Golden Oak Scale – Asterolecanium variolosum
Golden Oak Scale: Appearance, Territory, Damage and Life
Latin name: Asterolecanium variolosum
Appearances: The 1/8-inch-diameter and up to half-an-inch-deep golden oak scale is a pit scale, meaning it grows in the center of a pit in the bark. A female scales the size of a pinhead, round, white, and waxy-fringed, is present in the pit’s center. It is of a gold color. The withdrawal of fluids or the injection of toxins by the scale that prevents that section from expanding as much as the surrounding tissue is assumed to be the origin of the pit.
Host plants: Oak chestnut (Quercus montana), British oak (Quercus robur), Oak Kermes (Quercus coccifera), Oak (Quercus spp.), Oak sassafras (Quercus petraea), White oak (Quercus alba) is the host of choice.
Territory: Shade plants and bushes are frequently attacked by scale insects. In Indiana, there are more than 60 different varieties.
Damage insect caused: Due to feeding, this pit-forming scale may result in twig die-back. It’s possible to see poor growth. The effects of dieback usually become apparent in the summer or fall, and the damaged branches or twigs may continue to have dead leaves on them well into the winter. The spring leaf growth of hosts that have experienced severe infestations of this magnitude has been reported to be delayed. When significant infestations happen repeatedly each year, young trees may be killed by this scale. In the eastern US, it has been noted that the golden oak scale and anthracnose fungus both co-occur on oak, and that this combination is highly stressful to the host plants.
Life cycle and habits: Scales are unable to walk and must spend the majority of their lives feeding on the same portion of a plant. Young scales that hatch beneath females are known as crawlers because they can walk at this point. Small and flattened, crawlers resemble dust on the surface of the plant. Crawling insects that walk or are carried by the wind to surrounding plants or plant components cause scale infestations. An armored scale crawler flattens out and develops a clear wax shell after starting to feed. It remains hidden beneath its waxy covering while it keeps expanding. Insecticides have a hard time penetrating this exoskeleton. From behind their cover, wingless males emerge to mate with covered ladies who lay eggs.