Damage and nuisance

• Leaves

Argyrotaenia ljungiana attacks the vine in spring. At this time, the young larvae feed on the parenchyma in "sheaths" located on the underside of the leaves. They give the affected leaves a "skeletal" appearance which is often not very detrimental. At the end of the generation, they can pass over the inflorescences at the start of fruit set. The damage is then most often confused with that caused by other budworms, including Eudémis.

The next generation (s) of larvae directly attack the young clusters on which they feed on the outer epidermis of the berries. Note that this damage facilitates infections by various opportunistic or pathogenic microorganisms such as the agent of gray rot: Botrytis cinerea .