Last updated: October 10, 2024
Article
Nature Watch: Flying Jewels - Living Flashes of Light
Written By Ken Shea, Volunteer Dragonfly Citizen Scientist
Ken Shea
If you are lucky and in the right place and at the right time on Cape Cod, you might be surprised to learn that dragonflies can assemble with birds, butterflies, and even with people during the summer months. Why not enjoy the presence of dragonflies because, throughout the summer and into early fall, these creatures are conspicuously active over Cape Cod’s innumerable, coastal ponds and various wetlands?
But blink your eyes and you might miss them! Anyone who visits fresh water habitats in the summer most likely will notice our dragonfly community. With exotic names as fascinating as their behavior: Ebony Jewelwing, Variable Dancer and Sedge Sprite, dragonflies have now begun to fascinate nature lovers. Join the crowd!
Dragonflies and damselflies play key roles in both terrestrial and aquatic habitats. These insects are often considered indicator species for watershed health, while the status of these species can give scientists insights into how aquatic ecosystems are faring. Dragonflies are good indicators of habitat quality. They can also be used as tools to detect levels of heavy metals such as mercury accumulating in fresh water systems. Most recently they are also considered model organisms to assess the effects of global change. Want to learn more?
Ken Shea
Did you know that dragonflies are rich in history? Their ancient lineage dates to the Carboniferous period some 300 million years ago, long before the presence of dinosaurs and the appearance of mammals and flowering plants. They were some of the first winged insects to evolve at that time. Today, modern dragonflies have wingspans of only 2 to perhaps 5 inches, but fossil dragonflies have been found with wingspans of up to 2 feet. Amazing? It’s true!
Both dragonflies and damselflies come from the same scientific order, Odonata, and are collectively referred to as “odonates” or “odes” meaning “toothed ones.” They are the largest insects our visitors are most likely to see on Cape Cod. These unusual insects come in a dazzling array of colors and share characteristics which in combination, distinguish them from other insects.
On Cape Cod both dragonflies and damselflies begin life as larvae (nymphs) on the bottom of various wetlands including coastal ponds. Many species of dragonflies have the ability to live as long as 7 years as flightless nymphs.
Odonate nymphs serve as both predator and prey. Numerous predators feast on nymphs; odonate nymphs can also consume anything they can capture. When development is complete, the nymph is ready to emerge and transform itself into an adult dragonfly. Emergence generally occurs early in the morning before dawn to avoid predation. The nymph crawls from the water onto adjacent vegetation, logs, or even onto vertical structures. After several hours the newly emerged adult flies away leaving behind the nymphal skin or exuviae.
Ken Shea
Dragonflies and damselflies are most active during sunny conditions and can be found in fresh water ponds, wetlands or marshy wooded areas; these locations are the best and most productive places to observe these spectacular, colorful insects. Adults often spend the majority of their days aloft to hunt and to eat prey. Dragonflies are top predators, predaceous creatures in both their adult and larval stages, and are regarded as beneficial insects because they feed on large numbers of small flying insects such as gnats and mosquitos.
As a rule, dragonflies immediately disperse from wetlands following emergence from the nymph stage and travel almost anywhere; for example to adjacent uplands, surrounding fields, walking trails, and woodlands. Various habitats protect these insects while they forage, seek shelter and mature before returning to the aquatic environment to mate, deposit eggs and die. Most dragonfly species are relatively short-lived. Normally, adult dragonflies in temperate climates fly only during a single season; some for several weeks while others up to several months. Most of the dragonfly life is actually spent under water as an immature creature called a nymph in the benthic neighborhood among crayfish, caddisflies, mayflies and stoneflies.
Color is one of the most striking attributes that attracts our attention to odonates. Almost any combination of color is likely, from rich magentas to exotic sapphire blues to fiery crimson reds. The insect’s body colors may be dull and flat or shining and iridescent, even painted with leopard like spots or tiger stripes. Wings are often distinctively marked with dazzling spots or bands of color.
Adult dragonflies are very strong fliers with robust bodies, and when perched, they hold their slightly unequal pair of wings straight out to the their sides. The four transparent, ultraflexible wings are attached to the thorax portion of the insect’s body by separate muscles and can be maneuvered independently, lending the insect an extraordinary range of flight options. Dragonflies are magnificent aerialists; they can fly straight up and down, hover like a helicopter and even mate in mid-air. These remarkable creatures can fly in any direction, including sideways and backward, and can hover in a single location for a minute or more. There are few species in the animal kingdom that can match the dragonfly for spectacular flying ability.
