Red Pierrot - Adult and Caterpillar

After spotting these beautiful butterflies, I learnt that they lay their eggs in the Kalanchoe plant. I tracked down the sole Kalanchoe [in the terrace of my house] and with it the caterpillars feeding on the plant. I searched thoroughly to find an egg, but unfortunately all the eggs have been transformed to caterpillars.
Here, I would like to make a confession, before, I used to kill these caterpillars thinking that they would destroy the plant. I would never dare to do it unless they tend to threat the existence of the only Kalanchoe plant in the neighbourhood. I hope it will be for their own good.