[1] Wing coloration plays a key role in mate choice and has further implications in regards to sympatric speciation.

[6][7] Listed alphabetically:[8] H. cydno ranges from southern Mexico to western Ecuador in northern South America.

[1] Their most common host plants are in the genus Passiflora,[3] and at night, adults roost in twigs or tendrils from two to ten meters above the forest floor.

[1] Males generally tend to fly higher than females, who are found lower in the forest understory.

[10] Experiments performed pertaining to H. cydno oviposition reveal that they utilize chemoreception, not visual cues, when choosing their egg-laying sites.

[11] H. cydno's oviposition sites are generally the tendrils of their Passiflora host plants, and eggs are placed singly.

[1] While leaf shape experiments and egg mimics do not have significant effects on oviposition, chemical cues from methanol render sites less appealing to H. cydno.

[1] Pupae of H. cydno are characterized by antennae, an abdomen with long spines, and a general dark brown color.

[4] It is a species well known and widely researched for its tendency to hybridize with the closely related H. melpomene, from which it diverged around 1.5 million years ago.

[12] Their low levels of hybridization can, in part, be attributed to pre-mating isolation, as H. melpone is found in more open habitats, while H. cydno lives in a closed-forest environment.

[10] Studies suggest that changes in host use and mimicry in H. melpomene and H. cydno are genetically determined and may contribute to pre-mating isolation.

It has been suggested that the high degree of iridescence displayed by H. cydno can be attributed to their forest understory habitat, which generally has less-direct sunlight.

Research done on H. cydno in Costa Rica suggests that the species has 12- and 14-membered macrolide scent gland extracts which have a C-18 skeleton.

According to the study, other species' desire and ability to hybridize with H. cydno was not affected by their possession of macrolide scent gland extracts.

[6] In an experiment by Mirian Medina Hay-Roe and Richard W. Mankin, field-collected H. cydno females were found to produce wing clicks when interacting with members of the same species.

They demonstrated this behavior during the day and at roosting time, when individuals came close to one another so as to almost touch one another's head or wings.