Building a new body.
Butterflies are beautiful — a beauty which can belie the trials of their birth. It is well known that a butterfly’s lifespan starts with an egg, continues with a larva, then a pupa, before the fully-formed butterfly finally emerges — the true birth — and takes flight. What is less known, are the ardous stages the creature has to work through, in order to reach its imago, the final state. The crux of the matter is the formation of the new butterfly’s bodyparts. These parts have to be built from the remnants of its former state, and the finishing touches are vital for its survival.
The building project starts in the pupa, also known as the chrysalis. Inside the tough outer shell, the former larva first has to break down completely, in order for the creature to be pieced together anew. Essentially, the larva dies. Ironically, this is done by utilising some of the same juices that the larva used to digest food. The old body is broken down the way the food it used to sustain itself was broken down. Only a few tissues are left, and basic building blocks called imaginal discs are used to form the body of the imago.
When this process is finished, the butterfly needs to leave its chrysalis. It uses small claws to break its way out of the shell. However, the imago’s body is still not ready to take flight. Before it can leave, it must have functional wings. As it emerges from the shell, it only has the fragile beginnings of these. In order to form more stable structures that it can actually fly with, the butterfly must pump a liquid into the wings. This will enable them to fill out. Usually, the butterfly hangs upside-down under the remnants of the chrysalis while it does this, in order to utilise gravity. When the wings are filled, they must dry and harden before the butterfly can fly away.
There is another part of the imago that is vital to finish building after the emergence. The proboscis is like a long straw neccessary for eating. However, immediately after the butterfly’s emergence, it is still in two parts and not yet functional. The butterfly must form the straw-like shape of the proboscis by linking together these two pieces. This is done by using mouth parts called labial palps. After the two parts are joined together to form one strong proboscis, the butterfly will curl and uncurl it repeatedly, apparently to test its newly formed appendage. Only when the proboscis is functional will the butterfly be able to consume nourishment.
The formation and emergence of a butterfly’s imago is its true birth. The building of this final state in the creature’s life cycle takes place mostly inside its chrysalis, but isn’t finished until after its emergence. The finishing touches of the wings and proboscis are vital, and both have to be put together in a hurry to ensure survival. From the formation of new body parts in the liquidous remnants of the larva, to the blossoming of the wings and assembly of a healthy eating organ, this metamorphosis must surely be Nature’s finest building project.