Cornell Extension Bulletin, 371. Description and Life Cycle: The female scale cover is ⅛ inch long, dark brown to gray banded (varies depending on host), and shaped like an elongated oystershell. Recommended Steps to Control Oystershell Scale. Oystershell scale will overwinter their eggs under their protective armour. The new scale larvae are called crawlers. Armored scales usually have several generations a year, while soft scales have a single generation. Adults are small, about 2 – 3 millimeters long and can be gray or brown. Life Cycle—The insects overwinter in eggs beneath the female scale covering. • Description of oystershell scale • Feeding habits • Life cycle • Management/control methods The oystershell scale, Lepidosaphes ulmi, is a common armored scale insect on a variety of plants in the higher elevations of northern Arizona. Hosts—Oystershell scale has been recorded on over 125 species of plants, mostly hardwoods, and is most commonly found on aspen and other poplars, ash, maples, willows, and lilac. They are found mainly on stems, and only occasionally on leaves. Oystershell scale is an armored scale. Revista Fruticola, 7(3):95-100. This is the only time in the life-cycle of scale that the insect moves. The oystershell scale adult armor is light to dark brown and shaped like a tiny oystershell. Each insect lives under a scale or shell made of wax and other material. The oystershell scale Lepidosaphes ulmi (L.) (Homoptera: Diaspididae). Oystershell Scale. Oystershell scale (Lepidoasaphes ulmi) can be a tricky species to control without understanding their life cycle and biology. Griswold GH, 1937. The crawlers (mobile first instars) emerge in the spring after buds have burst. The life cycle of each species of scale can vary depending on the season and species. Oystershell scale overwinters as whitish eggs under the cover of mature females on bark. They can be easily differentiated from other scale insects by the oyster shell shaped scale that covers their bodies. Twig and branch mortality of American Beech infested with oystershell scale. Common insects of the flower garden. They occur in greatest numbers on the lower branches and leaves of the plant. While we have most commonly seen oystershell scale on cotoneasters, other plants such as lilacs, dogwoods, maples, poplars and willows are also vulnerable, so controlling spread is a key factor to maintaining a healthy garden. The eggs hatch Scale overwinters on leaves, needles, stems, or twigs of the infested plant under the covering (shell) it creates. Gonzalez RH, 1986. Life Cycle: The life cycle varies with the host tree species. Understanding the lifecycle of insects is the first step to control. Host plants include ash, dogwood, lilac, maple, and willow. Foliage may appear thin and chlorotic and there may be areas of the crown that lack leaves or where there are scattered clumps of leaves. Oystershell scale found in our area is either the gray race or the brown race. The female scale covers are broadly oystershell-shaped and dark brown. In mid Spring, May or June, the eggs hatch. To control scale insects effectively and to limit damage, Horticultural Oil Insect Spray should be sprayed on the tree in late winter and again before spring bud break begins. The CSU Extension Office says Memorial Day is often the approximate time when eggs hatch in most years. Oystershell scale spends the winter as eggs underneath the mother scale. Groot RC de, 1967. Upon hatching in … Oystershell scale. Evidence: Look for tiny brown to gray oystershell-shaped scales, usually densely packed, on the bark (a, b). Life Cycle. The male scale covers are elongate and white with three longitudinal ridges. Usually when a gardener Issue 4, May 21, 2018. 1). 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