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Sunday, July 15, 2018

Down in Jungleland: Disco at Dusk

Though not as glamourous, moths are similar to butterflies, but more evolved than them.

Written by Ranjit Lal | Updated: April 13, 2014 1:12:03 am
Whatever the reason, remember that moths are not the only creatures that dance dementedly around bright disco lights… Whatever the reason, remember that moths are not the only creatures that dance dementedly around bright disco lights…

We all admire butterflies — those tipsy, kaleidoscopic dilettantes of the insect world that flit and flutter in the bright sun.

Few of us have time for moths — well, they’re drab and dusky and doom-laden. They may come out to party at night, around the bright lights, but so many spiral hypnotically straight into hot bulbs or naked candle flames with a fizzing hiss… Those that manage to find a wall on which to rest and nurse their disco night hangovers will be picked off by birds, first thing next morning. It’s a tough life.

But let it be known that they’re more successful than their glamourous cousins. There are around 10 times as many species of moths as there are butterflies. Figures I’ve come across range from 1,20,000 to 1,60,000 species worldwide.

Technically, there’s no real difference between them and butterflies, except that they do not have clubbed antennae which butterflies do, and prefer to be out and about after dark, when all good butterflies are asleep… Their life cycles, too, are pretty much the same: going through the usual egg-caterpillar-pupa-adult metamorphosis. The largest, the Atlas moth, has a one foot (30 cm) wingspan, and is as big as a small songbird; the tiniest is the size of a pencil point. And while butterflies may be the glamour queens, all dressed up in flashy, rainbow hues, moths prefer earthy and ethnic colours — their tastes (I find) are more refined and genteel and classy. Their taste in food — like those of butterflies — is eclectic. Apart from nectar, they’ll enjoy liquid mud (for minerals), dung, wine, rum, urine, fruit juice, body fluids from dead animals, rotting fruit, and blood, sweat and tears — even yours! It’s a liquid diet, and some, like the Atlas moth, don’t eat at all — they have no mouths — and live off (for about two weeks) the fat they’re born with.

They’re not entirely defenceless: I was once “pepper sprayed” with a hot pungent liquid by a large hawk moth I was trying to photograph. Some caterpillars wear fur coats of stinging hairs (the Wooly Bear caterpillars), or an armour of spines and hooks. Some moths have furry bodies which muffle the ultrasonic clicks bats emit while homing in on them and literally “jam” their radar; others are bolder and emit clicks of their own, warning the bats that they’re revolting to eat and to stay away. They have a harder time dealing with us: we boil alive the pupae of silk moths to extract silk and consider many of them agricultural pests. At best, some moths get their revenge by laying their eggs in our cupboards so that their caterpillars eat our silk and woollen clothes. (I really wonder how many species of animals would consider us to be Pest Number 1 or Alpha Pest!) In one area, they completely outclass us: lady moths use perfumes so powerful and alluring, they can draw the gents from more than 11 km away. No perfume manufacturer can match that.

So why do moths do that “dance of death” around bright lights? We’re fighting over this issue too. Perhaps, the most popular explanation is that they use a form of celestial navigation, called “transverse orientation”, while flying, especially while on migration. By keeping a constant angle to a bright distant celestial light, such as the moon, they are able to fly in a straight line. But if the light source — such as a bulb or candle — is closer, they have to fly in a circle around it and towards it to keep that angle constant. And then it’s too late. Detractors of that theory say up to 70 per cent moth species are not migratory and don’t need these skills. Besides, if all those with kamikaze tendencies did crash and burn, they’d be extinct by now. Another explanation is that the infra-red light emitted by a flame contains a few of the same frequencies of light (very faint albeit) emitted by the pheromones (perfume) given off by females, so the poor males think they are diving into the arms of their beloveds and not into a funeral pyre. Some claim that moths are more attracted to ultraviolet light than infra-red, and UV light does not contain the come-hither wavelengths.

Whatever the reason, remember that moths are not the only creatures that dance dementedly around bright disco lights…

What are you doing Saturday night?

Ranjit Lal is an author, environmentalist and bird watcher. In this column, he reflects on the eccentricities and absurdities of nature.

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