Elm zigzag sawfly (Aproceros leucopoda)
Description: First detected in North America in Quebec, Canada in 2020 and has since been confirmed in Virginia, North Carolina, Maryland, Pennsylvania, New York, Ohio, Vermont and Massachusetts.Identification: Small, 1.88 mm. long and grayish-white in color. Mature larvae are green with a black band on their head and T-shaped brown or black markings above the second and third pair of true legs. Can reach 10-11 mm. long. Adults are small, shiny black, winged insects that reach 7-8 mm. long. They have a white patch on the underside of the thorax and yellow to white legs and smoky-brown wings.
Hosts: Native to East Asia. Hosts include all elm tree species (Ulmus spp.) including American elm (U. americana), Winged elm (U. alata), Siberian elm (U. pumila), Chinese elm (U. parvifolia), Ulmus 'Cathedral' Japanese X Siberian hybrid, and English elm (U. procera).
Life Cycle: Females reproduce parthenogenetically and lay up to 60 eggs singly along the tips of elm leaf serrations. Larvae emerge in 8 days and begin feeding. Larvae have 6 instars and pypate within 3 weeks. There are 2 types of cocoons: loosely-spun, net-like cocoon attached to leaves (summer mos.) or a solid-walled cocoon in leaf litter or soil (overwintering gen.)
Impact and Damage: Larvae create a zigzag pattern in the leaves, while older larvae feed more broadly on leaf tissue, leaving hehind only thick leaf veins and often eliminating the zigzag-shaped damage. Large outbreaks are capable of defoliating large elm trees.
Monitoring and rapid response: Small populations can be removed by hand but for heavy infestations or large trees, general-purpose insecticide labeled for use on trees and shrubs can be used. Treatments should occur in the spring as soon as larvae are present. Credits: The information provided in this factsheet was gathered from NC State Extension Publications (Aug.31, 2022) .
Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org).Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).