Caterpillar Cocoon: Complete Process Of Turning Into A Butterfly

The transformation of a caterpillar into a butterfly makes for a fascinating story.

But science has an equally fascinating explanation that can be told to any age group. It's actually worth learning about the transformation of this creature.

Butterflies go through several life phases, with the cocoon phase being one of them. As you'll learn later, the butterfly goes through an egg, caterpillar, pupa, and adult phase. It's the adult phase where butterflies grow their eyes, legs, wings, and antennae. After the adult butterflies mate, the females lay eggs and the cycle starts all over again. You should also know about the imaginal discs and their role in the development of a butterfly or moth. That's all covered in this article!

If you have this misconception that caterpillars are completely harmless, then read about caterpillar stings. If you're a bird enthusiast, why not check out this popular article about bird beaks.

Stages Of A Cocoon

Just like humans go from fetus to baby, baby to child, child to adolescent, adolescent to adult, and adult to elderly, butterflies pass through a life cycle.

To understand the caterpillar's transformation from a cocoon into a butterfly, you should learn about its life cycle. As already mentioned, butterflies or moths undergo a complete metamorphosis. Such insect species have four different developmental phases, namely, egg stage, larva stage, pupa stage, and adult stage. Let's explore each phase in more detail:

The first stage of a butterfly is the egg stage. When the egg-laying season starts, the female butterflies lay their eggs on a tree or plant, mainly on the undersides of leaves. They carefully select the trees because that's where the larva will spend the next stages of its life. Therefore, it must be safe. A butterfly egg is the size of a pinhead.

When the time comes for an egg to hatch, it begins to darken and will become transparent. When it does, you'll be able to see a fully-formed, tiny, caterpillar moving around. The larva will emerge by eating the eggshell after 1-2 weeks of being laid. So, the egg stage lasts for 1-2 weeks.

The next is called the larva stage. After the larva hatches from the egg, it usually starts to eat a leaf from the plant or tree. The larva will spend most of the time eating. It will consume multiple times its own weight to keep growing in size.

It's interesting to note that the larva will only eat the leaves on which it was born, also known as its host plant. They would rather not eat and die than consume leaves of other plants. The science isn't clear as to why, but most probably it is the choice of its mother.

During the larva stage, the caterpillar will undergo several phases of molting. It will usually shed its outer skin and grow a new one. Towards the end of this transformation stage, the larvae will stop eating. They will go about finding a good and safe place for the next stage.

The third is the pupa stage. It's when the caterpillar will hang itself upside down from a branch to undergo the final molt. In doing so, it starts to shed its outer skin. It will keep growing and finally form a sack-like structure called a chrysalis. Then, inside it, the process of metamorphosis, as discussed earlier, will begin. Imaginal discs will come together to form the body parts. Metamorphosis can last somewhere between two weeks to two months or more depending on the species and season.

The last stage of a butterfly's lifecycle is called the adult stage. The pupal case will split open and the caterpillar that went inside the case will have radically transformed into a butterfly. It'll have fully-developed eyes, legs, wings, antennae and everything a butterfly is supposed to have.

Adult butterflies have a short lifespan of 1-6 weeks. During this period, they have to mate and lay eggs. The male uses his eyes and vision to locate a female. Then it uses a chemical called pheromones to attract them. The adult butterflies will mate within their species.

How does a cocoon turn into a butterfly?

A chrysalis may look still from the outside, but, biologically speaking, there's a lot going on inside. The caterpillar isn't resting or taking a nap inside. The sequence of events allows the pupae to turn into beautiful, colorful butterflies.

Metamorphosis plays a big role in different caterpillar cocoon stages. It's a complex subject but, in short, it's a natural, biological process through which an animal experiences cell growth and differentiation as part of its development. The butterfly and moth species undergo complete metamorphosis or holometaboly.

Inside the chrysalis, the body of the caterpillar breaks down into a liquid as it starts to digest itself from the inside out. The enzymes that dissolve the body are the same that the larva uses to digest food. If you cut open the chrysalis during this time, a translucent liquid that contains the enzymes will begin to ooze out. Needless to say, that'll mean the caterpillar's death. Therefore, you should never try that.

Once the body is dissolved there's something even more interesting that begins. When a caterpillar is born, it's born with imaginal discs. As opposed to the name, imaginal discs aren't imaginary and exist for real. These are groups of epithelial cells that later combine to form different body parts like the wings, eyes, and legs. In the liquid, the cells rearrange themselves. There are different cells for wings, legs, antennae and other parts. That's how the butterfly is eventually created by nature. Once the metamorphosis is complete, the butterfly will emerge and fly into the outer world by flapping its wings.

How is a cocoon formed?

The cocoon is formed during the pupa stage. After the caterpillars have eaten enough and undergone several instars, they develop a firm outer layer called the chrysalis. This layer allows them to protect themselves from the dangers of the outer world while they develop into butterflies.

When learning about a cocoon's formation, it's important to learn how a cocoon is different from a chrysalis. Technically, butterflies never form cocoons. Cocoons, a layer of silky casing, are formed by moths. When the moths reach the pupae period, they spin a layer of silk around them. This layer hardens into the cocoon where the caterpillar develops into the moth. In the case of a butterfly, they do not weave this silky case. Instead, they hang themselves upside down and shed their outer skin layer. This layer changes its natural shape and becomes the butterfly chrysalis.

What is the role of the cocoon?

The cocoon or chrysalis serves an important purpose for these insects. Without it, caterpillars most probably won't transform to the next stage.

Caterpillars are timid creatures. Their soft body, boneless structure, and slow movement make them vulnerable as prey in nature. Animals higher in the food chain like birds, larger insects, and spiders like to snack on caterpillars. Moreover, when caterpillars become pupae, they do not move and stay still in one place. A larva will hang itself for several weeks before it turns into a butterfly. This makes them even more vulnerable. So the chrysalis' primary role is to protect the larva during this transition period. It offers a protective casing where the larva can pupate.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'Caterpillar cocoon' then why not take a look at 'Bee life cycle', or 'Paris peacock facts'!