Field observations of heterospecific mating attempts by males of Papilio polytes (Lepidoptera: Papilionidae) toward newly eclosed individuals

Mate discrimination is important for successful mating, whereas several studies have suggested that butterflies sometimes engage in heterospecific mating. In the polymorphic swallowtail butterfly Papilio polytes (Papilionidae), male preference for mimetic and non‐mimetic females has been extensively studied. On the other hand, indiscriminate mating attempts on heterospecific butterflies have also been reported in this species, raising questions about mate discriminability. However, due to the inherent rarity of opportunities to observe heterospecific mating attempts, the behavioral background in which such heterospecific interactions occur in the field is unclear, with more observational cases being awaited. In the present study, we report three observations of male P. polytes courting and pairing with heterospecific butterflies, including a male from another family, Nymphalidae. To the best of our knowledge, this is the second report in the world on the pairing between butterflies belonging to different families. Interestingly, the males attempted to mate with freshly eclosed individuals in all three observations. This indicates that active mating attempts by males toward virgin females, a behavior commonly observed in butterflies, may underlie such heterospecific interactions. This also raises questions regarding P. polytes males’ mate discriminability and their role in maintaining female‐limited mimetic polymorphism.