Indianapolis, IN – State officials are warning Hoosiers to watch for an invasive insect that targets elm trees, with confirmed activity across the Midwest, including neighboring Ohio.
According to the Indiana Department of Natural Resources (DNR), the elm zigzag sawfly (Aproceros leucopoda) attacks both native and introduced elm species (Ulmus spp.). The pest feeds exclusively on elm leaves from April through October, leaving behind a distinctive zigzag pattern in the leaf tissue. DNR reports that the insect appears to infest roadside and open-area trees more often than forest trees.
The adult sawflies are described as small, slender, black, wasp-like insects with yellow legs. They reproduce through parthenogenesis, meaning females can lay viable eggs without mating. So far, no male elm zigzag sawflies have been documented in North America.
The DNR urges residents to report any sightings or suspected damage by contacting the Division of Entomology and Plant Pathology at DEPP@dnr.IN.gov, calling 1-866-NO-EXOTIC, or using the online pest reporting portal at on.in.gov/report-pests. Reports should include the observer’s name, location, and any details or photos of the damage.
Photos provided by Virginia Tech show the insect’s feeding patterns, including jagged leaf edges and the insects resting on leaf surfaces. The agency stressed the importance of early detection to prevent further spread of the pest in Indiana.
Officials encourage tree owners to inspect elm trees regularly during the growing season and to be alert for unusual leaf damage patterns that could indicate the sawfly’s presence.
This article was produced by a journalist and may include AI-assisted input. All content is reviewed for accuracy and fairness.
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