Host-associated larval polychromatism is described for the first time for the Neotropical hairstreak Strymon bubastus (Stoll, 1780) (Lepidoptera, Lycaenidae, Theclinae, Eumaeini) based on larvae collected in the Atacama Desert of northern Chile on inflorescences of Phyla nodiflora (L.) Greene (Verbenaceae) and Waltheria ovata Cav. (Malvaceae) and reared to adult. This is the first record of a host plant in the family Verbenaceae for S. bubastus. Although other Malvaceae already have been recorded as its hosts, this is the first record of it feeding on W. ovata. Identical sequences (n=19) of the DNA barcode fragment (657 base pairs) of the cytochrome c oxidase subunit I (COI) gene were obtained from larvae collected on the two plants, providing additional support for conspecificity. However, deep divergence (>2%) was found among these sequences and others from geographically distant localities of the Neotropics. Deep divergence could be associated with phenotypic differentiation of S. bubastus over its wide geographic range.