'Vinegar fly' definitions:

Definition of 'vinegar fly'

From: WordNet
noun
Flies whose larvae feed on pickles and imperfectly sealed preserves

Definition of 'Vinegar fly'

From: GCIDE
  • Vinegar fly \Vin"e*gar fly\ Any of several fruit flies, esp. Drosophila ampelopophila, which breed in imperfectly sealed preserves and in pickles. [Webster 1913 Suppl.]