Eupoecilia ambiguella

Scientific Name Eupoecilia ambiguella Hübner
Synonyms Clysia ambiguella
Common Names English: Grapevine moth; German: Einbindiger Traubenwickler; Spanish: Polilla de la vid; French: Cochylis de la vigne; Italian: Tignola della vite
Description The adult moth has a dark brown band on its yellow-brown wings, which span 12-18 mm (0.47-0.7 inch). The larva is up to 12 mm (0.47 inch) long and brownish-yellow, with bristles over its whole body. The eggs are slightly elliptical and light yellow, measuring 0.8 mm (0.03 inch) in length.

Biology

Damage

Before the vine flowers, the larvae of the first generation appear and slip themselves between two or three flower buds to feed. During this first feeding period, they connect several buds together with silk threads, forming a web, which gradually thickens. They continue their development inside these 'glomerules'.

More severe damage is caused by the second generation of caterpillars that feed on the berries. This promotes infection by gray mould (Botrytis cinerea), which leads to even greater injury than the insect itself. Again, several berries are spun together to form a 'glomerule', so the fungus easily spreads to otherwise undamaged adjacent berries, and large numbers of them may become brown and moldy. Making wine from such grapes is difficult, and its quality will be negatively affected. Table grapes are unmarketable even if only a small proportion of the berries is blemished.

Lifecycle

E. ambiguella and Lobesia botrana are often confused because of their rather similar biology. However, they have slightly different climatic preferences. Lobesia botrana prefers warm and dry conditions and has replaced the other species in many of these areas during the last years. Eupoecilia ambiguella is also found in cooler and humid areas, and has only two generations per year, which are quite easily distinguishable.

The first of these appears April/May, the second in June/July. In both cases, the time during which adults are found lasts about 2-5 weeks. Flight activity, mating and oviposition mainly occur at dusk. The eggs (up to 100 per female) are laid singly on bracts and flower buds, but later on the berries. The larvae hatch after 8-12 days. In the first generation, they eventually pupate inside the 'glomerules': their pupal stage lasts about two weeks. The second generation builds its cocoon under old bark or in other suitable places, for example in the cracks of stake-posts. These overwintering pupae can diapause for months.

Occurrence

Additional Crop Information

Mainly grapevine, otherwise (black- and red-) currant, virginia creeper (Ampelopsis), as well as various wild plants such as blackthorn (Prunus spinosa), yellow bedstraw (Galium), Viburnum lantana, privet (Ligustrum), tin-laurel (Viburnum tinus) and ash (Fraxinus).

Agricultural Importance

The grapevine moth may cause considerable damage. It is considered the most serious insect pest in many wine-producing areas. Eupoecilia ambiguella is found throughout the vine-growing countries of Europe and Asia.

Control

Integrated Crop Management

The occurrence of the particularly destructive second generation can be predicted with considerable accuracy by monitoring daily maximum temperatures.

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