Your kitchen sink and garbage disposal is paradise for drain flies. Their ideal breeding environment is wet, humid, and laced with food waste to feed on. Your first course of action to deal with drain flies is prevention. Don't throw anything down your garbage disposal that will cause build-up.
Drain flies are attracted to small amounts of stagnant water they find in plumbing pipes, sinks or other drainage areas. The flies feed on tiny amounts of bacteria, algae and sewage, so you can find them gathering around kitchen and outdoor sinks, shower and bathtub drains, basement sinks, sewers and septic tanks.
What Causes Drain Flies? Drain flies thrive in stagnant and standing water. Common sources include slow or clogged drains, rarely used and unused toilets, refrigerator drain pans, and standing water created by leaking pipes. They typically enter buildings through basements, windows, and drains.
Boil a medium-size pot of water once or twice per week, and pour down and around the drain. Another easy option uses baking soda: Combine 1/2 cup salt with 1/2 cup baking soda and 1 cup of vinegar, and pour down the drain. Leave overnight, and finish by pouring boiling water down the drain in the morning.
Lavender, eucalyptus, peppermint, lemongrass, and citronella are just a few of the scents that insects despise (with lavender probably being the most effective). Pouring half or an entire cup of such essential oil onto a sponge or rag, then storing it in a small can, helps keep flies at bay.
At night, when they are active, they will congregate towards light sources, like lampshades. They will also feed and breed at night, so you'll see them near food sources or breeding areas. You'll most likely see only a few at a time, as you only rarely see drain flies in large numbers at once.
Adult flies emerge from the breeding sites but may remain nearby. Drain fly control often fails because people don't realize just how resistant the scum and the larvae are to boiling water, bleach, detergent, and even caustic drain cleaners (see How Can I Get Rid of Drain Flies?).
One common remedy for killing drain flies is using household bleach. This is a very useful and cost-effective manner for getting rid of these little pests with an item you already have around the house.
Baking Soda, Boiling Water & Vinegar
The pour half a cup of bicarb soda down the sink as well, followed by a half cup of white vinegar. Let it settle for a few minutes then poor some more boiling water down the drain. Follows these steps every few days until the drain flies have completely disappeared.
They do not bite, sting, or spread diseases, but their decaying bodies may cause allergic reactions. They can also spread bacteria from trash, decaying vegetables and fruits. Drain flies breed in areas that are moist and have a lot of organic remains, including: Sinks.
Drain fly problems can go away on their own—but only if the insects find the environment inhospitable. Those with a minor infestation can simply flush their toilets and run their faucets more frequently to flush out the flies and larvae. Others will have to deep clean their drains and set up traps.
These flies will breed in any moist area that they can find. So if you are facing a drain fly infestation that you cannot figure it out, you may want to look deeper for the cause. The problem could be from a leaking pipe or drain under the sink or even a leaking pipe inside of your walls.
The simplest method to clear out your drain fly issue is to pour boiling water carefully down your drain 1-2 times a day for about a week. This will ensure that the flies do not return overnight if the water did not catch all of the organic material built up inside.
Are they seasonal? Yes. Cold temperatures significantly slow down the biological processes of drain flies. For example, drain fly eggs will hatch more slowly in cold weather, which suggests that they may stay dormant until warmer weather returns.
For effective drain fly treatment, use three products: Forid Drain Gel Cleaner, Gentrol IGR Aerosol, and Pyrid. Forid is an organic microbial grease degrader that breaks down organic material and waste, which will eliminate their food sources and their breeding grounds.
Drain flies may keep coming back due to poorly executed or ignored mechanical cleaning; failure to eliminate all breeding grounds, surviving eggs, and larvae; and failure to conduct regular cleaning and maintenance of the drain pipes. Adult flies can continue to get in from outside, so seal all possible entry points.
Preventative Maintenance
Pouring bleach into the drain when the unit is not operating can leave residual bleach, which will damage the drain pan and line. Using vinegar for preventative maintenance throughout the year will keep your drain clean and clear and will not damage your line.
Maintain Clean Pipes
You can pour boiling water down the drain, use a vinegar-and-baking-soda mixture, or use a store-bought product to kill drain flies. Whatever you choose, use it consistently for the best results.
Many people associate the control of drain flies and bleach. The idea that pouring bleach down the drain gets rid of drain flies is actually a common misconception since doing so rarely helps get rid of these insects.
Drain flies, also known as sewer flies, filter flies, moth flies or sink flies, look similar to the average house fly as they are very small – about an eighth of an inch – and black/brown. They also have a unique vein pattern in their wings, which are covered in tiny hairs. They leave a powdery smudge when crushed.
For the most part, drain flies are not dangerous and not harmful. Having drain flies around your home does not mean your drains are dirty or your kitchen, bathroom or other areas are unclean. They are opportunistic insects and can get inside and find any moist area to lay their eggs and breed.
They reproduce in polluted, shallow water or highly moist organic solids where they feed on decaying organic material in mud, moss or water. In homes, the adult flies are most likely found on the walls of the bathrooms, kitchens, basements and other locations where sewer drains and plumbing fixtures are located.
Drain flies can breed outdoors during the summer with adults entering homes through open doors or windows. Low, wet areas where air conditioning units drain, or clogged guttering are excellent places for these insects to develop.