Fruit Fly Facts, Identification and Control
Scientific Order: Diptera (all true flies)
Family: Tephritidae or Drosophilidae
Common Fruit fly or Vinegar fly (Drosophila melanogaster)
Size: 3 to 4 mm long (25mm = 1 inch); maggots are 2.5 to 4.5 mm long
Color: Translucent brown or yellow, with red eyes.
Fruit flies and fruit fly larva primarily eat yeast created when fruits, vegetables, and other organic matter begins to ferment or liquify. Overripe bananas and tomatoes, rotten potatoes and onions, and the remains of alcoholic beverages such as beer are the most common breeding grounds for fruit flies.
Fermentation attracts fruit flies, so they’re commonly found around overripe fruits and vegetables. Female fruit flies lay eggs on the surface of food sources, so the hatched larvae have easy access to nutrition.
Fruit flies generally stay near food sources, alternately flying slowly over them and landing to eat. Eggs and larvae remain inside their foodsource or adhere to a surface near their initial food source as they transform into pupae.
The rate of fruit fly development depends largely on environmental temperature. A generation’s cycle from egg to adult can happen in as few as eight days in an 85°F or nine days at 70°F. At 68°F, the cycle may take around 15 days.
Fruit flies breed in and around any decaying, moist substance. Common breeding grounds include wet mops, food particles, rotting organic waste, drains, or puddles.
After reproduction, female fruit flies seek out a stationary, accessible food source. The fruit fly deposits her eggs on the surface of this food source, so larvae have food available immediately upon hatching. A single fruit fly may lay up to 500 eggs.
Fruit fly eggs generally hatch quickly, and maggot-like larvae begin feeding immediately. Larvae continue eating until they are ready to pupae, at which point they leave the food source and stick to a nearby surface to complete their transformation.
Most species considered fruit flies have distinctive red eyes. Drosophila melanogaster, in particular, can be identified by its large, bright red eyes.
Fruit flies are attracted to moisture, which they need to drink and reproduce. Dirty dish cloths, floor mops, moist towelettes, sponges, and dripping or leaking faucets may attract flies.
Signs of Infestation
Obviously, the easiest way to tell if you have a fruit fly infestation is to actually see fruit flies flying around food or crumbs. Check around your garbage and recycling cans for flies as well as any food you keep out in the open.
If you have any unprotected sources of moisture, check them for fruit fly breeding grounds. These are somewhat easier to spot, since several fruit flies will congregate in close proximity.
Look for dirty, rotten, decaying, or moldy food. Dirty or cluttered surfaces may also attract flies.
Dirty food, or food with small marks or bites taken out of it, may be a food source and/or a breeding site for fruit flies.
Treatment and Prevention
Store grains and other yeast-based products in hard plastic storage containers. Bread is not necessarily protected from fruit flies just because it’s in a bag or stored in a bread box.
Keep fruits and vegetables bagged and in the appropriate, temperature-controlled section of your refrigerator. Dispose of overripe or rotten food immediately, and put it in your outdoor can. Use plastic bags for transporting and disposing of garbage.
If you discover an infestation in or around your fruits and vegetables, dispose of all the fruits and vegetables in your home and thoroughly wash and clean the container or area where you kept the infested material.
Wash and dry dishes immediately after use. Do not leave dirty dishes in the sink.
Make sure cleaning and washing materials are properly dried. Don’t leave sponges and washcloths bunched up in the sink. Dry mops and other cleaning implements before putting them away.
Wash out all bottles and cans thoroughly before recycling. Even trace liquid remains of beer or fruit juice can attract breeding fruit flies. Take the recycling out frequently and periodically rinse out your recycling cans.
Don’t leave food out overnight.
After peeling fruits or vegetables, dispose of the peel in the disposal or outside garbage can. Do not throw it away in the indoor garbage can.
Ending a fruit fly infestation requires finding and eliminating every breeding area, which can be difficult.
Cornell University Insect Diagnostic Laboratory fruit fly entry
Penn State College of Agricultural Sciences, Department of Entomology insect fact sheets, fruit fly entry
University of Kentucky College of Agriculture, Food and Environment Insect and Pest Info fruit fly entry
Scientific Encyclopedia Drosophila melanogaster entry
Identification of Flies, a step-by-step guide by the Virginia Tech College of Agriculture and Life Sciences
“How to deal with indoor flies,” by the Cornell University New York State Integrated Pest Management program