Insects have two very different kinds of life cycles.
Some insects go through a “complete metamorphosis” where they hatch from their eggs as worm-like larvae (caterpillar) with mouthparts built for eating. They will eat and grow in size for a time and then cocoon themselves up to form a pupa. Inside their cocoon or chrysalis an insect will go through a complete physical change. When it comes out (emerges) from the cocoon it is an adult insect. This is the life cycle of butterflies and moths and many other insects.
The purpose of this change allows the insect to use several food sources. Early on as a caterpillar it can eat leaves. Then by the time the adult butterfly emerges, the plants have flowered and the adult butterfly can collect nectar. They can also survive over the winter protected inside their pupal phase and try again next summer.
Other insects hatch out as a very small version of their adult form. As they grow, they shed their hard exoskeleton and reform another, bigger one. These stages are called "instars". These insects will go through many instars to reach their adult size. This is called "incomplete metamorphosis” and is typical of insects like grasshoppers and katydids.
Print out the Monarch Butterfly Life Cycle below, cut out the stages and rearrange them to show the correct progression of the life cycle of a butterfly.
To make black and white copies for your whole class, see the copy-friendly versions below.