Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. See the North Carolina Agricultural Chemicals Manual for additional insecticide choices. G = greenhouse, N = nursery, L = landscape, I = interiorscape Insecticides labeled for use on ornamental plants to manage soft scale. After leaves open thorough coverage is very difficult. Horticultural oil can be used in winter when trees are without leaves to smother females living on branches. Therefore, systemic provide much longer control than contact insecticides and can kill all feeding stages. Contact insecticides such as pyrethroids may provide less consistent control because they rely on contacting the insect whereas systemics make the plant toxic for the insect to feed on. Foliar applications should target crawlers. Drench applications should be made when eggs are present so the tree can take up the material by the time crawlers become active. Many systemic products are available that can be applied as foliar spray or drench. The following pesticides are effective for control of cottony maple leaf scales. Thus by mid-June, the scale eggs have hatched, the crawlers are exposed on the undersides of leaves and the lady beetles are gone. As the scale eggs hatch, the lady beetles leave, apparently to look for other prey. Immature lady beetles are gray but soon become covered with a thick, cottony covering of wax that makes them look like mealybugs. Adult lady beetles are black with small orange spots. These lady beetles and their larvae feed on the scale eggs in the ovisacs. The most abundant are in a group of small lady beetles in the genus Hyperaspis. Several parasites and predators have been reported for the cottony maple leaf scale. After mating, the females crawl to the leaves to lay eggs. In April, male scales develop into tiny, winged, gnatlike insects which mate with females and then die. In late summer, the scales crawl to the twigs where they feed for the rest of the fall, winter and early spring. Crawlers hatch in late May to early June and feed on the underside of the host leaves, usually along the ribs of the leaf. These egg-laying scales do not feed and they soon die. In April and May, cottony maple leaf scales move to the leaves and lay up to 2,500 eggs in cottony ovisacs on the undersides ( Figure 3 and Figure 4). Twig dieback may occur resulting in sparsely foliated canopy ( Figure 2). Heavily infested trees have small flowers and leaves. Consequently infested trees are stunted and appear scorched and black. They excrete honeydew in which can grow sooty mold. Cottony scales suck sap from leaves (summer) and twigs (fall, winter, early spring) depriving the tree of valuable resources. This scale feeds primarily on maple and dogwood in North Carolina, but it also infests hollies, Andromeda, and gum. It has also been reported from some western states. Cottony maple leaf scale is found throughout the eastern United States and southern Canada.
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