New Exotic Pest Detected For First Time in New York Trees
A new exotic pest has been found for the first time in New York trees.
The elm zigzag sawfly was detected at three locations in St. Lawrence County, including Wilson Hill Wildlife Management Area, Brasher State Forest, and Lost Nation State Forest.
Zigzag Leaf Pattern
This exotic pest gets its name from the zigzag pattern young larva make on elm tree leaves. The New York State Department of Environmental Conservation (DEC) said it can cause severe defoliation, branch dieback, and crown thinning.
Although the sawfly has not yet been shown to cause tree mortality, repeated defoliation by established sawfly populations would put added stress on native elm trees already heavily impacted by Dutch elm disease.
Native to East Asia
The elm zigzag sawfly is native to East Asia but was discovered in southern Québec in 2020. DEC's Division of Lands and Forests staff began surveying for the pest along the Canadian-U.S. border in 2021.
At this time, sawfly populations appear to be at low levels and causing only minor damage.
Once the sawfly enters a region it's capable of flying up to 56 miles in a year. The female sawfly lays up to 60 eggs at a time and there are four to six generations a year, allowing these pests to quickly establish themselves in new areas.
"Assessing threats to the health of our forests and street trees is essential for maintaining the immeasurable benefits they provide," said DEC Commissioner Basil Seggos. "DEC will continue to investigate the potential threat of elm zigzag sawfly to determine if management actions are needed to protect New York's elms and the variety of wildlife that depend on these trees."
The DEC is encouraging the public to report sightings of the elm zigzag sawfly through NY iMapInvasives' online reporting system.
For more information about the elm zigzag sawfly, visit the Invasive Species Centre website.