The butterfly lays its egg on a leaf on a sunny day. After seven days the caterpillar will hatch. First they look for their food. The caterpillar eats the leaves of a milk weed plant.
Milk weed contains poison. This poison helps the adult butterfly to protect its self from predators, Caterpillars eat lots of leaves to make him fat. Once he is fat enough, the caterpillar turns into a chrysalis. When the butterfly emerges from the chrysalis it has to wait for his wings to dry.