The Melissa Blue (Lycaeides melissa) is a butterfly of the Lycaenidae family. It is found in Western North America, from Canada to Mexico. The Karner Blue (Lycaeides melissa samuelis) is a subspecies of the Melissa Blue, and was described by the novelist/lepidopterist Vladimir Nabokov. It is sometimes placed in the genus Plebejus.
The wingspan is 22–35 mm. The butterfly flies from April to August depending on the location.
The larvae feed on Lupin, Medicago and Lotus species.