It was warm and humid. The birding had slowed, but it probably wouldn’t have mattered. As we peered out from the shade of some large trees, someone noticed a large gold dragonfly drifting into view. Then another. And yet another. Soon the meadow in front of us had a cruising swarm of dozens of big golden dragonflies, coasting back and forth in a random, mesmerizing pattern. “Gliders”, someone said, “ Wandering Gliders.” For several of us, it was our first introduction to this iconic dragonfly. Pretty typical, too, that they would just suddenly appear. Wandering is what they do.
Wandering Gliders (Pantala flavescens) are the Chimney Swifts of the Dragonfly world. They rarely seem to pause for rest, and fly long distances to feed or breed. They have long, broad wings that seem perfectly designed for flying with minimal effort. And they seem to do everything on the wing. Feeding, check. They don’t pause to perch as they scoop up small flies, mayflies, and moths, eating them as they fly. They seem especially attracted to wetlands, but can hunt any open space, above fields or forests, as well. Here’s a good summary of their biology from a Canadian naturalist: https://ofnc.ca/wp-content/uploads/2024/01/Dragonfly-Profile-19-Wandering-Glider-TL-581.pdf
Mating is also aerial. Gliders have the classic weird dragonfly mating, where males extrude sperm onto a spike low on their abdomen, then clasp receptive females, who twist their abdomens into a half circle to take up the sperm. These tandem dragonflies form a rough circle, and are called the wheel position, like some strange entomological kama sutra. They stay in tandem even after breaking the circle, and fly low to the water’s surface, where the female dips her abdomen periodically to deposit eggs. They especially favor temporary pools, probably to avoid fish that could eat their larvae.
And then there’s that ‘wandering’. Although it may seem random to us. Gliders are actually storm-followers. Much of their biology is built around rain, so much so that one of their other names is ‘Rainpool Glider’. Swarms of them follow the updrafts around storm fronts, allowing them to move long distances expending little energy. The rain they follow produces 2 life-altering events for them: it creates a flush of insects for the adults to feed upon, and it creates temporary pools in which to lay their eggs. Glider nymphs are voracious feeders that can complete their entire larval life in 6-7 weeks, plenty of time to exit the temporary rain pools and flood pools into which they were dropped.
This dependence on rain has allowed Gliders to evolve a nomadic lifestyle of long migrations that are astounding in their distance and complexity. The best studied is a migration circuit that crosses the Indian Ocean between India and Africa, following the alternating monsoons that soak each continent at different times of the year. Here’s a video summarizing this epic migration: https://wosu.pbslearningmedia.org/resource/mol20-sci-epicmigration/an-epic-migration-driven-by-water-h20-the-molecule-that-made-us/ . North American migrations are not as well studied, but the appearance of Gliders over much of the East in late Summer and early Fall suggests that they are following storm fronts and hurricanes up from the tropics. The flooding that we consider such a nuisance is the reason Gliders come here.
Where can you find these wanderers? No place is a guarantee, but you can boost your odds by narrowing your possibilities. Large lakes and rivers might get some feeding flocks, but don’t offer much breeding potential. Vernal Pools seem like a logical bet, but have the wrong timing; they are flush in the Spring – long before these dragonflies arrive – and dry by late Summer. Shallow marshes and flood pools seem the best bet, since they can fill after a big rain, and offer both feeding and breeding opportunities. Places like Pickerington Ponds, Big Island Wildlife Area, Scioto Grove MetroPark, or the Battelle Darby Wetlands would seem to be ideal. If you visit these spots in early Fall, watch for the golden swarms of Gliders and wonder at their wandering lifestyle.