Answer: Even the best products will not keep a pest away. Erradication is not possible...management is however. I would suggest products containing B.t. as they are natural and are effective only against caterpillars, and won't harm other creatures. You will need to reapply every 5 days or as needed. Usually a pest, once brought into control, will tend to go away for a while. Just be observant and reapply the B.t. whenever you see catapillars appearing.
A final thought is to consider what the catapillars are going to turn into. Sometimes it is good to sacrifice a few leaves for the butterfly show to follow!
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