This scary looking black spiny caterpillar (or is it a worm) will eat all of the leaves off of your passionflower vine.  But have no fear, the plant can handle it.  The caterpillar will turn into the gulf fritillary butterfly.  It does not bother the plant until it has finished flowering for the year.  It also will not harm the passion fruit.  So I say let the bug have the leaves.  The passion vine is pretty invasive and you will have less leaves to clean up in the winter.  All creatures great and small.