Adults of the first generation in the Central Valley emerge from hibernating pupa in early spring to June. There are five larval stages. The fifth or last larval stage is about 0.6 inch long. This gives leaves a whitish paperlike appearance. When abundant, larvae can defoliate vines by July.
Defoliation can also result in sunburn of the fruit and quality loss.
Defoliation after harvest may weaken vines by affecting food reserves. Thousands of these parasites have been released in the San Joaquin Valley and Amedoria misella is common in many vineyards in the San Joaquin Valley. A granulosis virus, endemic in southern California has been introduced in selected areas with excellent success. This virus is transmitted from one generation to the next by disease-carrying adults that survive a low degree of infection in the larval stage. If the virus disease is not present, the amount of leaf damage will increase with each geneation.