Indoors, flies may be seen hovering around overripe fruit and vegetables, baked goods containing yeast, garbage cans and beverages such as fruit juices, cider, soft drinks, beer, wine and vinegar. Sometimes a rotten banana, potato, tomato, onion, melon, squash, pineapple or apple, dirty garbage receptacle, unclean sour mop or dishcloth, empty tomato catsup bottle, or drain water in refrigerators or iceboxes can yield a heavy population of these flies. Outdoors, they become numerous during summer and autumn where fruit and vegetables are harvested and then suddenly disappear when cold weather arrives. Some species are attracted to human and animal excrement, also feeding on fruits and uncooked foods, serving as a disease carrier. The head and thorax are tan-colored, while the abdomen is black and gray underneath.
Eggs are pearly white with two to four threadlike tubes seen under magnification.
Larvae have an extended stalk-like breathing tube at the tail end of the body. Eggs hatch in 24 to 30 hours into tiny larvae that feed near the surface of fermenting food masses. Larvae feed principally on the yeast in the fermenting fluids from five to six days and crawl to drier portions of the food or even out of it to pupate. The larva transforms into the pupa in the last larval skin or puparium. The life cycle may be completed in 8 to 15 days depending on the temperature.