Old World Swallowtail (Papilio machaon) Butterfly Chrysalis (WC)

Many thanks to “P” from England for taking the time to message me and asking this intriguing question! So what is the difference between a Cocoon, a Chrysalis and a Pupa? Let’s find out!

All insects go through a series of ‘instars’ or molts or life changes as they mature (called metamorphosis) because, unlike with mammals like us, their growth is constrained by their hard exoskeleton (external covering).

A Pupa is a life stage of some insects undergoing transformation. The Pupae of different groups of insects have different names, in the Mosquito family they are known as ‘Tumblers’. With Lepidoptera, Moths and Butterflies, the first life stage is the Ovum or Egg, the second stage the Larva (Larval stage) or Caterpillar, the third stage the Pupa (Pupal stage) is known as a ‘Chrysalis’ and finally it becomes the ‘Imago’ or adult, obviously commonly termed the actual ‘butterfly’ or ‘moth’. So a Chrysalis is the pupa stage of a Moth or Butterfly (Lepidoptera).

A Cocoon is a casing of spun silk produced by many insects to form a protective covering for the Pupa. Many Moth Caterpillars for example produce silk cocoons. Cocoons can be of various types, from hard to soft, with various colours dependent on the species involved.

Virginia Tiger Moth (Spilosoma virginica) Cocoon (WC)

Many people state that a Moth Pupa is enclosed in a Cocoon and a Butterfly Pupa is enclosed in a Chrysalis. However, the proper use of the terms is that the Chrysalis is the term for the Butterfly or Moth Pupa itself, and Cocoon is a protective silk covering. The fact that few, if any, Butterfly species produce protective silk Cocoons and the majority of Moths do is probably the root of this misinterpretation.

So to summarise the Pupa is a life stage that some insects go through, between the larva and adult stages. A Chrysalis is the name of a Moth or Butterfly (Lepidoptera) pupa. A Cocoon is a protective covering around the Pupae or Chrysalis of some insects. Hope this answers your question “P” and thanks again for taking the time to message me!

Interested in Butterflies? Why not check out my article on how to attract them to your garden!


  1. Cheers for clearing that up for me! That Eric Carle has got a lot to answer for – in The Hungry Caterpillar he says it’s a cocoon when it is clearly a chrysalis…

  2. I think Eric Carle was right!
    He said it built a small house called a cocoon.
    If the a Chrysalis is the name of a Moth or Butterfly pupa and a Cocoon is a protective covering around the Pupae or Chrysalis of some insects, then he was correct..

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