I had picked up my last dill plant, planning to toss it into my compost barrel. Noticed just in time that it had Black Swallowtail caterpillars all over it. Thirteen, on a tiny, nearly-dead plant. They were making quick work of what was left of its vitality. I have plenty of Florence Fennel in the garden, so I stuck a couple long fronds into the pot, alongside the dill. Within seconds, the caterpillars were happily munching on the fennel.