Instead of any kind of bug killer on your bud, dust around the bottom and leaves with diatomaceous earth... that will kill the caterpillars and any other kind of insects and it is non toxic. Just don't inhale it, maybe rinse whatever little is left at harvest before you dry it. I use it to keep my dogs free of fleas and it works on all bugs on my rose bushes.
It's cheap also. You can find food grade.