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Sunday, December 15, 2019

Butterfly Effect

Moths get a raw deal but are nature’s wonders no less.

Written by Ranjit Lal | New Delhi | Published: October 27, 2019 9:13:31 am
Butterfly Month, dusky gold, raw silk, sodium-vapour, caterpillars Will climate change affect the lifecycle of these insects? (Source: Ranjit Lal)

It’s typical of us to have celebrated all of September as “Butterfly Month” and given their cousins, the moths, the short shrift. You next-gen millennials hear this: While all the party-frocked, lacy-winged, glamorously skirted butterflies are safely home and tucked in bed by 7 pm, it’s the moths that come out to party. They dress with dignity and grace: usually in Gandhian shades of khadi, dusky gold and raw silk. Years ago, in March or April, I would go out into the garden at dusk and watch these stunning golden moths hover and blur around flowers, extending their proboscis into them for a sip of nectar. These glam guys and girls love bright lights: actually, a single bright light in a velvety dark night, which our sodium-vapour cities are less able to provide. But go out into the country and watch.

They’ll spin dizzily around the halo of light, many sadly crashing and burning, but no doubt, frying happily. The rest go on, taking a break from time to time on the nearest wall. Where, alas, the killjoy goons will be waiting to take them down: geckos, praying mantises and spiders. Still, some survive and are nursing their hangovers the next morning, when the rest of the demolition squad arrives: birds! I’ve watched great tits and bulbuls systematically work their way under the eaves and along the walls early in the morning, snapping up every sleeping moth.

No one is quite clear as to why they crazily and suicidally orbit hot bulbs. One school of thought thinks it’s their way of navigation while migrating: their original big bulb in the sky was the moon (which was far away and did not move) and they fly in a straight line so as to keep it at a constant angle. If the light source is closer, this means they have to fly in circles to keep that angle constant, drawing closer until they crash and sizzle into it. Others say we still don’t know the real reason.

They are very similar to their cousins, the butterflies, except that they don’t have clubbed antennae. They enjoy strong drink (rum and wine), sweat, blood, tears, fruit juices, fermenting fruit, rotting meat and, of course, nectar. Some, after pigging it out as caterpillars, won’t touch food when they finally emerge. They have the same life cycle; egg, caterpillar, cocoon and full-fledged adult. They’re far more successful than their cousins, being 1,20,000 to 1,60,000 species strong: butterflies number about one-tenth of that. They may be as small as the point of a pencil or, like the gorgeous Atlas moth, have a 1ft wingspan. The caterpillars of many species are considered crop pests and sprayed with pesticides. Some moths get their revenge by getting into our cupboards and eating our Armani suits and Hermès scarves. But we’re really the worst: we take their cocoons and boil them alive so we can pull out fine silk threads for our saris and sherwanis.

While resting on the wall they may seem vulnerable, but, in flight, some moths have learned self-defence. Their soft-edged wings jam the radar of hunting bats, and some have learned to emit ultrasound clicks of their own, letting the bats know that they taste like crap. Some sense the approach of bats by tuning in and suddenly just drop out of the night at the last moment, confusing the enemy.

As caterpillars, they may wear woolly coats of stinging hairs, or just poison-tipped spikes to keep enemies at bay. In spite of this, a huge number are paralysed by parasitoid wasps, which lay their eggs in them, so that their grubs can have fresh food when they hatch. Mother Nature is caring.

One remarkable species is the Arctic Woolly Bear Moth. It lives in the northern reaches of the Arctic and Canada and other such deep-frozen locations. The caterpillars hatch in late spring and begin eating — these guys cannot afford to be picky about their food. But before they can properly put on weight and tone, the winter clamps down — and they shut shop. They spin a light silken cocoon and squeeze into rocky cracks, and just seize up for as many as the next 11 months. They produce substances (cryoprotectants) to prevent freezing and cell damage and which break down the cells’ power sources, the mitochondria, which are re-synthesised when the weather becomes warm again. Woolly Bear moths need a temperature of between 15 and 30 degrees Celsius to get working properly — and it may take seven winters (earlier thought to be 14) to complete the process and emerge as a moth.

And, alas, Mother Nature has a twisted sense of humour: one would imagine that after seven years of hibernation (and avoiding parasitoid wasps) what would emerge would be something Cinderella-stunning: but the Woolly Bear Moth is a nondescript little grey thing, which will not eat and live, perhaps, for a fortnight — just enough time to mate and lay its eggs. Life sucks!

Will climate change affect the lifecycle of these insects? Will it shorten their seven-year sentence? Will they emerge quicker — in two years? If it does, alas, leaders of the free world will crow: “See, climate change is good! Look at these guys — they got an early release!” But then, climate change and nuclear armageddon are also good for cockroaches.

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