Lepidosaphes yanagicola is sometimes referred to as the fire bush scale or the yanagicola oystershell scale. This is a different species than the euonymus scale (Unaspis euonymi) which is also found on Euonymus spp. The fire bush scale is an armored scale pest of euonymus as well as other deciduous hosts. It will not be found on evergreen euonymus. On winged euonymus, this armored scale will be found most frequently on twigs between the bark ridges that form the "wings". In heavy infestations, however, the scales may be found near leaf midveins. Fertilized adult females of this species overwinter (approx. 2 mm long and oystershell shaped, brown; bodies beneath the test or armored covering are white). The female test is straight unless the population of scales is large and individuals become crowded. Males have shorter tests and are orange-brown in color. Egg laying at sites in Pennsylvania has been recorded in mid-June and continues for a month. Eggs are white. Immature fire bush scales (crawlers, also white in color) will mature into adults and mate prior to the arrival of frost. All life stages may be observed from late July into August. In Ohio, crawlers may be present by late-June. In Maryland, crawlers are also reported in June. Historically, in Massachusetts, the crawler stage has been reported by mid-to-late July (Robert Childs, personal communication). A single generation has been observed per year. The fire bush scale is reported from: Georgia, Indiana, Maryland, Massachusetts, Missouri, New Jersey, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Virginia, and West Virginia. The fire bush scale is also known from China, Japan, Russia, and South Korea. On Euonymus spp. hosts, the fire bush scale may be confused for L. gloverii (Glover scale), however that species is more commonly known to Citrus spp. A scale taxonomist would be able to differentiate between the species using slide-mounted characteristics viewed under a microscope (Miller and Davidson, 2005).
Heavy infestations of this armored scale can cause premature leaf drop, twig dieback, and susceptibility to winter injury. Scientists classify this insect as an occasional or significant pest, depending upon location. Heavy infestations on Euonymus spp. that cause premature leaf drop and dieback have been observed in Maryland. Heavy infestations and damage by the fire bush scale have also been reported from Ohio nurseries. On winged euonymus, heavy infestations have caused premature leaf drop and twig dieback in nurseries in the northeastern US; but in Pennsylvania, on the same host and in heavy populations, damage is rarely seen.
Inspect plants closely, especially the stems and between the winged, bark ridges. Populations may not be noticed until leaves are off-color or premature leaf drop occurs. Visually monitoring for this armored scale should be done in the fall and dormant season, so that heavily infested stems can be managed by pruning before egg hatch.
If found only on a few branches, the fire bush scale may be destroyed by pruning out and removing the heavily infested branches. If possible, do so before crawler emergence.
Two species of tiny, parasitic wasps are noted as natural enemies of the fire bush scale. These include Alaptus auranti and Alaptus pallidicornis (Herting and Simmonds, 1972).
Abamectin (NL)
Acephate (NL)
Acetamprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Chlorpyrifos (N)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Dinotefuran (NL)
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), acetamprid (injection), azadirachtin (injection, soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), imidacloprid (soil drench), and neem oil (soil drench).
When used in a nursery setting, chlorpyrifos is for quarantine use only.
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.