a biodiversity hotspot
Dragonflies and Damselflies belonging to the order Odonata are known to roam the earth for about 300 millions years. Palaeontology (study of fossils) records reveal that the largest fossil of dragonfly was found to have a wingspan of about 2 ½ foot from the Carboniferous Period. Evolution in these species for millions of years changed their characteristics. In Nilgiri Biosphere Reserve (NBR) these insects are commonly found near water bodies like ponds, lakes and slow moving streams and other wet lands. These are the common spots for them to lay eggs. Most dragonfly species are found in tropical areas. Here are some important dragonfly facts.
Odonata - Interesting Facts
Dragonflies are regarded as strict carnivores insects. Insects like ants, bees, butterflies, flies, gnats, midges, mosquitoes, and termites are on the menu of these insects. They also feed on larvae, tadpoles and even tiny fish. Dragonflies nymphs (the first stage after hatching) love to feed on mosquitoes. Odonates contribute a lot for biological control of mosquitoes by eating upto 50 mosquitoes in a day while flying around.
Most of the odonates dwell in healthy and breathable water in NBR. They are considered as indications of good water quality as they thrive in unpolluted water. Water bodies in NBR that support submerged and emergent vegetation provide shelter to these insects. These odonates lay their eggs in water or on vegetation near water or wet places. They spend a major part of their lives underwater as nymphs in their larval stage. Adult dragonflies' life span lasts for a very short time - about a month.
Wings and Flight
Dragonflies are equipped with two sets of wings, so they do not have to beat their wings simultaneously. They flap their wings at a rate of 30 beats per second. It is known that these fliers can reach a top speed of 100 km/h. Their flight is similar to that of a helicopter; they can fly forward, backward, up and down and they are also capable of hovering. Such flying skills are achieved by powerful flight muscles and wings that can move independently.
Eyes and Eyesight
Odonates are able to distinguish between colored, ultraviolet and even polarized light. These feature enable these insects to detect reflection in water. Among the most unbelievable fact about dragonflies is, they have a 360º field of vision due to their eyes' position and each of their compound eyes contain about 30,000 individual lenses.
Territory and Mating
Like most males in the insect world and the animal kingdom, male dragonflies are very particular about their territory. They stake their claim to a particular area alongside a river, pond, lakes and wetlands of NBR. Often, we can see that two dragonflies chase each other. When it comes to mating, these insects undergo a complex process. What is normally seen in a mating, is a couple attached to one another and flying through the air.
Birds are the natural predators of dragonflies and damselflies. In NBR we can see the bee-eaters feeding on the dragonflies. Apart from birds, these insects are also preyed upon by fish, water beetles, frogs, spiders, lizards and even larger species of other dragonflies.
Dragonflies and Humans
Dragonflies are harmless creatures and don't bite or sting people. They are beneficial to humans. They help in reducing the population of mosquitoes and other harmful insects.
Along with other birds and animal species, dragonflies also face a threat of extinction. We have witnessed the complete extinction of innumerable species of these insects in NBR. The remaining population have become rare and have been restricted to few areas in NBR itself. These Odonata face a constant threat from habitat destruction, pollution, and other environmental degradation.
Dragonflies and Damselflies form a small but an important part in the ecosystem and contribute to ecological balance in NBR, in someway or the other. Let us preserve and respect these wonderful fliers in NBR!
Convention on Biological Diversity