Thought I would get your attention with that title.

In the past 2 days, I have had 4 BST cats die. I find them hanging from the fennel by one single foot. Their osmeterium are out, the back 1/4th of their body is very skinny, and there is a long looking poop sticking out. I have healthy cats in all different instars on the same plant, and have had several pupate fine. Any thoughts?

I will admit to a first: One of the cats was still alive, so I gently wiped his butt! Got the poop off, but I'm certain he will die anyway :(