I think Don Schnell had a CPN article on _Exrya_ and it was
mentioned in his book. As I remember the caterpiller feeds
on the inner wall of the pitcher until it weakens and the top
collapses often folding over. _Exrya_ then has a dandy little
protected spot in which to pupate. However I don't know if it
has been found on other plants. It can be a major pest in wild
_Sarracenia_ stands.
Take Care!
Jeff