Arcas imperialis is in the family Lycaenidae, often called gossamer-winged butterflies. They have distinctly different coloring from either wing side, with green and black underside (ventral) and blue and black top (dorsal). And they have two trailing black ribbons on each of their hindwings.
Arcas are a neotropic genus, and the Arcas imperialis are usually found from southeastern Mexico into some northern regions of South America.
Learn more about the McGuire Center for Lepidoptera & Biodiversity at the Florida Museum.