There are two broad categories of scaled, soft and hard. Cottony maple cushion scale belong to the soft bodied type.

Cottony maple scale over-winters as immature females (nymphs) on twigs and branches. The females mature when the plant resumes growth in the spring. They secrete the white, cottony masses beneath which, they lay 500 or more eggs in late May to early June.

The eggs hatch around the first of July and the young, called crawlers, move away from the females toward the leaves. The settle on the underside of a leaf and insert their threadlike mouth parts into the tissue beneath the major veins.

The males mature in late August and early September, mate with the immature females and die. In late September, just before leaf drop, fertilized nymphs migrate from the leaves to the twigs and branches. Only one generation occurs per year.

Scale insects form a protective covering over themselves for most of the year while they feed on the sap of plants. Since the insects are unable to fully digest the sap, they excrete the excess in the form of a thick, sweet substance called "honeydew." When this material drops on leaves below the insect, a fungus called sooty mold begins to grow . This will turn leaves and stems black but does not hurt the plant. It is merely a sign that insects are active on the plant.

In early June, white, spongy masses begin to appear on the underside of leaves, stems and branches of maple trees. Although it may infest many types of trees, it is most commonly found on silver maple trees.

In severe infestations, leaves may turn yellow and drop prematurely. Sometimes a shiny, sticky coating will be on the leaves also. Twigs and small branches may die back.

One year of heavy scale infestation is unlikely to seriously stress an otherwise healthy tree. Generally, healthy trees should not be treated with chemicals since these will also kill predators and parasites of the scale. These natural enemies eventually bring the problem under control for several years. Eliminating them may make the infestation worse in future years.

 On small trees, pick off female scales that can be easily reached from the ground. Also, keep infested trees adequately watered and fertilized to maintain their strength. If the infestation is severe for several years or the honeydew is causing serious problems beneath the tree, a chemical treatment may be warranted.

 The young scale or "crawlers" hatch in early July. At that point, the adult females stop feeding and the amount of honeydew will begin to decrease for this year. For a few weeks after hatching, the young are vulnerable to sprays of insecticides. Later in the summer, they will form a protective shell and will not be vulnerable.

 An application of a labeled insecticide in early July to early August may help reduce next year's infestation. Dormant oils sprays applied in early spring before the new growth begins on the tree provide excellent control of over-wintering nymphs. They also do not kill predators. Do not use oils sprays on sugar and Japanese maples.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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