So right, Cindy. I used a lot of things - soapy water, oil spray and systemics - to keep spider mites at bay on my brugmansias, and the best thing has been just hosing the plants off a couple of times a week until all the mites are gone. You do have to repeat the treatment a few times, to get all the new hatchlings, but the hosing breaks the life cycle of the mites and shuts them down.
Be sure to hose the under sides of the leaves and the stems as well as the tops of the leaves. Mites love to hide and make webs and lay eggs underneath the leaves and in the axils.
