waiting to find a fresh emerald ash borer emergence in a choice location. Minnesota would be the sixth state to get the wasps, which like the ash borers are native to China. Scientists are rearing the wasps in a Michigan laboratory for eventual use against the ash borer.

Adult emerald ash borers are relatively harmless. It’s the beetles’ larvae that devour the inner bark of ash trees. This, in turn, interrupts the trees’ ability to transport water and nutrients.

Scientists don’t know for sure, but the emerald ash borer probably arrived in the United States via plane or cargo ship in the solid wood packing material from the bug's native Asia.

Because the emerald ash borer’s outbreak is so widespread—the beetle has been found in 14 states—researchers and specialists from Ohio, Michigan, Indiana, Wisconsin and Illinois have put together a publication for home and property owners that presents multiple options for treating ash trees. It can be found here.