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NC Commissioner Troxler: Elm Zigzag Sawfly

NC Commissioner Troxler: Elm Zigzag Sawfly

A county ranger with the N.C. Forest Service recently found the state’s latest invasive pest – the elm zigzag sawfly. It’s name comes in part by the zig-zag pattern created on leaves when the young larvae eat. It is native to Asia and has now only been previously found in Quebec, Canada and Virginia. NC Ag Commissioner Steve Troxler has details:

Not only is North Carolina an attractive state to people, but it is apparently also attractive to destructive bugs.

We have another pest in our state – the elm zigzag sawfly.

Young elm zigzag sawfly larvae create zigzag-shaped damage in elm leaves.

This pest is native to Asia and had previously only been found in Quebec, Canada in 2020 and Virginia in 2021.

One of our Forest Service county rangers found it in the Westfield community in Surry and Stokes counties, just north of Pilot Mountain.

The females can reproduce without mating and can have multiple generations per year. So, though they are small, this pest can be mighty destructive because they increase population size quickly.

Sawflies are a type of non-stinging wasp that is harmless to people and animals. When they are in the young larvae stage, they eat on leaves in a distinctive zig-zag pattern.

At this stage they are small, green caterpillar-like larvae less than half an inch long and feeds exclusively on elm leaves.

Sawflys are strong flyers, which increases their ability to spread from established areas.

It is still to be determined if trees can recover from defoliation from this pest. Certainly, with it being a foreign pest outside its native range there are concerns of it weakening, stressing and eventually killing trees.

If you have elm trees, it’s a good idea to watch for defoliation and signs of this pest. If you suspect you could have this pest, try to take a photo of it and leaves that have been eaten and contact your local N.C. Forest Service county ranger.

Images courtesy NC State University