Apollo (Parnassius apollo): mountain meadows and red eyespots

The Apollo, Parnassius apollo, is a large white butterfly of Europe’s mountains, named after the Greek god in keeping with the classical tradition used to name the genus Parnassius. It belongs to the swallowtail family, Papilionidae. The species ranges across the mountain ranges of continental Europe, including Spain, Scandinavia, central Europe, the Alps between France and Italy, and the Balkans south to northern Greece, with further populations reaching into parts of central Asia. It also holds a place in conservation history: it was the first butterfly protected by law, after Germany’s Emperor Wilhelm I led efforts to secure it.

Identification

The Apollo is one of the larger European butterflies, with a wingspan of 62–95 mm: males run 62–86 mm and females 65–95 mm, so females are usually the bigger of the two. The upperside is white with five large black eyespots on the forewings, while the hindwings carry two bright red, sometimes orange, eyespots whose size and shape vary by location; the red fades in sunlight, so older individuals can look more orange. The wings have a shiny look with slightly transparent edges. A mated female carries a telltale sign the male leaves behind: see Behaviour and flight period below.

Range and habitat

Within this European and central Asian range, the Apollo lives in flowery alpine meadows and pastures with sparse shrub cover, at elevations of roughly 400–2,300 m and typically above 1,000 m. Numerous subspecies are recognised, most restricted to a single mountain range or valley, such as the Alps, the Pyrenees, the Sierra Nevada and the Balkans; the Sierra de Gádor subspecies, gadorensis, is now extinct. Population trends vary sharply by region: numbers in Finland and Sweden fell drastically during the 1950s for reasons that remain unclear, possibly disease, while populations in the Swiss Alps show high variation with locally elevated extinction rates. Over-collecting once hurt populations in Spain and Italy, though habitat destruction is the bigger threat across the species’ range overall.

Life cycle and host plants

Caterpillars feed on low-growing succulents, among them stonecrops such as Sedum telephium, Sedum album and Sedum rupestre, along with Hylotelephium caucasicum and houseleeks of the genus Sempervivum. The caterpillar itself is velvety black with orange-red spots along its sides. The species overwinters as an egg, and once grown the caterpillar pupates on the ground inside a loose cocoon, from which the adult emerges after metamorphosis. There is a single generation a year.

Behaviour and flight period

Adults are on the wing from May to September across the European range, feeding on nectar. Mating leaves a lasting mark on the female: the male deposits a gelatinous plug called a sphragis on her abdomen, which blocks her from mating again. The species has also shaped the habits of one of its predators: water pipits have learned to avoid the butterfly’s poor taste by plucking off its wings before eating the body.

Conservation

The Apollo is assessed as shown in the facts box, a category drawn from its Wikidata record; it is also listed under CITES Appendix II and protected by law in several countries, including the Czech Republic, Turkey, Poland and Liechtenstein. Despite that overall standing, many mountain populations have declined, as conifer plantations, the overgrowth of open habitat into scrub, agriculture, and urbanisation destroy its meadows, with climate change and acid rain also implicated. Targeted conservation work has reversed some of that decline: a programme in Poland’s Pieniny National Park rebuilt a subspecies that had fallen to just 20 individuals in the early 1990s, through captive breeding and habitat protection, while in southwestern Germany conservationists work with shepherds to time grazing so that it protects the caterpillars’ most vulnerable stages.

Similar species

• Clouded Apollo (Parnassius mnemosyne): a lower-altitude relative that lives in valleys rather than high mountains.
• Small Apollo (Parnassius phoebus): a high-mountain species distinguished by its strongly marked black and white antennae.