From MSU Extension:
Tea scale, Fiorinia theae Green, is a very destructive pest of camellias and hollies. It is a small scale as the adults are about 0.1 inches long and covered with a hard, brown, wax cover. Males have a white, waxy cover while females are gray to brown. Both usually develop on the undersides of leaves. Leaves infested by this scale will develop yellow blotches on their upper surface. Crawlers of this scale appear in the spring in the southern states and timing of controls to eliminate this pest are best when either the bloom of honeysuckle or tulip popular starts. This timing can vary, so pay attention to these events if you need to apply a crawler spray.
Click here to read more on Identification, life cycle and control methods to prevent this destructive insect.