These Butterflies Have the Longest Known Migration Route

Painted ladies are one of the most widely distributed butterflies and can be found on all continents except Antarctica and South America.  The painted lady butterfly (Vanessa cardui) migrates across generations between Europe and Africa and is a key species for studying insect migration. 

The widespread presence of these butterflies can be attributed to their adaptability and resilience, as they can thrive in various habitats, including meadows, gardens, forests, and even arid deserts.

The species of butterflies is a resident of warmer areas, migrating in the fall towards more favorable climates.  While monarch butterflies are probably more well known for their epic migrations between North and Central America, the painted lady butterfly is known for having the longest migration route of all butterfly species.

Painted Lady Butterflies Migrate in the Fall

Each fall, large populations of painted lady butterflies (Vanessa cardui) migrate from Europe to subtropical Africa, crossing the Sahara Desert, with individuals traveling up to 4,000 kilometers.  The epic migration of painted lady butterflies crosses the Mediterranean Sea and the mountains of North Africa.

This species of butterfly makes the longest single-leg migratory flight of all known butterfly migration routes.

Where painted lady butterflies overwinter

It was only recently that scientists discovered exactly where painted lady butterflies overwinter in Africa (Talavera et al., 2023). Previously, ecological niche modeling (ENM) had predicted potential winter breeding grounds in the humid regions near the tropics from November to February.

Led by Gerard Talavera, an entomologist and evolutionary biologist with the Botanical Institute of Barcelona, researchers used fieldwork to not only confirmed the ENM predictions but also located new breeding locations, document the butterflies’ year-round life cycle, and indentify the plants used for laying eggs.

After two years of fieldwork scanning sites in sub-Saharan Africa, researchers discovered that after spending most of September to November in semiarid savannas, the butterflies follow the wetter weather further south to Central Africa’s savannas and highlands.

Preferred host plants for painted lady butterflies in the Afrotropics

These semi-humid areas provide the painted lady with hospitable breedings grounds. Painted lady butterflies can produce several generations in sub-Saharan Africa before adults make the reverse migration north in February.

During field surveys in the Afrotropics, researchers identified larval host plants for the painted lady butterfly from 12 genera across three plant families: Asteraceae, Fabaceae, and Malvaceae. However, in Western Africa, only two host plant species were found: Zornia glochidiata (Fabaceae) and Pseudoconyza viscosa (Asteraceae). These plants were abundant in typical habitats for the butterfly and were heavily used, with many caterpillars on each plant, suggesting they are the preferred hosts in this region.

The results of this study highlighted the importance of the Afrotropical region and helped to fill in gaps in understanding the longest known migratory cycle of any butterfly.

Studying How Painted Lady Butterflies Migrate from Africa to Europe

Once the areas of Central Africa start to enter the dry season, painted lady butterflies make the reverse migration back to Europe.

A study published in 2018 the Royal Society looked at isotopic evidence that some individual painted lady butterflies make a reverse migration back to Southern Europe in the spring.

While a reverse migration has been suspected, this is the first study to try and definitely shows that painted lady butterflies migrate back to Europe from Africa.  

In this study, researchers looked at hydrogen isotope values present on painted lady butterfly wings found between February and April in Europe to determine their originations.

Subsaharan greens affects the north migration of Paint Lady butterflies

According to a different study, the primary factor influencing the magnitude of spring immigration for the painted lady butterfly is the winter plant greenness in the savannas of sub-Saharan Africa.

Since the painted Lady breeds year-round, the abundance of winter plant greenness in the savanna of sub-Saharan Africa can affect the size of the spring migrating population up to 100-fold (Hu et al., 2021).

References

Garcia de Jesús, E. (2023, April 11). The last leg of the longest butterfly migration has now been identified. Science News. https://www.sciencenews.org/article/painted-lady-butterfly-migration-identified

Hu, G., Stefanescu, C., Oliver, T. H., Roy, D. B., Brereton, T., Van Swaay, C., … & Chapman, J. W. (2021). Environmental drivers of annual population fluctuations in a trans-Saharan insect migrant. Proceedings of the National Academy of Sciences, 118(26), e2102762118. https://doi.org/10.1073/pnas.2102762118

Talavera, G., Bataille, C., Benyamini, D., Gascoigne-Pees, M., & Vila, R. (2018). Round-trip across the Sahara: Afrotropical Painted Lady butterflies recolonize the Mediterranean in early spring. Biology letters, 14(6), 20180274.

Talavera, G., García-Berro, A., Talla, V. N., Ng’iru, I., Bahleman, F., Kébé, K., … & Vila, R. (2023). The Afrotropical breeding grounds of the Palearctic-African migratory painted lady butterflies (Vanessa cardui). Proceedings of the National Academy of Sciences, 120(16), e2218280120. https://doi.org/10.1073/pnas.2218280120

This article was first published on June 22, 2018 and has since been updated

See Also

• Mass Movements So Large You Can See Them on Radar
• From the Arctic to Mexico: Tracking the Epic Migration of Birds
• New Maps For Ungulate Migration Routes Across the Western U.S.
• Mule Deer Create Mental Maps Of Migration Routes
• Do Bison Influence the Spring Season?