- Name also: Mountain Apollo
- Family: Swallowtail Butterflies – Papilionidae
- Subfamily: Snow Apollos – Parnassiinae
- Wing span: Very large, 62–94 mm (2.48–3.76 in.). Finland’s largest butterfly.
- Wing upper side: White, with black blotches. Hind wing with two red, black-edged eye-blotches. Females darker than males. Tip of forewing transparent.
- Wing underside: Like upper surface.
- Habitat: Rocky terrain with an abundance of flowers.
- Flying time: Early July–mid-August.
- Overwintering form: Egg or small caterpillar.
- Larval foodplant: Orpine (Hylotelephium telephium) and other Stonecrop family plants (Crassulaceae), especially e.g. white stonecrop (Sedum album).
- Endangerment: Endangered, protected in all of Finland, including the Åland Islands.
The four species that are members of the Swallowtail family that can be found in Finland belong to two different subfamilies. The Snow Apollo subfamily (Parnassiinae) is home to the apollo and clouded apollo. The Swallowtails(Papilioninae) is home to the swallowtail and the scarce swallowtail.
The apollo is easy to recognise and impossible to confuse with other Finnish species. It can be easily differentiated from the clouded apollo by the red ring patterns on its hind wings.
Males fly around looking for females. Copulated females have at the back of their bodies, a shell-like structure called a sfragis. The male creates it during copulation, and it is assumed that it makes it difficult for the female to copulate again. Females lay their eggs one by one, among lichen and twigs next to the host plant.