Spongy Moth (formerly Gypsy Moth)

Lymantria dispar — the spongy moth, formerly called the gypsy moth (the common name was retired in 2022 by the Entomological Society of America for being a slur against the Romani people, and 'spongy moth' was selected as the replacement based on the spongy-textured egg masses) — is one of the most economically destructive forest insects in North American history. The species is native to Europe and parts of Asia, where it is held in check by native predators and parasitoids. In 1869 a French amateur naturalist named Étienne Léopold Trouvelot deliberately imported live spongy moth eggs to his property in Medford, Massachusetts as part of an attempt to cross-breed Lymantria with native silk moths and start a North American silk industry. The experiment failed; the moths escaped during a windstorm; the species spread. By 1890 the species was a major Massachusetts pest; by 1980 it had reached the Mississippi; by 2020 it was established across the entire eastern US, much of southern Canada, and into the central US plains. Periodic outbreaks defoliate millions of acres of preferred host trees (especially oak, but also birch, maple, willow, hickory, and dozens of other deciduous species) every 5-15 years. The 1981 outbreak defoliated 13 million acres in a single year. Climate change has expanded the species' tolerated range significantly. The federal Slow-the-Spread program (USDA Forest Service) uses pheromone trapping to detect new populations and aggressive eradication including the bacterial insecticide Bt and the fungal biocontrol Entomophaga maimaiga. Males and females are dramatically dimorphic: males are 35-40 mm wingspan, brown, and capable fliers; females are 50-60 mm wingspan, white-and-black-marbled, and FLIGHTLESS in the European subspecies (the female emerges, releases pheromone, mates with arriving males, lays eggs, and dies without ever moving from the cocoon site).