India's Fireflies and Vanishing Species: How Artificial Light Is Erasing Bioluminescence

Fireflies are not flies. They are beetles, members of the family Lampyridae, and their light is one of the most efficient chemical reactions in biology. The bioluminescence is produced when an enzyme called luciferase catalyses the oxidation of a compound called luciferin, releasing energy almost entirely as light, with almost no heat lost. Evolution has had roughly 200 million years to refine this system. A single flash lasts between 0.3 and 0.5 seconds depending on species, and the interval between flashes is species-specific, functioning as a species-recognition code. Males flash from the air. Females respond from the ground. Without the right answer, there is no mating.

India hosts an estimated 50 to 60 firefly species, though the actual count may be higher, formal taxonomic surveys of the subcontinent's Lampyridae remain incomplete. The Western Ghats alone, a biodiversity hotspot that runs 1,600 kilometres down India's western coast, shelters multiple endemic species whose ranges are small enough that a single development corridor can eliminate a population permanently. The problem is that most of these species have never been studied in detail. Some may not yet have scientific names.

The flash dialogue between male and female fireflies depends on contrast, the signal is only readable against darkness. Artificial light at night (a field researchers now abbreviate as ALAN) raises the ambient brightness of the environment so that individual flashes become harder to distinguish. A 2020 study published in Philosophical Transactions of the Royal Society B, co-authored by firefly biologist Sara Lewis of Tufts University, identified light pollution as one of the three primary extinction threats facing firefly populations globally, alongside habitat loss and pesticide use.

The mechanism is direct. Females stop responding to males when background light washes out flash contrast. Males fly longer searching for responses that don't come. Energy is wasted. Mating rates fall. In species where females are flightless, which includes several Indian species in the genus Abscondita, the female cannot relocate to darker ground. She is fixed to her perch. If the light finds her, the season ends without reproduction.

The LED streetlight rollout that has accelerated across Indian cities and highways over the past decade has pushed this problem into areas that were previously dark enough to support populations. The blue-spectrum wavelengths that LEDs emit are particularly disruptive to insect photoreceptors.

Purushwadi, a village in Maharashtra's Akole district, became one of India's first firefly tourism destinations in the early 2010s. The annual firefly season, June into July, timed to the pre-monsoon, draws thousands of visitors to watch synchronous firefly displays in the forest edges around the village. Similar events now run near Rajmachi in the Sahyadris, and at sites in Uttarakhand and Odisha.

The tourism is well-intentioned and, in some cases, genuinely conservation-adjacent, it gives local communities an economic reason to protect forest cover. The problem is that the events themselves introduce light. Torch beams, phone screens, and vehicle headlights during peak mating season apply exactly the kind of ALAN exposure that suppresses firefly activity. Several naturalists who have monitored Purushwadi over multiple seasons report that display density in heavily visited zones has declined, though no peer-reviewed longitudinal study from an Indian site has yet been published.

Khajuraho in Madhya Pradesh hosts a different kind of firefly gathering, one less organised around tourism and more embedded in the agricultural landscape. The fireflies that appear around the temple complex each monsoon have not been formally identified to species level. They may represent populations that have persisted because the surrounding farmland retains patches of dark corridor. Or they may not. Nobody has checked systematically.

The incompleteness of Indian firefly taxonomy is not a bureaucratic footnote. It has direct conservation consequences. Species that have not been formally described cannot be listed under the Wildlife Protection Act. They cannot be the subject of targeted habitat protection orders. They cannot appear in IUCN Red List assessments. A firefly population can go locally extinct in India without any official record that the species existed.

The Firefly Conservation Society of India, a citizen-science organisation, has been running observation networks to map species distributions using flash-pattern data collected by trained volunteers. Flash timing, colour, and pattern can distinguish species in the field without capture. This approach is producing distribution data faster than formal taxonomic expeditions can, but it still depends on the insects being present and visible, which requires darkness.

The deeper problem is that firefly larvae are aquatic or semi-aquatic predators of snails and slugs in moist soil. They spend up to two years as larvae before a single adult season. Habitat degradation that eliminates the larval environment removes the population long before the adult fireflies disappear from view. The adult display is the last thing to go. By the time a site stops lighting up, the collapse began years earlier in the soil.

The light that erases a firefly's signal and the development that drains its larval habitat are usually the same event, a road, a resort, a highway-adjacent settlement, arriving at the same time. The adult flash is the only part of that story most people ever see, which is why the silence, when it comes, always feels sudden.