The grapevine moth causes important losses to vineyard owners: the larvae perforate the grapes and help spread diseases. By doing so, they reduce the yield, but also increase the likeliness of grey mould (Botrytis cinerea) and acid mould (flies). The larvae of the first generation appear in April, while those of the last generation generally appear in August. The butterflies lay their eggs at dusk. The presence of larvae and rotten fruit lowers the quality of the crop; moulds render vine making difficult and may require the crop to be harvested prematurely. Growers faced with an infestation have no choice but to spray their vines with chemicals. As an alternative, bats and insectivorous birds can help control the grapevine moth, but need suitable habitat to be provided.