According to a new study that was published on Wednesday in the journal PLOS One, the key to success for a monarch butterfly that is migrating may be in its spots.
Based on previous research on seabirds, scientists assumed that monarchs with dark wings would fly most successfully. However, the opposite was shown by their findings.
The team looked at 400 photographed pairs of monarch butterfly wings and found that the ones with the most white spots were the ones that made it all the way to Mexico. According to the researchers, whiter wings may unevenly heat the surface of the wings, reducing drag. On their impressive migratory journeys, the insects might be able to move more quickly as a result of this.
Andy Davis, a co-author and animal ecologist at the University of Georgia, tells Kate Golembiewski of the New York Times, “No one even knew what these spots were for in monarchs.” They suddenly appear to be extremely significant.
One of the most well-known insect wonders is the monarch’s migration. The monarch butterfly is the only species that successfully completes a death-defying, two-way migration, unlike other butterfly species, which may migrate in a single direction, frequently in search of food. Monarch butterflies will make a mass flight each fall, traveling more than 2,000 miles from the United States and Canada to Mexico, where they will spend the winter. They also go north to breed in the summer, repeating the process.
Scientists propose that monarchs that are migrating benefit from a patchwork of heating and cooling along the edges of their wings caused by larger white spots. It could cause tiny, whirling pockets of air to form around the spots as darker wing areas become warmer and lighter wing areas remain cooler. The butterfly’s wings may experience less drag as a result of these eddies altering how air moves past it. The researchers speculate that the monarchs’ ability to migrate greater distances may have caused the spots to become larger and more numerous.
Nonetheless, some scientists assert that additional research is required to verify this connection. Mary Salcedo, a biomechanist at Cornell University who was not a part of the study, tells NPR’s Nell Greenfieldboyce, “I’d be really interested in more aerodynamic measurements.” I would love to see their lift and drag coefficients from aerodynamic tests.
To attempt to get this information, the group desires to construct and work counterfeit ruler wings in a test chamber that looks like an air stream. According to the paper, additional research may rule out other potential explanations for the white spot trend, such as predator defense or migration-induced sun bleaching.
However, engineers could benefit from the findings if they are true. The researchers assert that applying the white spots of butterflies to drones could boost their effectiveness. According to co-author Mostafa Hassanalian, a mechanical engineer at New Mexico Tech who has developed taxidermy bird-based drones, “your drone would be able to carry more, because this coloration helps them gain extra lift.”
“It’s hard to see with the naked eye,” Davis tells Corryn Wetzel of New Scientist. “It’s hard to see with the naked eye.” Only image processing software can reveal the subtle variations in spot size. Overall, there was little difference in the size of the spots on the insects; monarchs that made it to Mexico had white spots that were just 3% larger than those that ended up at sites in the United States.
