I've never seen this before. I spotted one of the leaves in a potful of Arisaema fargesii looking droopy and when I moved the petiole it split open and was mushy and full of little black beetles in the bottom third or so. Bleh! The leaf has since died and fallen off and I gave the thing a good spray of an imidacloprid insecticide. Anyone ever have this happen? Were the beetles taking advantage of a damaged plant or did they start the havoc? Are "black jack" beetles the next big pestilence?!?! I'm keeping an eye on the adjacent plants.