Swallowtail butterflies are large, colourful butterflies which form the family Papilionidae. There are at least 550 species, and though the majority are tropical, members of the family are found on all continents except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of Australia (genus Ornithoptera).

Swallowtails differ from all other butterflies in a number of anatomical traits. Most notably, their caterpillars possess a unique organ behind their heads, called the osmeterium. Normally hidden, this forked structure can be everted when the caterpillar is threatened, and emits smelly secretions containing terpenes. The adults are often tailed, giving the insect its name.

Swallowtail tribes Zerynthiini (Parnassiinae), Luehdorfiini (Parnassiinae) and Troidini (Papilioninae) almost exclusively use the Aristolochiaceae family as their host plants. Many species sequester aristolochic acids making them unpalatable, causing both the larval and adult stages to be unpalatable to predators.

The subfamily Baroniinae is represented by the sole representative species Baronia brevicornis. They are unique in the family to use the Fabaceae as their larval host plants.

The Apollos, Parnassiinae, are a distinctive group and all species are alpine and capable of living at high altitudes. Most species have two small reddish spots on their hindwings. The genera Parnassius and Hypermnestra were found to be extremely closely related based on molecular studies. After mating, the male Parnassines produce a glue like substance that is used to seal the female genital opening and prevent other males from mating.

The pupae are typically attached to the substrate attached by the cremaster but with head up held by a silk girdle. The apollos however pupate in debris on the ground and also build a loose cocoon. In the temperate regions the winters are passed in a pupal diapause stage.