The secret stage in the life of the butterfly

Papilio polyxenes - chrysalis
Credit: CC flickr (woodleywonderworks)
Papilio polyxenes - chrysalis
  • Papilio polyxenes - chrysalis
  • Antheraea polyphemus - cocoon
  • Monarch getting out of its chrysalis
The secret stage in the life of the butterfly

The caterpillar turning into a butterfly: that, we’re all familiar with. But in between those two stages of the life cycle a mystery lurks: the mystery of the chrysalis. Assuming the appearance of a dry or green leaf, imitating bird droppings or the thorn of a plant, the fragile chrysalis blends in with its landscape. Camouflaged and immobile, it can be really difficult to spot. Like the guardian of a noble secret, the chrysalis conceals the incredible transformation process that will lead to the emergence of the butterfly.

Hidden from view

The metamorphosis process begins inside the caterpillar’s body. The originating cells for the formation of the butterfly’s body parts are already present, although inactive. They’re waiting for a hormonal signal before they launch the great revolution. Once the message is received they start to multiply, differentiate and grow. Then the insect stops eating and being active: a break to allow for the caterpillar’s final molting. Under its old shell the discreet chrysalis is revealed, the seat of extreme transformations. The disused organs and limbs of the caterpillar are “recycled” to form wings, proboscis, antennae, nervous and digestive systems, reproductive organs and so on. It’s an extraordinarily complex reorganization. Even today, researchers are still trying to pierce all the mysteries involved.

The unveiling

Like a bud waiting to flower, the chrysalis drifts towards the end of its metamorphosis. Then, when the moment has arrived, its envelope breaks open to reveal the much awaited butterfly. Huddled up, a few minutes earlier, inside the chrysalis, it now deploys its wings, eager to take flight for the first time.

A little caterpillar becoming an elegant butterfly: what a prodigious feat! There’s something magical about it. And yet, this wonderful process unfolds millions of times every year. The chrysalis is a precious stage in the life of the insect and one of the most extraordinary secrets in nature.

Chrysalis or cocoon?
Whereas the term “chrysalis” is generally not well known, the word “cocoon” is very familiar to us. But are we talking about the same thing? As it happens, no. Chrysalis refers to the insect in the third stage of its life, while the cocoon is only a protective envelope made of silk. It’s woven by the caterpillar before it turns into a chrysalis.

Do all caterpillars make a cocoon? Again, no. Only certain moth caterpillars manufacture these shelters against predators and bad weather.

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