A Biologist Spotlights The World’s Longest Butterfly Migration (Hint: It’s Not A Monarch)

The painted lady butterfly—or Vanessa cardui—is a traveler like no other. At the onset of spring, this tenacious little butterfly sets out on a journey that defies all odds. By the end of the journey, an astonishing 9,000 miles (15,000 kms) would be covered across multiple continents—all in the space of a year.

One of the longest known migrations in the insect world, this trip is a truly collaborative effort. It connects up to 10 generations of painted ladies across land and sea in their quest for home—a home that moves in step with the whims of the shifting seasons.

While no butterfly that begins the journey ever makes it back, the painted ladies keep this enduring cycle alive even as climate change continues to sharpen weather conditions around the world.

Painted Ladies Breed On The Move

For the Vanessa cardui, migration is defined by the change in seasons and the need to find suitable grounds for breeding and sustenance. Starting from sub-Saharan Africa, the painted ladies move through the Middle East, northern Africa and Europe, before returning southward again during fall.

The painted ladies begin their seasonal expedition in the Afrotropical region, where they breed during the rainy season in places like the Sahelian and Sudanian savannas.

As conditions dry out, the painted ladies push further south into regions like Ghana, Uganda and Kenya, guided by the sun and the wind as they seek out the regions more likely to rain. As they move, the butterflies continue to breed, ensuring the new generation takes over along the way.

In the spring, the painted ladies make their way northward, traveling through challenging landscapes such as the deserts of the Middle East and the mountain ranges of Europe. Their ultimate goal is to reach temperate regions, where they take advantage of blooming plants.

As autumn approaches, the butterflies begin their southward return, driven by changing climatic conditions and dwindling food supplies.

Painted Lady Butterflies Are Exceptionally Resilient

The migration of the Vanessa cardui might seem like an improbable endeavor at the outset, but these painted ladies are built to endure any challenge that comes their way.

• They adapt as they move. Unlike many butterfly species that rely on specific host plants, painted ladies are polyphagous, meaning they can feed on a wide variety of plants. This flexibility allows them to thrive in diverse environments, from the African savannas to the European meadows.
• They move with the sun. Painted ladies use a solar compass to orient themselves during migration, adjusting their flight paths according to the sun’s position. This ability allows them to traverse challenging terrains, such as the vast Sahara Desert and the rocky peaks of the Alps.
• They never miss a good opportunity. With the change in weather patterns, there are often chances of rainfall affecting otherwise arid regions. In such cases, painted ladies capitalize on the sudden bloom of vegetation, migrating in vast numbers. Sometimes, these events trigger migrations so large that they become spectacles, with millions of butterflies seen moving in unison across entire landscapes.

And while cross-generational migration is common among butterflies, the painted ladies complete one migration cycle over 10 generations. This rapid reproductive cycle allows these butterflies to repopulate areas as they move, ensuring that new generations are always ready to carry on the migration.

The Looming Gloom Brought On By Climate Change

While the painted lady butterfly has demonstrated incredible resilience through its adaptability and multigenerational migration, the effects of climate change present new challenges that could disrupt its journey.

One of the primary concerns is the alteration of migration timing and routes. Painted ladies rely on specific environmental cues, such as temperature and rainfall, to begin their migration. As climate change affects these patterns, the butterflies may face a mismatch between the timing of their migration and the availability of food sources along their route.

Additionally, climate change could lead to longer migration distances. As conditions in traditional breeding grounds become less favorable, painted ladies may need to travel further in search of suitable habitats.

The changing rainfall patterns across Europe and Africa could have a significant impact on the movement of the painted lady butterflies, according to a June 2021 study published in PNAS. Moreover, extreme weather events, such as storms and droughts, could disrupt migration paths and destroy crucial breeding sites.

As climate change continues to affect the world’s ecosystems, the future of the painted lady’s incredible migration remains uncertain. While they have stayed resilient and adaptable, these butterflies may face an increasingly difficult journey as they navigate a world transformed by rising temperatures and changing weather patterns.

Continued research and conservation efforts will be crucial in understanding and supporting this remarkable species as it undertakes its epic journey across continents.

While the painted ladies could yet stand up to the trials of climate change, not everyone might share the same enthusiasm or adaptability. How do you feel about the impact of climate change on our future? Find out where you stand on the Climate Change Worry Scale.