Dynamine postverta, the Mylitta Greenwing or Four-spot Sailor, is a butterfly in the Nymphalidae family. It is found throughout most tropical and subtropical areas of central and South America, from Mexico south to Argentina and Paraguay. The habitat includes primary rainforests, humid deciduous woodlands, scrubby grassland and farmland at altitudes up to about 900 metres. The larvae feed on Dalechampia species. They are slug-like, with tiny rosettes of spines on the back.