Wax scales are commonly found on stems and seldom on leaves. The gummy white waxy covering is usually white or yellow, but it may be coated black with sooty mold, a fungus that feeds on the honeydew excreted by the insect. Females lay eggs beneath them in the spring. Flip back the cover to see the yellow or red female and her eggs. Remove them with a toothpick or tweezers.
Insecticides are available to control crawlers and recently settled nymphs.