We're going to try out our asphyxiation experiment this weekend, but in anticipation of failure I spent some time crushing a bunch of the adult scale feeding on Momma Daisy. I don't want her dying while we're fiddling around with treatments.
I also harvested another heavily infested leaf and stem from her and looked at it under the microscope. I saw a ton of adolescent scale, but couldn't see anyone moving. I then used a razor blade to scrape scales off the leaf and stem onto a piece of white paper and looked at that under the 'scope. Scale barely move and so it took about ten minutes to find anyone that was even wiggling. That tells me that any assessment of success is going to be problematic. The only thing I can think of is to pick a stem and then photograph it identically once a day for a week or so and count the scale bodies and measure their size in something like Photoshop. If the count and sizes don't change, I think we can decide we had success.
I wish I had a baseline of an untreated plant to work with, but there's no plant I hate so much that I wish to infest with scale.