Trees, Shrubs, and Vines: Cottonycushion Scales, Mealybugs, and Woolly Aphids

Problem
The undersides of the leaves and stems, branch crotches, or trunk are covered with white, cottony masses. Leaves may be curled, distorted, and yellowing. Knotlike galls may form on the stems or trunk. Sometimes a shiny or sticky substance coats the leaves. A black sooty mold may be growing on the sticky substance. Twigs and branches may die.

Analysis
Cottonycushion scales, mealybugs, and woolly aphids all produce white, waxy secretions that cover their bodies. This visual similarity makes separate identification difficult for the home gardener. Young insects are usually inconspicuous on the host plant. Their bodies range in color from yellowish green to brown, blending in with the leaves or bark. As the insects mature, they exude filaments of white wax, giving them a cottony appearance. Mealybugs and scales generally deposit their eggs in the white, fluffy masses. Damage is caused by the withdrawal of plant sap from the leaves, branches, or trunk. Because the insects are unable to digest fully all the sugar in the plant sap, they excrete the excess in a fluid called honeydew, which often drops onto the leaves or plants below. A sooty mold fungus may develop on the honeydew, causing the leaves and twigs to appear black and dirty.

Solution
Spray with an insecticide containing acephate.