A monarch butterfly resting on a flower
Shutterstock/Shelly Jefferson Morton
Monarch butterflies with larger white spots on their wings are more successful at migrating long distances. These spots may create temperature differences across the insect’s wings, reducing drag and improving flight efficiency.
Monarchs, scientifically known as Danaus plexippus, exhibit an impressive migration, considering their small size. Some populations travel up to 4000 kilometers from Canada and the US to the forested mountains of Mexico for winter hibernation.
Researchers, led by Andy Davis at the University of Georgia, investigated the role of the white spots on monarch butterfly wings. They analyzed images of over 400 monarch wings during their fall migration and expected butterflies with more black on their wings to be more successful, as black absorbs more sunlight. However, they found that the most successful migrants had slightly less black and slightly more white on their wings.
The researchers also compared migratory monarchs with other closely related species and found that migratory monarchs have larger spots than their non-migratory cousins.
The researchers propose that the white spots limit the absorption of sunlight and radiation, creating a temperature difference between light and dark areas of the wings. This temperature difference could potentially change how air flows over the wings, reducing drag and improving aerodynamics. However, these ideas still need to be tested.
Marcus Kronforst at the University of Chicago comments that this study opens up new possibilities in the study of butterfly color patterns.
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