135 moth species documented from aChennai neighbourhood, largely from one apartment

Away from the glare of the concrete jungle, attracting moths is as easy as a five-finger piano exercise. Actually, easier than that. Just a plain white screen generously washed with the rays of a properly placed light source would leave one beady-eyed from going sleepless, counting these lepidopterans.

Moth spotted in Valmiki Nagar. Photo: Vikas Madhav  Nagarajan 

At his home in North Carolina that is removed from the bustle, Vikas Madhav Nagarajan has had the pleasure of hosting 65 moth species in one night, with a black light-lit moth screen playing the genial usher. Before May 2021, when he moved to the United States for higher studies, at his apartment in Valmiki Nagar, Thiruvanmiyur, Vikas discovered the limitations of moth screens — no matter how brightly and cleverly lit — amidst the unblinking, sleepless lights of a bustling urban space. A criss-cross of competing lights is hardly good news for moth-spotting.

“When you are in a place that has a lot of light pollution — like the city — moth screens do not really attract that many moths,” notes Vikas, while discussing a hyperlocal project he spearheaded — “The Moths of Valmiki Nagar”.

He certainly required a slightly wider surface area to study moths and he found it in the roughcast walls and stairs of his three-block apartment. He would keep a night aside, every 15 days, and play Jack on the Beanstalk, clambering up and down the lit stairs of the apartment — on Fourth Seaward Road in Valmiki Nagar — bogged down with essential impedimenta: a torch, a camera and during the pandemic, a hand sanitiser to boot.

Vikas Madhav Nagarajan, Mahathi Narayanaswamy and Rohith Srinvasan who have published a paper on the moths of Valmiki Nagar in threatenedtaxa.org. 

“I did get a few on the screen that I kept in my flat. I got a lot of moths on the stairs of the apartment complex, whose buildings were left lit through the night. There are three buildings and all of them have four floors,” explains Vikas. That sounds like a great workout. Only that Vikas measures the benefits from the exercise not by toned calf muscles, but moths.

The project to document the moths of Valmiki Nagar racked up 135 species, with those stairs contributing a vast chunk of it.

“All the 135 moths are from — I would not even say, Thiruvanmiyur — Valmiki Nagar. Out of them, 98 had been documented at the apartment complex on Seaward Road in Valmiki Nagar.”

The effort is subsumed in a larger, pan-Chennai moth project, one that features two other well-known naturalists: R Bhanumathi — better known as ‘Butterfly Bhanu’ — and M Yuvan, author of A Naturalist’s Journal.

Explorations in the Adyar Poonga in the fag end of 2018 essentially signalled the launch of the pan-Chennai moth project.

“Yuvan, I and Rohith Srinivasan were carrying out the moth documentation work at the Poonga,” notes Vikas. Additionally, whoever was on board was carrying out moth studies in their own diggings: Mahathi Narayanaswamy started documenting them on the IIT-Madras campus; Rohith Srinivasan in the Velachery and Perungudi region. While wooing moths to his flat, Vikas was successful in coopting residents of his apartment into the project.

“They know that I work with moths — so, many of them would send pictures: ‘Hey Vikas, this moth came home!’ And if it is something new, I would be like: “Aunty, can you keep it there for some time?” and then go and take a few pictures. It did engage a few people — that was a very heartening thing to see.”

Pre-Covid — and when Covid-19 restrictions were eased — Vikas would head to the apartments his friends stayed in and study moths, again on lit stairways at night.

“By increasing the area of my focus, I tried to assess how diversity mattered and how diversity changed from place to place. But I could not see any great change in diversity within Valmiki Nagar, because it is obviously a very small area. “IIT-M, Guindy National Park and Madras Christian College, Tambaram — they are definitely much more diverse in their moth life. But I did see several interesting stuff at Valmiki Nagar,” remarks Vikas.

From the data acquired from December 2018 to May 2021, the paper notes that the most diverse family of moths recorded was Erebidae (39%) followed by Crambidae (30%) and Geometridae (8%).

“The moth diversity in the month of July was seen to be the highest,” it adds.

Mahathi and Rohith came on board the Valmiki Nagar project, largely intrigued by the environment it which it was being conducted.

They assisted Vikas’effort in the areas of paper preparation and presentation.

“When we started working on the paper as such, going through additional literature, especially since it was an urban setup Vikas was working in completely, not to mention it was along the beach, the data was very interesting,” remarks Mahathi.

Vikas reveals that Geetha Iyer, a moth expert from Kanyakumari, helped them confirm the moths that had been identified.

He notes: “Moth identification can be tricky. You often need to wait to know who you have met. You need to read up — even if you have experts on board, there could still be blind spots. There is just too much to know about moths. And there is a lot of old data floating around.”