Life cycle and appearance of European vine moth
The adults have a wingspan of 10-15 mm and creamy white forewings with brown, olive brown, blackish and bluish-grey markings. The hindwings of the female are dark brownish grey and the hindwings of the male are whitish grey.
The eggs are 0.7 x 0.6 mm and yellowish when laid. Later they become greyish opalescent.
The larvae are up to 11 mm long; body greyish green or yellowish green to brown and often translucent. Their head is yellowish brown. The pupae are 5-7 mm long and yellowish brown to dark brown.
Adults appear in late April or early May. The eggs are laid mainly on flower buds and hatch in about a week. The larvae then attack the flower buds and spin silken webs within the developing inflorescences. Pupation occurs in these habitations or a suitable sheltered place nearby. Moths of the next generation appear about a week later. The larvae of the second generation feed on the developing clusters of grapes. Their development is very rapid if the conditions are favourable and a further 1-2 generations may be completed in the same season. The pupae overwinter in a cocoon under bark, in cracks of supporting posts or other shelters.
The larvae destroy flower buds and also cause the death of open flowers and young fruitlets. Later in the season they destroy developing or maturing grapes. Fungal pathogens often invade the damaged tissue, which can lead to further losses. The silken larval habitations and sticky exudations from damaged fruits contaminate grape bunches.