Emerald Ash Borer

Emerald Ash Borer discovered in wood. Credit: Susan Greenhouse, California Department of Fish and Game

In the forests of Wisconsin, a quiet but fierce battle to save the state’s ash tree population has begun. In response to the infestation of invasive emerald ash borers, entomologists from the University of Wisconsin-Madison (UWM) have released hundreds of parasitic wasps to help rid the area’s forests of the destructive beetles.

Native to China, the emerald ash borer was first discovered in the United States in 2002, likely having been transported via shipping containers. Since then, the beetles have wreaked havoc on ash forests across the country by burrowing into the trees where they eat the wood and hatch their larvae. After about two years of the beetles’ habits, the trees finally die. The death toll of ash trees has climbed into the tens of millions.

While chemical treatments have proven to keep the beetles at bay in residential areas, greater steps must be taken to stop the infestation from spreading farther into forests. The UWM research team, consisting of entomologists and researchers, headed to China for a solution. There they discovered three types of parasitic wasps that are known to prey on the beetles. The team recently released hundreds of the wasps in isolated areas that have seen some of the greatest destruction from the beetles.

Though the team is optimistic about the wasps’ capabilities to slow or even stop the spread of the beetles, they aren’t quite certain what the long-term effects of releasing another invasive species into the wild will be. If all appears to be going well, the team plans to release another round of the beetle-hungry wasps later this summer.