蝶虫是蝴蝶的幼体。
A caterpillar is the larva of a butterfly.

蝶白费力气想抓住停在花上的蝴蝶。
He tried in vain to catch the butterfly on the flower.

蝶一只蝴蝶正在花丛里忽上忽下地飞着。
A butterfly is flying up and down among the flowers.

蝶觉得这虫子是蝴蝶的幼虫。
I think this worm is a larva of a butterfly.

蝶展示了从幼虫变成蝴蝶的过程。
It shows the metamorphosis of a larva into a butterfly.

蝶陋的毛虫会变成美丽的蝴蝶。
The ugly caterpillar will change into a beautiful butterfly.

蝶虫会变成蝴蝶。
Caterpillars turned into butterflies.

蝶蝶到处飞来飞去。
Butterflies flit hither and thither.