The elm zigzag sawfly originated in Asia. It quickly spread throughout Europe, and was detected for the first time in the U.S. in 2021.
Last summer, the wasp-like insect was found throughout Wisconsin.
David Horvath is an arborist in Lake Bluff. He said Illinois could be next.
“Illinois is at the doorstep of this pest. So I would, I would be kind of shocked if we didn’t see it in 2025 here in Illinois.”
In their larvae stage, elm zigzag sawflies eat elm leaves from the edges in a zigzag pattern. Trees impacted by these bugs often looked thinned out. In severe cases, they could eat leaves bare to the veins.
Horvath said that if you detect any signs of an elm zigzag sawfly, you should reach out to a local ISA-certified arborist and to the Morton Arboretum so their spread can be tracked and modeled.
Elm trees are prolific across the state. Horvath said it could enable the rapid spread of this invasive species.
“It kind of has a buffet out before it in this region. And that is one thing that’s enticing to this pest in this area is we have a lot of elm trees.”
Horvath said that if Illinois residents detect any signs of an elm zigzag sawfly, they should reach out to a local ISA-certified arborist and to the Morton Arboretum so the insect's spread can be tracked and modeled.
The Illinois Department of Agriculture confirmed that it was found in Busse Woods in Cook County in 2024.