PC: Wisconsin Department of Natural Resources
MADISON, WI (WTAQ) – A new invasive insect has made its way to Wisconsin elm trees.
The elm zigzag sawfly, named for the distinctive zigzag pattern its caterpillars chew in elm leaves, had its first Wisconsin sighting in Portage County on July 4. The insect has since been detected in at least 17 Wisconsin counties.
Originally from Eastern Asia, the elm zigzag sawfly was first detected in the U.S. in 2021 in Virginia.
In many cases, elm zigzag sawfly causes only minor or cosmetic damage to elm trees.
However, levels of damage can vary significantly, and the insect does carry the potential to cause significant defoliation.
P.J. Liesch, extension entomologist, says it’s unknown how the insect got to Wisconsin, but he had a few ideas.
“If someone moves from an eastern part of the country and brings some plants with them, or there’s a movement of nursery stalks and plants being sold at stores, that’s one possibility.”
Additionally, the adult elm zigzag sawfly can fly distances up to 50 miles per year, making it easy for them to move around.
In many cases, the presence of elm zigzag sawfly should not be a cause for alarm for landowners and foresters.
This isn’t the elm trees’ only cause for concern; elm trees in Wisconsin within the last 100 years have decreased due to Dutch elm disease.
“Elms are struggling in that they are still facing Dutch elm disease because it’s still present in the state, and it’s unfortunate that there is another issue popping up.”
Should you notice the insect, careful monitoring is recommended, and management may be warranted to help preserve the health of high-value trees.
The Wisconsin Department of Agriculture, Trade and Consumer Protection reports that there are no current or planned federal or state quarantines for elm zigzag sawfly.
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