N.Y. (WETM) — New York State has a new invasive pest, and the Department of Environmental Conservation (DEC) wants you to be on the lookout for it.

According to the DEC, the elm zigzag sawfly (Aproceros leucopoda) is an insect that only eats elm leaves. This insect is native to East Asia and gets its name from the distinct “zigzag” pattern larvae make when they chew through leaves. This pattern isn’t always visible because larvae will eat leaves down to the vein. Suspicious elm leaf loss can be a sign that these insects are present.

Elm zigzag sawflies haven’t been known to cause tree deaths (yet), but their larvae have significantly harmed the health of elm trees across the state. Larvae feeding can cause significant defoliation (large loss of leaves), branch dieback, and crown thinning for infested elms. Infestations also weaken the overall health of elms and leave them more vulnerable to other pests and diseases. Additionally, the competition between elm zigzag sawflies and native insects may cause problems for other sawfly species and other elm-eaters.

According to the DEC, elm zigzag flies were first spotted in New York State last August in St. Lawrence County, and their range has spread significantly within the past year. So far, these invasive insects have been found in a total of 10 counties across the state, and new sightings are reported each week.

If you see a zigzag pattern on an elm leaf or notice suspicious elm tree leaf loss, report your sighting to NY iMapInvasives or email pictures of your sighting to foresthealth@dec.ny.gov.