Heliconius cydno, the cydno longwing, is a nymphalid butterfly that ranges from Mexico to northern South America. It is typically found in the forest understory and deposits its eggs on a variety of plants of the genus Passiflora. It is a member of the Heliconiinae subfamily of Central and South America, and it is the only heliconiine that can be considered oligophagous. H. cydno is also characterized by hybridization and Müllerian mimicry. Wing coloration plays a key role in mate choice and has further implications in regards to sympatric speciation. Macrolide scent gland extracts and wing-clicking behavior further characterize this species. Subspecies Listed alphabetically: H. c. alithea Hewitson, 1869 H. c. barinasensis Masters, 1973 H. c. chioneus Bates, 1864 H. c. cordula Neustetter, 1913 H. c. cydnides Staudinger, 1885 H. c. cydno Doubleday, 1847 H. c. hermogenes Hewitson, 1858 H. c. gadouae Brown & Fernández, 1985 H. c. galanthus Bates, 1864 H. c. lisethae Neukirchen, 1995 H. c. pachinus Salvin, 1871 H. c. wanningeri Neukirchen, 1991 H. c. weymeri Staudinger, [1897] H. c. zelinde Butler, 1869 Distribution and habitat H. cydno ranges from southern Mexico to western Ecuador in northern South America. H. cydno is considered to be non-migratory, or sedentary. H. cydno lives in closed-forest habitats, specifically in the forest understories. They live at elevations from sea level to 2000 meters. Their most common host plants are in the genus Passiflora, and at night, adults roost in twigs or tendrils from two to ten meters above the forest floor. Males generally tend to fly higher than females, who are found lower in the forest understory. Host plant The diet of H. cydno larva is generalist. Passiflora are less common in the closed-forest habitats of H. cydno, and thus the species uses a wide selection within the genus. They tend to prefer orange and red flowers. Other species of Heliconius restrict their diet to a single species of Passiflora, while H. cydno is oligophagous (feeding on a restricted range of plants). There are records of five species of Passiflora being utilized by H. cydno, all in the subgenera Granadilla, Plectostemma, or Distephana. Both H. cydno and H. melpomene are known to utilize Psiguria warcsewiczii pollen. Parental care Oviposition Experiments performed pertaining to H. cydno oviposition reveal that they utilize chemoreception, not visual cues, when choosing their egg-laying sites. H. cydno oviposition sites are generally the tendrils of their Passiflora host