While it’s impressive that a creature as fragile as the monarch butterfly can travel 2,500 miles each way during its annual migration, the iconic butterfly’s title for the longest insect migration has just been usurped. Barely an inch and a half long, the Pantala flavescens dragonfly goes one step further, flying across continents and oceans.
Pantala dragonflies are found all around the world. It has long been suspected that they might be migrating between India and Africa across the Indian Ocean, but a genetic study published in PLOS ONE answers the question. Biologists looked at specimens from various continents to find out how closely related the dragonflies were — and they were surprised by the results.
It’s not just that some Pantala dragonflies migrate long-distance from here to there, but rather that the worldwide Pantala population is one giant gene pool, and individuals from all corners of the world are freely interbreeding. Dragonflies from the United States might be breeding with Japanese dragonflies which might be breeding with Guyanese dragonflies which might be breeding with South American dragonflies. You get the idea. This contrasts with other species of dragonflies that never leave the pond where they are born, barely traveling a few dozen feet in every direction during their lifetimes.
This Pantala dragonfly is a male from Japan. (Photo: Alpsdake/Wikipedia)
How is it possible for such a small insect to travel such long distances? How can they accomplish trans-continental migrations, an impressive feat even for large migratory birds?
“These dragonflies have adaptations such as increased surface areas on their wings that enable them to use the wind to carry them. They stroke, stroke, stroke and then glide for long periods, expending minimal amounts of energy as they do so,” Jessica Ware, an assistant professor of biology at Rutgers and senior author of the study, told Rutgers News.
How far they go may depend on how strong the available winds are. Some dragonflies might make relatively short hops from place to place, looking for fresh water to mate and lay their eggs, while others might travel for very long distances non-stop by gliding on powerful high-altitude winds, or even hurricane-force winds.
More research will be needed to gather the evidence necessary to fully prove this new hypothesis about travel via high-altitude winds, but the dragonfly's roughly 4,400-mile migration range puts it well ahead of any other migratory insect. It even beats Charles Lindbergh's historic flight across the Atlantic. Not bad for a fellow barely an inch and a half long.