How Far Do Painted Ladies Migrate? From Africa to the Arctic

The annual circuit, step by step

The painted lady cannot survive cold winters, so its population keeps moving to stay where plants are growing and temperatures are warm. Scientists now see the Europe and Africa movements as one great circuit.

From Iceland or northern Scandinavia to the savanna belt of West Africa is well over 6,000 km (3,700 mi) in a straight line, and the butterflies cover that distance in both directions every year.

How scientists measured the journey

For a long time, naturalists saw painted ladies arrive in Europe each spring but rarely saw them leave. Many thought the summer generation simply died in the autumn cold. Several lines of evidence showed otherwise.

Radar. Entomological radar in southern Britain, run by Rothamsted Research, detected large numbers of painted ladies flying south in autumn at high altitude. Because they flew far above the ground, people had not noticed them.

Citizen science. Thousands of volunteer records from across Europe and North Africa, collected through projects such as the Worldwide Painted Lady Migration project led from the Institute of Evolutionary Biology in Barcelona, showed waves of butterflies moving north and south through the year.

Wing chemistry. The wings of a butterfly carry a chemical signature, in the form of hydrogen isotopes, from the place where it grew up as a caterpillar. A 2018 study of butterflies caught around the Mediterranean in February to April found that many had been born south of the Sahara. This was the first solid evidence of a spring crossing of the desert from tropical Africa.

Field work in Africa. Researchers searching the African savanna in autumn and winter found painted ladies breeding in large numbers, confirming that it is the winter home of the European population.

How far can a single painted lady fly?

Each adult lives only around two to four weeks, but some individuals cover huge distances in that time. Migrants choose days with favorable tailwinds and climb to altitudes of hundreds of meters, where winds are faster.

The most extreme case was reported in 2024. Painted ladies found on a beach in French Guiana, on the northern coast of South America, were outside the species’ normal range. Pollen on their bodies came from West African plants, wind models showed a strong westward airflow at the time, and chemical tests suggested they were born in Western Europe. The scientists concluded that they had crossed the Atlantic from West Africa, at least 4,200 km (2,600 mi) in roughly 5–8 days, possibly after first flying from Europe to Africa. Such a flight was only possible with steady help from the trade winds.

How painted ladies find their way

Painted ladies use the sun as a compass. In laboratory tests, autumn butterflies flew in a southerly direction when they could see the sky, but lost their sense of direction when the sun was hidden. Spring butterflies head roughly north.

They also seem to adjust their direction for wind and terrain. Radar studies show that high-flying migrants select altitudes and days when the wind is blowing roughly in their preferred direction, and partly correct for drift. This lets them travel fast without wasting energy.

Painted lady migration in North America

North American painted ladies make a separate migration. They spend winter in the deserts of the southwestern United States and northern Mexico, then move north and north-west in spring, with some reaching Canada. Their autumn return to the south is less well studied than in Europe.

The size of each spring flight depends on winter rain in the desert. After the wet winter of 2018–2019, Southern California saw many millions of painted ladies streaming north-west in March 2019. The same winter brought an exceptional migration of an estimated one billion painted ladies through Israel.

How it compares with other migrations

The painted lady’s circuit is longer than the famous migration of the monarch butterfly, whose eastern population flies up to about 4,000–4,800 km (2,500–3,000 mi) from Canada and the northern US to central Mexico. Monarchs, however, are better known because a single “super generation” makes the whole southward trip and gathers in dense winter roosts.

Dragonflies are also great migrants. The common green darner migrates across North America over several generations, and the globe skimmer may cross the Indian Ocean between India and East Africa. For the champions of all animal groups, see our list of the longest animal migrations.

Myths about painted lady migration

Myth: Painted ladies seen in autumn are dying, not migrating. Fact: Radar and field studies show that the autumn generation flies south, often too high to be seen.

Myth: Painted ladies spend the winter hibernating in Europe. Fact: No stage of the painted lady can survive a northern European winter. The species avoids winter by moving.

Myth: The migration happens in the same numbers every year. Fact: Numbers vary enormously. In boom years, such as 2009 and 2019 in Europe, many millions arrive; in other years painted ladies are scarce.