RALEIGH, N.C. (WNCN) – If it looks like a caterpillar and eats like a caterpillar, is it really a caterpillar? In this case, no.

The North Carolina Forest Service says an invasive pest, the elm zigzag sawfly, has been spotted in two counties in the state. It had only been previously found in Canada in 2020 and Virginia in 2021. It’s native to Asia but has spread to numerous countries outside of its native range.

photo of elm zigzag sawfly larva scattered in the dirt
Elm zigzag sawfly larva. (Courtesy of North Carolina Department of Agriculture)

NCFS said sawflies, a type of wasp, are harmless to other animals and people as they are unable to sting. Young larvae leave a zigzag-like patterns in the leaf when they feed. The small, green, caterpillar-like larva are less than half an inch long and feed on the leaves of elm trees.

These caterpillar lookalikes can also cause harm to elm trees.

NCFS said that trees defoliated by native caterpillars generally recover, it’s too early to tell if trees defoliated by the zigzag sawflies can recover.

NCFS said repeated defoliation of a tree by the invasive spongy moth can result in weakened or stressed trees and in some cases, death.

“If you see a defoliating elm tree that you suspect is being impacted by this new invasive pest, note the location, try to safely photograph the insect and the leaves that have been eaten upon, and contact your local NCFS county ranger,” said Agriculture Commissioner Steve Troxler. “As North Carolina’s list of invasive species gets a little longer, you can help us keep our forests healthy and thriving by reporting these bad bugs.”

The flies have been found in Surry and Stokes Counties.

Homeowners within infested areas are asked to take caution to prevent spreading the sawfly as they can hitchhike on plants or soil, or as cocoons attached to various objects, Heath said.