Barefoot Notes: The Fall of Specialists and the Rise of Generalists, Or, What Ails Urban Insects?
|Photographing moths in the central Western Ghats. Light curtains are the best way to explore moth diversity.
Many years ago, I used to wait for moths to enter my urban home through the old casement windows, and hover over to photograph them on an incandescent light. It feels so long ago; today, those windows have changed to the sliding ones, coupled with a netted window that keeps most insects out – even when it is open, the only ones to sneak in are mosquitoes all year round. Moths that would visit were of various sizes and colours. Mind you, my house is in the middle of one of the most densely populated cities in India. Seeing any insect here was allowed due to proximity to the remnant copse comprising of mangroves, gardens and urban farms – and, perhaps more so, vegetable wholesale markets – more on the latter in a while.
|Moths from years ago: Top Underwings: Thyas coronata and Achaea janata;
Bottom Hawkmoths: Theretra alecto and Agrius convolvuli.
From the Underwings to Hawkmoths, my nights during summer
holidays were about reading and checking the porch and window lights at
short intervals. I would leave windows ajar to let all insects and spiders in.
Sometimes, a pleasant visit would be by a praying mantis, mostly the Asian Giant
Mantis who would spend a few hours till I let it out to find its own kin. At
other times, the Ladybird beetles would visit – mostly the Six-spotted Zigzag Ladybird – who would be promptly let out as well. Moths, however, always dominated. Over
months, I would wait for that one colourful moth over a visit among the browns,
it would usually be an Underwing, rarely a Convolvulus or Oleander Hawkmoth.
Such nights were a win. For me, their haven was mostly the adjoining copse.
This was at a time when internet was a budding source of identifications for
the popular group of insects. Most of the early guides published were from
North America and Europe. Among Yahoo and Google Groups for the more popular
butterflies and dragonflies that I was already drawn to, photo-hosting
platforms such as Flickr, run by moth experts, is where I started documenting
moths from my hometown. Eventually, the picture became more and more clear. I
was to discover that there is more to these urban insects than meets the eye.
You see, their presence was not entirely of causes
associated with wilderness in the strict sense, save those that belonged to the
remnant natural spaces, such as those along rivulets and lakes, in the city. It
was because of the surrounding country farms, large wholesale vegetable
markets, and gardens and urban farms that could sustain several species. Most
were pestiferous in nature – they fed on vegetables grown for human
consumption, and only few eked out a living naturally on rooted plants within
the city. I traded my weekends for trekking and exploring the western ghats to
my east and the Konkan wilderness to the west. Here I met many more moths and
other insects and reptiles and birds, and my virtual collection grew. Doing
this, I realised a distinction in moths from the city and from wilderness areas
far from the city. Clearly, both showed distinct populations with little
overlaps. Moths in wilderness areas showed higher species diversity than the
city, no doubt, but they also indicated why this is so – quite obviously, the
wilderness moths are more diverse because of more plants – their larval host
plants – make up natural spaces than city spaces. I believe my theory made
sense, albeit without empirical evidence. Turns out, almost all the moths at my
home were some or the other kind of pests on vegetables grown for human
consumption. They comprised a larger part of the urban biodiversity in the
heart of the city – not on outskirts, nor in a less-developed area with remnant
forests and open spaces. Farmlands showed a mix of both, wilderness moths and
pest species, but in varying proportions. Eventually, I found this link with
the beetles too, and gradually with ants.
|A feast of urban moths: Pygospila tyres (bottom) and Anomis flava (top), along with two Erebid moths, feeding on Lantana camara flowers late in the night.
This made me wonder, when we celebrate urban biodiversity,
what exactly are we cherishing? How do we know who ekes out a living and who
thrives? Where are they in the city – the ever growing periphery consuming more
wild and farm lands, or the urban concrete jungle? Who is the last species or
generation of a densely human-populated part of a metropolis? And finally, what
is the proportion of non-pest and pest insects in this habitat? I believe the
pest ones thrive in terms of species diversity and abundance, the non-pest
barely – and they both represent urban biodiversity. I could never put this to
test. Eventually, I moved to a wilderness area and became used to wilderness,
often non-pest, moths. Over the years, my hometown went through a dramatic
|A Google Earth snapshot (2000 to 2021) of urbanization in my hometown.
In the first two decades of this century, as I was engrossed
exploring insects of the countryside, a rapid change was taking place all
around my home. Old copse, plantations, and mangroves were being razed or
buried in debris to build newer homes. My apartment complex, too, was once a
marshy part of a small rivulet, now turned to a sewage canal. The leftover
marsh and lakes around were reclaimed – as is the term used for urban
development – throughout my childhood. Mantises stopped visiting, as did
Ladybird beetles. Moths returned once in a while. Today, there are hardly any
visitors at all, only uninvited guests – the mosquitoes, as the city sees a
rise in malaria and dengue. I left behind this concrete jungle early in the
previous decade. In the wild, moths were everywhere, I set out light canvas to
attract them, and submerged into this sea of moths big and small, black as coal
to rainbow-hued. I was delighted to be surrounded by so many as much as I feel
ashamed now to admit that for long I forgot about my urban moths. Back home, they
were disappearing even as I was relishing in the company of their distant wild
|Two of the most common urban moths to be encountered in India.
