How Vanessa Cardui Butterflies Crossed the Atlantic: A Ten-Year Investigation into Insect Migration Across Continents

In 2013, a team of entomologists led by Gerard Talavera at the Barcelona Botanical Institute made a startling discovery: several Vanessa cardui butterflies on the beaches of French Guiana in South America. This sparked a ten-year investigation into how these butterflies were able to make such an incredible journey from Europe to sub-Saharan Africa, a distance of 14,500 km.

After conducting extensive research and analyzing weather data, genetic sequencing, isotope analysis, and DNA from pollen grains found on the butterflies, the researchers concluded that these insects likely crossed the Atlantic Ocean from West Africa to South America. The Saharan Air Layer was identified as playing a crucial role in their journey, as it carries dust from the Sahara desert in Africa to South America and helps make the Amazon basin more fertile.

Eric Toro-Delgado, another biologist involved in the study, emphasized that wind patterns are essential for these butterflies’ long-distance flight. Without favorable wind conditions, they would not be able to complete their 5-8 day journey due to the high energy demands of active flight. This research highlights how even tiny insects can harness wind currents for their extraordinary migrations across continents.