I had some thing like that on several
plants a few years back and thought them to be white flies. I treated with Rotenone (?) to no effect, and then found a bottle of Orthene, which claimed white fly, aphids, mealy bugs, etc as victims and that worked well. Just mix it up in a little hand spray bottle and shot the
plants every couple days for a week and they were gone. Stinky stuff.
Correct me if I am wrong, everybody, but I think white flies are all white and kinda pop off the
plant when disturbed. They seem to love my hostas in mid summer.
I have solved most of my in house winter beastie problems by spraying the soil with rotenone before bringing my
plants in for the winter. I let them sit for a few days and drag in all 40 of them.
Hope this helps.
JoLee