New research shows that the butterflies fly better when they have more spots on their wings
ENTOMOLOGY
Monarch butterflies with more white spots on their wings are able to survive longer migrations, according to scientists. A study conducted by ecologists at America’s University of Georgia, Athens, focused on the butterflies – which migrate thousands of kilometres every year to reach their wintering destination – found that evolution favours spottier specimens.
It’s not yet clear exactly how the spots aid migration, but the authors’ conjecture is that they change airflow patterns around the butterflies’ wings.
“Monarch butterflies are able to fly incredible distances and this research shows that their ability may be more than just a product of the physical structure of their wings and muscles,” entomologist and broadcaster Prof Adam Hart, who was not involved in the study, told BBC Science Focus. “Dark and light-coloured spots on their wings heat up in the sunlight differently,” he continued. “This could cause a pattern of tiny eddies and airflow around the wings that might help the butterflies reduce drag. It’s early days, but similar effects have been found in birds.”
Lead author Andy Davis, an assistant researcher in UGA’s Odum School of Ecology, said: “We actually went into this thinking that monarchs with darker wings would be more successful at migrating because dark surfaces can improve flight efficiency. But we found the opposite.”
Monarchs travel from their native homes in the northeast of the US and southeast of Canada to south and central Mexico – over 4,800km (3,000 miles) away. The researchers behind the study, published in PLOS ONE, analysed the wings of around 400 wild monarchs collected at different stages along the route and measured their colour proportions.
The monarchs found at their f
