Not sure I get this...
When Syl is on the train and all those things start breaking out of her body leading up to the coccoon thing, did that happen EVERY time she grew a size bigger?
shareNo, that was the only time. The species does that only when they need to make the jump from early adolescence to adulthood. She hadn't done it while in captivity because she needed to gorge on food in order to have the calories stored for such a metamorphsis (a comment is made in passing about this).
Believe me, nothing is trivial. - Eric Draven, The Crow