Certified GKH Gardening Expert
They appear to be spider egg sacs. Green Lynx Spiders will, commonly, attach to Lantana. They are likely attracted to the thrips or other insects present. They usually pose no threat to a plant, and can be quite beneficial.
I would continue treatment, as thrips are very difficult to rid from a plant. It will likely require several treatments.
Here is an article that will help you to continue the care of your plants: