Invasive elm zigzag sawflies eating their way towards NYC trees
NEW YORK -- The state Department of Environmental Conservation is warning the public about a potential invasion of the elm zigzag sawfly.
The insects are native to China and Japan and are named for the patterns they eat into the leaves of elm trees. While we have not seen evidence of these invasive insects in the city yet, experts believe their imminent approach could prove disastrous to green spaces.
NYC Parks said in a statement: "As requested by the New York State Department of Environmental Conservation, we are currently monitoring for the elm zigzag sawfly, and will be reporting any sightings to them."
"At least in the short term, the impact is going to be higher on urban and suburban trees, you know, street trees and trees in people's yards, than it will be in a forested setting," said New York DEC Forest Health research scientist Jessica Cancelliere.
In the adult stage, the elm zigzag sawfly looks similar to a more familiar fly. The larvae feed on the leaves of elm trees, munching their namesake zigzag pattern across the jagged green surfaces. After the buffet, the larvae create cocoons before transforming and flying away.
"It's the young larvae that make that pattern, but as they grow and they eat more, they eventually just devour the whole leaf," Cancelliere noted.
Combined with the already present Dutch elm disease brought by beetles, the sawfly larvae's insatiable appetite for leaves can kill entire trees, destabilize forest areas and eliminate a food source for other insects, the effects of which Europe is already seeing.
"Don't rush to cut down your tree and just kind of play it by ear and see where it goes," Cancelliere advised anyone with affected trees, "because things might ease up next year, and your tree might get some respite."
The state wants the public to report any signs of zigzag patterns left on leaves. The iMapInvasives portal tracks thousands of unwanted guest species across the state. So far, only the spotted lanternfly makes Manhattan's list for sightings.
If you've seen signs of the elm zigzag sawfly or any other invasive species, click here and create a free account to enter data.
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