Scale

This is a serious infestation! If all your holly’s leaves are this thoroughly covered you will probably be better off removing this shrub and starting over. If only a few leaves are like this, we suggest you prune off those leaves and stems and treat the memainder of the shrub with an insecticide. Scale insects are mostly immobile; they suck the nutrients out of the leaves and branches and if untreated, can seriously damage a plant. Many insecticides cannot penetrate the insect’s shell, so you’ll need something specially formulated for scale. We suggest you take a few leaves into a local nursery and explain your problem. They can recommend a horticultural oil or systemic poison formulated for ornamentals. Good luck!