What Exactly Are Drain Flies? Here's How To Keep Them From Taking Over Your Kitchen

If you think you just spotted a tiny, fuzzy moth fluttering around your kitchen, think again: You actually may be dealing with drain flies. “These are little filth flies that live in the gelatinous slime that can build up in drain pipes,” says Faith Oi, PhD, entomologist and extension professor at the University of Florida. “You’ll often see them hanging out in areas such as near kitchen or bathroom drains.”

The larvae breed in sludge and a buildup of organic matter, such as food particles, inside your drain, says Oi. But they also can be found in areas where there’s standing water, such as a sewer or septic leak, inside dirty garbage cans or rain barrels, areas where air conditioner condensate lines drain, or even in tree holes, abandoned birds nests, and condensate pans under fridges or air conditioners.

The good news is that drain flies aren’t believed to transmit diseases, and they don’t bite people or pets. However, because they’re breeding in unsanitary places, they’re not something you should ignore and just hope they go away, says Oi. Fortunately, most of the time, getting rid of them is straightforward.

Identifying Drain Flies

Drain flies are fairly easy to identify because they look like tiny, fuzzy moths. “Their appearance is distinctive, and they don’t look like any other pest,” says Oi. The adults are about 1/16-inch long with yellow to brown-black hairy bodies and wings which they hold over their bodies when resting. Adult flies can live for about two weeks, says Oi. Females can lay masses of 10 to 200 eggs, with new adults emerging in a few days.

If you’re not sure if you have drain flies, take a clear container, smear petroleum jelly on it, and turn it upside down over the drain overnight. Drain flies will attempt to fly out and get stuck, says Oi. Try this for a couple of nights if you don’t catch anything the first time.

How To Get Rid Of Drain Flies

Typically, you won’t see drain flies in huge numbers in most homes, says Oi. It’s usually just a few before you catch the problem and deal with it. However, if you do see many of them in an area, consult a plumber or professional pest control company to locate potential leaks and clogged drains.

If you’ve seen just a few of these pests, try these tips from Oi to get rid of drain flies:

• Clean the drain manually with a stiff drain brush or drain snake, says Oi. Move the brush around so it contacts the ridges inside a drain, says Oi. You want to dislodge any sludge and the eggs or larvae developing there.
• Use an enzyme cleaner inside the drain. “You should never put pesticides down the drain, but biological products will dissolve the sludge where drain flies are breeding,” says Oi. Look for enzymatic products that are labeled specifically for drain cleaning, and follow the directions exactly.
• Forget about using home remedies such as essential oils or sonic devices. There’s no scientific evidence these products are effective in dissolving sludge or keeping these tiny pests away, says Oi.
• If you don’t achieve control after you’ve cleaned your drain, you may have broken pipes or moisture problems that need identified. Hire a plumber or pest control company to locate any underlying issues.

How To Prevent Drain Flies

Drains often are a forgotten maintenance chore, says Oi. To keep them clean, use a stiff brush at least quarterly to clean out sludge and food particles. You also may consider using an enzyme cleaner on a regular basis to prevent buildup of the slime where drain flies breed.