NJ Pest Guard Blog · Updated October 2026

Drain Fly Control in NJ: Get Rid of Drain Flies for Good

Short answer: drain flies breed in the slime inside drains, so sprays and bleach rarely finish them. Find the breeding drain with the tape test, scrub the slime out, and the flies die off within a week.

First: are they really drain flies?

Drain flies — also called moth flies — are tiny, fuzzy, grayish flies that look like miniature moths and barely fly. They hop near sinks and floor drains. Small, fast flies hovering over fruit are fruit flies, not drain flies, and need a different fix.

Drain flies do not bite or spread disease to people. What they signal is a buildup of organic slime somewhere in your plumbing. We get drain fly calls from across North Jersey, from Paterson to Hackensack, and the cause is almost always the same: a drain that does not get cleaned or used often enough.

Find the breeding drain with the tape test

Spraying adult flies leaves the larvae untouched, so the first real step is finding the source. Cover each suspect drain overnight with clear tape, leaving a small gap. In the morning, the drain with flies stuck to the underside is the breeding site. Check every drain, including the rarely used guest-bathroom sink.

Clean the drain the right way

• Scrub the slime out. Scrub inside the drain opening and as far down the pipe as you can reach with a stiff brush. This removes the eggs and larvae.
• Use an enzyme drain cleaner several nights in a row. It eats the slime on pipe walls instead of running past it like bleach.
• Flush with hot water after each treatment.
• Clean the drain cover, stopper, and overflow opening.
• Fix slow drains. A drain that does not fully empty stays wet, and wet slime is what the larvae need.

Skip the bleach. It runs down the center of the pipe, misses the slime on the walls, and can damage septic bacteria. It may knock the adult flies down for a day, but the larvae survive.

When cleaning is not enough

If flies persist past two weeks of cleaning, there is usually a second breeding site: a cracked pipe behind a wall, a broken wax ring under a toilet, a sump pit, or a floor drain with a failed trap. In Passaic and Clifton apartment buildings, we also see drain flies breeding in a shared line, so the fix has to reach the building's plumbing, not just one unit's drain.

Keep them from coming back

Once the breeding drain is clean, prevention is simple: run rarely used taps and flush rarely used toilets weekly so traps stay full of water, and use an enzyme drain cleaner monthly in problem drains. If a floor drain rarely sees water, pour a bucket down it every couple of weeks — a dry trap lets flies and sewer gas up.

The bottom line

Drain flies are a plumbing-hygiene problem wearing a pest costume. Find the breeding drain, scrub the slime out, and the flies go away — no foggers, no sprays. If you have cleaned twice and they are still there, call us. We handle drain fly jobs across Garfield, Lodi, and the rest of North Jersey.

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