Mating behavior of the Old World swallowtail, Papilio machaon

Abstract

Butterflies have been a frequent subject of studies on sexual selection or mating systems due to their colorful wings. One problem in studying mating behavior of butterflies is that they often exhibit no typical behavior toward the opposite sex before copulation, which makes it difficult to assess their sexual intent. It was said that males of the Old World swallowtail, Papilio machaon (Lepidoptera: Papilionidae), hold a mating territory on a hilltop, and that males perform a typical flight to a flying female. In the present study, I precisely observed and described territorial and mating behavior of this butterfly. Males gathered around a hilltop in the daytime. Upon an encounter, two males chased each other until one of them flew away from the hilltop. The other returned to the hilltop. Therefore, the male-male interactions functioned as territorial contests. Males also chased various flying organisms such as other insects or birds. However, these heterospecific interactions were much shorter than conspecific interactions. When a female flew to the hilltop, a male occupying it rushed to her, and then he flew just beneath her before flying up in front of her, and dropped back behind her to perform his flight routine again. If the female alighted nearby, the male also alighted by her and they copulated. Therefore, the specific flight is regarded as a part of P. machaon’s courtship behavioral sequence. One can use this behavior as an index of sexual intent.