European spongy moths (formerly known as gypsy moth) were introduced into Massachusetts in 1869 by an amateur entomologist. Since then, spongy moths have defoliated millions of acres of trees in forests and urban areas in at least 20 states and the Washington DC area.
Spongy moth caterpillars feed on more than 300 species of deciduous and evergreen trees. Their populations tend to outbreak in localized areas about every 10 years. During outbreaks, they may defoliate entire stands of trees or forests.
Spongy moths were first found in Wisconsin in the mid-1970s in the eastern part of the state. By 1989, they had settled along Wisconsin's eastern shore from Milwaukee to Green Bay. Moths have since been found in every county. The eastern two-thirds of the state is considered generally infested and is quarantined. The quarantine prohibits the movement of items that could harbor spongy moth eggs, caterpillars, or adults and allow them to be moved to uninfested areas. For information on what items are regulated and how to comply with the law, go to the Wisconsin spongy moth quarantine page.