About Scale Insects
Scale insects are tiny creatures that look as if they have no legs. They will attach themselves to trees, shrubs and even indoor plants and feed off of the sap. This can cause serious damage to the plant over time, so scale insects are often considered pests. Many scale insects will produce a sticky substance known as honeydew, which is gathered up by ants and wasps. Scale insects are divided into two main types--soft and armored scale insects. Their populations are normally regulated by predators, such as ladybugs.
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Features
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A common feature shared by most scale insects is a long mouth that is tubelike and many times longer than the insect itself. With it, the bug can access the inner sap of a plant and suck it up to nourish itself. Armored scale insects have the ability to form a protective shell over their body. The female will lay her eggs on a plant and then the shell will keep the eggs safe during the winter. in the spring, these eggs will hatch into what are best described as "crawlers." The young will migrate to other plants to feed and secrete their own covering, in the process getting rid of their legs.
Armored
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Depending on where in the United States you live, you will encounter different species of scale insects, of which there are over 8,000. One of the most prolific and widespread is called the San Jose scale and it is a major problem for fruit and shade trees and landscaping shrubs for ornamental purposes. These insects will appear circular and black once they have settled onto a host plant and are no longer than 1/16th of an inch. Oystershell scales are shaped like their namesake and are brown. They are known to feed on over 120 different types of trees and shrubs.
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Types
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Other common armored scale insects include the pine needle scale, euonymus scale, juniper and hemlock scales. The pine needle type is all white and shaped like an oyster's shell. They are parasites of pine and spruce trees, being a particular nuisance to Christmas tree species. This kind of scale can cover the needles of a tree and make it appear white. The euonymus scale is a troublesome insect that attaches to evergreen trees. Juniper scales and hemlock scales prefer to dine on the plants that they are named for.
Soft
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Soft scale insects are, in most cases, bigger then the armored ones, with the look of small turtle shells. They will cover themselves with what appears to be wax and lay their eggs in the spring. The crawlers will look for a suitable place to feed, but in many species they do not lose their legs and are able to move short distances to find a place to spend the colder winter months. The magnolia scale is one of the largest scale insects, attaining 1/2 inch in length. It manufactures plenty of honeydew, as does the Fletcher scale; this substance encourages the growth of molds that further damage the host plant. Another soft scale species is the cottony maple scale, which seeks out maple tree species as well as hickory, elm and alders.
Prevention/Solution
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Other insects such as ladybugs and various species of wasps hold scale insects in check most of the time. Ladybugs will actually live around a plant where scale insects reside. Dormant oils are one extremely effective treatment for scale insects that is applied before the buds of the tree begin to grow when the plant is dormant in the early spring. Other oils can be used in the warmer months but some trees are sensitive to them. Various forms of insecticides can be utilized when the scale insect eggs have hatched into crawlers but the time frame for these being employed is small. Oils kill scale insects in most instances by suffocating them as they serve to block up the air holes through which they breathe.
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Resources
- Photo Credit asgap.org.au
