Most species have a reduced pair of forelegs and many hold their colourful wings flat when resting.

However, the under wings are, in contrast, often dull and in some species look remarkably like dead leaves, or are much paler, producing a cryptic effect that helps the butterflies blend into their surroundings.

Throughout the family, the front pair of legs in the male, and with three exceptions (Libythea, Pseudergolis, and Calinaga) in the female also, is reduced in size and functionally impotent; in some, the atrophy of the forelegs is considerable, e.g., the Danainae and Satyrinae.

Several taxa are of unclear position, reflecting the fact that some subfamilies were formerly well-recognized as distinct families due to insufficient study.

Some suggest the forelegs are used to amplify the sense of smell, because some species possess a brush-like set of soft hair called setae, which has led researchers to believe the forelegs are used to improve signaling and communication between the species, while standing in the other four.