top of page

Drain Flies - A Common Carolina Nuisance

An all-too-common site in many Carolina homes on these mid-summer days are pesky drain flies. These irritating pests are usually seen (as their name implies) around plumbing fixtures such as your bathrooms. But are drain flies just cumbersome pests that pose no real risk to your health or property, or are there legitimate concerns if you have a drain fly infestation? Nelon-Cole breaks this down for you with some helpful information and (as always) we can easily help rid your home of drain flies for good.


Commonly called drain flies across our region and in the Carolinas, they are also known as moth flies or filter flies, sink flies, or sewer gnats in other parts of the country. Small flies at only 1/6 to 1/5 of an inch long drain fly adults are covered in thick dark hairs and are typically dark gray to black. They hold their single pair of wings high above their body when at rest. Primarily active in the evenings, drain flies are only capable of flying short distances of only a few feet in a single attempt. Drain flies live both on the exterior and interior and can reproduce and survive indefinitely indoors as long as food supplies are plentiful.

drain flies are a common summer sight to Carolina homeowners

Drain flies are problems for homeowners when their population grows excessively in your home’s plumbing and water system. As the name would suggest, they are commonly found in drains as they are attracted to moist, organic areas – this is where they get their nutrients. They are also attracted to decomposing or decaying organic material and compost piles. There are over 4700 species of drain flies, they are mostly harmless but can seem indestructible and can be a major annoyance when found in your own home.


Although they can be quite a nuisance mainly in bathroom areas, drain flies typically pose no physical danger to your health as they do not bite. However, in large quantities, drain flies could become an issue due to their tendency to block parts of plumbing pipes.

Drain flies are attracted to still, stagnant water. If you have noticed these pests around your home, it could signify the presence of drain blockage or leaks. Drain flies enter your home in the same way regular household flies do — they squeeze through windows and drains, fly through opened doors or come up from the basement or crawlspace.

Drain flies breed and lay their eggs near the source of waste they are attracted to, including household drains and sewers. These eggs can hatch after about 48 hours. After the eggs hatch into larvae, they are white and usually found inside the gelatinous part of the build-up. They stay in this membrane until adulthood.

Once the larvae grow into adults, they have an average lifespan of about two to three weeks. However, drain flies reproduce quickly — so once the adults' lives have ended, there will almost certainly be a new batch of larvae ready to take their place.


Indoor drain fly infestations here in the Carolinas typically occur in or around toilets (especially those that are infrequently used), condensate lines for icemakers including those on home refrigerators, and any areas containing drains such as sinks, bathtubs, showers, floor drains and appliance drains. Infestations can however occur in any area where moisture and decaying organic material are present. Adults can only survive a matter of a few days without food unless nectar or a similar liquid substance is available.

lesser-used drains and pipes are a prime breading ground for drain flies


For the Nelon-Cole pest control professional, eliminating a drain fly infestation in the Carolinas starts with identifying the source or sources of the infestation. Drains can be confirmed or eliminated as a breeding source by completely covering the drain with tape and monitoring the tape for the presence of adult flies. Seeing flies stuck to the tape indicates that the drain is a breeding ground for the drain flies. Drains should be regularly cleaned to remove the slime layer in which drain flies breed and feed.

Also, manual cleaning using a stiff long-handled brush will aid in eliminating the organic matter from within the drain. Boiling water can be used as a rinsing agent for this type of cleaning. Bacterial drain treatments are available over-the-counter to biodegrade organic matter, although most common drain and toilet cleaners have also been shown to work well.

Make sure that chemical agents are compatible with your pipes and waste system before application. This is where it is best to consult with your local trusted pest control professionals. The use of ammonia and/or chlorine bleach not only has no benefit it can when mixed with caustic cleaners can form chlorine gas or other toxins that are extremely hazardous upon inhalation. In the case of extremely high infestations, your trained Nelon-Cole pest control technician has scientifically proven and safe treatment options available to them to help successfully remove all traces of Drainfly activity.

Nelon-Cole is ready to rid your home of drain flies and other pests

Carolina homeowners face so many unique challenges when it comes to pest and moisture control issues that are unique to our region. Nelon-Cole wants to be the name you call to defend your home the issues that (when left undiagnosed) can cost you thousands in repair bills. Our award-winning service is the product of the thousands of satisfied clients across the Carolinas who have trusted our services in the past. And we take that trust seriously – we treat your home as we would treat our own. Call Nelon-Cole today and get a FREE consultation on how we can eliminate drain flies in your home – and protect you from further pest and moisture control issues in the Carolinas in the future!


bottom of page