When Do Caterpillars Cocoon?

Cocoons are only made by moth caterpillars that pupate into a moth. Metamorphosis is a fascinating process through which a caterpillar goes from its larval stage to become an adult moth (or butterfly), but when do caterpillars cocoon to undergo adulthood?

When caterpillars have eaten and stored enough food in their bodies and are ready to pupate, they will make a cocoon and cover themselves with it. 

The larvae of moths and butterflies are caterpillars, and their only objective in life is to eat as much as possible until they’re ready for the pupation stage. This is why people often want to do all they can to get rid of caterpillars.

As caterpillars are unconscious and dormant inside a cocoon, they cannot eat or move in pupation, so they need to store enough food to survive the cocoon stage of their life, and when that is done, they make their cocoons and enclose themselves.

When they’ve finished altering their bodies in their cocoons to become adult moths, they break out from it.

Bagmoth caterpillars take an odd approach; they make very hard coverings earlier than most other caterpillars. These caterpillars use twigs, debris, and leaves to make a strong casing to cover themselves and camouflage themselves, so no predator can easily spot them.

When they’re ready to pupate, they do it while inside their already made covering. You can learn more about the Bagmoth caterpillar on Wikipedia.

What Time of Year Does a Caterpillar Turn Into a Cocoon?

The time of year a caterpillar encloses itself inside a cocoon depends on the lifecycle of the caterpillar, and every species of caterpillar has a different time of metamorphosis.

Several caterpillar species pupate sooner than others. They’ll weave their cocoons when summer comes, while others plan to pass winters while enclosed inside their cocoons, start weaving cocoons in autumn, and spend several months inside them. 

There is no definitive answer as each caterpillar has its own traits.

How Long is a Caterpillar in a Cocoon?

The time taken for a caterpillar enclosed in a cocoon to either develop into an adult butterfly or an adult moth depends entirely on the caterpillar species.

For many species, it takes less than 30 days. It can take about a week to some months to even a year for certain species.

A monarch butterfly caterpillar, for example, takes 9 to 14 days inside a chrysalis, while a painted lady butterfly caterpillar will only require 10 days to fully develop into an adult in the chrysalis. 

What is the Difference Between a Cocoon and a Chrysalis?

A cocoon is made by a caterpillar that will pupate into an adult moth, while a chrysalis is made by a caterpillar that will develop into an adult butterfly.

Cocoons are made from silk that the caterpillars themselves weave, and a chrysalis is more like an outer shell formed on the caterpillar to undergo pupation.

Where Do Caterpillars Make Cocoons?

Some caterpillars will climb down from a tree branch, twig, or leaf they’re at to enclose themselves in a cocoon in the ground camouflaged by twigs, leaves, and dirt. Other caterpillars will hang themselves upside down from the bottom of a stem or leaf. 

Cup moth caterpillars can make hard and strong pear-shaped cocoons that look like eggs and attach them underneath a twig, and there’s a lid on the base from where they can exit.

The bumelia webworm makes a pretty-looking golden cocoon that seems made out of mesh. The cocoon suspends from vegetation like a Christmas ornament. It’s said that the open structure of the cocoon is designed for ventilation in a humid environment.

Each species of moth caterpillar have varied cocoons. Their size, shape, and colour distinguish from species to species.

Why Do Caterpillars Stop Eating Before they Cocoon?

A caterpillar stops eating before pupation because caterpillars, while inside a cocoon, cannot eat or move; they’re dormant and unconscious, and their bodies are rearranging themselves inside the cocoons.

While they’re in their caterpillar stage, they set eating as their top priority because once they reach pupation, they wouldn’t be able to eat anymore; hence they store as much food as they can while in caterpillar form. 

Caterpillars also stop eating when they’re shedding their skin. They shed skins when their current exoskeleton reaches its limit, so the caterpillar sheds the old skin and forms a new skin that is comfortable with its growing size. 

Why Do Caterpillars Cocoon?

Caterpillars cocoon to undergo the transformation of becoming an adult moth or butterfly. Their bodies completely change to an adult moth or butterfly in the cocoons.

Caterpillars are only the larval form of moths and butterflies and cannot reproduce on their own, to reproduce and continue their life cycle. They must undergo the process of metamorphosis to become adults. 

Do All Caterpillars Turn Into Butterflies?

No, some caterpillars will become butterflies whilst other caterpillars will become moths. Generally, if a caterpillar makes a cocoon then it will become a moth. If a caterpillar makes a chrysalis then it will become a butterfly.


Caterpillars need cocoons to carry out the most important process in their lives: Metamorphosis.

Without metamorphosis, a caterpillar cannot grow into an adult and the caterpillar cannot reproduce. A caterpillar is only a larval form of moths and butterflies, so it doesn’t have reproductive organs.

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