Dragonflies

The dragonfly is a species of non-stinging insect that belongs to the Odonata order. Its characteristic features are large eyes that are multifaceted, two pairs of wings that are transparent and strong, and a body that is elongated.

Distinguishing the Dragonfly from the Damselfly

Often, damselflies are mistaken to be dragonflies, however, both these insects are quite different. When at rest, the damselfly holds its wings above its body, and together, or a little open. The dragonfly, on the other hand, keeps its wings horizontally, or sometimes a little forward and down. Plus, the dragonfly’s hind wings are broad at the base and are larger in size than the front pair of wings, whereas the both the wings of the damselfly are basically similar. The eyes of the dragonfly touch, while the damselfly’s eyes are separated.

The Physical Features of the Dragonfly

The dragonfly has a large head and huge compound eyes, relative the rest of its body. Each of its eyes is made up of about 28,000 ommatidia, or small, cone-shaped simple eyes. The two eyes cover most of the dragonfly’s head, and over 80 percent of its brain analyzes visual information. Their antennae, in contrast, are very small. The mouth of the dragonfly is adapted for biting, which makes them very good hunters. It also has a prehensile labium, or lips, which they can extend very fast before a prey can get away. The dragonfly has six legs, which are all close to the head. They hardly ever use them for walking, but instead use them to stand on plants in order to lay eggs or rest, and also for hunting.

The dragonfly’s iridescent wings are membranous and elongated, with extensive crossveins, making them strong and flexible. And the wings have a notch, or nodus, at the front edge. The absence of hinges is what prevents the dragonfly from folding its wings.

The design of the wings enables the dragonfly to hover in the air for almost one minute, fly forward at around 100 lengths of its body per second, and backwards at around three lengths of its body per second. The male dragonfly’s wings are comparatively narrower and longer than the female’s, particularly in larger species.

The wingspan of the adult dragonfly can be from 17 mm to 20 cm, depending on the species. The wingspan of most species that occur in the temperate zone is around 5-8 cm in length, and 2-12 cm in breadth.

The Life Cycle of the Dragonfly

The dragonfly spends most of its life as a larva, wherein it undergoes molting about 6 to 15 times, depending on the species. The female lays its eggs either near water or in it, usually on plants that float or grow out of water. Some dragonfly species submerge themselves fully while laying eggs, in order to find a suitable place to lay them on. Once hatched, the larva can exist in the water by breathing through its internal gills, and making use of extendable jaws to capture its prey, which can be either invertebrates, or sometimes even vertebrates like tiny fish or tadpoles. This larval stage can be as long as 5 years in larger species of dragonflies, while in smaller species it can be from 2 months to 3 years.

Once it is time for the larva to turn into an adult dragonfly, the nymph comes out of the water, climbing up on a reed or any other plant, and emerges from its old skin one last time, coming out as a dragonfly with wings. This usually takes place at night. Once it comes out, the new dragonfly waits for sunrise, and then pumps its wings out, and flies away, to feed and to find a mate. The larger species of dragonflies can live up to 4 months in their adult stage.

As is evident, unlike beetles and butterflies, there is no pupal stage between the larval stage and an adult stage. This is why, it is said that dragonflies are hemimetabolous, which means that they undergo ‘gradual’ or ‘incomplete’ metamorphosis.

The Feeding Habits of the Dragonfly

The dragonfly eats just about anything that they find in abundance. They often hunt for food in groups when ants or termites are available in large numbers, or when there are swarms of gnats, caddisflies, or mayflies.

The Dragonfly’s Predators

Although they are predators themselves, the dragonfly too must be careful about various predators that make them a meal, such as water bugs, fish, spiders, frogs, lizards, birds, and even larger species of dragonflies preying on smaller species. Nevertheless, the dragonfly is well adapted to escape being eaten, their visual responses and agile flight are exceptionally good.

The Natural Habitat of the Dragonfly

The habitat of the dragonfly is highly variable, depending on the species. While some species are highly localized others are quite widespread. While some species prefer marshy areas, others favor clear waters or ponds that have still water, while still others have a preference for cool rivers or streams. When dragonflies are present, it is indicative that the ecosystem is in good condition, since they are sensitive to pollution. They are also useful since they feed on mosquitoes.