This is what it did and is doing. First it got sticky, like it was getting covered with some sort of sugary substance. Then the leaves all began to die. I didn't want to cut it back as it was also covered with butterfly pupa and I wanted to see if they would survive, which they did. After the butterflies emerged I once again contemplated cutting it back but then it started to grow from the tips. Then more butterflies came, laid their eggs and the caterpillars ate all the green leaves so that all you saw was dead plant again. But then, I didn't want to cut it back because there were more pupa, which only a few survived. And now, it is turning green again and the butterflies are arriving to lay more eggs. I haven't been really worried about it totally dying off as it is a category two plant here, so people aren't encouraged to grow it, but I am curious as to what caused the leaves to die. It is an amazing plant and the flowers are most remarkable.