Hetaerina americana or the American Rubyspot Damselfly
Dragonflies and damselflies are among the most frequently encountered and easily recognized insects while out kayaking. Different species live in almost every kind of freshwater habitat, from rivers, streams, and seeps to ponds, lakes, marshes, bogs, and roadside ditches.
The Seaside Dragonlet (Erythrodiplax berenice) even breeds in the salty waters of tidal marshes and estuaries. Because they leave the water to mature and to find food and shelter, you can also see them in meadows, open fields, and forests.
These adults are fast fliers, so one of the best ways to watch dragonflies and damselflies going about their daily business is from the cockpit of a kayak.
While out paddling I have been strafed by mosaic darners on their ceaseless patrol flights, served as a landing pad for curious damselflies, and cruised past bluet mating pairs all busily laying eggs in a long row.
The bright colors, startling size, and acrobatic flying skills of these insects have captivated people for centuries. To some Native American tribes, dragonflies symbolized swiftness or pure water; to Japanese warriors, they were an emblem of strength.
European and Euro-American cultures attributed a darker symbology, calling them Devil’s darning needles, eye-pokers, snake doctors, and horse stingers, and folk stories warned that children who lied risked having their lips stitched together by a dragonfly.
Their varied and evocative common names, such as shadowdragon, amberwing, sylph, boghaunter, spinyleg, sprite, firetail, jewelwing, and dragonhunter, echo the diversity and beauty of these insects.
Dragonflies and damselflies are in the order Odonata, a word that means “toothed” in reference to their remarkable mouthparts. Dragonflies are large and sturdy, and perch with their strong wings held horizontally; damselflies are smaller and more delicate-looking, and hold their wings closed over their slender abdomens at rest. Adult odonates come in every color of the rainbow, but their aquatic young (called nymphs or larvae) are dull-colored and cryptic to blend in with their environment.
Dragonfly nymphs can be streamlined to help them swim through vegetation or broad and flattened to burrow into mud. They obtain oxygen by pulling water into a gill chamber at the tip of the abdomen; this chamber doubles as a jet-propulsion unit, as the nymph can shoot water back out to escape from danger.
Damselfly nymphs are slender and minnow-like; they absorb oxygen through their skin and three delicate leaf-like appendages at the tip of the abdomen.
All odonates are aggressive predators. Nymphs hunt using their remarkable mouthpart, a hinged lower lip (labium) armed with teeth that folds under the head and shoots out to snatch aquatic insects, tadpoles, and even small fish, bringing them back to the mandibles to be chewed. Nymphs develop across one to five years, depending on the species. Like all insects, they grow by molting through stages called instars; with each molt, the developing adult wing pads become larger.
When it is ready to emerge as an adult a nymph leaves the water and climbs onto a nearby twig, plant, rock, tree trunk, or dock. As emergence begins, the skin splits along the top of the thorax and the adult pulls its head, thorax, and legs free, followed by the abdomen. The newly emerged (teneral) adult is soft, pale, crumpled, and vulnerable to attack; many birds scoop up fresh tenerals for themselves and their young. Soon the wings expand, the abdomen extends, and the dragonfly takes to the air in a fluttery maiden flight, leaving its cast-off skin (exuvia) behind. Tenerals move away from the water to feed, develop their full coloration, and become sexually mature.
Adults lack the hinged labium of nymphs but have other specializations to make them ferocious hunters, including spiny, forward-directed legs held out in flight like a basket to scoop up flies, beetles, leafhoppers, gnats, and mosquitoes.
Their huge compound eyes are composed of individual units called “ommatidia”; one eye may have 30,000 ommatidia. These amazing eyes give dragonflies an almost 360-degree field of vision, and can detect visible and ultraviolet light plus movement and shape, to let the insects home in on prey and avoid being caught themselves.
Their remarkable flying skills also make odonates excellent predators. The two pairs of large, transparent, intricately veined wings look delicate, but the strength of these wings and the underlying flight muscles make dragonflies some of the most dynamic fliers on the planet. Each wing can work independently, enabling them to stop, hover, shoot up, make sharp turns, and even reverse for short distances. Some dragonflies fly as fast as small songbirds (30 mph), and some species even migrate, making annual flights across thousands of miles.
Odonates are have a notable mating style. Before mating, the male transfers a sperm packet from a pore near the tip of his abdomen to his secondary genitalia, on the underside of the 2nd abdominal segment. He then uses appendages on the tip of his abdomen to grab a passing female behind the head; if receptive, she curves the tip of her abdomen up to lock onto the male’s secondary genitalia for sperm transfer.
These secondary genitalia can also remove stored sperm from a female’s previous mating. The pair forms a circular shape called the wheel position, in which they may remain perched or in flight for minutes or even hours.
In many species, the male continues to hold the female behind the head and flies with her as she lays eggs, protecting his reproductive investment. If the male releases the female, he may fly along with and guard her, or she may oviposit alone.
Depending on the species, eggs may be inserted into vegetation or sediment, dropped onto the water, or laid on the soil of dry seasonal wetlands that will flood later.
Odonates have an ancient lineage; fossils of giant proto-dragonflies (Meganeuridae) with 26-inch wingspans have been found in three hundred million year old sediments. Given their long history, diversity, and wide distribution, it is tempting to assume that odonates will keep flying successfully over our changing landscape, but their absolute reliance on freshwater ecosystems means they are losing habitat at an alarming rate.
Much of the world’s wetlands have been drained, filled, or polluted, and introduced fish can devour nymphs. The effects of global climate change are already being seen, with some species disappearing locally from seasonal ponds that have dried out repeatedly from recent severe droughts, and other species’ ranges beginning to change. As aquatic ecosystems worldwide are lost and degraded, the survival of odonates can’t be taken for granted.
There is still much to learn about odonates, and anyone who is interested can make a real contribution to what we know about their ecology, distribution, and status.
Digital photography has made identification at a distance even easier, and photos can be submitted to Odonata Central, a citizen-science initiative to track the diversity and distribution of odonate species in the New World.
If you go paddling at the same site on a regular basis, keep an eye out for some of our migratory dragonfly species and submit your observations to the Pond Watch project of the Migratory Dragonfly Partnership, an international effort using citizen science to expand our understanding of dragonfly migration in North America.
Many excellent field guides facilitate identification, and listserves and Facebook groups provide a friendly chorus of expertise and advice.
So the next time you head out, grab your camera and binoculars along with your PFD and paddle, and keep your eyes open for these beautiful insects that the poet Tennyson described as “a living flash of light”.
|Celeste A.S. Mazzacano, Ph.D is Staff Scientist / Aquatic Conservation Director and Project Coordinator for the Migratory Dragonfly Partnership of The Xerces Society for Invertebrate Conservation. You can learn more about the Xerces Society by clicking here.|
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