August Invasive Species News - New York's Newest Exotic Pest: The Elm Zigzag Sawfly

New York State Department of Environmental Conservation
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August Invasive Species News

Have you heard about the Elm zigzag sawfly (EZS)?

Elm zigzag sawfly leaf damage

What is it?

The elm zigzag sawfly (Aproceros leucopoda) is an exotic insect pest native to East Asia that feeds exclusively on the leaves of elm trees. It was first detected in St. Lawrence County in August 2022 and has since been found in many locations across New York State.

Elm zigzag sawfly leaf damage

EZS can most easily be identified by their unique zig-zag feeding pattern. Learn more about EZS and how to identify it.

Where is it in New York?

Just this summer, EZS has been found in Allegany, Ontario, Madison, Ulster, Schenectady, Albany, Saratoga, Warren, and Clinton counties, with new counties being confirmed weekly.

How is it impacting our forests?

As a newly introduced species, the impact of EZS on our forests is not yet clear. Most reported defoliation has been minor, with only 2 – 5% of leaves showing damage. However, one Niskayuna resident reported several Siberian elms in their yard that were severely defoliated. Potentially, urban forests could endure the worst of EZS damage, as various elm cultivars are widely planted in ornamental landscapes. Open-grown elms with large canopies provide abundant foliage to support multiple generations of EZS within a growing season.

What is DEC doing about it?

The DEC has partnered with the SUNY College of Environmental Science and Forestry to conduct research on the phenology, damage severity, and associated insect community of EZS. This research will help us better understand how EZS interacts with our environment and what, if any, natural controls might be present. The DEC also participates with a working group of practitioners and researchers from all states with EZS present, in order to stay up-to-date on current research and best management practices.

What can I do to help?

Keep an eye out and report sightings to iMap Invasives! This pest is being detected in new counties weekly, so reports are incredibly valuable right now to help us understand the full range of this pest.

If you are in or near the St. Lawrence Eastern Lake Ontario region, you can help with early detection efforts! The SLELO PRISM has developed an invasive species Volunteer Surveillance Network with partners and community members. To join this effort, please visit the SLELO Elm Zigzag Sawfly webpage and fill out the form at the bottom of the page.

Photo credit (2nd photo): Gyorgy Csoka, Hungary Forest Research Institute,

Participate in the Asian Longhorned Beetle Pool Survey!

Asian Longhorned Beetle op top of a float in a pool

Do you own a pool? You can help protect NY’s trees from the invasive Asian longhorned beetle (ALB)! Check your pool filter for insects that resemble ALB and email photos of suspects to

Visit our website for ID tips and common look-alikes.

No pool? No problem! You can still help. Watch for signs of ALB in trees including round, dime-sized exit holes and sawdust collecting on trunks or branches.

Learn more about the Asian Longhorned Beetle.