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Cooperative Extension Service |
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Agricultural
Experiment Station |
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Dale Bumpers College
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Crawford County Home & Garden
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The female’s first order of business is to produce the protective shell in which she will spend the rest of her life. She will then lay up to 100 eggs inside the shell before she dies. This is where the eggs will spend their winter. In the South there can be two generations. The second generation of crawlers will emerge around July.
Because of their protective coating, adult scales are hard to kill. Control is best achieved by timing an insecticide application when the crawlers are present. Sprays that kill the second generation of Pine Needle Scale crawlers are reputed to be more effective. Orthene, diazinon, or horticultural summer oil are recommended. A February spray with dormant oil will also help. A systemic insecticide can also be of help. Always follow the labeled directions. In the forest, natural predators help control this insect.
Another common scale pest is the Euonymus Scale, Unapsis euonymi (Comstock). It is a major pest of euonymus plants in the landscape. Often, the presence of the scale is not noticed until infections are severe (Fig. 2). Infestations resemble a “salt-and-peppery” mildew. Control of Euonymus Scale is similar to Pine Needle Scale. Sprays of Cygon or Orthene when crawlers are present are recommended. Spray horticultural oil in the fall. To check and see if there are crawlers present, hold a plain white piece of paper under a branch and shake the branch vigorously. If there are small orange specks moving about, there are crawlers present. You may need to repeat the spray for good control. It is important to get good spray coverage to control these pests.
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Most fruit trees, woody landscape plants, and even many houseplants can get scale infestations. There are many important scale species, not just Pine Needle and Euonymus scales, but their control is similar. See Figs. 3 and 4.
On houseplants, there is often a sticky substance covering the leaves. This can be the honeydew from soft scales. (aphids can cause this, too.) Upon closer inspection, you may notice small, round scales on the leaves. Often, these have come into your house on a weeping ficus plant (Ficus benjimina). Ficus trees are susceptible to scale and will spread scale on to other houseplants. If there are just a few, you can usually physically remove them. If infestations are heavy, you will need to take them outside and spray them with a labeled pesticide. Don’t bring freshly sprayed plants back indoors until they are dry
In short to control scale insects, kill the crawlers with a pesticide and smother the scales with an oil. It often takes more than one spray to control scales. Use a dormant oil on deciduous trees and shrubs in February or a summer oil when temperatures have cooled down in the early fall.
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Figure 4. San Jose Scale on an Apple. Looks like a small barnacle. Primarily found on plants in the Rose family, especially fruit trees. Sometimes mistaken for a Codling Moth egg, however with the scale, there is usually red or brown surrounding it. |
Some helpful links:
Janet Carson has answered many peoples’ questions about Euonymus Scale.
If you would like to more pictures of try ScaleNet: A Database of the Scale insects of the World
Here is a good informational report from Purdue University in PDF format. Remember that its recommendations are for Indiana.
Here is some information about Cottony Cushion Scale, which produces a striped, fuzzy mass behind it. It is a pest in warmer places than Arkansas (common on citrus), but it is interesting as a very successful case of biological control. A real favorite in entomology classes.
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