Daisy, you do realize that the Bonide granules you recommend are a pesticide? Namely imidacloprid, 0.22%.
Insects do not reproduce fast enough to build up resistance to pesticides in your yard. It doesn't happen. They might come in from somewhere else already resistant, but the chances of them building up resistance in your own garden are microscopic. Acquired pesticide resistance happens in a statistical sense, only in a really measurable way if it's used in thousands or millions of gardens.
I prefer insecticidal soap (I think Daisy and I both use the Safer brand) and I promote its use as a less toxic alternative to neonicotinoid pesticides (eg. imidacloprid) which may also harm beneficial insects. The trick is to hit every single bug when you spray the plant, and repeat every few days until they are gone forever. When soap does not work, I use the same pesticide that Daisy recommends (but in a liquid form that I drench the soil with). Because it's a systemic, it has to go into the plant and then be consumed by the bugs for it to have an effect, which takes time, and does not typically work as a treatment on its own. Plants in crisis might not be able to perform the necessary tasks for the systemic to work.
I find soap solves the problem most of the time, and the 1-2 combination of soap and imidacloprid is a total solution almost all the time.
That said, I agree with Sue that the best move is probably to toss the plant. It's really far gone.
