That low-flying dragonflies are harbingers of rain is a well-known fact. But, did you know that they are extremely important bio-indicators of the health of an ecosystem? The fewer dragonflies there are around, the more the cause for concern regarding ecological resources and pollution levels.
To spread awareness about dragonflies and their significance, as part of the ongoing Dragonfly Festival happening in 13 states in India, WWF India Goa organised a talk on October 9, 2024, with ecologist Parag Rangnekar as the speaker.
In Goa, two lakes are under survey with regard to dragonflies, i.e. the Carambolim Lake and the Nanda Lake (Goa’s first Ramsar site). Thirteen college and university students from Goa are part of this initiative. By the end of November, the data collected will be analysed and uploaded on the India Biodiversity Portal.
Often identified or connected with the Devil in folklore, this fascinating insect which spends half its lifecycle in water, has survived mass extinctions.
Dragonflies and damselflies belong to the scientific order called Odonata (toothed ones), because the predatory insects, which catch their prey on wing, have biting mouth parts.
“I’m sure many of you may have tried to catch dragonflies as youngsters. If you catch a bigger one, they try to bite your fingers,” said Parag, elaborating on the insects’ predatory behaviour.
Trying to study the lifecycles of dragonflies is a difficult proposition because dragonflies require live feed. During the monsoons, it is easy to feed the larvae because of an abundance of tadpoles and mosquito larvae.
Apart from dragonflies and damselflies, there are damsel-dragonflies that have attributes of both odonates. There is only one species that was found in Meghalaya, India, described on the basis of a nymph (aquatic larvae of odonates).
There has been no sighting of the adult of this species of damsel-dragonfly in India. This species is legally protected under the Wildlife (Protection) Act, 1972.
Goa has 108 species of dragonflies detected so far, and Parag believes that the ongoing survey at the lakes will discover even more, perhaps even species unique to Goa.
When trying to tell damselflies and dragonflies apart, there are some marked differences. The first difference is overall size with the damselfly being slender (thus its name “damsel”).
Dragonflies have close-set eyes while damsel flies have them set apart. Damselflies have their forewings and hindwings in the same shape and size. Whereas the forewings and hindwings of the dragonfly are a different shape and size and much stronger than the damselfly.
Dragonflies undergo, what is called, an incomplete metamorphosis, going from egg, larva/nymph to adult. They lay their eggs in water usually and have a lifespan of 7 to 56 days
“Right now, we have no idea on what basis they choose where to lay eggs, whether it’s the depth of the water body, vegetation, the turbidity, temperature…Much of this has to be studied for long-term conservation."
Parag Rangnekar, Ecologist
“Right now, we have no idea on what basis they choose where to lay eggs, whether it’s the depth of the water body, vegetation, the turbidity, temperature…Much of this has to be studied for long-term conservation,” said Parag.
Trying to study the lifecycles of dragonflies is a difficult proposition, said Parag, because dragonflies require live feed. During the monsoons, it is easy to feed the larvae because of an abundance of tadpoles and mosquito larvae.
“We used to get chicken or fish from the market, boil it until it’s soft, hold it with tweezers and shake it on top of the larvae so they would grab it. But they also realised it wasn’t alive and stopped taking it,” says Parag, describing how they attempted to improvise when live feed wasn’t available.
Dragonflies have sexual dimorphism where the males are more vibrantly coloured, to attract mates. The females have a more subdued colour as this protects them from predators. Females also have a smaller anal appendage compared to the males, and males have secondary genitalia.
Dragonflies are cannibalistic and can feed on their own. Their predation success rate puts the apex predator, the tiger, to shame at 95%.
Within a population of a species, you can have females of two different colours, which is again to reduce predation, because one colour may be picked up by a predator more easily.
Identification of female dragonflies is a difficult undertaking with the existence of andromorphic females i.e. female dragonflies that look like males.
After mating in the tandem or the wheel formation with the male holding the female’s head with the anal appendage, the female abdomen is folded back towards the male and picks up the sperm from the male’s secondary genitalia.
The male will guard the female when she is laying eggs in the water.
Dragonflies are cannibalistic and can feed on their own. Their predation success rate puts the apex predator, the tiger, to shame at 95 per cent.
Another astonishing feature of this insect is that their four wings can move in different planes.
This amazing creature inspired the researchers at Draper and Howard Hughes Medical Institute at Janelia Research Campus, under its project DragonflEYE, to develop a drone that used live dragonflies with a backpack consisting of electronics, sensors and a solar cell.
To learn more about dragonflies, you can visit the website Odonata of India.