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Sunday, March 29, 2020

Down in Jungleland: In the Beat of a Wing

How a caterpillar transforms into a butterfly is a miracle of nature.

Written by Ranjit Lal | Updated: July 28, 2019 7:54:46 am
process of becoming butterflies, catterpillars becoming butterflies, how catterpillers become butterflies, indian express, indian express news Watch them fly: they seem drunk, but they land with pinpoint precision. (Source: Ranjit Lal)

I must have been 7 years old when I first observed this miracle. In our dim classroom, the teacher had put a jam jar on a table: it had a twig placed inside and from the twig, hung a small silvery bag-like structure. This was, we were told, a “chrysalis”, which is a big word when you’re 7 years old. Then, one morning, the teacher beckoned us to look at what it had become. And hanging from the twig was a gorgeous newly-minted butterfly. The dry, opened-up husk of the chrysalis left no doubt as to where the butterfly had come from.

Many decades later in Delhi, I observed the entire process. First, the tiny pearl-like eggs on the leaves of the kumquat plant near the front door, then, the emergence of tiny caterpillars which resembled bird-droppings (no bird would touch them), and their new, handsome leaf-green attire as they grew. And, most of all, the way they ate. As they ballooned, they sawed through leaf after leaf, generally feeding at night and then resting along the mid-rib of the leaf during the day, belching and digesting. Excreta, called frass, was shot away as far as possible. Plants have tried protecting themselves by steeping their leaves in poison — but the caterpillars have found a way to evade trouble. They know where the poisons are concentrated — near the midrib — and carefully eat around those areas – or they simply ingest the poison, being immune to it, but giving themselves lifelong protection from birds and predators, which they carry forward to their forthcoming avatar.

One day, maybe a week or two into their gastronomical orgy, they’ll suddenly forsake all food. They spin themselves a silken cocoon with their mouths — in the case of my caterpillars, this resembled a little leaf-shaped hammock that merged perfectly with the foliage. Cocoons spun during the monsoon were green, while those spun post-monsoon, when the foliage had dried up, were brown. Inside them, something truly bizarre was taking place. Caterpillar cells do not divide like normal cells — they just get bigger and bigger as the creature eats. The caterpillar contains the prototype butterfly cells, biding their time. Once the chrysalis is formed, the hefty caterpillar cells begin to dissolve into a nourishing soup — and the dormant butterfly cells get their go-ahead signal.

They nourish themselves on the soup and begin to divide and transform into various parts of the butterfly: the wings, the proboscis, the eyes and feet. When it’s all done and ready, the newly-minted butterfly emerges, breaking through the now-dry husk of its cocoon. It makes its way up to a suitable branch and hangs out its crumpled wings to dry. Blood and fluid pump through the veins of the wings, stretching them — and stiffening them. This is a vital process: if the wings are unable to unfurl properly, they will remain crumpled as they stiffen, leaving the butterfly crippled for life. After an hour or two, the butterfly tests its wings a couple of times and then is off. I had to wait for almost two hours, early in the morning, to watch this happen — and it was worth it. Imagine, now, this delicate flying flower would subsist on something as ethereal as nectar. Wrong! Give butterflies rum and blood and sweat and tears, and dung and mud and rotting bananas and they’d love you forever. And they taste with their legs.

Look at their wings, how delicate they seem: touch them and powder dust (scales) comes off in your hands. Yet, these guys fly up there with the big boys — eagles and vultures — and are the ultimate migrants. No wall will prevent the monarch butterfly’s migration from the northern US to Mexico and back. Also, they use their scales to spread their personal perfumes (pheromones) far and wide. In some lady moths, these can summon eager partners from 11 km away. (Moths are, I like to think, tech-savvy butterflies that party at night: some can jam the echo-locating radar of bats and use the moon and stars as their GPS system).

They’re built tough: Imprison them in a jam jar, pump all the air out and then let it back in with a whoosh — and they won’t bat an eyelid. Watch them fly: they seem drunk, but they land with pinpoint precision. They’re the ultimate sugar freaks, too, and can winkle out one part of sugar in 300,000 parts of water. And yes, they are territorial and will guard their lantana (alas many love this pernicious weed!) or buddleia patch like Rottweilers.  So stay out of their way lest they tap dance around you seeking your blood, sweat, tears and a tot of your rum.

(Ranjit Lal is an author, environmentalist and bird watcher)

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