Drain flies, also known as moth flies, are small gnat-like bugs that are commonly seen flying around a bathroom sink given that they live in damp, dark spaces where their larva can feed. They hatch in water, much like mosquitos, and live for about two weeks. You might also see them in your tub or basement, or any place where standing water can accumulate. If uninterrupted, the flies can lay up to 300 eggs within 48 hours, and although they don’t carry disease these bugs can be irritating and quickly take over your home. Thankfully, drain flies can be eradicated with just a few household tools. Here are some ways to eliminate the infestation and stop the spread.
Capture them with tape
To stop drain flies at the source, place a piece of tape glue-side down, blocking the drainpipe overnight. In the morning, slowly remove the tape to inspect the number of flies captured. Do this for several nights to assess the infestation. If the tape is covered and the flies continue to multiply in the house, you may need to try something else or call a professional exterminator. But if you notice the numbers shrinking, your household efforts should be enough.
Trap them with vinegar, sugar, and soap
Control the infestation by trapping adult flies with vinegar with a bowl and plastic wrap.
You will need:
A medium-sized bowl
Apple cider vinegar
Pour one-fourth of a cup of apple cider vinegar into the bowl, with one fourth a cup of sugar and five to ten drops of dishwashing liquid. Place the plastic wrap tightly over the bowl and poke small holes into the cellophane. The drain flies are attracted to the sugar and vinegar solution, while the soapy consistency keeps them from escaping.
Flush the pipes with hot water
Hot water breaks up grime and releases larva from the pipes, flushing them down the drain in the process. Heat a kettle of water to boiling (a kettle makes for easy pouring, but a pot works just as well), and pour slowly down the drain once or twice a day for a couple of weeks to kill and remove any larva. Spray soap down the drain to keep new larva from forming—dish soap mixed with warm water has an insecticide effect, killing the bugs instantly and coating the area to prevent future infestations.
This story was originally published in 2011 and was updated on December 11, 2020 with additional information and to meet Lifehacker style guidelines.