Diaphania indica and Spoladea recurvalis.
Moving back to a small city – in the heart of it – I found
the company of urban moths as I did as a young explorer. Here, in a dusty
central Indian city, they visited my apartment in all seasons. I was thrilled.
Only that my stay was short-lived. Eventually, I realised that most moths were
not from nearby forests (there wasn’t any close by), but urban vegetable
gardens and bramble along Arpa River. Indeed, these were mostly pestiferous in
nature – moths on cereal, grain, vegetables and fruits… that they comprised a
large proportion of urban diversity was not surprising. In the larger
discussion around urban biodiversity, we seem to have disregarded what
comprises this diversity, and why it matters when we clump them all as
|Two of the wild moths, not uncommon in forest areas, from India.
Trypanophora semihyalina and Artona sp.
It is not solely about native versus invasive species. As an
ecologist, I have come to realise that they all play a part in an ecosystem. In
such an altered and disturbed environment, invasives fit for survival – the
generalists – do outcompete native – specialist – species, but in the given
context of an altered ecosystem where specialist habitats itself are rare, invasives
are not all bad, it is the management of invasives that is bad, as much as it
is the protection of the native that is often disregarded in the face of
development. When it comes to pest species, both, native and invasive, can be
equally damaging, whether to natural standing vegetation or farms. This, is
about knowing who calls urban ecosystem home. When I say there are more pestiferous
moths in my hometown or my workplace, it is not to belittle the hardy species
that are fittest to survive this unforgiving ecosystem. It is to give them
space in the umbrella term of urban biodiversity. Moths of spinach, carrots,
cucurbitis and fruit-piercing moths that stalk fruit lorries, are all to be
appreciated as much as the native sunbirds, tailorbirds, and sparrows. It is
important to know and acknowledge their presence.
But it is also a reason of caution: What if most cities are
now dominated by such hardy, often pestiferous, species? What does that say
about urban biodiversity? The thing is, we don’t know, I present only a rough
idea. It is only anecdotally known that urban bees, butterflies, and non-pest
flies are disappearing (and replaced) from urban ecosystems; at what pace, by
what rate, remains unknown. We Indians don’t know what is happening to insects
in the most easily accessible of an ecosystem, what are we to know about the
wilder species declines?
Out of nostalgia, but also for something more pressing, I dig
into my memory to reach those simpler days of finding moths in the middle of
the city. I wish we didn’t have to do this. The more pressing issue is that
there are no long-term insect monitoring projects in India. A few exist by moth
hobbyists who have been putting up curtains in the same locale for years, such
as to celebrate Moth Week, by opportunistic photographers like me, and by
insect samplers which are increasingly rare, but these are not collective in
approaches. All India has of its past – a decade or more ago – are samples in
vaults that a researcher cannot ordinarily access and record. It is time to
digitize this database so that biogeographic and diversity related historical
studies can be made accessible to foresee what’s to come.
|Moths enjoy visiting flowers in the day as well. Planting native flora (such as this Senecio grahamii aster being visited by Amata sp.) and shrubs (such as this Lea indica being visited by a Sesiid moth), are a boon for urban adult moths.
For urban biodiversity-seekers, it is important to see the
big picture. Today’s cities need no gardens or Miyawaki forests, it needs
native micro sanctuaries – brambles and seasonal grasses and slow-growing herbs
shrubs trees. Merely seeking solutions to carbon emission has further destroyed
India’s understanding of a natural space or wilderness, right from government
officials to urban researchers, everyone is blindsided by the quest to
sequester carbon, putting biodiversity in peril. Ideas such as nature-based
solutions are considered as far-off places where wild elephants and tigers
roam. It is natural spaces, made up of naturally grown indigenous plants with
regular upkeep to remove invasive flora, that strengthens native species
diversity and fights climate change.
Over the years, shuffling between moths far from urban areas
and those from urban, I noticed a trend. Beyond the native versus invasive
species debate, with due credit to the invasives that are indeed a part of
biodiversity in the Anthropocene, no matter what one says, I wondered what is
more intrinsic to diversities of moths in these two habitats. Is there anything
at all beyond species count? I believe there is.
|Twenty of the common species of non-urban and urban moths, mostly from Central India.
