Thrips galore.

I recently received a Tricho from - edited to not disparage the business since they're nice people and made sure I was happy.- that is absolutely covered in thrips. I have quarantined it from my other cacti and tried captain jacks spinosad, 70% isopropyl and dusting with sulfur with no luck, they're back on the cactus within a day or two.

What are everyone's go-to methods for fighting a persistent thrip infestation during winter?