How to Identify and Get Rid of Drain Flies

The term "drain fly" covers many species in the Psychodida family of insects, such as sink flies, filter flies, and sewer gnats. One of the most common drain fly species is Clogmia albipunctata, often called the common drain fly or the moth fly (due to its fuzzy, mothlike appearance). It's about 1/8-inch long.

Drain flies do not cause damage but are a nuisance in large numbers. They gravitate toward rotting, decaying organic material and standing water to lay their eggs. If you remove or clean the decay spot and keep all areas of your home dry and clean, the flies should disappear and stay away.

Read on for tips and tricks to get rid of pesky drain flies the next time they pop up.

How to Identify Drain Flies

Tiny drain flies are often mistaken for fruit flies, which are about the same size—about 1/8 inch. Drain flies look fuzzy, while fruit flies do not. You can also distinguish drain flies from fruit flies based on where they're hovering. Fruit flies circle a fruit basket or decomposing food, while drain flies are found near drains.

What Causes Drain Flies?

Drain flies are attracted to the combination of moisture and decaying organic material. Fixtures and floor drains—especially those not flushed out often—are prime locations for these flies. Mature breeding drain flies are naturally drawn to moist areas where there is a source of decaying organic material for their larvae to feed upon after they hatch from eggs.

5 Ways to Get Rid of Drain Flies

Continuous cleaning, eliminating standing water sources, and removing drain fly breeding grounds are the best ways to get rid of drain flies. Here's more specific information on how to do each:

Clean and Repair Drains

1. Clean the drains, sinks, and drain pipes in and around your home. Wash out drains with a long, stiff brush, then pour boiling water through the drain to remove any remaining sludge.
2. Sterilize the areas. Here's how:

• To sterilize your drains, create a good natural rinse with baking soda and vinegar.
• Mix 1/2 cup salt and 1/2 cup baking soda and pour the mixture into the drain.
• Pour 1 cup of liquid white vinegar into the drain. The vinegar will begin foaming with the baking soda.
• Allow the mixture to work overnight to kill any remaining larvae.
• After 12 hours, pour hot water into the drain to rinse it and any remaining fly larvae away.

1. Try drain gel for stubborn drain issues. Biodegradable drain gels and liquids can also thoroughly clean the pipes, eliminating the breeding ground for drain flies. Avoid using chemical cleaners.
2. Replace leaky pipes and drain traps. If you find any leaky traps or pipes, replace them. Dripping water can provide water and food for flies on the floor of cabinets or in wall cavities.

Clean Indoor Garbage and Recycling Areas

1. Remove lingering organic materials. Clear any organic material from floors and walls around garbage and recycling containers,
2. Use hot, soapy water to clean the containers thoroughly.
3. Dry the containers before putting them back. Clean, dry containers will not lure drain flies.

Clean Floor Drains and Sump Pump Pits

Floor drains often collect standing water in their drain traps, and the stagnant water and sludge in these traps are prime areas for drain flies to lay eggs. Sump pump pits are other popular locations for drain flies to breed.

1. Wash out floor drain traps. Clean floor drains with a stiff brush and hot water, then rinse with a baking soda and vinegar mixture (see above).
2. Drain sump pump pits. Ensure the pump completely drains the sump pits.

Eliminate Standing Water

Any area where moisture or water can grow stagnant is attractive for drain flies, especially if organic material is nearby. Eliminate standing water or perpetually moist areas, such as:

• Wet lint in the laundry area,
• Standing water in the drain pan beneath a refrigerator
• Soggy areas around house plants

Remove Outdoor Sources of Stagnant Water

Wherever possible, eliminate areas where water can puddle and grow stagnant, as these are areas where drain flies will lay eggs. Thoroughly clean and dry out these spots, including:

• Dirty birdbaths
• Rain barrels
• Garbage bins
• Soggy compost bins
• Dog kennels
  

How to Prevent Drain Flies

The key to controlling drain flies is finding and eliminating their water and food sources. You can use simple traps with plastic cups or insect glue boards.

Check the traps regularly. If no flies are detected after several days, move the trap to another suspected spot. If you cannot find a source inside the house, expand your search to the outdoors, looking for any areas with moisture and decaying material.

Make a Plastic Cup Trap

1. Lightly coat the inside of the cup with vegetable oil or petroleum jelly.
2. Invert the cup over a drain where you suspect flies may live.
3. Leave the cup in place for several days, checking it daily.
4. If flies live in the drain, they will begin accumulating on the cup's interior surface.

Try an Insect Glue Board

1. Place an insect glue board upside down on a frame.
2. Leave the board above a drain for several days, checking it daily.
3. Flies exiting the drain will likely stick to the glue board.