NEWS

Have you seen this new invasive insect emerging in Ohio? State officials want to know

Chad Murphy
Columbus Dispatch

A new invasive insect is emerging in Central Ohio, and state officials want to know if you see one.

Elm zigzag sawfly adults were trapped in Delaware County the week of April 15, according to the Ohio Department of Natural Resources Division of Forestry, as reported by Ohio State University's Buckeye Yard & Garden Online.

Elm zigzag sawfly larva create a distinctive zigzag pattern through the elm tree leaves as they feed.

What is an elm zigzag sawfly?

The insect is an invasive species native to Asia, said Tom Macy, forest health program manager with the ODNR Division of Forestry. It was first found in Canada in 2020, and then in multiple eastern U.S. states in 2021 and 2023.

In Ohio, the insect larvae were found infesting elm trees at the U.S. Department of Agriculture’s Forest Service Northern Research Station lab in Delaware and in northern Franklin County in July 2023, according to a statement from ODNR. The species was officially confirmed by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service on July 21.

Elm zigzag sawflies:Invasive insects found in Ohio for the first time

How did the elm zigzag sawfly get its name?

The insect's larvae feast on elm leaves, leaving a zigzag pattern as they move, according to ODNR. The larvae are up to a half-inch long, resemble caterpillars and are light green in color. They feed exclusively on elm leaves, from both native and non-native species.

Adults are less commonly seen, but are about a quarter-inch in length, shiny black and winged.

How destructive is the elm zigzag sawfly?

According to ODNR, the larvae are capable of "significant defoliation" of elm trees. However, there are no reports of tree deaths from the insect. The elm zigzag sawfly's impact on forests and urban insects is currently being researched. Also, ways to manage the species are being studied.

What should you do if you spot elm zigzag sawflies?

If you believe you found an elm zigzag sawfly or see signs of infestation, ODNR asks that report the sighting using the Great Lakes Early Detection Network mobile app. ODNR also suggests trying to get a good photo or collecting a specimen and notifying the ODNR Division of Forestry at (614) 265-6694.

Alternately, you can report it to the Ohio Department of Agriculture using its Plant Pest Reporter or to your local OSU Extension Office, according to Buckeye Backyard.