Sorry to hear you lost some plants. I am getting in on this conversation late, but I would back the folks suggesting the ladybugs. For the past two years, my OW plants brought in aphids. Last year, I tried to manually removed them, then tried pesticides and neither worked. I bought a bunch of ladybugs and a netting and over the course of a couple of weeks, the aphids were gone. This year, I noticed the aphids early and purchased ladybugs again. Released all of them (hundreds) and put the netting up. This time, a week later, all aphids and shells were gone. They have not come back. 99% of the ladybugs have perished. I still see one from time to time.
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Thus, I will assume every year I try to OW, I will get aphids and I will kill them with a sea of ladybugs. It works.