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Spongy moths (Lepidoptera: Erebidae) are invasive leaf-eating (defoliating) pests that threaten trees and shrubs in urban, suburban, and rural landscapes. The spongy moth was accidentally introduced to the U.S. in 1869 by an amateur French entomologist in Massachusetts who sought to establish a hardier American silkworm industry. These moths now commonly occur in the northeastern U.S. and are also found in parts of Illinois, Indiana, Michigan, Minnesota, North Carolina, Ohio, Virginia, West Virginia, Wisconsin, California, Oregon, and Washington. In Utah, according to the Utah Department of Agriculture and Food (2021), the spongy moth is anticipated to survive and multiply rapidly if populations become established. This pest was first detected in Utah in1988 in monitoring traps and was quickly eradicated via extensive trapping and spray applications of Bacillus thuringiensis kurstaki (Btk), a naturally occurring bacterium. Since that time, additional specimens have been detected and eradicated, most recently in 2016 (1 moth) and 2020 (1 moth). This fact sheet describes this pest, its hosts, life stages and history, damage symptoms, and management.

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