Cottony cushion scale
produced by the scales coat the leaves, blocking the stomata and impeding gas exchange. Sooty moulds grow on the honeydew, blocking the light from the leaves [...] months. After leaving the egg sac, the crawlers settle along the midribs and veins of the leaves. The next two instars migrate to the larger twigs and branches [...] General The cottony cushion scale, Icerya purchasi , is considered to have originated in Australia. It was accidentally introduced to California in about