IWN Feature — Saturday, 13 June 2026

Every year in the weeks before the monsoon breaks, stretches of the Western Ghats go dark and then start to glow. Trees along riverbanks light up one by one, in pulses, as thousands of fireflies flash in near-unison to find each other before the rains arrive and the breeding window closes. It is one of India’s most photographed wildlife spectacles — and, until earlier this year, one of its most poorly documented.

That changed in March 2026, when a study published in the journal Zootaxa produced India’s first comprehensive checklist of fireflies — 92 species across 27 genera, compiled from more than two centuries of scattered records dating back to 1758. The lead researcher, Parvez, told Mongabay India that most Indian firefly species had simply never been looked at again after their first description, some not since the 1800s.

A glow with a purpose

Fireflies are beetles, not flies — members of the family Lampyridae, of which more than 2,000 species are known worldwide. Their light comes from a chemical reaction between a compound called luciferin and an enzyme, luciferase, inside specialised cells in the abdomen. Each species has its own flash pattern — a private signature in a shared language of light, used almost entirely for finding a mate.

The synchronous displays that draw crowds to the Western Ghats each pre-monsoon season are part of this courtship. As fireflies cluster in dense numbers on a single tree, males flashing in rough unison appear to improve a female’s chances of spotting — and choosing — a mate amid the crowd. The display usually peaks in the weeks before the monsoon and fades once the rains begin, which is why the window for seeing it is short, and why timing matters more than almost anything else for anyone hoping to witness it.

What the checklist found

The Zootaxa study’s most striking finding was the scale of India’s firefly diversity relative to how little of it has been studied. Of the 92 species recorded, more than 60% are found only in India — a level of endemism the researchers say is exceptional for a group of insects this poorly surveyed. The subfamily Luciolinae, which includes most of the fireflies visible in large synchronous displays, accounts for the largest share at 37 species.

Geographically, the Western Ghats came out on top, hosting just over a quarter of all recorded species — consistent with its status as one of the world’s biodiversity hotspots — followed by Northeast India, the Gangetic plains, coastal regions, and the Deccan plateau. Desert and semi-arid zones recorded none. More than 50 species, the study notes, have not been seen again since they were first described well over a century ago — meaning nobody currently knows whether they still exist.

Why a checklist matters

Fireflies are considered bioindicators: their presence, in healthy numbers, generally signals a relatively undisturbed habitat with clean water, low pesticide use, and dark night skies. Researchers and conservation groups, including the Wildlife Conservation Trust, have flagged habitat loss as the most serious threat facing Indian firefly populations, followed by light pollution and pesticide use — both of which interfere directly with a species that communicates, finds mates, and survives almost entirely through light and darkness.

Until this year, there was no baseline against which to measure any of this. A species cannot be assessed for conservation status, and a decline cannot be confirmed, without first knowing what exists and where. The 92-species checklist is explicitly framed by its authors as exactly that: a starting point, not a conclusion — one that exposes how much remains unknown about a group of insects most Indians have watched in a garden or field at some point in their lives without ever learning its name.

Seeing it without adding to the problem

Pre-monsoon firefly viewing has become a significant seasonal draw in villages across the northern Western Ghats — Bhandardara, Purushwadi, Rajmachi and Igatpuri among them — where community-run firefly festivals and homestays have turned the phenomenon into a source of local income. Several of these villages now actively manage visitor behaviour during the season: restricting flash photography, loud music, and vehicle movement near breeding trees, on the basis that the same light and noise that draws visitors can disrupt the display they have come to see.

The closing argument from both the scientific and travel literature is, unusually, the same one: fireflies depend on darkness and quiet to do the one thing that defines their short adult lives, and a phenomenon that took two centuries to properly catalogue could be diminished within a few tourist seasons if that balance isn’t respected.

Sources: Mongabay India · Down To Earth · Wildlife Conservation Trust

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