What happens inside a chrysalis?

What happens inside a chrysalis?

By Connor Butler 

Jon Hawkins - Surrey Hills Photography

The lifecycle of a butterfly is mysterious and fascinating. Caterpillars emerge from their chrysalis as beautiful butterflies, as if by magic! What exactly is going on inside? 

Mullein moth caterpillar

Mullein moth caterpillar ©Chris Lawrence

What is a chrysalis?  

After hatching from an egg, caterpillars have one goal – food! They are fussy and will often eat only one type of plant. When they are completely full, from their all-you-can-eat plant feast, they find a safe spot to rest and attach themselves with silk. That might not sound very strong, but it acts just like Velcro! Then, the caterpillar sheds its skin to reveal a hard shell underneath. This is called a chrysalis. It will protect the caterpillar whilst its insides turn to goo – gross! 

Mush: what happens inside?  

A butterfly’s lifecycle has four stages egg, larva, pupa, and adult.  

When inside a chrysalis, the butterfly is called a pupa. To turn from a larva into an adult, the pupa starts to digest its body from the inside. How weird! It uses the same sort of chemicals that it used to digest its food. Imagine being digested by your own stomach – no wait, don’t imagine that!  

Caterpillars are eating machines and can grow 40 times their original size

Not quite all goo 

Lots of important parts, like the digestive system, the airway and the brain, don’t turn to goo. Instead, they’re just moved around! The caterpillar’s “mouth” is recycled into the butterfly’s proboscis – a tube which is uses to eat. There are also special blobs floating around which begin to grow into the wings, antennae and legs. Once everything is in place, this sack of goo is ready for the next step! 


After 5-21 days, the chrysalis changes colour and the butterfly is ready to emerge. The casing splits and the butterfly squeezes out through a small crack. Its wings are soft and crumpled so it can’t fly away yet. Like stretching your legs after a long car ride, the butterfly spreads its wings to fill them with blood and straighten them out. When it’s ready, the butterfly takes to the air to begin the last part of its lifecycle. After feeding, finding a mate, and laying eggs, the cycle starts again! 

Peacock butterfly

Peacock ©Rachel Scopes