Scale
There are many kinds of scale insects present in the landscape, but because of their appearance, they're easy to miss. In general, they look like round or oval scabs without legs or wings or a head. Usually several are found in colonies on branches. Like aphids, they secrete honeydew that attracts ants and sooty mold, and their numbers are often kept in check by parasitic wasps or various lady beetles. If scale is a problem, the young crawler stage can be sprayed with a horticultural oil spray.