Cyclist Jon Scott was cruising along at 25 miles per hour (mph) when he noticed that there was something itchy on his head. He decided to stop and investigate. When he removed his shiny black helmet he found that a Blue-eyed darner (Rhionaeschna multicolor, syn. Aeshna multicolor) dragonfly had been hitching a ride. The Blue-eyed darner is found in western North and Central America.
The dragonfly (Anisoptera) shares the order Odonata with the damselfly (Zygoptera), but they are separate suborders. Dragonflies are attracted to shiny objects, possibly mistaking them for water. They can fly up to 30 mph, making Jon’s 25 mph cruising speed within range. In addition to speed, capabilities such as hovering, rapid ninety-degree turns, flying straight upwards, downwards and backwards have made the flight of the dragonfly a popular subject of study and simulation. Adult dragonflies may range far from fresh water, but they must return to the water to breed. Dragonflies: Four Wings Will Travel, a publication of the Dragonfly Migratory Partnership, provides a detailed description of the dragonfly’s reproductive dance.
At the larval stage, Jon’s passenger dragonfly would be referred to as a nymph. Jon will probably never find a nymph riding on his helmet, unless his helmet really is made of water. The nymph lives in fresh water for several years where it feeds on a wide variety of mature and larval aquatic insects, small fish and tadpoles. It obtains oxygen from the water via internal gills. The Blue-eyed darner nymph molts from ten to thirteen times. The variable number of molts may depend upon availability of prey and climate conditions. Like most other dragonfly species, it spends the bulk of its lifespan as a nymph. When it is ready to become an adult, the nymph leaves the water at night, crawls up a stem or stalk so that it will be perpendicular to the ground, then molts once more. The body of the newly emerged young adult, or teneral , is soft, stubby and filled with hemolymph, the insect equivalent to blood. The teneral’s wings appear far too small for flying and in fact it cannot fly at this point. With its first breaths of air, the teneral’s circulatory system starts pumping hemolymph into its abdomen and wings. The abdomen elongates, becoming long and slender; the wings fill out and strengthen. When the wings fill out and are strong enough, the Blue-eyed darner flies away from and may range far from water where it hatched. As its body, chitin armor-plated, yet flexible, continues to harden, the brilliant blue markings that are characteristic of the Blue-eyed darner start to emerge.
Fossil remains of the largest ancestors of the contemporary dragonfly date back to 300 million years ago. Some of these ancient ancestors (known as griffinflies) from the extinct genus Meganeura were enormous in size, with wing spans over 25 inches. The griffinflies became extinct during the Great Dying, or Permian mass extinction event, when 96% of all life perished. “The more recent developing Odonata first appeared some time during the middle of the Permian period, near the end of the griffinflies’ aerial reign, and was one of the few winged orders of insects that survived ‘the Great Dying.'”¹
What do we have in common with the Blue-eyed darner? What do we have in common with all living things on earth? We are all descended from some ancestor among the 4% that made it through the Permian.
¹Whitney Cranshaw and Richard Redak, Bugs Rule! An Introduction to the World of Insects (Princeton: Princeton University Press, 2013), 148.