Narrator: What would you do for the power to fly ... This, on the other hand, is what's called a chrysalis. It's not a sack or a pouch; it's actually the caterpillar's own body.

In the final caterpillar stage, the imaginal discs begin to activate, and with the decline of juvenile hormones, another surge of ecdysone pushes the caterpillar to transition into a chrysalis.