Q: I have six passionvines. What can I use to kill the spiked caterpillar that can strip the whole vine in less than a week?
A: The other-side-of-the-coin nature of butterflies is that they all come from caterpillars. And caterpillars are typically described as “a stomach on legs”. So if you admire passionvine, which serves as a host plant for the larvae of the Gulf fritillary butterfly, decisions have to be made. Fortunately, there is an easily available organic caterpillar control. Bacillus thuringiensis (abbreviated as B.t.) is sold in products with names like Dipel or Caterpillar Killer. It is safe for garden use but deadly toward caterpillars of all kinds.