What are the butterfly and moths used for, can I sell them?

The great thing and sometimes the most frustrating, is every item is useful and needed, but only when a mission, daily task, etc is on your agenda. This of course is one of the main parts of this game, space management. So to answer your question simply; yes technically everything is sellable; especially when your current task does not need moths/butterflies. However they both lead you to new merge item tier trees that cannot be reached without them. So the real question is do you need them right now? I hope this helps.