They looked like stars that decided to fly down to earth for the night. It took a while for my mind to register them as insects that carried light on their bodies — fireflies. They could be seen in clumps along the densely wooded path at the tiger reserve. Sprinkled like sparkles, a little here and a little there. The fireflies hovered about, communicating with each other through light.
What are they saying? That they are ready to mate and start a family. The light is primarily used by male fireflies to attract a female. Naturalist ‘Poochi’ Venkat says that a female chooses one among the many males.
It is interesting to note the way fireflies use their lights to grab the attention of those in their community. In The Insects – An Outline of Entomology , Penny J. Gullan and Peter S. Cranston speak of how the duration, number, and the frequency of flashes are “species-specific”. A male “advertises his presence” with a flash or more and the female responds to him with a flash — she has a manner of flashing that’s unique to her species. These signals are sometimes mimicked by a carnivorous female of another species, says the book. She lures a male and eats him up!
There have not been serious studies on fireflies in India so far; as a result, their world remains vastly unexplored. This lack of information makes them more intriguing. In Fundamentals of Insect Life , C.L. Metcalf and W.P. Flint explain the mechanism behind the formation of light in these insects. The substance that produces light in fireflies is called ‘luciferin’. “It is formed in certain specialised cells of the insect body….When air is admitted under the control of the insect, the combustion of luciferin takes place in the cells that produce it and the production of light is instantaneous,” they write. This light has a special quality. For, it emits no heat rays. The energy is entirely converted into light. In a gas flame or an incandescent bulb, for instance, most of the energy is lost as heat.
Apart from the wild, the insects are usually seen at the fringes of urban spaces and in rural areas where the air is pure. Venkat says that their presence is an indicator that the area has “good atmospheric conditions”. For, they need a balanced eco-system where “everything is in its natural form” to survive.
Fireflies are often elusive to photographers. Macro photographer K. Jayaram who has a frog and a spider species named after him, says that he has never been able to capture them on lens. Their “light intensity is very low” to be photographed, he says. Perhaps the current crop of lenses will help? Karthik Muthuvali, an upcoming macro photographer says that even with cutting-edge technology, photographing fireflies is “very difficult”. For their light is visible only when they fly out at night and use of the camera flash “nullifies it”. But there are photographers such as Radim Schreiber who have shot the insects in action. He writes about this in his website >fireflyexperience.org .
Jayaram was witness to “billions of fireflies one night in the jungle.” It was a night he would never forget: It was 1985 and he was high up in Top Slip, when an unworldly display unfolded before him. The fireflies arranged themselves in four-tiers, each consisting of thousands of insects. Each tier lit up one after the other, flashing in fascinating synchrony. “They appeared to be doing sorties like aircrafts,” he remembers. He has not seen anything like that since. “Their numbers have reduced,” he says. He attributes this to habitat destruction and population increase.
Ace photographer T.N.A. Perumal too feels that there has been a “general decline” in firefly population. He recalls seeing a “firefly orchestra” some 20 years ago in Nagarhole during the wet season. “They flashed on and off like lights on a Christmas tree,” he recounts. The flashes were beautifully synchronised. How did they do it? “It’s a mystery,” says Perumal.
Firefly facts
- Firefly lights are termed as “cold lights” since they are 100 per cent energy efficient
- Also known as lighting bugs, these insects have a very short lifespan — an adult may die soon after mating and laying eggs
- The eggs of some species tend to glow if tapped or due to gentle vibrations
- There are thousands of firefly species across the world
- Bright artificial lights such as those from houses, cars, and streetlights tend to affect their flashing patterns
- The chemicals from fireflies can be used to study diseases such as cancer if injected into diseased cells. They have even been used in electronic detectors in spacecraft to detect life in outer space!
(Source: >firefly.org , an educational resource on fireflies)
