Sorry Carol, cross-posted with you and Bill about your pest problem, as I was typing the long story above. Do try going outside with a flashlight and your magnifying glass, to see if you can see the miserable little beastie.
If not, I'd recommend you try the Cap't Jack's spinosad stuff as described above. It's my go-to currently for desperate times. Death to thrips, aphids, spider mites, mealies, white flies, you name it.
