Endemic populations may defoliate small groups of poplar and willow, especially trees growing in the open. Epidemic populations may completely defoliate large cottonwood plantations. Complete defoliation twice during the same growing season will result in growth loss, crown dieback, and in some cases, tree mortality. Identifying the Insect. They have four light yellow lines on the back, and a bright yellow and several indistinct lines on each side.
Adults are brownish gray, with three whitish lines crossing each forewing.
The hindwings are crossed by a wavy band. Identifying the Injury. Severe defoliation occurs during summer and early fall. Many one or two-leaf webbed tents hang from the branches. The larvae are gregarious and live in tents or webs constructed by pulling together the edges of one or more leaves and lining them with silk.