Between the two moth communities, I noticed the urban ones
to be often dull and drab in colour, but I wasn’t so sure. I decided to put
this to test: I selected ten moths each common to non-urban and urban
ecosystems that I have encountered over the years in Central India, and created
a colour profile using Adobe Color, a free Adobe™ online software that allows
one to extract colours from a photograph. Taking snapshots of the thorax,
abdomen, wing shoulder, mid-wing, and wing-tip, I created a five-point colour
theme for these moths. Of course, my method is crude – I did not correct for
exposure, calibrate colour, nor segregate flash photos from natural-light
photos, neither did I use a robust method to select these moths. Nonetheless,
there was something to be seen.
The result seem to indicate what I theorize – urban
diversity, symbolised by moths, is largely dull or plain. In other words, urban
moths are usually less brightly coloured or aposematic than their wilder
counterparts. This is nothing unusual, most pestiferous insects are dull/drab
in colour to blend with the environment. This is not to say that there are no
dull/drab moths in non-urban ecosystems, there are many. What is important is
that as urbanization increases, urban insect biodiversity is represented more
by dull-coloured species (with exceptions) than the non-urban. Of course, this
needs better testing, and I speak only of moths. Urban areas with plentiful
green spaces might not stand this test.
The fading colours of urban biodiversity should ring alarm
bells. Just as trees are being cut, rivers smothered, and forests making way
for concrete jungles, specialist insects are disappearing or are being replaced
by generalists – mosquitoes such as Aedes, Anopheles and Culex are more common
than hoverflies, soldierflies, and robberflies. Butterflies replaced by moths
that eke out a living hidden away in leftover vegetables. Mormons, Sailers,
Bluebottles, Evening Browns and even Grass Yellows have fast disappeared from
my hometown, replaced by Cutworm, Bagworm, Caseworm, Stemborer moths.
Last week, I found myself up in the highlands of Central
India, by the Sipna River of Melghat Tiger Reserve. Even as I was musing the
idea of differences in colourations between non-urban and urban moths, I was
talking about insects of a protected area, dominated not by colourful moths as
I predicted, but by a dull/drab pestiferous moth, the Teak Skeletonizer, that
was the most common in the forests and at porch light. This well-known moth
skeletonizes green leaves by eating the non-veiny part of the leaf, leaving
behind a leaf-skeleton. Does that mean that my theory is incorrect? No.
Skeletonizer outbreaks are climate-dependent phenomenon, and are not always the
most dominant in all years. This year, I was told, happened to be an exception
when hundreds of teak trees were skeletonized by their caterpillars, painting
an otherwise green mountain-scape a drab brown, as if it is summer.
|A swarm of Small Mayflies around a porch light by the bank of Sipna River.
Yet, the insects showed their force in numbers. On the day
of my arrival, the long August dry spell broke, and rain resumed over much of
Melghat mountains. That night, millions (no exaggeration) of mayflies and
non-biting midges emerged from Sipna River, as its water gradually swelled with
fresh rain. They shrouded all lights at the camp, making it difficult to walk
by the porch light, yet it was delightful to be amidst their swarms. This
continued for two nights. During this time, there were very few moths around –
this is because August in central India is a time of caterpillars; it is in the
early and late monsoon that we can see a large diversity of adult moths. In a
corner of the canteen, we were witnessing Central India’s first Dobsonfly,
Nevromus intumus, a Himalayan species. Apparently, this is major range expansion
for this species, a rather rare insects whose aquatic larvae spend years in
unpolluted flowing mountain rivers.
After talking about insects and being amidst large swarming
mayflies, I was back at Amravati. The weather was pleasant, rains had lashed
the city in the plains as well. However, scarcely any insects flew around
lights in the city, even along the outskirts. There were no moths, no mayflies,
just a handful flies. This stark contrast was not solely because of habitats –
mountains versus plains, it alluded to the dwindling insects in urban
ecosystems. Ironically, I deduce this in an already altered habitat – porch
lights by a wild river and incandescent lights by city streets, both altering
insect assemblages because of artificial lighting.
|This is how natural spaces are reclaimed, and biodiversity rechristened as
'urban biodiversity' a blatant exploitation of nature for 'views' - an example of Green Washing.
This is not a celebration of urban biodiversity, this is a
lamentation. Every day, we inch farther from understanding how and why and at
what speed insects are declining in India, especially cities, even as cities
encroach upon wilderness and revel in labelling displacing wildlife as urban
biodiversity. Without academic nor institutional support, urban insects remain
one of the most underappreciated and understudied part of biodiversity. It is
true what one has said, a known devil is better than an unknown devil – maybe
we understand cities too well as harbingers of destruction, a sure-shot way to
extinction, than, say, climate change which we race to try to understand better.
Maybe urban insects are already doomed, and it starts with specialists
disappearing and colours fading. Maybe, and I hope this is more correct, I am
wrong in this assumption, but truth be told, we are ignorant of the fact that
there are significant changes happening around us.