fruit fly

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various small flies of the family Drosophilidae, having larvae that feed on fermenting or decaying plant material, especially the common species Drosophila melanogaster, often used in genetic research.
• noun Any of various flies of the family Tephritidae, having larvae that hatch in plant tissue and are pests of fruit and vegetable crops.
• noun Offensive Slang A woman who enjoys socializing with gay men.

from The Century Dictionary.

• noun A dipterous insect of the family Muscidæ and genus Drosophila, the larvæ of which are found in decaying fruit, preserves, etc. The adult flies are small yellowish species with transparent wings.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun any insect of the Tephritidae family, whose larvae damage plant tissue.
• noun any insect of the Drosophilidae family, whose larvae feed on ripening fruit, especially the species Drosophila melanogaster that is used in genetic research.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of numerous small insects whose larvae feed on fruits