Cottony Maple Leaf Scales About to HatchCottony maple leaf scale, Pulvinaria acericola, is one of several ‘cottony’ scales in the genus Pulvinaria. Cottony camellia scale and cottony maple scale are other similar species. Female scales produce cottony white ovisacs in spring then die. These are pretty easy to find if you look up at the undersides of maple and dogwood leaves. As with all scales the time to use foliar insecticides is when crawlers are active. Cottony maple leaf scale has one generation per year. They overwinter as nymphs on branches. Females mature in spring then migrate to leaves to produce the ovisac. Once crawlers emerge from the ovisac horticultural oil or insecticidal soap can be used to reduce their abundance if the infestation is severe. For a small infestation on an isolated twig just remove the twig.