Gloomy scale (Melanaspis tenebricosa) is a serious insect pest that affects maple trees in urban Georgia. It can go undetected for years. Affected trees can show branch dieback and canopy thinning after 6–10 years, when the population reaches extremely high densities. A waxy shield covering protects females from predators and insecticide exposure, and usually gives them a convex shape. The armored scale wax covering on the bodies of gloomy scale can be detached using a knife. This is different than soft scales, such as wax scales, which are glued to the females’ bodies. Gloomy scales do not produce honeydew, also unlike soft scales. Female gloomy scales have piercing and sucking mouthparts that look like tubes that are inserted into the parenchyma cells (cells that synthesize and store trees’ organic products) in the epidermal layer of tree bark. Male gloomy scales do not have mouthparts. The black and gray dust that deposits on tree bark makes scale detection even more challenging over time, as they camouflage to the color and texture of the bark. This is especially true for trees planted along right-of-ways and parking lots.
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Published on Oct 23, 2023