Vanessa cardui · the painted lady
The painted lady (Vanessa cardui) flies one of the longest migratory circuits of any insect: between Europe and Africa, across the Sahara to the tropics. In autumn, some of the butterflies born in Europe cross the Mediterranean and the Sahara; others stay around the Mediterranean. Later generations follow the rains towards the tropics, and in spring other generations head north again, reaching Romania and beyond. The circuit, up to about 15,000 km a year, is a relay of roughly 8–10 overlapping generations. Follow it month by month.
See the yearly circuitThe map of the year
Drag the slider and see where the butterflies are, month by month. The patch shows occupied zones, not a flock: migration runs on a broad front, along parallel routes, and the map separates what was directly observed from what was inferred from models.
June: the most Romanian records; reaching northern Europe
The zones are approximate: the legend says which rest on direct observations and which on models and inference. For scale: Bucharest to the Sahel is about 3,700 kilometres as the crow flies.
October–November
Some of the butterflies born in 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.
Others stop around the Mediterranean and winter there: migration runs on a broad front, and individuals travel very different distances. They fly by day, downwind — 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 breeding zones stretch across both sides of the Sahara: in the Afrotropics and around the Mediterranean.
The butterflies do not enter diapause: they keep moving and breeding all year. In the Afrotropics, four or five generations could succeed each other between October and February.
February–April
The offspring of the butterflies that reached south of the Sahara cross the desert 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 runs to about 15,000 kilometres — the 2018 reconstruction gave about 12,000 — crossing the Sahara in both directions.
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, June has the most records in the GBIF set.
From late August the butterflies head south again and breed once more on the way, in September–October.
The yearly circuit is flown by roughly 8–10 generations that overlap in time and space. The diagram is a simplification: in nature, generations are not separate carriages but intermingling waves.
Indicative diagram: about 8–10 overlapping generations a year.
The east is no longer a blank patch. A 2024 study using hydrogen and strontium isotopes brought the first direct evidence of migrations between the eastern Mediterranean and East Africa, reaching Kenya. But the exact route of the butterflies appearing in Romania has not been tracked individual by individual — the map does not turn a regional link into an invented Bucharest–Kenya route.
The size
The painted lady (Vanessa cardui) is orange with black and white above, marbled brown below. The drawing below shows it to scale, next to a ruler — and you can calibrate it to its true size.
Some 27–36 million butterflies end to end would span 1,500–2,000 kilometres of Sahara.
Want to see it at its true size?
No screen shows true millimetres out of the box. Hold a bank card against the screen and drag the slider until the rectangle is exactly the card's width (85.60 mm). The drawing and the ruler then match the true size.
Uncalibrated: the drawing is relatively scaled, not to the millimetre.
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 hundreds of eggs, singly on the host plant; in one laboratory experiment the average exceeded 1,000 eggs over a lifetime. In Britain and Ireland, the caterpillars prefer thistles; they also eat mallow, nettle and a few other plants. Egg to butterfly takes 23–45 days in warmth and over 60 days in the cold. The species lives on every continent except Antarctica and Australia.
How long a wild adult lives is hard to measure directly: the current estimate is about 3–6 weeks. In the laboratory adults live about 10–24 days. The circuit of up to 15,000 kilometres is on the order of 200–300 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 for one butterfly is over 4,000 kilometres: from Europe to the tropical savannah, across the Mediterranean and the Sahara. The rest of the circuit, up to about 15,000 kilometres, is flown by the generations that follow.
Roughly 8–10 generations succeed each other in a year, overlapping in time and space. Each flies one leg and lays its eggs; the offspring continue the journey. The whole circuit belongs to the population, not to one individual.
Some stay around the Mediterranean; others cross the Sahara and winter in the Afrotropics, some reaching the Equator. Both zones are winter breeding grounds, and the two strategies show no genetic difference.
Painted ladies have no dormant state: they keep moving and breeding all year. Migration is a broad front of individuals travelling different distances, not one flock.
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: the energy model says that 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: the continuous-active-flight model 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 energy-model outputs, not measurements; the third is the minimum distance reconstructed from the winds. Source: Suchan et al. (2024).
A 2025 study of the genomes of 300 butterflies from Africa and Europe found a chromosomal inversion of about nine million bases, associated with northern- versus southern-hemisphere origin — a sign that southern African painted ladies run their own seasonal circuit, distinct from the Europe–Africa one. The Equator would be the contact zone.
This is a genomic association, not proof that the inversion 'causes' migration — and the page's main story, the Europe–Africa circuit, stands untouched.
Romania
The GBIF database holds 961 Vanessa cardui records from Romania. Here are the months they were seen in.
The 12 monthly values from the GBIF query (Vanessa cardui, Romania). Each record carries its dataset's licence; see the exact query.
| January | 0 |
|---|---|
| February | 0 |
| March | 1 |
| April | 22 |
| May | 185 |
| June | 326 |
| July | 188 |
| August | 124 |
| September | 68 |
| October | 28 |
| November | 4 |
| December | 0 |
In the GBIF set consulted, records rise steeply in April–May and are most numerous in June: 326, about one in three. After September, records grow much scarcer, into 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 shows where people looked, not the true size of the population — and June is the month with the most records, not necessarily the month with the most butterflies.
Game
Eight statements about the butterfly. Some sound like stories and are true.
The eight statements and their answers:
Sources
Figures come from scientific papers, databases and reference guides; calculations made for this page are labelled separately. The list says what each source 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.
No butterfly on this map carried a GPS tracker. The route is reconstructed from several kinds of evidence, with different uncertainties — the table below sets them side by side.
Two things stay hard to pin down: how long a wild adult lives, which is hard to measure directly, and the exact route of the butterflies reaching Romania. The page says so plainly next to each.
The page's own calculations — the Bucharest–Sahel distance, the June share, how many butterflies span the Sahara — are automatically verified at every release of the page.
| Claim | Evidence | Strength and limit |
|---|---|---|
| Europe–sub-Saharan Africa, autumn | isotopes and observations | direct support for some individuals |
| Sub-Saharan Africa–Mediterranean, spring | hydrogen isotopes | strong evidence for many sampled individuals |
| Monthly tropical breeding zones | fieldwork, monitoring and niche modelling | regional and monthly, not individual routes |
| Eastern Mediterranean–East Africa | dual hydrogen and strontium isotopes | first direct evidence, 2024 |
| The crossing to French Guiana | wind, genes, pollen, isotopes and modelling | solid reconstruction of a rare event |
| Romanian seasonality | GBIF records | shaped by observer effort |
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