For example, one cluster will develop into the adult's compound eyes. Ecdysone is the molting hormone of insects. It causes an insect to molt. After the molt, while the new skin is still soft, they swallow a lot of air, which expands their body. Then, when the cuticle hardens, they let the air out and have room for growth.
Caterpillars molt four or five times as they grow.
Each different caterpillar stage is called an instar. The Monarch caterpillar is brightly colored and is poisonous. Caterpillars come in many colors and patterns. Caterpillars are soft bodied and slow moving. This makes them easy prey for predators, like birds, wasps, and mammals to mention just a few.