How to tell if the invasive NC sawfly is in your garden


RALEIGH, NC (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 zigzag elm sawfly, has been spotted in two counties in the state. It had previously only been found in Canada in 2020 and in Virginia in 2021. It is native to Asia but has spread to many countries outside of its original range.

Elm zigzag sawfly larva. (Courtesy of North Carolina Department of Agriculture)

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

These caterpillar look-alikes can also cause damage to elm trees.

The NCFS said trees defoliated by native caterpillars generally recover, it is too early to tell if trees defoliated by zigzag sawflies can recover.

The NCFS said repeated defoliation of a tree by the invasive gypsy moth can lead to weakened or stressed trees and, in some cases, death.

“If you see a defoliated elm tree that you suspect may be affected by this new invasive pest, note the location, attempt to safely photograph the insect and the leaves that have been eaten, and contact your local NCFS County Ranger. “said Agriculture. Curator Steve Troxler. “As North Carolina’s list of invasive species grows a little longer, you can help us keep our forests healthy and thriving by reporting these nasty insects.”

The flies were found in Surry and Stokes counties.

Owners of infested areas are urged to exercise caution to avoid spreading the sawfly as they may hitchhike on plants or soil, or as cocoons attached to various objects, Heath said.


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