The lycaenid butterfly, Niphanda fusca, has a parasitic interaction with the ants, Camponotus japonicus. The larvae of N. fusca were carried by the ant workers to their nests at third-instar stage. In the ant nest, N. fusca larvae are fed primarily on regurgitations from workers. In this interaction, N. fusca larvae may exploit their host’s communication signals. Cuticular hydrocarbons, known to be nestmate and queen recognition cues in ants, were analysed by GC and GC-MS for N. fusca larvae. Before adoption, N. fusca larvae had different cuticular hydrocarbon composition from that of the host ants. In contrast, the hydrocarbon composition of the larvae changed dramatically after adoption and closely matched to that of the host ants. The multivariate analysis revealed that N. fusca larvae have host colony-specific hydrocarbon profiles on their cuticle. Furthermore, cuticular hydrocarbon profiles of N. fusca were different from that of the ant larvae and resembled to the adult ants, especially the male ants. Male-like hydrocarbon profiles may play an important role for N. fusca in achievement of social status in the ant nest.