Many species of moths and butterflies are known to exhibit a seasonal polymorphism, where one form predominates at one time of year and an alternative form occurs in a different season. Some species also show differences in adult size between two seasonal forms. In some cases, the change in seasonal markings has been shown to correlate with temperature; in these instances it is believed that one color form can provide more rapid or effective solar heating through a larger proportion of darker patterns. In other cases, the seasonal forms are believed to be connected to a more effective cryptic ability according to the nature of available background surfaces.

This Developmental Biology text site offers several well illustrated examples of seasonal forms in butterfly species.

Among the Geometrinae, several species have been shown to exhibit polyphenism, including Nemoria bistriaria, pictured below.

Bright green and darker melanic adult forms can be found in Nemoria lixaria, but may not be as tightly tied to season.