New pest affecting elm trees in St. Lawrence County

Published: Oct. 3, 2022 at 5:10 PM EDT
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BRASHER FALLS STATE FOREST, New York (WWNY) - A new invasive species is threatening a certain kind of tree in St. Lawrence County.

“To find this pest in that area, with the high concentration of elm that are there it is a bit alarming.”

That’s what New York Department of Environmental Conservation Entomologist Liam Somers says about the elm zigzag sawfly -- an Asian bug – that’s now in St. Lawrence county and set to slowly eat the region’s elm trees.

According to Somers, experts knew the sawfly was close in Quebec, but admits he’s shocked it’s now at Brasher Falls State Forest.

“They do have the ability to cause severe defoliation damage,” he said. “So far, there hasn’t been any mortality linked to their defoliation, but with an elm tree that’s already been severely impacted by Dutch elm disease, this is just another stressor added on top of that.”

While the zigzag sawfly is more prevalent in forested areas, DEC officials are more concerned about the elms in urban areas.

Elms that are more separated from each other are at high risk of getting infested with the sawfly.

DEC officials say if you see a zigzag eating pattern on any elm leaves you should contact the DEC immediately.

In the meantime, Somers and his team will continue to learn more about just how much danger the elms may be in.

If you do see something like this on your elm trees, the DEC wants to hear from you through iMapInvasives’ online reporting system.