Painted Lady Butterfly

Vanessa cardui — the painted lady butterfly — is the most cosmopolitan butterfly species on Earth, present on every continent except Antarctica and South America. The species is one of the most extraordinary migratory insects known: the round-trip annual migration from sub-Saharan Africa to the Arctic Circle and back covers approximately 14,000 km and is completed across 6 successive generations — no single butterfly makes the entire journey, but the population's annual cycle returns predictably. The European migration was first proven to be multi-generational and not a one-way population sink by a 2012 study using stable isotope analysis (Stefanescu et al., Ecography). The species' population dynamics are remarkable for occasional 'painted lady years' — population explosions in which billions of individuals migrate from North Africa across the Mediterranean into Europe, and then onward to the British Isles and beyond. The 2009 painted lady year was one of the largest documented insect migrations of recent decades, with population estimates exceeding 1 billion butterflies. Caterpillars feed on thistles (especially Cirsium and Carduus), nettles, and over 100 documented host plants. The species was one of the first insects in space — V. cardui caterpillars were sent to the International Space Station in 2009 to study microgravity effects on metamorphosis.