Egg
A butterfly begins life in an egg. The egg, which is very small (sometimes microscopic), is usually round or oval in shape. The shape of the egg is determined by what type of butterfly it is. The adult butterfly lays the egg on a leaf or a plant stem. Because each type of butterfly eats a specific type of food, the egg cannot be placed on a random plant; it must be the correct type of plant that feeds that species. When the egg hatches, the caterpillar eats the leaf that has been its home.
Caterpillar
The caterpillar that emerges from the egg usually looks like a chubby worm, and is referred to as the first instar. It may have stripes or a pattern on its body. The legs, antennae and eyes are all small. The caterpillar has two jobs: to eat and to grow. As the caterpillar grows, it molts, or sheds its skin. The caterpillar does this several times, with each new molting being called a new stage (second instar, third instar, fourth instar and fifth instar). The fourth instar looks different than the other stages since it's the last one before the caterpillar gets ready to become a butterfly. When the caterpillar molts as a fifth instar, it forms the chrysalis.
Chrysalis
The metamorphoses, or transformation, takes place in the chrysalis. The chrysalis hangs from a branch or stem, but can also be found underground. During this stage, the tissues and organs change from those of a caterpillar to those of a butterfly. The legs and antennae grow longer. The eyes become compound eyes, which means there are many small eyes inside a larger eye that each see part of an object and work together to see the object as a whole. The wings form during the metamorphoses stage as well. This process takes approximately two weeks, but can take longer.
Adult Butterfly
When the butterfly emerges from the chrysalis, it cannot fly because its wings are wet. The butterfly spreads its wings to help them dry. It also needs to expand the wings to their full size, so it uses its abdomen to move fluid into the veins in the wings. Once the wings are dry and have expanded, the butterfly will begin making test flights. The butterfly is now ready to find a mate, reproduce and migrate. The butterfly will not grow bigger, but it will drink nectar from flowers if it is hungry.