Size
Small fruit fly and vinegar fly adults are about 1/8 in (3-4
mm) long, including wings.
Characteristics
True fruit flies are in a different group from these Drosophila
species. Adult small fruit flies have antenna with a feathery
bristle; wings with thickened front margins, intersected in two
places. Mature Drosophila melanogaster larvae are about 1/4-3/8
in (7-8 mm) long, eyeless, legless, and tapered from large rounded
rear to the pair of dark mouth hooks at the "head" end.
Color
Adult Drosophila are dull tan to brownish yellow or brownish
black; eyes usually bright red. Larvae are nearly white, except
mouth hooks which are black, and the tips of the abdominal breathing
pores which are yellowish.
Comparison with other species
True fruit flies are in the family Tephritidae, a different
group. Small dung flies have wings with thickened front margins
broken in three places. Humpbacked flies have humpback appearance.
Moth/drain/sewage flies have body and wing veins covered densely
with hairs. Fungus gnats and darkwinged fungus gnats are more
mosquito-like, long legged, slender, antenna without the bristle.
Habitat
Food! Small fruit flies develop on fruit. Vinegar flies develop
in briny or vinegar-like liquids at the top of poorly sealed canned
fruits and vegetables.
Food
Fresh fruits and vegetables, such as bananas, grapes, peaches,
pineapples, tomatoes; fermenting liquids, such as beer, cider,
vinegar, and wine. When fresh materials decay they are less attractive
to these flies, due to bacteria and fungi.
Biology
Drosophila females lay eggs near the surface of fermenting
fruits and vegetables or in poorly sealed jars of these foods.
Eggs take about 30 hours to hatch. Larvae develop in brine or
vinegar of fermenting material. They feed near the surface, mostly
on the yeast, for 5-6 days. They go to drier places to pupate.
Newly emerged adults mate in about 2 days. The life cycle may
be completed within 8-10 days at 85 degrees F (29 degrees C).
Damage
Small fruit flies and vinegar flies are nuisance pests which
also transmit disease. Its short life cycle has made the species,
Drosophila melanogaster, especially useful in the laboratory for
biological research.
Invasion
Vinegar flies and small fruit flies are small enough to go
through ordinary screens.
