I have been battling scale for about three years. For a year and a half I used Bayer 3in1 which would keep the crotons scale-free for about 2-3 months. They kept coming back so I sprayed the ground for ants as well as the 3in1. They still came back. I learned that the 3in1 was bad for bees so I stopped using it. I sprayed with soap a couple times but basically got fed up. I took a break, or didn't have time, and the scales really took off. They weren't killing the plants so I just left them. After a while a saw some Mealy Bug Destroyers, which eat the scale and later turn into Lady Bugs. I refrained from any spraying and spread them around once or twice. Today, 2-3 months later, my crotons are covered in Lady Bugs and Mealy Bug Destroyers and 95% scale free. Great news!