They have returned! After being eaten down to nothing but stems, the passion flower vines have started to grow leaves again, hurray! This time, I am going to give the plants some time to grow and fill out before I let them be butterfly host plants. I picked off the caterpillar I found, then sprayed the leaves with my diluted neem oil mixture (neem, peppermint, Castile soap). Once the plants are well established, then I’ll let up on the neem treatment so the caterpillars have delectable bits to gnaw.