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(Lepidosaphes ulmi), an insect of the family Diaspididae of the order Homoptera, a pest of many fruit and timber trees and shrubs.
The oystershell scale is distributed in apple-growing regions. The body is 0.8–1.5 mm long. It is protected above by a shell, measuring about 3 mm in length. In females the shell varies from cinnamon to chestnut brown in coloration and often resembles a comma in shape. In males the shell is sometimes light brown. The eggs, numbering 20 to 90, are deposited in August, mainly on young tree bark. After wintering over under the shell of the female, the larvae hatch and crawl all over the branches, attaching themselves by suction. The larvae feed on the juices of the plant, thus damaging the cambium and the cells of the cambial zone. Control methods are prophylactic and chemical.