Found all over the world, the wandering glider (Pantala flavescens) is aptly named. The dragonfly has truly global reach, and it is found on every continent except Antarctica. To get to all those far-flung corners of the planet, the winged insect (also sometimes called the "globe skimmer") makes epic migratory flights: They have been seen, for example, traversing the Indian Ocean in the hundreds of thousands on their way from Asia to Africa.
But just how far they go has shocked researchers. New research suggests that these dragonflies make transcontinental voyages on a regular basis, which is quite a feat for an insect less than 2 inches in length.
Since it's impossible to directly track dragonfly migration with existing GPS technology—any monitor would be too heavy to attach to their small bodies—researchers examined the genes of specimens found around the world. This information can reveal how often animals from different areas breed with one another, a proxy for how far and frequently they migrate, says Jessica Ware, a biologist at Rutgers University.
As it turns out, wandering gliders mate so frequently with dragonflies (of their same species) around the world that their gene pool is one big, relatively undifferentiated melting pot, according to a study published March 2 in the journal PLOS One, authored by Ware, her former student Daniel Troast, and others.
Usually one sees a "neighborhood" effect, where individuals living near each other are more closely genetically related to each other than they are to individuals found on the other side of the world, Ware explains. But with the wandering glider, that's simple not the case. "Because the entire world is their neighborhood, any [wandering glider you see] is likely to be as closely related to one in Europe as it is to one in South America," Ware says.
One previous 2012 PLOS One study on the subject suggested these creatures can fly 3,700 miles, but this study suggest they probably travel much farther. "This puts them into competition with whales and birds for being the longest migrators," Ware says.
John Abbott, a researcher at the University of Alabama who wasn't involved in the study, says that birds definitely migrate longer distances, but that these dragonflies do clearly fly farther than any other insect, beating out monarch butterflies. "This is a significant study because it reveals for the first time that this globally distributed, migratory species should really be looked at as a singe global panmictic population," he says. (A panmictic population is one where all individuals of the same species are potential breeding partners.)
These dragonflies fly high up in the air, and are capable of using their wings to glide, so they don't have to flap constantly. "The winds do a lot of their work for them," she says.
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