Question

Help! Our house is full of fruit flies. It seems to be a chronic problem. I see probably 10 or 12 flies every day, mostly in my kitchen. But there isn’t any fruit sitting around, or even any fresh vegetables. I’ve started keeping everything in the refrigerator. Where could they be coming from?

Answer

The first thing to do is to have the flies identified to make sure that you are dealing with fruit flies. There are several small gnat-size flies that look similar and can be found in homes. A pest control company or your county extension agent should be able to identify the flies; collect a few in a small jar. (HINT: If they’re fruit flies, you can lure them into a jar with a small amount of vinegar, beer, wine, or cider in it.)

Certainly overripe or rotting fruits and vegetables are the number one source of fruit flies in a home, but there are other often overlooked sources. Fruit flies are attracted to fermenting foods and to the yeasty odors of fermentation. That’s why you can find them hovering around your glass of wine or beer. They’re also strongly attracted to vinegar or products containing vinegar, but they will breed successfully in many things. To find where they are breeding, think moist or semi-liquid fermenting goo or gunk. It takes very little gunk to breed fruit flies.

Some Typical Fruit Fly Breeding Sites in a Home

Ripe or rotting fruits or vegetables.

Think about out-of-the-way, forgotten produce like a bin of potatoes under the sink, or even a box of apples in the garage.

Spills of food or liquid.

Look under and behind refrigerators and other appliances or cabinets for food that may have spilled or dropped unseen into a void.

Dirty garbage cans or leaking garbage bags.

Sometimes we just remove the garbage bag from the can and don’t notice the liquid or food spills that have accumulated on the bottom of the container.

Recycling bins.

Look for liquid or food spills on the bottom of your recycling containers. Containers that still have residues of beer, wine, cider, juice, vinegar, or ketchup are all attractive to fruit flies because they give off a yeasty, fermenting odor.

Collections of scummy water.

Check any drip pans under refrigerators, air conditioners, or hot water heaters. Scummy water left in mop buckets or slop sinks can breed fruit flies, as can dirty trash compactors or garbage disposals.

One reason that you can’t find the breeding site for the flies may be that they are not fruit flies at all. Phorid or humpbacked flies look very similar. Phorids are often associated with sewer line breaks and can enter homes from breaks below. Drain or moth flies are another group of tiny flies that are most often associated with scummy drain pipes in sinks or tubs. Fungus gnats can develop in overwatered house plants.

Give Colonial a call. Our technicians can identify the pest flies, find the source, and set up a pest management program to get rid of the offending flies.

Photo credit: mschmidt62 / Foter.com / CC BY-NC-SA