To convey the meaning, you would likely use a descriptive phrase focusing on the pupa stage of a butterfly's life cycle. For example, you might use something like:
* (Scottish Gaelic): Something like "stàd pupa" (pupa stage) or a more descriptive phrase involving the words for "cocoon" (a related, but not perfectly synonymous term) and "cuileag" (butterfly).
* (Irish Gaelic): Similarly, you could use "céim pupa" (pupa stage) or a phrase incorporating "cóicín" (cocoon) and "feileacán" (butterfly).
Ultimately, the best translation would depend on the context and the intended audience. A native speaker would be best equipped to choose the most appropriate and natural-sounding phrase.