Invasive elm zigzag sawfly causing concern in Stokes, Surry counties

North Carolina officials are warning of a new invasive species in the region, the elm zigzag sawfly.

The sawfly is a type of wasp considered to be harmless to humans and animals. But experts say that despite their diminutive size, sawflies can cause significant damage to elm trees due to rapid population growth.

The elm zigzag sawfly begins as a small, green, caterpillar-like larva that feeds on the leaves of elm trees. It’s named for what biologists call a saw-like appendage used for egg-laying, and for the zig-zag pattern it creates in leaves when feeding. 

Forest health specialists say trees usually recover from defoliation caused by native caterpillars. But they warn that repeated defoliation from species such as the sawfly can weaken or stress the trees to the point of killing them.

According to a news release, the elm zigzag sawfly had only previously been found in Virginia and Quebec, Canada. But it has recently been spotted just north of Pilot Mountain, raising concern about an impact in Surry and Stokes counties.

State officials are urging residents to photograph any sightings and report them to a Forest Service ranger.