Why Caterpillar change become Butterfly?

Long, long ago, Kiko and Citty, two Caterpillar which lived in the jungle full with tree, but the only one tree which leaf can't ate.
One day, Kiko and Citty walked round jungle and passed the tree which leaf can't are. Suddenly City felt want ate the leaf.

Kiko forbid, "The leaf in the tree can't ate, although delicious." Citty and Kiko come back.
One night Citty dreamed ate the leaf. Citty was saw changed the self became beautiful butterfly. The followìng day she was went secretly without know Kiko. With felt not believed Citty was ate the leaf. After 3 day ate the leaf, suddenly, Citty as which wrapper with thread white thick. Day ofter day Citty was silent and Kiko was only cried.
The moment full moon brightly jungle, wrapper in body Citty was opened. Citty changed became Butterfly which beautiful. And all Caterpillar in arround jungle ate the leaf order became Butterfly.