Ages 6 to 8 years. Butterflies are the most beautiful insects, and this latest Crabtree title shows these colourful creatures in all their glory! The book starts with the stages of metamorphosis from egg to worm-like caterpillar to pupa, and finally, to a magnificent butterfly. It then introduces some caterpillars and butterflies and asks children to notice their similarities and differences. The book then challenges children to guess which caterpillars would change into which butterflies.