Wasps released into Chippewa National Forest for emerald ash borer control

CASS LAKE — State and federal agencies are working on a joint effort in the Chippewa National Forest to slow down the spread of emerald ash borer.

The effort throughout September has involved the release of three species of non-stinging wasps to target the borer at different life stages.

The parasitoid wasps are small and do not harm humans. The U.S. Department of Agriculture has tested these species to ensure the wasps won’t impact the forest's environment.

While Minnesota's ag department oversees the program statewide, the agency enlisted the Minnesota Department of Natural Resources for assistance in releasing wasps in the Chippewa National Forest.

"Parasitoid wasps are a proven biological control that target EAB without harming other species. By releasing them at the forest landscape level, we’re adding a long-term tool to slow the spread and protect Minnesota’s ash trees,” stated Eric Otto, DNR forest health specialist.

More than 5,000 parasitoid wasps were released into 200 acres of infested areas of the Chippewa National Forest this year, with nearly 4,000 released last summer.

The Minnesota Department of Agriculture began releasing wasps in 2010 to slow the spread of emerald ash borer, with the wasps released into 55 infested sites since.

Emerald ash borer was first discovered in Minnesota in 2009. In its larval stage, the invasive pest kills ash trees by tunneling under the bark and feeding on the part of the tree that moves nutrients up and down the trunk.

Minnesota forests are home to an estimated 1 billion ash trees. Minnesota cities also have an abundance of ash, making up 60% of the trees in some communities.