Ken Shea
These insects are true visionaries, having a full field of vision. Their eyes are perhaps the largest and possibly the keenest in the insect world. Surprisingly this group of insects maintains enormous eyes almost completely covering the insect’s head. Tens of thousands of different lenses in these compound eyes enable the insect to see almost all around - nearly 360 degrees.
The smaller, delicate, odonate cousins - the damselflies, on the other hand, are slender, delicate and weak fliers, flying at low altitudes and staying within the reach of the cover of vegetation, seldom moving far from their early stage habitats. When at rest they hold their wings folded or slightly spread over their abdomen in butterfly fashion. Damselfly compound eyes are widely separated on either side of their head. I have observed that these flying insects can see you when they are flying toward you and still see you when they’re flying away. Something strange and hard to believe!
Males are known to grapple or spar with other males in-flight and persistently descend downward chasing females. Once captured the unique spectacle of mating occurs while airborne. In some situations other than aerial events, the dragonfly mating process is a rough-and-tumble affair. Generally speaking the process is a very conspicuous event, easily recognized by the heart-shaped "wheel" formation of mating pairs. Normally some males will patrol around water to set up and defend territories and await arrival females. The body of water has to be suitable for the female to lay her eggs.
On Cape Cod, there are 3 families of Damselflies (Zygoptera) which constitute approximately one-third of our odonate population; they are Broad-winged Damsels, Spreadwings, and Pond Damsels. Dragonflies (Anisoptera) compose the remaining two-thirds of the population of the families of dragonflies on the hooked-shaped peninsula of Cape Cod. They consist of Darners, Clubtails, Emeralds, Cruisers, and Skimmers.
In North America, dragonfly migrations occur annually in late summer and early fall. In North America, approximately 16 migratory dragonfly species move from Canada and Alaska to places located in southern latitudes traveling along both United States coasts and through the Midwest. Some of the migratory species engage in annual, seasonal migrations while others are more sporadic migrants. Regrettably, dragonfly migration is a poorly understood phenomenon and shrouded in mystery. Where are they going? As of yet this remains unanswered as do many questions about dragonflies. Knowledge regarding migratory cues, flight pathways, population connectivity, and the southern limits of overwintering areas remain fragmentary. A better understanding of dragonfly migration requires long-term, coordinated study by citizen scientists across a wide geographic range.
Dragonfly nymphs and adults create an important link between aquatic and adjacent, terrestrial ecosystems and serve as indicators of ecological health. While most people are not familiar with the names of individual species, young and old alike are enchanted by both dragonflies and damselflies. Try and visit a pond during the peak summer months when it is quite possible to discover 15 or 20 different dragonfly species flying about. When you do encounter them, you may find it useful to carry with you some close focusing binoculars and a field guide, as well as a digital camera or iPhone to enable you to capture their image, perhaps making them easier to identify at a later date. Depending upon color, scheme and flight behavior you may encounter any one of a number of exotic sounding families including the Emeralds, Darners, Skimmers and Cruisers. After all, our population of odonates consists of pretty amazing creatures.
Ken Shea
For the last 20 summers following retirement in 2003 from the National Park Service, I volunteered to monitor and survey odonate (dragonfly) populations at Cape Cod National Seashore and hope to continue for as long as I am able.
What made the project exceptionally appealing to me was the discovery that dragonflies and damselflies allowed me the opportunity to take detailed digital photographs of these fabulous insects in order to document their presence. Working on my surveys, I’ve covered numerous fresh water wetlands including vernal ponds, fresh water bogs, coastal plain ponds and fresh water marshes. My time afield enabled me to obtain a new vision, a sense of accomplishment and a renewed determination to grow and discover more about the delightful dragonfly. I have learned a lot about dragonflies but I still have a lot more to learn. Nature is full of endless opportunities for discovery and adventure. Our natural curiosity about these aerial marvels can bridge the gap between perception and truth about the natural world. Be it myth or science, odonates are treasured for their elegance on the wing that causes our imaginations to soar.