How does a caterpillar change into an adult butterfly or moth?

Butterflies and moths undergo a process called complete metamorphosis, which involves a dramatic transformation from a larval caterpillar into a winged adult.12

After completing its growth through several molts, the caterpillar stops feeding and seeks a location to pupate. It then enters the pupa stage, a resting phase where the insect is protected by a chrysalis (in butterflies) or a cocoon (in most moths).314

Inside this protective covering, the caterpillar’s larval tissues undergo a process of breakdown, while adult structures—such as wings, antennae, and legs—develop from existing rudiments. This complex physiological rebuilding is regulated by hormones. Once the transformation is complete, the adult emerges by splitting the pupal skin or exiting the cocoon. The new adult typically spends time drying its wings before it is capable of flight.156