Fruit Fly (Vinegar Fly)

The common fruit fly, Drosophila melanogaster, is likely the most extensively studied insect in scientific history thanks to its short generation time and simple genetics, but outside the laboratory it is simply a small, fast-breeding fly drawn to fermenting sugars. It has spread to nearly every part of the world alongside human food distribution.

Also called the vinegar fly, this species is attracted less to fresh fruit itself and more to the yeast and bacteria that grow on fruit as it begins to ferment, which is why fruit flies so often appear around ripening bananas, wine glasses, and open containers of vinegar.

Because of its remarkably fast life cycle, a fruit fly population can seem to appear suddenly and grow quickly around any available source of fermenting organic material, whether in a kitchen, market, or orchard.

• Tiny body, only 2-4 mm long
• Tan to yellowish-brown coloring
• Bright red compound eyes
• Clear wings held flat over the body
• Faint dark banding visible at the tip of the abdomen in males
• Weak, fluttering flight
• Lookalikes: drain flies are fuzzier with broad, moth-like wings, while fruit flies are smooth-bodied with narrower clear wings and distinctive red eyes

Fruit flies are found nearly worldwide, especially indoors around kitchens, produce markets, wineries, and breweries, and outdoors around orchards, vineyards, and compost piles where fruit is fermenting. They are most abundant during warm weather when fermentation occurs readily.

Adults are strongly attracted to the odor of fermenting or overripe fruit and other sugary, yeasty liquids, feeding primarily on the yeast and microorganisms growing on the decaying material rather than on the fruit's flesh itself. Their extremely short generation time allows populations to expand rapidly wherever a suitable food source persists.

Eggs are laid directly on fermenting fruit or other moist organic matter. Larvae feed on the yeast and microbes present in the rotting material for about four to five days before pupating nearby. Under warm conditions, an adult can emerge roughly eight to ten days after the egg was laid, and many overlapping generations occur throughout the year wherever suitable food is continuously available.