The elm zigzag sawfly, or Aproceros leucopoda, first arrived in the United States in 2021. It feeds on the leaves of elm trees, and researchers are not sure what that will do in the long-run to the ecology of the area.
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A new paper tracking the insect's spread reports the sawfly first arrived in North Carolina in 2022.
"This is a very new invasive species first found in Canada in 2020 and in the U.S. in Virginia in 2021," said the study's first author Kelly Oten, assistant professor of forest health at NC State. "In 2022, four additional states confirmed it. It happened very quickly. This paper was our effort to document the very first stages of the invasion, and let people know where it is, and what we know about its biology and management so far."
So far, the sawfly is not spread all across North Carolina; it's only been confirmed in one region. Oten said a homeowner in that area reported the large elm trees on their property being severely defoliated. When Oten went to investigate, she found thousands of sawflies.
The homeowner's elm trees came back full of leaves this year, but the sawflies attacked again.
"Usually defoliation doesn't harm a tree unless it happens over and over again. If they are getting defoliated year after year, we have to consider the impact on the trees' health," Oten said.
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Oten said North Carolina has more than 210 million elm trees and it's too early to tell if the sawflies pose a significant threat to elms in the Tar Heel state.
"Our recommendation for the public right now is to not freak out. We don't think this is going to be a tree killer, so people don't need to start cutting down their elms," Oten said.
If you have elm trees near your property, you should periodically check their leaves. You're looking for a very distinctive zigzag pattern -- which is how these sawflies got their name.
If you see that pattern, you should contact the NC Forest Service as soon as possible.