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Gloomy Scale

ID

ENTO-44NP (ENTO-318NP)

Authors as Published

Eric Day, Manager, Insect Identification Laboratory, Virginia Tech

Plants Attacked: The Gloomy Scale is a major pest of shade trees, particularly in urban situations where the trees grow next to streets and parking lots. Primarily red and silver maple; also: elm, hackberry, and boxelder. This scale is very destructive to forest and shade trees.

Description of Damage: The bark becomes roughened and encrusted with scales. Branches and limbs die back and result in a rapid decline in tree vigor, occasionally resulting in the death of trees. Seriously weakened trees are common in Virginia as a result of scale populations, especially red and silver maples. Identification: The scale cover is circular, dark gray, with a black nipple on dorsum. The underside cover is snowy white. Damaging stage - nymphs and adults. Homoptera: Diaspididae, Melanaspis tenebricosus (Comstock)

Life History: Immatures complete development in the spring. In early- to mid-June eggs are hatching, the newly hatched immatures are called crawlers. These crawlers settle and produce a second brood by late summer to early fall. These immatures overwinter until spring when development is completed. This scale can have two or more generations per year and overwinters as an immature stage.

Control: Spray with dormant oil in late winter. Sprays for crawlers may help, but crawlers emerge over a long period. There is a peak in mid-June, but 2 or 3 sprays at weekly intervals are necessary to obtain only fair control.

Management check list for gloomy scale in urban situations

___ Avoid planting near pavement or sidewalks

___ Avoid excess nitrogen fertilizer, do a soil test before applying any fertilizer

___ Try a pressure washer to dislodge the scales with using pesticides, make sure the water pressure does not damage the bark

___ Apply dormant oil in late winter before bud break

___ Treat in mid-June with a contact insecticide to control the crawler stage

___ Use a soil drench of a systemic insecticide such as dinotefuran or imidacloprid


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Publication Date

April 29, 2019

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