An atlas moth caterpillar

Caterpillars of the Attacus atlas species can grow up to an inch thick © Phanthit Malisuwan/Shutterstock

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Spotlight: the atlas moth

One of the goliaths of the insect world, the atlas moth is a gentle giant – but behind every oversized moth is a very hungry caterpillar.

The atlas moth is among the biggest insects on the planet, with a wingspan stretching up to 27 centimetres across - that’s wider than a human handspan.

And the caterpillars of the species reach up to 12 centimetres long, spending every spare second eating.

Luke Brown, manager of the Museum's butterfly house, says, 'It is impossible not to be fascinated by the atlas moth. This is due to its beauty, the detail on its wings, and its sheer size at every stage of its life cycle.'

A race to grow

Adult atlas moths may be massive, but they do not feed at all after they have emerged from the cocoon.

The proboscis, which other butterflies and moths use to drink nectar, is tiny and does not work. Without the ability to feed, atlas moths only manage between one and two weeks of life before the energy to power their huge wings runs out.

An adult atlas moth

Atlas moths don't move much during the day, preserving their energy for mating © Vladimir Sazonov/Shutterstock

It means they spend most of the day resting to preserve energy, only looking for a mate at night.

The pressure is on the caterpillars to consume enough food before going into the cocoon to sustain the moth when it is reborn.

In the wild, atlas moth caterpillars eat the leaves of cinnamon, citrus fruit, guava and Jamaican cherry trees.

In the butterfly house, they are fed on privet from the Museum Wildlife Garden.

Luke says, 'We don't let them roam free in the exhibition because they eat so much. This allows them to build up fat reserves for the adult to live off.

'If we didn't monitor their eating, we would have no plants left in the butterfly house, so we keep them in their own feeding area while they are growing.'

An enduring giant

Native to China, India, Malaysia and Indonesia, the moth shares a name with Atlas, the Titan god of Greek mythology.

Atlas was burdened with the task of holding up the heavens for all eternity, and has become known as the gigantic god of endurance and astronomy.

It is fitting that one of the biggest moths in the world shares a link with Atlas, but it is not clear whether the insect was directly named after him.

Scientists have speculated that it could have been given its name because of the patterns on its wings, which also look like a paper map.

The moth's Cantonese name translates as snake's head moth, because the tips of its wings look similar to the head of a deadly cobra.

When threatened, the moth will drop to the floor and writhe around, slowing flapping its wings to imitate snake head and neck movements and scare away predators.

Harvesting silk

Atlas moth caterpillars also produce silk similar to the product created by domesticated silkworms.

It is secreted as strong, brown, broken strands called fagara, and is used to build a cocoon when the time comes to pupate.

In some Asian countries, the abandoned cocoons are used as purses because they are so durable.

Luke adds, 'The atlas moth captures people's imaginations. It is a great learning tool for us in the exhibition because it is so intriguing.

'Often I will ask a volunteer to sit on the bench holding a cocoon, with the huge insect resting on it. It gives visitors a unique chance to get very close to the moth and see all the details.'