Pest description and crop damage The female scale is approximately 0.05 to 0.1 inch in diameter and white in color with a notable, central yellow spot. The male scale has a more elongated appearance. This insect feeds on the sap within the stem or leaf. Leaves, twigs, branches, and cones may be attacked. Their feeding can reduce the vigor of the foliage supported by that stem. Symptoms of scale feeding include loss of normal color and luster of foliage, no new growth, and yellowing and death of branches. Severe infestations may kill entire plants. The scale excrete large amounts of honeydew, a sweet, sticky material, which may become covered with sooty mold.
Biology and life history The insect overwinters as a mature female, filled with eggs. The crawlers emerge in late spring. There is one generation per year.
Keep plants healthy in order to resist infection better. Remove small infestations by hand, and cut out heavily infested branches.
Apply to control the immature crawler stage, usually in late spring to early summer. Scout for crawlers and gather life history data.
For more information
Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 106).