Hello! I have done research on killing caterpillars. Mugwort JHS works great, however you can use, rosemary, mint, chili peppers, coffee beans and leaves, purslane, castor plant, and marigolds! There's also a book 100 herbs for Jadam pesticides that gives other substitutes.  

Hello,

If you cannot find those herbs there, you can use oleander instead.

Thank you