All about dragonflies
Dragonflies are living fossils! The oldest known fossilized dragonfly is 320 million years old. This predates the earliest dinosaur by at least 90 million years. But unlike the dinosaurs that died out 65 million years ago, the dragonflies are still around today - virtually unchanged!
So what is a dragonfly?
A dragonfly is a carnivorous insect. Scientist have placed them in the order Odonata. They are further classified into the suborder Epiprocta. Their close cousins, the damselflies have been placed in the suborder Zygoptera.
Dragonflies have multifaceted composite eyes. Their four wings are transparent, though often colored and are never able to be folded back.
The life of the dragonfly starts as an aquatic egg. After the egg hatches the dragonfly begins its larval stage which is called a "naiad" Depending on the species, the naiad will spend up to five years under water eating other aquatic insects, small fish, and tadpoles. When the time is right, the naiad will climb a piece of emergent vegetation, shed its skin, and a dragonfly will emerge.
Newly emerged dragonflies are very weak and it may take several hours before they are ready for flight. Even then, the flights are usually very short and only taken when necessary. By the next day, the dragonfly is ready to fly with the best of them and spends the rest of its life searching for food and mates. All species are carnivorous. Common foods include mosquitoes, midges, and black flies. Butterflies, grasshoppers, spiders, and other dragonflies may often be on the menu.
Dragonflies are often territorial and will will attack other dragonflies that enter into their mating territory. When a mate is found, the male dragonfly will clasp the female around the neck with specialized claspers of its abdomen forming what is referred to as a copulation_wheel. The sperm is transferred to a pouch in the females abdomen where it will remain until it is needed to fertilize the eggs. Depending on the species, the transfer may take place while set on vegetation, or may take place while flying in the air. Different species lay their eggs in different manners. Some will fly low dropping them into the water. Others will fly right above the surface dipping their abdomens into the water periodically and releasing their eggs. Still others will perch on emergent vegetation while depositing their eggs in the water. At least one species is known to deposit eggs on the land near the waters edge. The eggs have a special shell that protects them until rain washes them into the water. This may have developed as a means of avoiding the the aquatic predators that readily feast on egg laying females.
Predation of dragonflies is great and as a result, the average dragonfly only lives a very short time. Dragonflies that successfully avoid predators generally dies before the onset of winter. As summer ends, however, many North American species of dragonflies migrate South. Few will make it to Florida with predation and natural death occurring along the way. One species, the Common Green Darner not only can be expected to reach Florida, but have also been reported arriving in South America. Like the monarch butterfly, the Common Green Darner does not make a round trip. Naiads from the South produce dragonflies that migrate Northward in the spring. In tropical climates, dragonflies may live longer. Some Brazilian species may live for as many as seven years.
Where dragonflies naiads live?
Different dragonflies naiads require different habitats. Most species prefer ponds and lakes. Others require the acidity of bogs. Some species will live in slow moving rivers. Others require riffles and swift moving water. Dragonfly species may even differentiate between areas in the same body of water. Some living among emergent vegetation while others prefer bottom weeds.
Where can I find dragonflies?
Dragonflies can be found from the arctic circle to the tropics and on every continent except Antarctica. Some species found in Pennsylvania can be found in Europe, Asia, and even Africa.
Locally, dragonflies may be found near almost any permanent body of water. But you may also find dragonflies cruising through fields, forests, and backyards. Many dragonflies can be found where you would least expect them. During the days many dragonflies such as the Halloween Pennants will cruise around grassy fields and perch on top of the grass. Other dragonflies such as the Slaty Skimmer, Spangled Skimmer, and Dot-tailed Whiteface may be found perching mid-way down the stalks of grass. After a rain, when the grass is still wet, you may find many species hiding on the ground. Many species, particularly clubtails, will make a habit of perching on trees in the forest.
Taxonomists classify dragonflies as follows:
|Corduliidae||baskettails, emeralds, sundragons, shadowdragons, etc.|
Not found in Pennsylvania
Not found in Pennsylvania
The Common Names of dragonflies offer another means of classification based on body attributes, the preferred means of perching, or method of flying. For example, emeralds have large bright green eyes. Clubtails have thin abdomens that form a club at the end. Pennants rest on the tips of grasses or other vegetation and appear as little flags flying in the breeze. Cruisers patrol ponds and lakes a few feet above the water surface.