Complete Metamorphosis

Adult Queen butterfly, Danaus gilippus, emerging from a chrysalis.

Metamorphosis is a Greek word meaning transformation or change in shape. It is a process used by the majority of insects, and as insects are the largest group within the animal kingdom, the majority of all animals. There are two types of metamorphosis: incomplete and complete. In incomplete metamorphosis, the young, called nymphs, often look similar to the adult form, but without the wings. In complete metamorphosis, the young, called larva, not only look different, but have a different food preference as well. Therefore, one advantage of complete metamorphosis is the removal of resource competition.

Various stages of emerging Queen butterflies, Danaus gilippus.

The complete metamorphosis of a butterfly is an intensive process. It begins with the caterpillar surrounding itself in a chrysalis or cocoon. Once encased, the caterpillar then releases digestive enzymes which dissolve all of its tissues into a liquid soup. While it seems a mess, highly organized cells known as imaginal discs survive the process. There are discs for each adult body part. Within the protein-rich soup, rapid cell division begins as directed by the imaginal discs. The thought that everything is completely reorganized within the pupa is mostly true, but some systems, such as the tracheal system, are complete almost from the very beginning. Either way, by the end of a couple of weeks, species dependent, from within the chrysalis or cocoon soup emerges a complete (if wet) butterfly.