Fireflies can't find love in Kerala these days, here is what messes up their dating

Love has no language but for the fireflies, it is light. Kerala's summer evenings used to be lit up by the glowy, winged beetles with their rhythmic, brief flashes of light to woo mates. Of late, this love story has had a twist. Firefly congregations are on the wane in the state. 

A pilot study on the behaviour of fireflies by the Shadpada Entomology Research lab, Department of Zoology, Christ College, Irinjalakuda, shows that habitat loss caused by urbanisation poses a significant threat to fireflies. 

"Light pollution is one of the major causes driving fireflies away from human habitats," said Dr Bijoy C, Assistant Professor of the Department of Zoology and Head of the Shadpada Entomology Research Lab at Christ College, Irinjalakuda.

"Fireflies emerge above ground after completing their pupal stage to mate. Their adult life lasts about three to four weeks, and they die after fulfilling their life’s purpose," he said. Darkness- a natural night sky- is essential for them to find a mate. Male fireflies emit their signature neon glow to attract females.

"Once they become adults, the males begin to produce their beautiful glow to lure potential mates. After the darkness falls, they fly to nearby trees, and later at night, they circle around them. The females, which usually stay close to the ground, choose their perfect partner from the display," Bijoy explained.

However, artificial lights illuminating the night sky pose a serious threat to their mating. Reflections from streetlights and high-beam lights from houses interfere with their ability to communicate, disrupting the delicate process of finding a mate. "Bioluminescence is the fireflies’ way of communication," said Bijoy. "When artificial light floods the environment, it confuses them and interrupts this natural interaction," he added.

As a result, these insects are moving away from human habitats, seeking darker areas with little to no artificial light. "Their unique adaptability has driven them away from the places where we used to commonly find them. We don’t see them as often now, not necessarily because their numbers have dropped drastically, but because they’ve escaped to more suitable, darker environments," Bijoy said.

He added that fireflies are now often seen congregating in large numbers in areas where darkness prevails, including forests. "Researchers sometimes spot a soft glow deep within forests, it is not a mysterious light, but a congregation of fireflies lighting up in unison," he said.

Noted conservationist and research scholar at the Department of Biotechnology, Calicut University, Dr Sandeep Das, echoed this observation. He said that in recent years, he has often witnessed large gatherings of fireflies in forest areas. "Compared to previous years, yes, we have noticed an increase in firefly activity in forests," he said, adding that this is not a significant surge. "No formal studies have been conducted to confirm this pattern."

Fireflies, which belong to the family of beetles, were once a common sight in Kerala’s village landscapes, where abundant undergrowth and moist conditions provided an ideal environment for them to thrive. Female fireflies lay their eggs in the soil, often in areas covered with dead leaves and organic matter.

Today, however, widespread landscaping and the clearing of natural vegetation destroy the habitats necessary for laying eggs and larval development. Compounding the problem is the use of chemical fertilizers and pesticides, which not only harm the larvae but also kill their potential prey, including snails. 

Firefly larvae play a vital role in controlling snail populations, a growing problem in many parts of Kerala today. Yet, most people remain unaware of this natural predator.

Although much smaller than snails, the larvae enter the snail’s shell and inject venom into its body. "They then feed on the snails, effectively keeping their numbers in check," said Bijoy.

He added that the recent spike in snail infestations across the state may be linked to the disappearance of fireflies from human surroundings. Firefly larvae require suitable soil conditions to survive. However, the removal of vegetation and covering of topsoil with tiles destroys their natural habitat, contributing to a surge in the snail population.