An iNaturalist.CA report triggered the discovery of a new invasive pest in North America. The elm zigzag sawfly, Aproceros leucopoda Takeuchi, was confirmed present by the Canadian Food Inspection Agency in the province of Quebec, Canada this summer.
The larval stages of this invasive pest cause severe defoliation damage to elm trees. During growing season, the larvae chew distinctive zigzag-shaped tunnels between the midrib and edges of elm leaves.
The pest is a strong flier and can easily hitchhike on infested nursery stock. Sightings of the elm zigzag sawfly can be reported directly to the Canadian Food Inspection Agency or the Department of Environmental Conservation in the US.