The scientific name of the gypsy moth comes from the Greek word "porthein", meaning "to destroy", due to the ability of its larvae to defoliate trees; and the Latin-derived word "dispar", from the verb to separate, which refers to the differing characteristics between the sexes. Males have a wingspan of 35 to 50 millimetres, while that of the females is between 55 and 90 millimetres. The sexes also differ in terms of colour and antenna structure.
The gypsy moth lives in deciduous forests and orchards in Europe (with the exception of the far north), North Africa, and temperate regions of Asia.
Female gypsy moths deposit up to 2,000 eggs at the base of tree trunks or on twigs or rocks. The eggs are covered in white or gray hairs to protect them from predators and insulate them from the cold. The larvae winter inside the eggs and may be transported over large distances by the wind. Once hatched, they feed on leaves, completely stripping trees of their foliage. Gypsy moth larvae feed on over 300 plant species and can cause serious damage in deciduous forests and orchards. They prefer the leaves of oak, elm and fruit trees.