Dip in fireflies raise ecological concerns
Fireflies are best sighted just before or after monsoon rain arrives. The insects mate in India between May and early June.
A group of over 20 people, equipped with water bottles, umbrellas, cameras and special permission for a visit to south Delhi’s Deer Park, huddle close in the dark at 8pm on Sunday, as they walk in a tight formation in a bid to spot an elusive soft-bodied beetle — the firefly.
This park, despite being one of the few habitats where fireflies are spotted, is also recording a declining firefly population, says environmentalist Verhaen Khanna, the group’s leader. He says that while the downtrend started in 2016, the problem has been exacerbated over the past two years, since authorities decided to keep the park well-lit through the night.
Fireflies are best sighted just before or after monsoon rain arrives. The insects mate in India between May and early June. Their population is highest in July and early August, and can be sighted at spots in Delhi that are dark, green, undisturbed and moist.
Khanna, who used to spot hundreds of fireflies in a single visit, now says even spotting one or two together at the same spot is a rarity.
“The lights remain on even after the park closes. These are operational throughout the night, perhaps for security reasons, we do not know. But the light pollution directly impacts the fireflies that would otherwise mate at Deer Park. In the absence of darkness, fireflies find it difficult to spot each other, and this is likely impacting their population,” Khanna says, pointing to the Hauz Khas Lake, another location where fireflies were spotted till last year.
He said fireflies naturally regulate the mosquito population by preying upon them and thus, are a sign of a healthy ecosystem. He noted that sensor-based lighting — lights that turn on when sensing motion in the form of footsteps — was an alternative.
The Delhi Development Authority did not immediately comment to HT’s queries on artificial lights at the Deer Park.
Experts said protecting green spaces and ensuring existing firefly hot spots are protected are crucial to maintaining a steady population. “Once we know there are specific places where fireflies breed year-on-year, it is important to ensure these areas see minimal interference from humans. In general, we need to ensure natural green spaces remain natural and do not turn into manicured lawns,” Khanna says.
This year, he says, they are yet to spot a single firefly near the lake.
“This is how habitats get gradually destroyed. With commercialisation, not only do we have bright lights from restaurants located next to the lake; we have extremely bright lights at the park that are impacting bats and fireflies too, both of whom require darkness to mate,” says Khanna, who is also founder of NGO New Delhi Nature Society (NDNS).
Other habitats fading too
Experts say the gradual impact of bright lights and manicured gardens directly combine to impact firefly numbers in Delhi, making them an increasing rarity these days.
“If we speak to the younger generation, they have not seen fireflies anywhere. Earlier, we would spot them in our lawns and even out in the open, wherever there was greenery and some moisture,” says Surya Prakash, a zoologist with the Jawaharlal Nehru University (JNU).
He said there were specific locations at JNU in the 1990s where hordes of fireflies could be spotted, but locating them on the same campus now requires patience and time.
“Over the years, we have seen natural habitats getting disturbed. Particularly along the internal roads of JNU, we have seen installation of these bright lights, concretisation through sidewalks and lawns too have become manicured. All this gradually reduces their natural habitat and fireflies, similar to fish that live at the bottom of the sea, rely on bioluminescence and cannot mate if the ambient light is bright. This makes it difficult for the male and female fireflies to spot each other,” Prakash says.
A similar trend is being seen at Sanjay Van, Prakash says, stating there had been a reduction in the natural habitat for fireflies. “There are specific spots at Sanjay Van where we would earlier find fireflies, but are no longer being spotted there. The overall trend is worrying,” he says.
Conservation measures needed as a priority
Reducing firefly habitats and their population is not just a trend in Delhi, but across the country too. Research, though limited, has found artificial light percolation is pushing these insects, part of the Lampyridae family, to the brink.
In Maharashtra, firefly festivals are held annually in June, with local communities and wildlife enthusiasts celebrating these insects. However, a 2019 study by the Tamil Nadu-based National Centre for Coastal Research (NCCR), which studied firefly density in Andhra Pradesh’s Barrankula village, found the count dropping from around 500 in 1996 to hardly 10-20 in 2019.
A year earlier, a study in China found fireflies there were shining brighter, with longer intervals, in a bid to compete with artificial light.
“We are seeing something similar in Delhi. Light pollution has increased to such an extent that natural and undisturbed habitats are not as rare anymore. Fireflies require a particular dark, moist and woody habitat and if these locations also have ample light, fireflies will not only be able to spot each other and thus, mate,” says Sumit Dookia, assistant professor at Delhi’s Guru Gobind Singh Indraprastha University (GGSIPU) and part of Delhi’s Biodiversity Council (DBC).
Dookia says not enough has been studied about fireflies across the country, but more needs to be done. “We (DBC) will certainly also look into this aspect,” he says.
Khanna says that with increased awareness, comes the need to ensure firefly habitats remain undisturbed. “The idea behind these walks is to show the next generation how fireflies look like and why these habitats need to be preserved. But, we also try to only take a limited number of people. Human activity should be limited at these spots and commercial activity in the form of bright lights even more so (limited). Deer park even has a gym now, which has its lights operational all through the night, even though this is a green space,” says Khanna.
Entomologist Mohammad Faisal says light pollution is not the only source to blame, citing Delhi’s high air pollution for the dipping numbers.
“Fireflies are still found in Delhi, but in very limited habitats, including at biodiversity parks. The habitat should be dark, green and mostly untouched. The air quality in Delhi is so poor and fireflies, being sensitive creatures, invariably appear to be suffering,” he says.
He says the use of pesticides and insecticides in NCR is another possible reason.
“Outside of Delhi, we would see plenty of fireflies in agricultural fields. Now, they are hardly seen, as insecticides are being used on a large scale,” he says, adding there was a need for a detailed study in NCR to assess and protect their habitats.
At 8.30pm, the group exits Deer Park disappointed, the sightings of fireflies few and far between — only isolated fireflies spotted in dark patches — and worried. Khanna tells the group that in the past, one could see complete groups congregating at one spot.
“Though a magical experience, it was also bittersweet. It makes you realise about the harsh reality threatening these creatures and why very few are left now,” said Divyasha Arora, who took part in the nature walk.
Until efforts are made to reduce light pollution and human interference at firefly hot spots, the next generation may find it even tougher to spot and identify a firefly in the Capital.
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