Re: what is the difference between a cocoon and a crysalis?

Dear ?

The term 'chrysalis' refers specifically to the pupa of insects that show complete metamorphosis - i.e. those in which the juvenile forms are completely dissimilar to the adults. Common examples of these insects are butterflies and moths, whose young are caterpillars, and the flies, which spend their early lives as maggots.

The pupa is enclosed in a protective case, and the word chrysalis is sometimes used to refer to the case itself too.

The coccoon is often used to refer to a protective case for eggs or larvae themselves before they become a pupa or chrysalis. The coccon is thus an earlier stage in the life cycle of these organisms. The word coccon is however, used more generally refer to a protective bag enclosing the eggs or young of many organisms. FOr example, the mucus and protein bag that earthworms excrete to enclose their eggs is also referred to as a 'coccoon'.

Confusingly, the word coccoon is even somtimes used when talking about a chrysalis. Basically, the word chrysalis refers specifically to the pupa of insects, or more often the case the pupa is enclose in. The word coccoon can be used to refer to protective covering for eggs, larvae or pupae more generally. I guess a chrysalis is a particular type of coccoon.

Ruth Allard's previous answer includes links to some sites that have photos of lepidopteran (butterfly and moth) chrysalsi.

Here are some more links:
A photo of a chrysalis, and the butterfly and caterpillar it belongs to
An earthworm coccoon

I hope this answers your question, Yours,

James