Magic of the Night: Tuning in to the Fireflies of Kodaikanal

My interest in fireflies came from my travels in Maharashtra, when I lived in Mumbai, before moving to Kodaikanal in 1984. When my children were small and I was working with the Bombay Natural History Society (BNHS), I used to travel to the hills of the state to look at birds, insects and other small creatures and educate my children on the importance of keeping the environment stable. On one such trip, we were staying in a tiny forest bungalow near Nashik and were initiated into the way that local people used fireflies to light up their rooms.

The species of Lampyridae we saw there is slightly larger than the local form seen in Kodaikanal—if put into a jar, the bioluminescence can significantly light up a corner of a room. I am particularly fascinated by the species here in the Palanis; it is very small, unlike other members of the family, which can be much larger and display in huge numbers in parts of India and around the world.

These tiny fireflies (Lampyridae in the order Coleoptera) have been a source of wonder over the years. This soft-bodied beetle has a brown head and a darker brown body and wings. At night a green bioluminescence shines from the end of its abdomen–a mating call for the female (females occasionally do light up too, in flashes). The application of this luminescence in medicine is still being explored.

When I first came to live in Kodaikanal, the lights of firefly larvae and larger fireflies in the evenings were a frequent sight all through the monsoons. My children were fascinated by this and tried to catch the fireflies to see if they could reproduce the lighting. Fireflies light up en masse at the end of the southwest monsoon and in the first part of the northeast monsoon, in late October and November. (The Palani region, which is an eastern offshoot of the Western Ghats, experiences both monsoon types.) This was in the mid to late ’70s, when they were still everywhere.

An interesting local legend featured this tiny firefly and its perceived connection with the baya weaver (Ploceus philippinus), a small, sparrow-sized bird that lives and nests in open grassy marsh areas in the lower Palanis. The baya weaver bird makes the most amazingly complex nests out of grasses such as guinea grass and other similar species. In the 1990s, these nests were seen hanging from trees in great numbers. However, with changes in agriculture and the removal of their natural habitat, they are now rarely seen.

These birds feed on grains and insects but have also been known to include geckos, molluscs and small frogs in their diet. The male is the nest builder and spends much of his time finding the right grasses to construct the nest, which hangs, easily seen, from tree branches. The female does not play any part in the nest building. Once the nest is finished, the male perches on a hanging loop below the nest’s major chamber.

The female will examine it carefully to see if the nest reaches her expected standards, before acknowledging the male. She will reject any nest that doesn’t meet her standards. Her job is to then plug the inside chamber with tiny pieces of clay, which will protect the interior walls and make the nest more resilient to bad weather.

Here is where the firefly may or may not come into the equation. Science textbooks from 30 years ago mention that the clay the female baya weaver bird would carry back to the nest would contain tiny fireflies, which would then light up the inside chamber.

I have talked to nearly 20 long-term residents in the Palani Hills, and they are all familiar with the idea of fireflies in baya weaver birds’ nests from their school years; several have told me that they have seen a glow inside these nests. So I can presume that perhaps female bayas, in the process of collecting small clay particles, also pick up the fireflies and attach them inside the main chamber. Whether this is deliberate or not is difficult to say, as there is little proof on the websites that popularise this myth even today.

Personally, I love the idea that fireflies are lighting up a nest for the birds. However, when one realises that perhaps the fireflies are not always available during the baya breeding period in spring, it seems more likely that it lies in the realm of folklore.

Found in tropical and temperate regions, fireflies have a very important role to play in retaining environmental links in other parts of the ecosystem. Of course, the decline of this species over the last 30 or 40 years has resulted in the weakening of these links.

Tiny though they may be, fireflies–like their luminescent cousins, glow-worms, that feed on snails, slugs, mites and earthworms, and countless other small, essential creatures– are a vital part of the larger ecosystem. In addition to serving as prey, their larvae are active predators, keeping populations of creatures such as snails, slugs and earthworms, and thus ecosystems, balanced.

In cities, the abundance of light deters fireflies, which rely on reduced light for reproduction (Shreya Sharma in Quartz, June 2022). Since the ’80s, artificial lighting in towns and cities has increased enormously, and it is proven that fireflies move away from any light source. Today, their population is decreasing across the country. In Kodaikanal, over the last 30 years, town and village night lighting has become part of life here. The wooded areas, marshes and wetlands where fireflies live have also been severely degraded, and, of course, pesticide use is rampant. Spotting the few fireflies who display their tiny green bioluminescent light at night is a rare treat, even here.

Although I have lived 9km outside Kodaikanal on and off since 1997, October 2021 was the first time I saw this little firefly (or ‘light poochi’ in Tamil), recently. This is probably because when your house is lit, you just do not see the tiny green specks of light. Climate change is going to be a very important factor in monsoon and thus firefly luminescence, in the future. We need more studies conducted in India on firefly species, documenting their decreasing numbers due to habitat loss, pesticides and artificial light. The cascading effects of the loss of fireflies are not yet fully known, but one can fathom it will not bode well for the fragile Western Ghats habitat at large. 

Firefly season in Kodaikanal runs from October to December. At this time of year, gatherings of fireflies can be sighted in forested areas and hillsides away from artificial light. Should you witness the spectacle, be mindful: Avoid torches and flash photography; do not collect or displace the insects, and keep insect-repellant use to a bare minimum.