Dragonfly or Damselfly?

Recently, my 25 year old son and I set off on a wilderness adventure. We headed for a local wildlife sanctuary near the ocean, complete with tidal pools and hiking trails. It was a typical sunny, hot and humid August day here in Connecticut as we set off on a hiking trail.

The first part of the trail led through a fairly open marsh area. We were completely taken aback as we rounded a corner and were greeted by literally dozens of dragonflies swirling in the air around us. I have always loved these beautifully mysterious little creatures, so I was totally in awe as several of them landed on my arms and shoulders. My son, who is an amateur photography buff clicked away a whole roll of film taking some amazing photos of these little beauties in their natural habitat.

As we entered the woodsy shaded area ahead of us, we noticed that the dragonflies stayed back in the sun filled marsh. Within minutes we were assaulted by just about every kind of flying and biting insect native to this neck of the woods. Even after liberally spraying ourselves with heavy duty insect repellent, we were still being bomb-dived by deerflies and mosquitoes. After walking about half a mile, we emerged into another sun-filled marsh area. We very quickly became aware that the flying demons who had been attacking us were gone and that we were once again surrounded by dragonflies. My son watched in astonishment as a dragonfly swooped by his arm and literally inhaled a small deerfly that had lingered upon his T-shirt.

By the end of our hike, we had a new appreciation and respect for dragonflies. My curiosity was piqued and I decided to learn more about my insect eating friends. Here's what I found out!

Dragonflies belong to an order called Odonata which translated means "toothed ones." This order includes some of the most beautiful and ancient insects that have ever existed upon our Earth, as well as a few of the largest flying invertebrates that have ever lived. The two most common members of this group are the dragonfly and the damselfly. There are about five thousand different species of dragonflies all over the world except in Antarctica. Four hundred and fifty of the species can be found in the United States with about eighty in British Columbia. Most of the five thousand species are found in remote, tropical areas.

The characteristics that distinguish Odonata from other groups of insects are minute antennae, extremely large eyes that fill most of the head, a long narrow abdomen, extendable jaws located underneath the head and two pairs of transparent membranous wings with numerous small veins. Both dragonflies and damselflies start out in an aquatic larval stage called a nymph with posterior tracheal gills.

Even though both groups belong to the Odonata grouping and have much in common, there are some noticeable differences between dragonflies and damselflies. It all starts with the egg. Dragonfly eggs are round and about 0.5 mm long, whereas damselfly eggs tend to be cylindrical and about 1 mm long. After hatching the nymphs (or larvae) of the damselfly have long and narrow abdomens with three fin-like gills projecting from the end. Dragonfly nymphs, on the other hand, have gills which are located inside of the abdomen which allows the nymph to expand and contract its abdomen to move water over its gills, squeezing the water out rapidly for underwater jet propulsion.

Interestingly, most of a dragonfly's life is spent in the larval stage where it molts from six to fifteen times. Larval development can vary from one to two years and sometimes, depending on conditions, can last as long as six years. When the nymph is ready, it crawls up out of the water and molts one last time. It then emerges from its old skin as a fully functional winged adult with a lifespan of less than a year.

Both dragonflies and damselflies have very large compound eyes composed of nearly 28,000 individual lenses and a dragonfly can see all the way around itself. More than 80% of their brain is utilized towards analyzing visual information. All Odonata have a prehensile labium, or extendable jaw located underneath their heads. They literally extend their jaw forward faster than their prey can react. Their six legs are located near their heads and are seldom used for walking, but rather for catching prey, perching on vegetation, and egg laying. Odonata literally form a "basket" with their legs in order to entrap and carry their prey through the air.

One of the main differences between dragonflies and damselflies are their wings. Both groups have two pairs of elongated membranous wings which are strong and flexible as well as a notch in the front edge of each wing. Dragonflies wings are larger in the back and smaller in the front, whereas damselflies have front and back wings of roughly the same size. As a result damselflies fly slower than dragonflies. The most visible difference is that dragonflies do not have hinges which would enable them to fold their wings together while resting and damselflies do.

Dragonflies are capable of flying forward at about 100 of their body-lengths per second, and backwards at about 3 of their body-lengths per second. And, they can hover in the air for about a minute. The wings of male dragonflies are somewhat longer and narrower than those of the females in the larger species.

Fossils of Odonata have been found which are thought to have been formed about 325 million years ago. They seem to be similar to modern day Odonata, with the exception of a wingspan of about 30 inches across.

The general diet of Dragonflies are flies, gnats and many different types of insects. Studies show that food shortage may limit reproductive behavior as females carrying eggs feed almost constantly, as do maturing dragonflies.

Dragonflies do not hunt in cold weather, although damselflies don't seem to have this limitation and have been observed hunting even during cold spells. Males of both species are territorial sometimes swooping in on prey for hours at a time. The main predators of Odonates are birds. Although they also fall prey to lizards, frogs, spiders, fish, water bugs, and even other larger dragonflies.

The mating rituals of Odonata vary from sub-group to sub-group. Some mate in flight, while other mate while perched. One of the most interesting facts about the mating habits of Odonata is the fierce competition among the males for females. In some species, the male will remove all the sperm of rival males from a females body before transferring his own sperm. These species are equipped with a "scoop" at the tip of the males abdomen for this purpose.

The preferred environmental habitat of Odanata seems to be pretty widespread. Some are restricted to cool streams and rivers, others to ponds or still, clear waters, and some to marshlands. Wherever they may be found, the presence of dragonflies and damselflies indicates a good ecosystem quality. The greatest numbers of species tend to be found at sites that offer a wide variety of microhabitats. Dragonflies seem to be much more sensitive to pollution than are damselflies. Some species tend to tolerate a broad range of environmental conditions while others appear to be more sensitive.

Now, no article concerning dragonflies would be complete if I didn't include their symbolic representation within different cultures. The interpretations vary from culture to culture, but many agree that the dragonfly represents renewal and positive life force. Because the dragonfly is a creature of the wind, it also represents transition and change. In Japanese tradition the dragonfly represents new light and joy whereas in some Native American tradition dragonflies represent the souls of the dead.

Even now that I know the 'facts" concerning dragonflies, I still tend to feel the same sense of awe and magic as I watch them darting through the marshes on a hot summers day. Perhaps the very thought of a dragonfly brings out the childlike wonder in all of us. I know it does in me.