To find where drain flies are coming from, use the clear tape test: Dry off your sinks and tubs at night, place a piece of clear tape or a glue trap sticky-side down over the drain opening, and leave it overnight. The flies will get stuck on it as they emerge.
To find exactly where drain flies are coming from, you need to identify which pipes, drains, or moist areas serve as their breeding grounds. Adult flies rarely stray far from their nurseries, which are filled with the decomposing organic slime and stagnant water they feed on.
Vinegar and Dish Soap - Fill a bowl slightly with apple cider vinegar, wine or honey with some dish soap (washing up liquid). Cover the bowl with plastic wrap with punctured holes or leave uncovered. Flies will be attracted to the smell and will get stuck within the liquid.
Drain fly presence indicates moisture or pipe system issues. To deal with drain flies, clean and remove organic buildup from drains, fix leaks or standing water, scrub drain walls, and for major infestations call in a professional service to treat breeding sites and monitor.
To permanently eliminate drain flies, you must destroy the gelatinous biofilm deep inside your pipes where they lay their eggs. Merely killing adult flies will not solve the issue. You need to physically clean the drains and use targeted treatments to prevent future infestations.
Furthermore, there are essential oils that have insect-repellent properties, which can help deter drain flies, including peppermint, eucalyptus, and lavender oils. To use these oils as a deterrent, just dilute a few drops in water and use a spray bottle to wash down the areas that are infested.
Pouring bleach down your drain is not an effective or recommended solution for killing drain flies. Bleach washes through pipes too quickly to penetrate the thick, organic sludge where these flies lay their eggs, meaning the infestation will likely return.
Boil a pot of water and pour it down the drain where you suspect the drain flies are breeding. Pour a 1/2 cup of baking soda down the drain. Slowly pour a 1/2 cup of vinegar down the drain. Cover the drain with a drain plug, and let it sit for at least 5 to 10 minutes.
Where Do Drain Flies Lay Eggs? Drain flies lay eggs in the same areas where they spend time and get their food. Drains with organic debris provide just the right environment for drain fly breeding. Female drain flies will lay up to 200 eggs at a time directly in the organic debris along pipe walls and sink drains.
Adult drain flies live for about 10 to 14 days. However, their entire life cycle—from egg to adult—takes only 1 to 3 weeks. Because females can lay up to 100 eggs at a time, infestations can persist indefinitely if the breeding source in your plumbing is not cleaned.
The folk remedy of hanging a bag of water with pennies inside is based on light refraction and the unique structure of a housefly's eyes. While widely used in outdoor dining areas and porches, scientific evidence supporting its effectiveness is limited.
To find where flies are coming from, you must first identify the type of fly, as different species breed in different environments. Trace them by their food source: Fruit/Drain flies breed indoors on organic decay, while House flies/Blow flies usually find their way in from larger outdoor breeding grounds.
Dryer sheets can temporarily deter flies and other insects due to their strong scents and chemical compounds, but they are not a proven, long-term repellent.
Drain flies are strictly nocturnal and are most active at night. During the day, they rest on walls or ceilings near plumbing fixtures.
To remove the adults, which can live for a few weeks, you can place a small amount of vinegar in a shallow pan, and place this pan in locations where the flies are common. They are attracted to the vinegar and some may get trapped in the liquid, and you can use an aerosol to spray the others that are waiting there.
Identify Insects or Larvae
Any drain flies, small insects, or fruit flies around a toilet or drain may mean buildup in the pipes, attracting flies to lay eggs – which can hatch and turn into small worms. You may also notice larvae in the toilet, which are worm-like critters that breed in blocked drains.
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.
Drain flies aren't necessarily hard to get rid of, but they are stubborn. Because they breed and lay eggs deep within the slimy biofilm lining the inside of drain pipes, simply killing the flying adults or pouring a quick splash of boiling water and bleach down the drain won’t solve the problem.
Drain fly eggs typically hatch into larvae very quickly, taking just 32 to 48 hours. Because a single female can lay up to 100 eggs at once in moist organic matter, infestations can multiply and spread very rapidly.
To kill drain flies, you need to eliminate the organic slime (biofilm) inside your pipes where they lay eggs. The most effective solutions are commercial enzyme/bacteria gels (like InVade Bio Drain Gel or Green Gobbler Drain Gel), which eat through the gunk safely.
They reproduce and lay their eggs in groups of 30 to 100 inside drains. These eggs hatch within 48 hours, so infestation begins very quickly, and they multiply rapidly.
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, eliminating their food sources and their breeding grounds.
Vinegar is the safer, more effective choice for household sink drains. It safely eats away at organic buildup without damaging pipes. Bleach is too harsh, can corrode pipe joints and protective finishes, and does not dissolve hair or soap scum.
Flies don't hear human voices the way we do, but their antennae can detect the sound waves. Rather than using traditional ears, many flies use tiny, feathery hairs on their antennae to sense vibrations caused by airborne sounds. While they physically perceive the noise, they don't understand what you are saying.