OK, you've been a big help Bugs, and I'm sorry if I'm being a pest, but what about the acephate? I would just go with the malathion and leave it at that, except I keep finding things that look vaguely like scale on the above mentioned trade plants that formerly had scale. I'm confused, though; the little whitish things on the leaves fall off readily when poked, which I'm told is a sign that they're dead, but keep reappearing, which suggests to me that they're very much alive. This is such a headache! While I'm still asking questions, do you think that being in a greenhouse with 4 mil semi-translucent plastic sheeting will provide enough shade for the malation-treated plants?
Thanks again Bugs, you're a lifesaver.