Why Do Caterpillars Change Into Butterflies?

A caterpillar’s transformation from a grubby squishy crawling insect to a pretty fairy-like flying insect is one of the things in the wild that fascinates people the most. But, why do caterpillars change into butterflies?

Caterpillars are simply the larvae of butterflies and moths and can’t reproduce. They need to morph into adult butterflies or moths to reproduce.

Caterpillars aren’t adult insects. They’re the larval form of butterflies. They cannot reproduce and continue their circle of life, so they transform into butterflies to reproduce and continue the cycle.

Not every caterpillar grows and pupates into a butterfly, many species of caterpillars morph into moths. Moth caterpillars are usually fluffy and hairy, while butterfly caterpillars are smooth bodied.

A caterpillar’s only purpose in life is to eat as much as possible during its larval phase. All the food a caterpillar consumes gets stored in its body and will help it when it’s inside a chrysalis or cocoon during pupation. 

Do Caterpillars Feel Pain During Metamorphosis?

There is no physical pain that a caterpillar feels during metamorphosis as the caterpillar inside the cocoon or chrysalis during pupation is unconscious throughout the time.

During pupation, inside a cocoon or chrysalis, the caterpillar is dissolved into a liquid using enzymes. Hormones trigger these enzymes. 

Then the caterpillar’s organs, limbs, and tissues begin changing and altering and rearranging themselves. The caterpillar then fully becomes a butterfly or a moth if it’s a moth caterpillar.

New colours, longer legs, antennae, compound eyes that are better and larger, and other characteristics of a butterfly start to emerge. The mouth changes from mandibles to a proboscis. A proboscis is used to suck nectar only as butterflies don’t eat solid food.

Incomplete and Complete Metamorphosis

Metamorphosis is of two types which are complete and incomplete metamorphosis. Incomplete metamorphosis is when a larva of an insect looks like an exact replica of the adult but only smaller.

This is common with cockroaches, earwigs, cicadas, grasshoppers, dragonflies, and termites. 

Complete metamorphosis is what caterpillars go through. It’s when the larva of the adult insect looks drastically different from the adult and must change and alter completely to look like the adult insect.

Flies, bees, beetles, butterflies, moths, and sawflies go through this type of metamorphosis. 

Do Caterpillars Only Change Into Butterflies?

Not all caterpillars turn into butterflies, and lots of species of caterpillars turn into moths. If you come across a pupating caterpillar, a butterfly or a moth would either come out.

There are several visible differences between a moth caterpillar and a butterfly caterpillar that greatly help in figuring out what the caterpillar will grow into. 

If a caterpillar has lots of hair like quills on its body, spines, thorns all over its body or on certain areas such as the head or abdomen or only on the sides and has very odd appearances, then its most likely a moth caterpillar that will grow into becoming an adult moth.

A butterfly caterpillar is smooth-bodied and soft and squishy with an absence of any quills or spines. Both caterpillars are known to be colourful, both can have fake eyes, and both of them have the same limbs such as mandibles, prolegs, antennae, etc. 

Do All Caterpillars Turn Into Butterflies?

No, not all caterpillars turn into butterflies. Some caterpillars will turn into moths. All caterpillars will turn into either a butterfly or a moth.

Do Some Caterpillars Become Moths?

Yes, some caterpillars will turn into moths and others will turn into butterflies. All moths come from caterpillars.

How Do Caterpillars Turn Into Butterflies?

The process of complete metamorphosis, through which a caterpillar turns into a butterfly, goes through several steps to be completed:

Stage 1: Eggs

An adult butterfly lays eggs. The eggs are tiny, round, or oval in size. The shape of the butterfly egg varies in different butterfly species.

Most butterflies like to lay eggs on a food source such as leaves or trees, so when the caterpillar hatches, it has something to eat from the start. The eggs are attached with an adhesive fluid, so they don’t fall off from the surface they’re attached to.

Adult butterflies lay hundreds of eggs, as not all of them become a butterfly. 

Stage 2: Caterpillar

When the egg hatches, the larvae come out, and the butterfly in this stage is in its caterpillar phase. The caterpillar in this stage is small and looks nothing like a butterfly.

It has several tiny eyes called ocelli, short legs, and an extra pair of legs called prolegs, mandibles, and a pair of antennae. It has some bundles of cells that become butterfly parts when it reaches pupation.

These are imaginal discs. These imaginal discs turn into wings, long antennae, and longer legs. 

The caterpillar at first is tiny but grows in size throughout its larval stage. Caterpillars pass their time only eating.

They eat a lot, including the leave they hatched on. Caterpillars will eat leaves, bark, flowers, fruits, veggies, and even dead animals. If food is very scarce, then a caterpillar may get cannibalistic and eat other insects.

If the situation is very dire, it will start eating other caterpillars. 

The caterpillar keeps on growing, and its internal organs start to change. Since caterpillars have exoskeletons and these can’t stretch while the caterpillar grows, they moult and shed their old skins with new ones.

Stage 3: Pupa

A caterpillar eats so much specifically to store enough food that’ll come useful in the pupa stage. So when the caterpillar has stored the required food amount, it reaches pupation. The caterpillar forms a chrysalis or a cocoon to change into a butterfly.

Caterpillars can’t eat during pupation, so the stored food comes in handy. The pupation takes time, but it depends on the species.

Stage 4: Butterfly

The chrysalis or cocoon breaks and a butterfly emerges with its new look. It takes a little while for the antennae and long legs to stretch and pump hemolymph, which is an alternate for blood in insects.

The wings are also wet, so the butterfly waits for them to dry so it can fly.


Caterpillars cannot reproduce on their own as they are only larvae of butterflies and moths, so they have to physically alter themselves into adult butterflies and moths to reproduce.

Caterpillars are unconscious during pupation, so they don’t feel any physical pain while rearranging their bodies into butterflies. 

Leave a Comment

Latest Reads

Are Black Cats Bad Luck

Are Black Cats Bad Luck?

Does Cinnamon Deter Cats

Does Cinnamon Deter Cats?

Do Slugs Eat Chives

Do Slugs Eat Chives