I agree this is a real problem, Sherry. I wish I knew the answer.
On another thread, someone was talking about how a lot of nurseries use the term 'organic' pesticide to mean something that actually kills the caterpillars trying to use a plant as a host.
Seeds are safe, or plants shared from other gardeners whom we know don't use pesticides. I got some milkweed from a wildlife group in a neighboring county and the Monarch cats did great on it. The BST cats also did great on my parsley, which had overwintered from last year. Last year however, the first year I had this particular parsley plant, I found no cats on it, so I suspect it had been pre-sprayed. But this year it was fine. At this point, I'll probably be adding to my pollinator plants more selectively to make sure things are safer for them.