Vanessa cardui, the painted lady
A butterfly with a 5–6 centimetre wingspan leaves Europe in autumn, crosses the Sahara and winters in the tropics. Its descendants return in spring. The circuit runs about 12,000 kilometres a year, flown by about six generations in relay. Follow them month by month.
See the yearly circuitThe map of the year
Drag the slider and see where the butterflies are. The dot shows the approximate position of the population in each month, after the monthly maps of the model in Talavera et al. (2023).
June: peak in Romania; reaching northern Europe
Positions are approximate, after the monthly maps of the model in Talavera et al. (2023). The dot shows where the bulk of the population sits in each month. For scale: Bucharest to the Sahel is about 3,700 kilometres as the crow flies.
October–November
The butterflies leaving Europe cross the Mediterranean and the Sahara and reach the Sahel savannah, where they start breeding. This is the longest leg in one butterfly's life: over 4,000 kilometres.
They fly by day, downwind, hundreds of metres up. Radar measured about 45 kilometres an hour in autumn.
December–February
As the savannah dries out, the offspring move south, to 5° north in West Africa and to the Equator in the east. From December to February the bulk of the population sits in the Afrotropics, not in the Maghreb.
The butterflies do not enter diapause: they keep moving and breeding all year, in up to ten generations where it never gets cold.
February–April
The offspring of the autumn arrivals cross the Sahara northwards and recolonise the Mediterranean shores. The proof came from hydrogen isotopes in the wings: many butterflies caught around the Mediterranean in spring had been born south of the Sahara.
The yearly circuit of the successive generations measures about 12,000 kilometres, crossing the Sahara twice.
May–August
From the Mediterranean the wave moves north: local generations appear from May–June, and northern Europe is reached in late May and June. In Romania most records are from June.
From late August the butterflies head south again and breed once more on the way, in September–October.
One caveat: the routes above were measured on the western circuit. Other populations circulate in Eastern Europe and Asia and meet this one, and how much they mix is unknown. Some butterflies reach Europe from the Middle East and Central Asia too.
The size
The painted lady (Vanessa cardui) is orange with black and white above, marbled brown below. The drawing below shows it life-size, next to a ruler.
27,272,728 butterflies end to end would span 1,500 kilometres of Sahara; 36,363,637 would span 2,000 kilometres.
The wingspan, the distance between the wingtips, is 50–56 mm in the British guide and 55–60 mm in the Czech identification key. The drawing uses 55 mm, the middle of the European values.
A female lays about 500 eggs, singly on the host plant. In Britain and Ireland, the caterpillars prefer thistles; they also eat mallow, nettle and a few other plants. Egg to butterfly takes 33–44 days in warmth and over 60 days in the cold. The species lives on every continent except Antarctica and Australia.
How long an adult lives in the wild has never been measured. In the laboratory adults live about 10–24 days. The 12,000-kilometre circuit is about 218 million times longer than the butterfly itself.
Guess
Pick an answer for each. The page will not show the explanation until you commit.
The longest leg known in butterflies is over 4,000 kilometres: from Europe to the tropical savannah, across the Mediterranean and the Sahara. The rest of the circuit, up to 12,000 kilometres, is flown by the generations that follow.
About six generations succeed each other in a year. Each flies one leg and lays its eggs; the offspring continue the journey. About three generations separate the butterfly that left for Africa in autumn from the one in your garden: hence the great-grandchild.
From December to February the bulk of the population sits in the Afrotropics, not in the Maghreb. Some reach the Equator. They breed there, and their offspring head north in spring.
Painted ladies have no dormant state: they keep moving and breeding all year, in up to ten generations a year where it never gets cold.
Across the ocean
One October morning in 2013, painted ladies turned up on a beach in French Guiana. The species had no stable populations in South America.
Three of the ten or so butterflies were caught alive at around 6 in the morning on 28 October 2013. Analyses of winds, genes, pollen and isotopes showed they had crossed the Atlantic from West Africa: at least 4,200 kilometres in 5–8 days. The isotopes suggested some were born in Western Europe, which stretches the whole journey past 7,000 kilometres.
Without wind they would never have made it: on its fat reserves a butterfly can flap for 780 kilometres at most. Even with wind they would have failed had they flapped all the way: that ends around 1,900 kilometres. In 2013, the butterflies alternated flapping with gliding, like monarch butterflies: about 15% flapping and 85% gliding.
It is one of the longest flights ever documented in individual insects.
The first two bars are what the energy models say; the third is the minimum distance reconstructed from the winds. Source: Suchan et al. (2024).
Romania
The GBIF database holds 961 Vanessa cardui records from Romania. Here are the months they were seen in.
The wave arrives in April–May and peaks in June: 326 records, about one in three. The last vanish during October–November.
Most records are from 2026, the current year (186), and from 2019 (172). The years 2009 and 2020 show no Romanian records at all: a sign of how little was recorded then, not of missing butterflies.
The records come mostly from people photographing nature (iNaturalist, Observation.org) and from a museum database (ZOBODAT). So the chart also shows where people look, not only where butterflies fly.
Game
Eight statements about the butterfly. Some sound like stories and are true.
The eight statements and their answers:
Sources
Distances and dates come from published studies, read in full; the list says what each one was used for. Where sources give different values, the range is printed: the 12,000–15,000 km circuit, the 1,500–2,000 km Sahara, the 50–60 mm wingspan.
Two things are missing because they were never measured anywhere: how long an adult lives in the wild, and exactly which way the butterflies of Eastern Europe travel. The page says so plainly next to each.
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