Tiny nymphs or crawlers hatch and emerge from under their protective covering around mid-June. They're flat, oval and pale green to brown. A wide variety of fruit trees, ornamental shrubs and trees can be affected. Later, they move to older wood, turn brown and settle in for the winter.
Plants show signs of a general decline often before the crawlers or adults are even noticed.
Brown scale leave behind honeydew, a sticky, undigested sap. Eventually, this sap grows a dark, sooty mold on leaves and stems. After their shells have formed, scrub scale off with a brush and soapy water or rubbing alcohol. Remove and destroy heavily infested branches. Horticultural oils sprayed when the plant is dormant suffocate adult scale and eggs.