Answer: Thrips can be difficult to control and may have developed resistance to many sprays. Rather than continuing to try to control them on your own, and based on your description of the extent of the problem, I would strongly suggest you consult with your local county extension for assistance. They will be able to advise you exactly what to use and how/when to apply it for maximum results. Here is the link for contact information for the different county offices.
I hope this helps!
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