We typically recommend Spinosad for looper control as it is highly effective against the adults and young larvae Customers have had great success when plants are treated as needed with the adequate amount of coverage. However, Fenvastar EcoCap is labeled for looper control as well but unfortunately, we have not heard any feedback from customers using Fenvastar Eco Cap on Bougainvillea to control loopers and we are also not aware of any IGR on the market that is labeled for loopers. Be sure to read and follow the label instructions and if we can help further please let us know.