larvae feed on the expanding berries, and feeding sites are visible
as holes. Larvae may web together multiple berries.
Larvae of the
third generation feed inside berries before and after veraison.
Berries may be hollowed out by feeding, and larvae at this time
may contaminate harvested fruit. Damage by grape berry moth after
veraison predisposes berries to infection by Botrytis and sour rots
and can attract fruit flies, wasps and ants.
Pennsylvania, northern Ohio and New York, it is important to scout
in mid- to late July for eggs and larvae. Detecting egg laying and
egg hatch helps accurately time insecticide controls. In high-pressure
vineyards, egg laying may continue over many weeks late in the season.
Infestation is often greater on the border than the interior of
vineyards, particularly near woods or hedgerows.
sampling in the vineyard interior and at the borders (particularly
next to woods) can help to assess berry moth infestation levels
and determine management needs.