Stems and leaves are covered with white, cottony, cushionlike masses or brown, crusty bumps. The cottony masses do not move when touched. The bumps can be scraped or picked off easily. Leaves turn yellow and may drop. A shiny or sticky material may cover the leaves and stems. Sooty mold may develop on the sticky substance.
Isolate infested plants as soon as scales are discovered. Remove as many scales as possible with a cloth or toothbrush dipped in soapy water. Apply a horticultural oil labeled for use indoors, or an insecticidal soap labeled for these pests. After working on outdoor plants, wash up and change clothes before handling orchids.