A mature female cottony maple scale is 1/8″ long, and has a brown, flat, oval body. Infestations are most easily noticed during the summer when females produce white, cottony egg sacs that resemble pieces of popcorn on twigs. These scales also produce large amounts of liquid waste (honeydew) so leaves may be shiny and sticky and black sooty mold fungus may cover branches and the trunk.
Cottony maple scales commonly infest silver maple but can feed on several species including other maples, boxelder, basswood, birch, elm, and linden. They spend the winter in an immature stage on twigs or branches and complete development in June when the egg sacs appear. Eggs hatch during June and July and crawlers move to the lower surface of leaves where they settle to feed on sap for the rest of the summer. Just before leaf drop, the small insects will move back to twigs and branches to spend the winter. There is one generation each year.
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