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NUISANCE FLIES INSIDE THE HOUSE

GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written December 6, 2015

There are two types of insects found in homes that I hate, flies and ants. Flies are my nemesis in the fall, entering the house when the door is open and then bothering me. While these flies look like houseflies, they are probably face flies, a pest of livestock. Adult face flies feed on the moisture around the eyes, noses, and mouth of livestock and reproduce in their manure. Yuck!

A couple of face flies inside the home are a nuisance, not a serious problem. Once cold weather prevails, their chance entrance into the house ceases. However, they can continue to be an annoyance if there is a significant outdoor population that overwinters within outside house walls or in attic voids. This more often happens in rural areas where there is livestock raised nearby.

If the flies do overwinter within the walls, some face flies may continue to appear indoors through the winter months when sunshine warms the house walls. The best management for a face fly problem is excluding them from the home with screening and by caulking any openings to the outdoors.

There are some other types of flies that may become a nuisance in homes. Fruit flies are one of the most common. Fruit flies are brownish in color with bright red eyes. These little flies are usually found flying around overripe or decaying fruit or veggies being stored inside the home and they are also attracted to wine, beer, and sugary drinks.

Fruit flies are easy to control by simply getting rid of overripe produce and storing ripe fruit in the refrigerator when possible. Also, rinse out any empty food and beverage containers being stored indoors for recycling. The liquids in these containers ferment and provide a great place for fruit flies to breed.

Moth flies, also known as drain flies, are often mistaken for fruit flies. A close reveals that they are tiny (1/5 inch long) hairy flies resembling moths. They can breed in the decaying organic matter and slime found in the drains of sinks and tubs, garbage disposals, and dishwasher food traps.

One step in control is to keep organic materials from getting into drains by using drain baskets or filters. Chemical drain cleaners may or may not remove the slime in a drain. If not, you will need to manually remove it using a brush or use a biological drain cleaner that contains enzymes that digest slime and organic debris. Also, clean your garbage disposals and dishwashers as recommended by the manufacturer.

Finally, fungus gnats are another nuisance fly found inside homes. These are minute (1/8 inch long) blackish flies. They breed in decaying plant matter and often arise from houseplant potting mixes that are kept overly moist. Potting mixes that contain undecayed organic materials from compost provide an excellent breeding ground for fungus gnats.

At this time of year holiday plants, such as poinsettias, may be a source of fungus gnats, especially if adequate drainage is not provided. The best bet for controlling the problem is to keep the potting mix of house plants slightly moist, not wet. Also, make sure your plants have good drainage and pots are not “sitting” in excess water.

All these flies can be a nuisance. Aerosol pesticide sprays labeled for indoor use will kill the ones flying about when you spray, but they can pose a health risk to you and your family. The real key to control is determining the type of fly and then using the right control measures to get rid of them.

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