The polyphagous larvae live on a variety of deciduous and coniferous trees[5] and can cause severe damage in years of mass reproduction.

[9] The species epithet dispar means 'to separate' in Latin; it refers to the sexual dimorphism observed in the male and female imagines.

[8]: 9 In July 2021 the Entomological Society of America decided to remove the name "gypsy moth" from its Common Names of Insects and Related Organisms List as "hurtful to the Romani people", since gypsy is considered an ethnic slur by some Romany people in North America.

The Asian subspecies (Lymantria dispar asiatica) is native to temperate Asia east of the Ural mountains.

[citation needed] Lymantria dispar was accidentally introduced into North America by artist and astronomer Étienne Léopold Trouvelot in 1869, who imported it from Europe while looking for a source of silk to replace the shortage of cotton caused by the American Civil War.

[citation needed] Since the introduction of the species to North America, L. dispar has caused significant ecological damage.

Over the past century, its range has expanded at an average rate of 21 km (13 mi) per year, resulting in the cumulative defoliation of 33,000,000 ha (82,000,000 acres) of forest between 1970 and 2013.

[20] Defoliation by L. dispar triggers chemical defenses in quaking aspen, rendering them unfit host trees for Polyphemus moths, posing an additional threat to their conservation.