I've had excellent results using products containing Spinetoram. There is a withholding period, but for outdoor plants I've not come across anything that works better so far, BT works well, but this stuff is even better.Interesting thanks for the responses. My uncle used BT last year I think but his complaint was having to remove the dead caterpillars daily or every other day. I guess I'm trying to find something that would deter the pest completely to avoid that. Thanks again I'll give those products a look!