Q: My mother has crepe myrtles on which flying bugs have taken over. She says they are slowly dying and the leaves are oily looking. They also get on the hood of her car and turn it oily.

A: Undoubtedly they are crapemyrtle aphids but I’m going to try to persuade your mother not to control them with insecticides. According to Russell Mizell and Gary Knox at the University of Florida, crapemyrtle aphids and their oily, sugar-filled honeydew serve as food for twenty species of beneficial insects. The abundance of food encourages good insects to remain in her garden. Lady beetles in particular feed on aphids. If your mother didn’t have the crapemyrtles, she might have worse insect problems in her garden. I hope you’ll advise her only to occasionally wash the tree bark, as well as her car, with a water hose. Water dissolves sticky honeydew and prevents it from turning black. No other control is usually warranted.