Question: What are the small, white bumps on the branches of my crape myrtle? The trunks then turn black in the winter.

Answer: Those are scale insects that first appeared in the United States in north suburbs of Dallas around 2005. They don’t seem to do major damage to the plants, other than the disfiguring appearance they can give to the trunks. The black discoloration is sooty mold. It grows in the sticky honeydew residue the scales leave behind. Apply a systemic insecticide in spring or early summer, and apply a dormant (horticultural) oil spray in winter. The scales will remain attached even after they have been killed. Press them with a pencil point. If they ooze a red blood-like fluid, they are alive. If not, they are dead. During the growing season, watch for a predatory beneficial lady bug to be feeding on them. It will be shiny black, with two orange-red spots on its wings. If you see them, do not spray. They are very efficient at eliminating the scales.