Life Cycle. The oystershell scale Lepidosaphes ulmi (L.) (Homoptera: Diaspididae). Host plants include ash, dogwood, lilac, maple, and willow. This is the only time in the life-cycle of scale that the insect moves. 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. They are found mainly on stems, and only occasionally on leaves. Appearance and Life Cycle. Griswold GH, 1937. 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. The male has the same color and shape but is considerably smaller. Armored scales usually have several generations a year, while soft scales have a single generation. Upon hatching in … Eggs begin to hatch about May-June. Each insect lives under a scale or shell made of wax and other material. Evidence: Look for tiny brown to gray oystershell-shaped scales, usually densely packed, on the bark (a, b). In mid Spring, May or June, the eggs hatch. The new scale larvae are called crawlers. 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. The CSU Extension Office says Memorial Day is often the approximate time when eggs hatch in most years. The oystershell scale adult armor is light to dark brown and shaped like a tiny oystershell. Issue 4, May 21, 2018. Nymphs develop through two increasingly larger instars. Recommended Steps to Control Oystershell Scale. Common insects of the flower garden. Adults are small, about 2 – 3 millimeters long and can be gray or brown. Oystershell scale overwinters as whitish eggs under the cover of mature females on bark. Oystershell scales overwinter as whitish eggs underneath the female scale cover. These tiny crawlers move about in Oystershell Scale. Oystershell scale found in our area is either the gray race or the brown race. They resemble tiny sea shells with a mottled grey appearance (Fig. The female scale covers are broadly oystershell-shaped and dark brown. Oystershell scale (Lepidoasaphes ulmi) can be a tricky species to control without understanding their life cycle and biology. The life cycle of each species of scale can vary depending on the season and species. Oystershell scale. Usually when a gardener 1). Oystershell scale will overwinter their eggs under their protective armour. Oystershell scale is an armored scale. The crawlers (mobile first instars) emerge in the spring after buds have burst. 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. Cornell Extension Bulletin, 371. The scale overwinters in the … Understanding the lifecycle of insects is the first step to control. • 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. Life cycle. Oystershell scale spends the winter as eggs underneath the mother scale. Scale overwinters on leaves, needles, stems, or twigs of the infested plant under the covering (shell) it creates. Groot RC de, 1967. The scale usually has one generation per year in Northern California and two generations in Southern California. By fall the insects are mature, and each female has up to 100 white eggs under its cover. Adults eventually die, and the eggs pass the winter under the covers. Life Cycle—The insects overwinter in eggs beneath the female scale covering. They occur in greatest numbers on the lower branches and leaves of the plant. 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