The golden oak scale is one of at least three closely related species that are found on the twigs of oak in the eastern (and western) United States. The scientific name of the golden oak scale, as is the case with many insects, has changed over time. In past literature, it may be found under Asterolecanium variolosum or other variations. In the field, the appearance, life cycle, and host plant preferences of the group of closely related species is so similar that Johnson and Lyon (1991) argue that accurate species identification may not be necessary when making management decisions. The populations of this insect are primarily female, and males are either rare or not described. Circular-shaped females vary in size from 1 to 2 mm. (0.04-0.08 inches) and may be golden, greenish, or brown in color. The golden oak scale may also be known as a pit-making scale, due to the fact that the insects are often found in tiny depressions made in the twig as a result of the feeding of the insects. The bark around this pit may also be slightly swollen. Mature females overwinter and produce living young (crawlers) which are observed in the spring and summer months. Females have been observed to produce young for up to 5 months. Crawlers are not thought to disperse far from the female and often colonize the same current season or 1 year old twigs. Golden oak scales feed using piercing sucking mouthparts to remove host plant fluids. One generation per year is reported.
This pit-making scale may cause twig die-back as a result of feeding. Poor growth may be observed. Dieback is first noticeable in the summer or fall and the affected branches or twigs may retain their dead leaves throughout the winter. Severe infestations of this scale have been observed to delay leaf growth of infested hosts in the spring. Young trees may be killed by this scale when repeated, heavy infestations occur yearly. The golden oak scale has been observed to co-occur with anthracnose fungi on oak in the eastern US, which, when combined, is particularly stressful to host plants.
Current year’s growth and 1-year-old twigs of host plants. Look for pits and circularly shaped scales, especially in areas where dieback may be noticed. If anthracnose damage on white oak is noticed, also monitor for the presence of the golden oak scale.
The parasitic wasps Habrolepis dalmanni and Metaphycus asterolecanii have been reported in golden oak scale populations. In closely related species of scale, H. dalmanni is reported to parasitize up to 20% of their populations. However, the efficacy of these natural enemies at managing Asterodiaspis variolosa populations is not fully understood.
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Chlorpyrifos (N)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Dinotefuran (NL)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (L)
Neem oil (NL)
Pyrethrin + sulfur (NL)
Pyriproxyfen (L)
Spinetoram + sulfoxaflor (N)
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), imidacloprid (soil drench), and neem oil (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
