The plant can tolerate some amount of it but consider that, by the time you see those white patches, the eggs have developed and the adults may have left the scene. If you see no movement or if you squish them and nothing comes out, they may be gone already. They can only be detected on the shrub early with a 10x magnifying lens.

Hint: If you need help viewing these small white patches, take a picture of the same leaf today and tomorrow. Then compare both pictures to see if there is movement.

You can apply some Bayer products with Imidacloprid if you want to but I think it would be more effective if you do it starting in May 2012 especially if the pests may have left already.

Thanks, Luis!