Drain flies love moisture—stagnant, shallow water—and organic debris, and are most likely to be found near sources of food or bacteria, like sinks and showers. They often favor areas that are not used frequently, like a basement or workshop sink, and are also spotted after a long time away from home, like a vacation.
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.
Use dehumidifiers to control moisture levels in your home to help make it less attractive to these moisture-seeking pests. Make sure to ventilate any crawl spaces.
Your home has high humidity levels.
Like most pests, flies need moisture to survive. If your kitchen or bathrooms are humid or have leaking pipes or drippy faucets, flies will be attracted to them.
They are attracted to the lights inside your home, cool temperature, and availability of food. Your air conditioner can offer easy access to the inside of your home. The bugs most commonly found in your AC system are flies, cockroaches, mosquitoes, ants, and spiders.
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.
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.
Essential oils are sometimes used to keep flies away from infested sections and also to kill them. Lavender, eucalyptus, peppermint, lemongrass, and citronella are just a few of the scents that insects despise (with lavender probably being the most effective).
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.
Do Drain Flies Die in Winter. Most fly species cannot survive outside temperatures below 32°F (0°C). They die unless they find a warm and conducive place to overwinter, such as your home. Drain flies are one of the few insects that can tolerate cold weather conditions.
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.
Life Cycle: Adult females lay 30–100 eggs in sludge around sewage and drainage areas. Eggs hatch in 32–48 hours, larval stage lasts 8–24 days, pupal stage 20–40 hours. Adults live about two weeks.
Bleach will absolutely kill drain flies. However, using bleach comes with certain risks. It's better to try other methods first and use bleach as a last resort.
The best way to get rid of drain flies is by eliminating their breeding grounds. Get rid of organic matter in your drains using DIY homemade solutions or store-bought products.
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.
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 gather, mate, and lay eggs in moisture or standing water. The slimy film that forms in sewers and drains is a favorite breeding spot. Putting off regular cleaning and maintenance of these areas may attract the pests and offer them a place to feed and develop.
There are a few reasons drains flies appear more often in the summer months. This includes expansion of breeding sites, additional food sources, better temperature and humidity and increased water sources. All of these elements create ideal conditions for infestation.
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.
Flies are naturally attracted to the odors created by decay and fermentation because they indicate a potentially good food source for their larvae. Drains can provide ideal harborage and breeding grounds for flies – both large and small.
Moist air might be enough to attract desperate bugs. Install a dehumidifier in your home to remove moisture from the air and keep your relative humidity around the ideal 45 percent. If a whole-home dehumidifier is a bit outside of your budget, you can find portable dehumidifiers for a lot less.
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.
In hot and dry weather, you tend to see more bugs in your house. They need water during those times, more than ever. Many species are more active in warmer weather, as they're out of hibernation and they need food.