Piotr Naskrecki / Large Striped Swordtail (Graphium antheus) butterflies, Gorongosa National Park, Mozambique

Ralph Martin/ BIA / Oldworld Swallowtail (Papilio machaon) wing, Baden-Wurttemberg, Germany

Ingo Arndt / Close-up of wing detail of Emperor swallowtail butterfly (Papilio ophidicephalus) Africa

Ingo Arndt / Lemon / Common lime swallowtail butterfly (Papilio demoleus) on flower head, Asia, Captive

Peter Schwarz/ BIA / Oldworld Swallowtail (Papilio machaon) butterfly, Hesse, Germany

Pete Oxford / Thoas Swallowtail (Papilio thoas) butterfly, Mindo Cloud Forest, Ecuador

Silvia Reiche / Oldworld Swallowtail (Papilio machaon) caterpillar on fennel, Netherlands

Thomas Marent / Citrus Butterfly (Papilio demodocus) drinking minerals and salts from soil, Jozani National Park, Zanzibar, Tanzania

Thomas Marent / Oldworld Swallowtail (Papilio machaon) caterpillar, Switzerland

Paul Harcourt Davies,Paul Harcourt Davies / Common Swallowtail butterfly (Papilio machaon) backlit showing wing structure. Podere Montecucco, Orvieto, Umbria, Italy, October

Paul Harcourt Davies,Paul Harcourt Davies / Apollo butterfly (Parnasius apollo) feeding on flower, Mount Terminillo, Rieti, Lazio, Italy, July 2011

Stephen Dalton / Citrus swallowtail (Papilio demolius) in flight, controlled conditions, native to South and Central America and Caribbean