The invasive elm zigzag sawfly has been detected in St. Clair County, the first detection in Michigan, according to the Michigan Department of Agriculture and Rural Development (MDARD).
According to the state, the invasive insect was identified by the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (USDA APHIS). An arborist submitted the report through the Midwest Invasive Species Information Network (MISIN) online reporting tool.
“While this is the first detection of the invasive elm zigzag sawfly in Michigan, it’s important to emphasize the insect does not pose a significant threat to Michigan’s people, animals, agriculture or natural resources,” MDARD Director Tim Boring said in a statement. “The elm trees this invasive pest feeds on can typically recover from defoliation by producing new foliage. We encourage residents to be aware of this pest and report suspected sightings to help track its distribution in Michigan.”
According to the state, the elm zigzag sawfly feeds on the leaves of elm trees and can defoliate several elm species. The young larvae create a distinctive zigzag patterns on the leaf as they feed.
It's native to Asia and was first detected in Canada in 2020, then first identified in the U.S. in Virginia in 2021. Since then, it's been reported in several eastern & midwestern states.
Most people are likely to encounter the insect in its larval stage. They can be recognized by a brown band on the head and dark T-shaped markings on the hind legs. Adult sawflies are less commonly found.
The MDARD is encouraging the public to track the spread using the online reporting tool.
